Smog checks
08-13-2011, 07:14 PM
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Smog checks
OK, what would cause a 1980s Porsche to fail smog NOx in the morning with good HC, and fail HC in the afternoon with good NOx?
This actually happened to my 944 one day in June, but I'm worried about smog checks in general and I will have to smog my 928 soon enough. I'm still struggling to understand what is going on with these smog tests. Are they random?
-Sean
This actually happened to my 944 one day in June, but I'm worried about smog checks in general and I will have to smog my 928 soon enough. I'm still struggling to understand what is going on with these smog tests. Are they random?
-Sean
08-15-2011, 04:45 AM
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NOx is generally the O2 sensor. High HC is generally a bad Cat. You did not give the numbers so it is a question how far things are out. HC on my 78 is 0 at 2500 RPMs. The 928 is generally very good on HC even with a marginal cat. It might be you have both a failing cat and a marginal O2 sensor.
08-15-2011, 04:54 AM
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The numbers were wildly variant. NOx in the morning was 750 (Fail), but in the afternoon it was 330.
HC in the morning was 65, but in the afternoon was 150 (borderline of Fail).
These tests were conducted at two different smog shops. The car had smogged excellent (no borderline) three months prior, but then saw limited use. I put the problem down to simple lack of use, which is known to cause failing smogs. Between the morning and afternoon tests, I drove the car 40 miles on the freeway. I don't see how driving the car could make the cat perform worse, especially since it was not even properly warmed up for the morning test with good HC figure.
This is all academic at this point since I sold that car, but it is just curiosity and I'm worried about what will happen with the 928, it was borderline failing HC last year.
I've been told that bad HC can be caused by bad O2 sensor giving too much fuel. Running rich leaves incompletely burned fuel, hence soot in the exhaust. I've also been told that high NOx is due to a bad cat, since it is mostly the cat that scrubs the NOx. So, pretty much the opposite of what you're saying, though you're not the only person to say that. It is like there is widespread misunderstanding of these issues. The techs at the two smog shops were completely flummoxed and had no suggestions.
-Sean
HC in the morning was 65, but in the afternoon was 150 (borderline of Fail).
These tests were conducted at two different smog shops. The car had smogged excellent (no borderline) three months prior, but then saw limited use. I put the problem down to simple lack of use, which is known to cause failing smogs. Between the morning and afternoon tests, I drove the car 40 miles on the freeway. I don't see how driving the car could make the cat perform worse, especially since it was not even properly warmed up for the morning test with good HC figure.
This is all academic at this point since I sold that car, but it is just curiosity and I'm worried about what will happen with the 928, it was borderline failing HC last year.
I've been told that bad HC can be caused by bad O2 sensor giving too much fuel. Running rich leaves incompletely burned fuel, hence soot in the exhaust. I've also been told that high NOx is due to a bad cat, since it is mostly the cat that scrubs the NOx. So, pretty much the opposite of what you're saying, though you're not the only person to say that. It is like there is widespread misunderstanding of these issues. The techs at the two smog shops were completely flummoxed and had no suggestions.
-Sean
08-15-2011, 04:34 PM
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** This is a repost of a good entry I found on a Volvo site from 2008. It is by a smog tech in CA explaining all this stuff. You can see how complicated it all is, so there's no way for me to explain it any better than this guy. ***
Well smog failure seems to be a running theme and I always see lots of advice given. Some good, some very misleading but always with good intention of course. Im going to set up a guide here of things to check and what the numbers mean. Hopefully this will give you some idea of where to go to fix your smog issue quickly and efficiently as some of these parts are pricey and often replaced needlessly.
I have been a smog tech for over 5 years and repaired many many cars that haven't passed smog in years, legally anyway. Im also a master technition and work in California, one of the more strict states for smog rules. And always this advise I feel is as accurate as it gets but your situation may differ as im not at your house with a 5 gas analyzer looking at your car!
