Running rich, just how much smoke?
10-10-2006, 10:09 PM
#1
Burning Brakes
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Running rich, just how much smoke?
I've got a 1988 S4 5 speed with the old FAST supercharger kit.
I drove it down from Erie Pa. which is approximately 750 feet above sea level to Myrtle Beach which is at sea level. It didn't seem to have any symptoms until I got here at the beach, could the elevation change have anything to do with it? then again I didn't really hot rod until I got here either....
Sometimes it puts out a pretty good size cloud of smoke, dark color, usually it happens on take off under a slightly heavy throttle, it doesn't smell like burning oil. And there is a spray pattern on the cement right behind where I park that looks like a sprinkling of pepper, it must happen sometimes when I start it up but from the number of them not every time. The tail pipe is sooty but not oily.
I was going to pull a few plugs this evening and check them but the mosquito's and a lack of a spark plug wrench made put that off until tommorow.
I think it might be running too rich, the PO said he had it set up slightly on the rich side for safety's sake. Based on the air/fuel gauge, which is a digital bar graph type with "lean" on the bottom followed by two red bars then two yellow then two green then two yellow then two red then "rich" at the top, it seems to favor the rich end of the scale anytime I'm accelerating.
Also it seems to surge at idle from around 500 to 1000 rpms a second or two at the low RPM's then a second or two at the higher RPM's although sometimes it sems to stay smooth at around 800-1000 RPM's.
the exit port from the blow off valve is always releasing hot air and doesn't feel like it increases/decreases (cycle) in sync with the surging idle.
It hasn't used any oil since I've been driving it and the oil pressure stays pegged at 5 anytime I'm at 2000 RPM's or more although the needle will drop a bit during downshifting/engine braking and coasting to a stop with the clutch in it drops to around 2.
Sorry if I'm rambling on a lot here just to ask how much smoke could this car put out running rich but I thought you guys might see something in the details that I don't since I'm not a very experienced mechanic....
My plan tommorow is to pull a few plugs and see if they are dark (I assume it's wise to clean them all if I find signs that they are loaded up) and if they are should I lower the fuel pressure?
The fuel pressure gauge on the front end of the passenger side fuel rail reads @27 lbs at idle and actually seems to drop to @25 if I give it some gas. If I understand it correctly the fuel pressure doesn't sound like it's too high.
I really need some good advice on that part of the puzzle.
also I'm hoping to put a gauge in the vacum line upstream of the check valve at the computer so I can see what kind of boost the SC is actually putting out. The PO didn't want to drill the intake to mount it permanently but according to the FAST instructions I can T off the vacuum line coming to the computer to get a reading on the pressure there. does that sound right?
The injectors are 30#'s I believe and it has chips in it from Superchips Inc out of Florida. and the car has an H pipe into two resonators and then the rear muffler bypass pipe (loud and sweet sounding)...it breathes through a K&N filter.
Well that just about wraps up anything I can think of that might help you guys take a few educated guesses.
OH, yea! The car runs great!! Other than the semi regular puff of smoke out the tail pipe that is....
I drove it down from Erie Pa. which is approximately 750 feet above sea level to Myrtle Beach which is at sea level. It didn't seem to have any symptoms until I got here at the beach, could the elevation change have anything to do with it? then again I didn't really hot rod until I got here either....
Sometimes it puts out a pretty good size cloud of smoke, dark color, usually it happens on take off under a slightly heavy throttle, it doesn't smell like burning oil. And there is a spray pattern on the cement right behind where I park that looks like a sprinkling of pepper, it must happen sometimes when I start it up but from the number of them not every time. The tail pipe is sooty but not oily.
I was going to pull a few plugs this evening and check them but the mosquito's and a lack of a spark plug wrench made put that off until tommorow.
I think it might be running too rich, the PO said he had it set up slightly on the rich side for safety's sake. Based on the air/fuel gauge, which is a digital bar graph type with "lean" on the bottom followed by two red bars then two yellow then two green then two yellow then two red then "rich" at the top, it seems to favor the rich end of the scale anytime I'm accelerating.
Also it seems to surge at idle from around 500 to 1000 rpms a second or two at the low RPM's then a second or two at the higher RPM's although sometimes it sems to stay smooth at around 800-1000 RPM's.
the exit port from the blow off valve is always releasing hot air and doesn't feel like it increases/decreases (cycle) in sync with the surging idle.
It hasn't used any oil since I've been driving it and the oil pressure stays pegged at 5 anytime I'm at 2000 RPM's or more although the needle will drop a bit during downshifting/engine braking and coasting to a stop with the clutch in it drops to around 2.
Sorry if I'm rambling on a lot here just to ask how much smoke could this car put out running rich but I thought you guys might see something in the details that I don't since I'm not a very experienced mechanic....