Any suggestions or addition to this article please let me know so I can add or correct them.
When I say high, I will usually mean towards the upper limit or over the allowed amount
WHen I say low, I will usually mean within 5%-10% of the allowed amount to zero
WHen i say mid, I will usually mean 40-60% of the allowed amount
When I say high O2 I usually mean .3ish to 1% and up
CO is burned fuel
HC is unburned fuel
Nox is a byproduct created by high combustion chamber temps. Creats the brown air asociated with smog
All the numbers can usually pivot on CO
For the below examples we will assume the CAT is operating properly
High CO means the car is running rich. If the CO is high, usually you will have high HC also as there is too much fuel to be burned by the spark.
Low CO mean the car is running lean. Low CO will also cause high HC as the fuel atoms are too far apart. When the spark happens the fuel burns as a chain reaction. If the atoms are too far apart they will not all catch and will not all burn, leading in raw fuel again going out the tail pipe.
You can think if HC and CO as a giant X CO has to be close to the proper volumetric efficiency of the engine to burn as much of the fuel as possible, thereby creating the least amount of HC. As CO crossed the center point going up and becoming richer HC will also increase, same for going the other way back down
High HC alone can usually be caused by the ignition system be worn, plugs wires cap rotor coil, etc.
Nox is created by high combustion chamber temps. If the CO is high, the extra fuel usually cools the combustion chamber and therefore lowers Nox.
If CO is low which indicates lean, Nox will usually be high as the lean mixture heats the combustion chamber.
Ignition timing on all cars except LH 2.4 You can technically 2 deg + and - to work with legally. If your close and trying to just squeak by you can retard to timing 2 degrees. This will lower mainly HC and Nox and a little CO, advancing goes the other way.
High CO, HC, mid to high NOX check the O2, vacuum leaks, ignition timing and CAT
Low CO, mid - high HC and high NOX, check the O2, vacuum leaks and the MAF. If you repair something and CO comes up and it still fails, check the CAT
If you only have high Nox, check the EGR and ignition timing, also check the O2. Its possible the Nox reduction bed in the CAT has failed, but very unlikely just the Nox bed.
Ive found not all smog reports have O2 listed on them. Also ive noticed not all reports have percentages or PPM listed. This is unfortunate cause it makes diagnosis a little easier, hopefully some relation between my examples will help. My examples will all be in percentage and PPM as it is what I am most familiar with. This is important because it can help you determine the condition of the CAT and if you truly have a fuel mixture problem or some kind of outside influence. Low CO readings can be considered good, when in reality they are too low and causing other problems such as high Nox or high HC.
We will again assume the car has a good CAT and no air injection system.
Low CO, high O2 and sometimes mid-high HC and high Nox can indicate a lean mixture.
Normal CO, HC and high Nox, no or very very little O2 can indicate a failed EGR system if the car is equiped
There are many more details but since this is a Volvo forum, im gonna stick to common failures and how to diagnose them. This will be general advise that can probably be used on 200/700/900 series cars mostly equipped with LH 2.2 or 2.4 systems. Some of the advice can also be carried over to K-jet systems.
The common items found on 2/7/9 series cars are a CAT, O2 sensor, MAF, ECT, some cars have EGR, air injection or AIR and TAC (thermostatic air cleaner, thats the heat door in the air cleaner)
The point of the O2 sensor is to regulate the fuel mixture, but mainly to keep the CAT happy, keep the CAT happy by not dumping too much raw fuel or too much O2 in it. This is why we have the switching O2 sensor, lean rich lean rich. Pump O2 in the CAT to basically charge it, and them dump fuel or harmful exhaust gas into it. The O2 is stored in the car to aid in the burning if harmful gases. Without the O2 the cat will not work to its best efficiency. If the CAT is worn and does not have the ability to store the O2 for its burning process, then you will have excessive O2 content in the exhaust. Also high O2 readings on the 5 gas can be falsely be created by large exhaust leaks up stream of the machines probe. As you think its just exhaust leaking out, its actually sucking air in at the exhaust leak which can introduce a false reading of O2.
The O2 sensor creats voltage. 0-1 volt. 0 being lean 1 being rich with .45-.5 volts being optimal and the center point of switching. The EFI system operates in a way so the O2 sensor will fluctuate EVENLY between 0 and 1 volt. A good sensor will move between 0-1v 4-8 ish times every second. The proper operation of this sensor is very important as if the computer does not get the proper feed back for what its doing, it will throw everything off as the sensor is its only eye.
As the sensor ages a few things happen. A heated sensor will usually have slow heater failure. A heated sensor (3-4 wire) should be at operating temp anywhere from 10-20 seconds for a brand new sensor. operating temp is average 600 ish deg F. Aside from heater failure the sensor can become biased rich or lean and can stop working all together and sometimes just get stuck at one voltage. Commonly the sensor will become biased, this goes for heater and non heated (1 wire) By biased I mean the sensor will not fluctuate evenly. It may be biased lean and make voltage from 0-.7v The fuel mixture may very well be over .7v but the sensor is incapable of creating voltage higher due to wear or age. Now, with a center point of .35 due the the biased sensor the computer will start adapting to make the fuel mixture richer to get .7 back up and make the middle point .5 again. This will create a falsely rich mixture.
The other direction a biased rich sensor (which is not as common) may switch from .25-.9v again, this shifts the center point and will force the ECU to create a falsly rich mixture. Also a sensor reading like this may be working properly but due to as unknown fuel source such as a faulty EVAP system can throw the sensor off. But pelase note, this is not a common scenario for out cars!
To properly test the sensor you need a time based oscilloscope. But very few of us have that so realistically heres how to do it. You need a good DVOM with a decent refresh. 2 times per second is prolly fast enough. You connect - to ground and + to the sensor. On a 1-wire thats obvious. On the 3 wire found on later cars it will depend on the brand of sensor you have. But since out cars have a 2 wire connector for the heater and a seperate 1 wire for the sensor, this is the one you want. Pull teh black cover off and leave the sensor connected, use an alligator clip to connect your meter. The car must be at operating temperature and has to be running for up to a full minute at operating temp to be sure the computer went into closed loop and is using sensor feedback. You want to see the meter read voltage between .1 and .2 volts on the lean side and .8-.9 on the rich side. The sensor will switch faster at higher RPMS. Start at 2,000-3,000 and watch the meter, try to figure the low and high point as the meter is changing. Your goal is the see it pretty even between high and low. Like i said if its .1-.7 its biased lean and could make the mixture falsely rich. .25-.7 isn't great, but its not bad as its closer the center point.
You also want to check max and min voltage the sensor will produce. A few ways to do it. One put the meter in the window so you can see it from the drivers seat. Rev the engine hard, ALL the way to WOT but DO NOT LET IT REV OUT! only let it rev to 2,500 or 3,500 RPMS! and do it a bunch in a row, kind like your pumping the gas on a carbed car before starting, you wanna force a rich mixture. Note how high the voltage goes. Another way is pull a vacuum line and spray carb cleaner slowly into the intake to create a rich mixture. But don't stall it. It should go to a high of .8v or .9 or the full 1v.
Then check the lean side, gun it to 3500-4500 rpms and remove your foot from the accelerator quickly to slam shut the throttle. The injectors will turn off untill its reached 1500 ish RPMS. the voltage should drop to 0v or very close to it.
All of the above steps should help you determine how far off the sensor is or if its even your problem. If you failed by a lot then your looking for something pretty obvious in the readings. If you off by a little, then it may not be so obvious. REMEMBER A BAD COMPONENT CONTROLLING THE ECU CAN EFFECT THE O2 READINGS. If you have a vacuum leak, the sensor WILL be biased lean, or may not switch at idle, and may switch at 2,000 RPMS!