My plan tommorow is to pull a few plugs and see if they are dark (I assume it's wise to clean them all if I find signs that they are loaded up) and if they are should I lower the fuel pressure?
The fuel pressure gauge on the front end of the passenger side fuel rail reads @27 lbs at idle and actually seems to drop to @25 if I give it some gas. If I understand it correctly the fuel pressure doesn't sound like it's too high.
I really need some good advice on that part of the puzzle.
also I'm hoping to put a gauge in the vacum line upstream of the check valve at the computer so I can see what kind of boost the SC is actually putting out. The PO didn't want to drill the intake to mount it permanently but according to the FAST instructions I can T off the vacuum line coming to the computer to get a reading on the pressure there. does that sound right?
The injectors are 30#'s I believe and it has chips in it from Superchips Inc out of Florida. and the car has an H pipe into two resonators and then the rear muffler bypass pipe (loud and sweet sounding)...it breathes through a K&N filter.
Well that just about wraps up anything I can think of that might help you guys take a few educated guesses.
OH, yea! The car runs great!! Other than the semi regular puff of smoke out the tail pipe that is....
10-11-2006, 01:09 AM
#2
Burning Brakes
Sounds like rich running, actually very rich if you are getting spotting out the tail pipes. I would pull plugs as you are planning to do to confirm but them I think you need to decide how to address the source of the excess fuel as it doesn't appear to be consistent. Just a guess but you might have a bad vacuum control that is leaking fuel into the vacuum line whenever the conditions are right.
10-11-2006, 02:27 AM
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Burning Brakes
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May be running rich, but first issue is to validate/investigate that fuel pressure reading.
25 PSI is WAY too low to get any kind of atomization out of the injector - it would be close to a stream and would consequently not combust completely, run down the cylinder walls and generally be a very bad thing. Check (or have it checked) with a real shop fuel pressure guage.
If the fuel system was deliberately jury rigged to run low pressures to make up for oversize injectors, then you might want to look at redoing that sysytem correctly - by running injectors closer to stock size and then overpressuring them to deliver needed fuel in a boosted condition. There's a whole lotta reasons that is the (more) correct way to achieve fueling in a mildly boosted scenario.
The ONLY way to validate your a/f ratio is with a WIDEBAND O2 sensor unit. It must be installed either before your cats, or you can use the tailpipe if your car is catless.
Any of the $49 blinky units that utilize the factory narrowband sensor are USELESS other than to indicate in very rough terms whether your engine is at stoich. Standard narrowband O2 sensors are accurate at stoich (14.7:1) ONLY. They can determine "rich'' or "lean", but not to whether you're at 12:1 or 10:1.
Sticking a wideband O2 sensor in the end of tailpipe of a cat-equipped car is also (worse than) pointless. I only mention this because I have seen more that one dyno-operating-meat-puppet try to pull that stunt. The sad part is they really don't know any better. So just watch out...
I recommend the Innovate unit. I have had one for four+ years now and it is bulletproof. Oh yeah, Porsche likes (and is playing with) the Innovate unit too. And, it's very inexpensive.
25 PSI is WAY too low to get any kind of atomization out of the injector - it would be close to a stream and would consequently not combust completely, run down the cylinder walls and generally be a very bad thing. Check (or have it checked) with a real shop fuel pressure guage.
If the fuel system was deliberately jury rigged to run low pressures to make up for oversize injectors, then you might want to look at redoing that sysytem correctly - by running injectors closer to stock size and then overpressuring them to deliver needed fuel in a boosted condition. There's a whole lotta reasons that is the (more) correct way to achieve fueling in a mildly boosted scenario.
The ONLY way to validate your a/f ratio is with a WIDEBAND O2 sensor unit. It must be installed either before your cats, or you can use the tailpipe if your car is catless.
Any of the $49 blinky units that utilize the factory narrowband sensor are USELESS other than to indicate in very rough terms whether your engine is at stoich. Standard narrowband O2 sensors are accurate at stoich (14.7:1) ONLY. They can determine "rich'' or "lean", but not to whether you're at 12:1 or 10:1.
Sticking a wideband O2 sensor in the end of tailpipe of a cat-equipped car is also (worse than) pointless. I only mention this because I have seen more that one dyno-operating-meat-puppet try to pull that stunt. The sad part is they really don't know any better. So just watch out...
I recommend the Innovate unit. I have had one for four+ years now and it is bulletproof. Oh yeah, Porsche likes (and is playing with) the Innovate unit too. And, it's very inexpensive.
10-11-2006, 03:06 PM
#4
Burning Brakes
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Originally Posted by 2V4V
May be running rich, but first issue is to validate/investigate that fuel pressure reading.