MAF diagnosis is not easy and expensive. If you have no vacuum leaks, the engine is timed properly, the O2 is good, CAT and EGR are good and all other components are working properly, I have seen a worn or dirty MAF cause a lean mixture and cause a NOX failure. Because the MAF is dirty it cannot properly meter the air going into the engine, and therefore throws the fuel mixture off, normally making it lean. You may not see excessive O2 in the exhaust, but you will see a low CO reading!
The CAT should be the last part on your list to replace. The CAT should be a 3 way cat which will take care of HC, CO and Nox. Assuming again you have no vacuum leaks, the engine is timed properly, the O2 is good, EGR are good and all other components are working properly, the CAT can be the culprit. For a failed cat you may see higher than average CO, HC and Nox. You may see mid-high CO normal Nox and mid HC and high O2. High O2 and high CO can indicate a CAT that can no longer store O2 and therefore cannot burn the HC and CO. This is an indicator of a failed CAT. Remember exhaust leaks can also cause false O2.
Air injection system can also cause high O2, but I am not familiar with the air injection systems on 900 series Volvos. I assume they are for warmup only and should be shut off when warmed up, an air injection system pumping air into the exhaust manifold where it can throw off the sensor will create a falsely rich mixture because of flooding the O2 with oxygen.
ECT's rarely go bad and when they do they make a pretty drastic drivability issue.
The TAC should be closed when the engine is warmed. Im not sure what this will effect directly then premature failure of the MAF, just amek sure its closed when the engine is warm.
Some of out cars have EGR. EGR LOWERS Nox ONLY!!! To check the EGR system get your vacuum pump and connect it to the EGR valve. Engine running, if you open the valve with the vacuum pump it should start to stumble and possible stall. This means the valve and passages are clean. If it doesn't stall or stumble and the valve holds vacuum, the passages are clogged and will need to be cleaned. If it doesn't hold vacuum, the valve is bad. The easiest way to test the entire system is too tee your vacuum gauge into the line to the valve and engine warmed up drive the car at a steady speed and steady throttle, make sure vacuum comes on and stays on till you remove your foot from the accelerator, or accelerate hard.
Learning how everything works and what causes what takes a lot or experience. I hope this will help you to understand a little more about how the components work and how to repair and adjust things to get the car fixed faster and cheaper. Again, much if this is general info and can be used on many cars. Your situation may differ, take this advice at your leisure.
Mark
Well smog failure seems to be a running theme and I always see lots of advice given. Some good, some very misleading but always with good intention of course. Im going to set up a guide here of things to check and what the numbers mean. Hopefully this will give you some idea of where to go to fix your smog issue quickly and efficiently as some of these parts are pricey and often replaced needlessly.
I have been a smog tech for over 5 years and repaired many many cars that haven't passed smog in years, legally anyway. Im also a master technition and work in California, one of the more strict states for smog rules. And always this advise I feel is as accurate as it gets but your situation may differ as im not at your house with a 5 gas analyzer looking at your car!
Any suggestions or addition to this article please let me know so I can add or correct them.
When I say high, I will usually mean towards the upper limit or over the allowed amount
WHen I say low, I will usually mean within 5%-10% of the allowed amount to zero
WHen i say mid, I will usually mean 40-60% of the allowed amount
When I say high O2 I usually mean .3ish to 1% and up
CO is burned fuel
HC is unburned fuel
Nox is a byproduct created by high combustion chamber temps. Creats the brown air asociated with smog
All the numbers can usually pivot on CO
For the below examples we will assume the CAT is operating properly
High CO means the car is running rich. If the CO is high, usually you will have high HC also as there is too much fuel to be burned by the spark.
Low CO mean the car is running lean. Low CO will also cause high HC as the fuel atoms are too far apart. When the spark happens the fuel burns as a chain reaction. If the atoms are too far apart they will not all catch and will not all burn, leading in raw fuel again going out the tail pipe.