25 PSI is WAY too low to get any kind of atomization out of the injector - it would be close to a stream and would consequently not combust completely, run down the cylinder walls and generally be a very bad thing. Check (or have it checked) with a real shop fuel pressure guage.
25 PSI is WAY too low to get any kind of atomization out of the injector - it would be close to a stream and would consequently not combust completely, run down the cylinder walls and generally be a very bad thing. Check (or have it checked) with a real shop fuel pressure guage.
The ONLY way to validate your a/f ratio is with a WIDEBAND O2 sensor unit. It must be installed either before your cats, or you can use the tailpipe if your car is catless.
Any of the $49 blinky units that utilize the factory narrowband sensor are USELESS other than to indicate in very rough terms whether your engine is at stoich. Standard narrowband O2 sensors are accurate at stoich (14.7:1) ONLY. They can determine "rich'' or "lean", but not to whether you're at 12:1 or 10:1.
...../snip / ....
I recommend the Innovate unit. I have had one for four+ years now and it is bulletproof. Oh yeah, Porsche likes (and is playing with) the Innovate unit too. And, it's very inexpensive.
...../snip / ....
I recommend the Innovate unit. I have had one for four+ years now and it is bulletproof. Oh yeah, Porsche likes (and is playing with) the Innovate unit too. And, it's very inexpensive.
as to pulling the plugs, I pulled a few and they were very black, as if someone spray painted them with a flat black can of bar-b-que paint.
I'm guessing it's alright to clean the plugs and put them back in so I can check for signs of rich or lean conditions after adjustments are made to the mix. Is there any particular method or tool I need to clean them?
Sorry for the rookie questions but I am a rookie!
10-11-2006, 06:55 PM
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Burning Brakes
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The low pressure sounds like a work around for running large injectors. Stock fuel pressure should be about 3.8 BAR (like around 55 PSI). If you start running that pressure with your current injectors, you will be definately running too rich. The 85-86 was spec'd around 2 BAR at idle, IIRC.
There are injectors that are designed to work with lower pressures like that, but not knowing what you have, I shan't guess. If you can, try to read the numbers off the side of one of the injectors.
You can safely clean the plugs and reinstall them. Quick shot with aerosol carb cleaner, then a quick shot of brake parts cleaner to dry them off works well for a quickie clean.
You can install the Innovate unit in place of the factory O2 sensor. The Innovate can then take the output from the wideband sensor and send it to the LH so that the ecu thinks that the factory narrowband is still there. Oh yeah, and you can datalog all sortsa stuff with the Innovate unit.
In the crossover is a good place as it will get you the average of all the cylinders.
There are injectors that are designed to work with lower pressures like that, but not knowing what you have, I shan't guess. If you can, try to read the numbers off the side of one of the injectors.
You can safely clean the plugs and reinstall them. Quick shot with aerosol carb cleaner, then a quick shot of brake parts cleaner to dry them off works well for a quickie clean.
You can install the Innovate unit in place of the factory O2 sensor. The Innovate can then take the output from the wideband sensor and send it to the LH so that the ecu thinks that the factory narrowband is still there. Oh yeah, and you can datalog all sortsa stuff with the Innovate unit.
In the crossover is a good place as it will get you the average of all the cylinders.
10-12-2006, 11:25 AM
#7
Burning Brakes
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Originally Posted by John Speake
What you need is a SharkTuner....
First according to the Sharktuner website's list of things I'll need:
5) A good general knowledge of the principles of engine management systems.
I'm just learning and although I'm confident I'll have this knowledge pretty soon, right now it looks like it's more tool than I'm qualified to use without supervision.
And second, the cost, although I already put the SharkTuner in my long term budget plans right now it's out of reach.
Maybe you could schedule a tour of North America and visit all of us leaving a trail of freshly burned chips and happy customers in your wake
I know I'd be happy to see the SharkTuner Man show up in my neck of the woods!
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10-12-2006, 11:32 AM
#8
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Originally Posted by aggravation
Maybe you could schedule a tour of North America and visit all of us leaving a trail of freshly burned chips and happy customers in your wake
I know I'd be happy to see the SharkTuner Man show up in my neck of the woods!
I know I'd be happy to see the SharkTuner Man show up in my neck of the woods!
10-12-2006, 06:30 PM
#10
Burning Brakes
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Here's an update for 2V4V...(or anyone else who wants to jump in and give some advice)...
The injectors installed in the car right now came out of a box labeled:
Ford Racing Performance Parts
#30 injector kit (8)
M-9593-B302
I haven't been able to get any one to check the fuel pressure, the pressure guage that is on the end of the fuel rail is my only source for right now and it seems to stay between 25 and 29. I don't have any information on which brand or the specs of the fuel pressure regulator the PO put in.
I pulled the vacuum line off the fuel pressure regulator and there was no gas dripping from it.