You can think if HC and CO as a giant X CO has to be close to the proper volumetric efficiency of the engine to burn as much of the fuel as possible, thereby creating the least amount of HC. As CO crossed the center point going up and becoming richer HC will also increase, same for going the other way back down
High HC alone can usually be caused by the ignition system be worn, plugs wires cap rotor coil, etc.
Nox is created by high combustion chamber temps. If the CO is high, the extra fuel usually cools the combustion chamber and therefore lowers Nox.
If CO is low which indicates lean, Nox will usually be high as the lean mixture heats the combustion chamber.
Ignition timing on all cars except LH 2.4 You can technically 2 deg + and - to work with legally. If your close and trying to just squeak by you can retard to timing 2 degrees. This will lower mainly HC and Nox and a little CO, advancing goes the other way.
High CO, HC, mid to high NOX check the O2, vacuum leaks, ignition timing and CAT
Low CO, mid - high HC and high NOX, check the O2, vacuum leaks and the MAF. If you repair something and CO comes up and it still fails, check the CAT
If you only have high Nox, check the EGR and ignition timing, also check the O2. Its possible the Nox reduction bed in the CAT has failed, but very unlikely just the Nox bed.
Ive found not all smog reports have O2 listed on them. Also ive noticed not all reports have percentages or PPM listed. This is unfortunate cause it makes diagnosis a little easier, hopefully some relation between my examples will help. My examples will all be in percentage and PPM as it is what I am most familiar with. This is important because it can help you determine the condition of the CAT and if you truly have a fuel mixture problem or some kind of outside influence. Low CO readings can be considered good, when in reality they are too low and causing other problems such as high Nox or high HC.
We will again assume the car has a good CAT and no air injection system.
Low CO, high O2 and sometimes mid-high HC and high Nox can indicate a lean mixture.
Normal CO, HC and high Nox, no or very very little O2 can indicate a failed EGR system if the car is equiped
There are many more details but since this is a Volvo forum, im gonna stick to common failures and how to diagnose them. This will be general advise that can probably be used on 200/700/900 series cars mostly equipped with LH 2.2 or 2.4 systems. Some of the advice can also be carried over to K-jet systems.
The common items found on 2/7/9 series cars are a CAT, O2 sensor, MAF, ECT, some cars have EGR, air injection or AIR and TAC (thermostatic air cleaner, thats the heat door in the air cleaner)
The point of the O2 sensor is to regulate the fuel mixture, but mainly to keep the CAT happy, keep the CAT happy by not dumping too much raw fuel or too much O2 in it. This is why we have the switching O2 sensor, lean rich lean rich. Pump O2 in the CAT to basically charge it, and them dump fuel or harmful exhaust gas into it. The O2 is stored in the car to aid in the burning if harmful gases. Without the O2 the cat will not work to its best efficiency. If the CAT is worn and does not have the ability to store the O2 for its burning process, then you will have excessive O2 content in the exhaust. Also high O2 readings on the 5 gas can be falsely be created by large exhaust leaks up stream of the machines probe. As you think its just exhaust leaking out, its actually sucking air in at the exhaust leak which can introduce a false reading of O2.
The O2 sensor creats voltage. 0-1 volt. 0 being lean 1 being rich with .45-.5 volts being optimal and the center point of switching. The EFI system operates in a way so the O2 sensor will fluctuate EVENLY between 0 and 1 volt. A good sensor will move between 0-1v 4-8 ish times every second. The proper operation of this sensor is very important as if the computer does not get the proper feed back for what its doing, it will throw everything off as the sensor is its only eye.
As the sensor ages a few things happen. A heated sensor will usually have slow heater failure. A heated sensor (3-4 wire) should be at operating temp anywhere from 10-20 seconds for a brand new sensor. operating temp is average 600 ish deg F. Aside from heater failure the sensor can become biased rich or lean and can stop working all together and sometimes just get stuck at one voltage. Commonly the sensor will become biased, this goes for heater and non heated (1 wire) By biased I mean the sensor will not fluctuate evenly. It may be biased lean and make voltage from 0-.7v The fuel mixture may very well be over .7v but the sensor is incapable of creating voltage higher due to wear or age. Now, with a center point of .35 due the the biased sensor the computer will start adapting to make the fuel mixture richer to get .7 back up and make the middle point .5 again. This will create a falsely rich mixture.
The other direction a biased rich sensor (which is not as common) may switch from .25-.9v again, this shifts the center point and will force the ECU to create a falsly rich mixture. Also a sensor reading like this may be working properly but due to as unknown fuel source such as a faulty EVAP system can throw the sensor off. But pelase note, this is not a common scenario for out cars!
To properly test the sensor you need a time based oscilloscope. But very few of us have that so realistically heres how to do it. You need a good DVOM with a decent refresh. 2 times per second is prolly fast enough. You connect - to ground and + to the sensor. On a 1-wire thats obvious. On the 3 wire found on later cars it will depend on the brand of sensor you have. But since out cars have a 2 wire connector for the heater and a seperate 1 wire for the sensor, this is the one you want. Pull teh black cover off and leave the sensor connected, use an alligator clip to connect your meter. The car must be at operating temperature and has to be running for up to a full minute at operating temp to be sure the computer went into closed loop and is using sensor feedback. You want to see the meter read voltage between .1 and .2 volts on the lean side and .8-.9 on the rich side. The sensor will switch faster at higher RPMS. Start at 2,000-3,000 and watch the meter, try to figure the low and high point as the meter is changing. Your goal is the see it pretty even between high and low. Like i said if its .1-.7 its biased lean and could make the mixture falsely rich. .25-.7 isn't great, but its not bad as its closer the center point.
You also want to check max and min voltage the sensor will produce. A few ways to do it. One put the meter in the window so you can see it from the drivers seat. Rev the engine hard, ALL the way to WOT but DO NOT LET IT REV OUT! only let it rev to 2,500 or 3,500 RPMS! and do it a bunch in a row, kind like your pumping the gas on a carbed car before starting, you wanna force a rich mixture. Note how high the voltage goes. Another way is pull a vacuum line and spray carb cleaner slowly into the intake to create a rich mixture. But don't stall it. It should go to a high of .8v or .9 or the full 1v.
Then check the lean side, gun it to 3500-4500 rpms and remove your foot from the accelerator quickly to slam shut the throttle. The injectors will turn off untill its reached 1500 ish RPMS. the voltage should drop to 0v or very close to it.
All of the above steps should help you determine how far off the sensor is or if its even your problem. If you failed by a lot then your looking for something pretty obvious in the readings. If you off by a little, then it may not be so obvious. REMEMBER A BAD COMPONENT CONTROLLING THE ECU CAN EFFECT THE O2 READINGS. If you have a vacuum leak, the sensor WILL be biased lean, or may not switch at idle, and may switch at 2,000 RPMS!
MAF diagnosis is not easy and expensive. If you have no vacuum leaks, the engine is timed properly, the O2 is good, CAT and EGR are good and all other components are working properly, I have seen a worn or dirty MAF cause a lean mixture and cause a NOX failure. Because the MAF is dirty it cannot properly meter the air going into the engine, and therefore throws the fuel mixture off, normally making it lean. You may not see excessive O2 in the exhaust, but you will see a low CO reading!
The CAT should be the last part on your list to replace. The CAT should be a 3 way cat which will take care of HC, CO and Nox. Assuming again you have no vacuum leaks, the engine is timed properly, the O2 is good, EGR are good and all other components are working properly, the CAT can be the culprit. For a failed cat you may see higher than average CO, HC and Nox. You may see mid-high CO normal Nox and mid HC and high O2. High O2 and high CO can indicate a CAT that can no longer store O2 and therefore cannot burn the HC and CO. This is an indicator of a failed CAT. Remember exhaust leaks can also cause false O2.
Air injection system can also cause high O2, but I am not familiar with the air injection systems on 900 series Volvos. I assume they are for warmup only and should be shut off when warmed up, an air injection system pumping air into the exhaust manifold where it can throw off the sensor will create a falsely rich mixture because of flooding the O2 with oxygen.
ECT's rarely go bad and when they do they make a pretty drastic drivability issue.
The TAC should be closed when the engine is warmed. Im not sure what this will effect directly then premature failure of the MAF, just amek sure its closed when the engine is warm.
Some of out cars have EGR. EGR LOWERS Nox ONLY!!! To check the EGR system get your vacuum pump and connect it to the EGR valve. Engine running, if you open the valve with the vacuum pump it should start to stumble and possible stall. This means the valve and passages are clean. If it doesn't stall or stumble and the valve holds vacuum, the passages are clogged and will need to be cleaned. If it doesn't hold vacuum, the valve is bad. The easiest way to test the entire system is too tee your vacuum gauge into the line to the valve and engine warmed up drive the car at a steady speed and steady throttle, make sure vacuum comes on and stays on till you remove your foot from the accelerator, or accelerate hard.
Learning how everything works and what causes what takes a lot or experience. I hope this will help you to understand a little more about how the components work and how to repair and adjust things to get the car fixed faster and cheaper. Again, much if this is general info and can be used on many cars. Your situation may differ, take this advice at your leisure.
Mark
08-15-2011, 06:33 PM
#5
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08-15-2011, 08:31 PM
#6
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Well, local smog techs always advise to drive a car 50 miles before a smog check if it is not regularly used. Lack of use is a documented cause of failing smog, but the exact reason for it probably varies from car to car.
-Sean
-Sean
08-15-2011, 08:38 PM
#7
Nordschleife Master
I would guess at flaky injectors, a few working but maybe bad patterns and out of spec flow rates. The 928 fires all the injectors at the same time and for the same duration, so if they flow different amounts some cylinders will be lean, and some rich. The catalytic converters should catch most of it, but beyond some range it will fail smog.
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08-15-2011, 10:05 PM
#8
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Sean,,
All it takes is one lean cylinder to have a slight miss and fail on high HC. CO will be OK, since that's only the product of combustion and doesn't change with a miss. A working oxy sensor will normalize on a good CO number, and can easily leave one or more cylinders lean enough to miss with just partial injector blockage. NOx happens with any lean cylinder that's not lean enough to fail. Again, any partial injector obstruction can be enough to fail on NOx.
Several locals have had excellent results using the BG intake and injector cleaning system. The intake cleaning flushes the oil slick out of the belly of intake where blowby gathers. The problem has been discussed extensively. The injector cleaning part will help with partially plugged or fouled injectors.
After all that.... I tried the BG system at home, and it seemed to help some. I wasn't having a noticeable problem with the way the car was running, but it had a history of barely passing on NOx. So I gathered all the tools and chems, and took the car for a smog check to get a baseline number. And it passed. So I ran the stuff through anyway for grins, and it seemed to run a little better. No quantitative data though. Fast-forward a year-plus. Intake is off, and new Ford injectors go in as part of the refresh. No torn hoses, leaks, failures of anything found, just a couple days of fun for the cosmetics. But the new injectors... Car is very noticeably smoother. VERY noticeably smoother. I buy good gas, run a bottle or two of Techron through it every year. Yet new injectors at 100k helped a lot in the smoothness. So smog is due next month, and we'll get to see the real numbers. I'll be disappointed if it's at all NOx dirty.
The injectors came from BlueOval, the correct O-rings for them came from Roger. I think Roger now has the whole package available competitively. The most work seemed to be getting the electrical connectors off the injectors. Rest of the injector part R&R was relatively easy. Rob did the hard part of the connector removal.
All it takes is one lean cylinder to have a slight miss and fail on high HC. CO will be OK, since that's only the product of combustion and doesn't change with a miss. A working oxy sensor will normalize on a good CO number, and can easily leave one or more cylinders lean enough to miss with just partial injector blockage. NOx happens with any lean cylinder that's not lean enough to fail. Again, any partial injector obstruction can be enough to fail on NOx.
Several locals have had excellent results using the BG intake and injector cleaning system. The intake cleaning flushes the oil slick out of the belly of intake where blowby gathers. The problem has been discussed extensively. The injector cleaning part will help with partially plugged or fouled injectors.
After all that.... I tried the BG system at home, and it seemed to help some. I wasn't having a noticeable problem with the way the car was running, but it had a history of barely passing on NOx. So I gathered all the tools and chems, and took the car for a smog check to get a baseline number. And it passed. So I ran the stuff through anyway for grins, and it seemed to run a little better. No quantitative data though. Fast-forward a year-plus. Intake is off, and new Ford injectors go in as part of the refresh. No torn hoses, leaks, failures of anything found, just a couple days of fun for the cosmetics. But the new injectors... Car is very noticeably smoother. VERY noticeably smoother. I buy good gas, run a bottle or two of Techron through it every year. Yet new injectors at 100k helped a lot in the smoothness. So smog is due next month, and we'll get to see the real numbers. I'll be disappointed if it's at all NOx dirty.
The injectors came from BlueOval, the correct O-rings for them came from Roger. I think Roger now has the whole package available competitively. The most work seemed to be getting the electrical connectors off the injectors. Rest of the injector part R&R was relatively easy. Rob did the hard part of the connector removal.
Last edited by dr bob; 08-16-2011 at 07:55 AM.
08-15-2011, 11:22 PM
#9
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OK yeah, smoothness is a bit of an issue with my car. It runs great in general, but the idle is, well, sort of not smooth. We won't say *rough* because that would mean a real problem. I bet that new injectors would improve this condition greatly.
-Sean
-Sean
08-16-2011, 07:58 AM
#10
Chronic Tool Dropper
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There are places that will clean the originals, but the cost for new (~$200/set on sale at the time) made the choice easy. I have a set of "good" original injectors in the spares box, and may build a test/clean setup to make them closer to new. One of these days when I am home and have too much spare time. 
08-17-2011, 12:32 AM
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Chronic Tool Dropper
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Better if we can clean the ones you have. The originals for my car will stay with the car. Big box of spares/parts removed/changed goes with it. I've suffered through a few interesting cars where too many original pieces had been replaced with cheap non-original just to save a few bucks. Makes it tough to return to original collectible status at a later date. Anyway, I want to flush the varnish out of he ones I have, then get them lubricated so they will store OK without seizing.
08-17-2011, 01:59 AM
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Under the Lift
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The injectors came from BlueOval, the correct O-rings for them came from Roger. I think Roger now has the whole package available competitively.
I can no longer find new 19 lb Ford injectors for a reasonable price, if at all. Blue Oval doesn't appear to have them, although they have 24 lb for a very good price. The 19s seem to have disappeared. Did you get them a while ago?
08-17-2011, 11:51 PM
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Chronic Tool Dropper
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Yeah, a couple years ago now. Somebody here posted that they were on sale, so I grabbed a set knowing it was just a matter of time for the intake refresh.
I'm surprised that they aren't available any more at all. Other places must have them.
I have the cannister setup for pushing cleaner through injectors still in the car, and can probably adapt that to push through individual nozzles out of the car and into a jar. How many times can I recycle the cleaner?
I'm surprised that they aren't available any more at all. Other places must have them.
I have the cannister setup for pushing cleaner through injectors still in the car, and can probably adapt that to push through individual nozzles out of the car and into a jar. How many times can I recycle the cleaner?