I warmed up the engine, turned it off and disconnected the electrical plug from the MAF then restarted...well tried to restart anyway. The engine turns right over but wont run it dies immediately so I tried again and this time gave it some gas right after it turned over, it sputtered a bit for just 1 second and died.
Plugged the MAF back in and it fires right up but the surging idle resumed as well.
The 02 sensor is in the "H" part of the pipe but I didn't get a chance to pull it and see if it needs cleaning because a friend let me put the car up on a lift this morning to take a quick look but I had to get out of his way as he had a lot of customers cars to deal with this morning.
I read somewhere that the Temp sensor (NTC II) could cause the too rich conditions. Does anyone know if that is right? I'm about to look in the service manual to see if it tells me how to find it and how to check it but if any of you have any experience finding and checking it I'm listening....
One thing is certain the surging idle is the result of whatever is making it run rich because once in a while the idle levels off to normal (no surge at all) and when that happens the smoke stops coming out of the pipe!
I'm up for any suggestions at this point.
The injectors installed in the car right now came out of a box labeled:
Ford Racing Performance Parts
#30 injector kit (8)
M-9593-B302
I haven't been able to get any one to check the fuel pressure, the pressure guage that is on the end of the fuel rail is my only source for right now and it seems to stay between 25 and 29. I don't have any information on which brand or the specs of the fuel pressure regulator the PO put in.
I pulled the vacuum line off the fuel pressure regulator and there was no gas dripping from it.
I warmed up the engine, turned it off and disconnected the electrical plug from the MAF then restarted...well tried to restart anyway. The engine turns right over but wont run it dies immediately so I tried again and this time gave it some gas right after it turned over, it sputtered a bit for just 1 second and died.
Plugged the MAF back in and it fires right up but the surging idle resumed as well.
The 02 sensor is in the "H" part of the pipe but I didn't get a chance to pull it and see if it needs cleaning because a friend let me put the car up on a lift this morning to take a quick look but I had to get out of his way as he had a lot of customers cars to deal with this morning.
I read somewhere that the Temp sensor (NTC II) could cause the too rich conditions. Does anyone know if that is right? I'm about to look in the service manual to see if it tells me how to find it and how to check it but if any of you have any experience finding and checking it I'm listening....
One thing is certain the surging idle is the result of whatever is making it run rich because once in a while the idle levels off to normal (no surge at all) and when that happens the smoke stops coming out of the pipe!
I'm up for any suggestions at this point.
10-12-2006, 07:08 PM
#11
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The basic problem you have is that the LH ECU has been mapped for 19# injectors. You have fitted 30#. Even thouigh you have dropped the fuel pressure to around 30psi rather than the stock 47psi used with the 19#, you are still overfuelling.
This is because 30# at 30psi look more like 24# injectors, so you are still overfuelling.
The idle control system can't handle this degree of overfuelling, probably because the O2 loop isn't in control any more.
If you drop the fuel pressure even more, the spray pattern will suffer, which has its own issues.
I don't think the problem is temp 2 because if it goes open or short circuit the LH ECU reverts to "full hot engine" condition. So a faulty temp 2 is going to give cold start and running problems, not hot.
This is because 30# at 30psi look more like 24# injectors, so you are still overfuelling.
The idle control system can't handle this degree of overfuelling, probably because the O2 loop isn't in control any more.
If you drop the fuel pressure even more, the spray pattern will suffer, which has its own issues.
I don't think the problem is temp 2 because if it goes open or short circuit the LH ECU reverts to "full hot engine" condition. So a faulty temp 2 is going to give cold start and running problems, not hot.
10-12-2006, 07:24 PM
#12
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FAST used to recommend a FMU. Do you have one? 24 pound injectors will probably work better as previously suggested. Since you have an 88 you'll save yourself a lot of frustration (and in the long term probably save money) by getting it tuned via the SharkTuner. DR in NC is close to you www.928gt.com
10-12-2006, 07:54 PM
#13
Burning Brakes
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Thanks for the update.
As I have said and John has said, you have too much injector.
Smaller injectors, rising rate reg and tune it with a wideband on a dyno. I'd do it for you, but there's others that are closer.
I'll assume Rick knows what he's talking about with the FAST kits having RRRs. Does your car have one? Should be located connected somewhere near the "out" end of the fuel rail, close to the firewall. Or, at least, it will mounted somewhere nearby, with a line from the end of the rail and then connected to the fuel retun line to the tank.
Greg
As I have said and John has said, you have too much injector.
Smaller injectors, rising rate reg and tune it with a wideband on a dyno. I'd do it for you, but there's others that are closer.
I'll assume Rick knows what he's talking about with the FAST kits having RRRs. Does your car have one? Should be located connected somewhere near the "out" end of the fuel rail, close to the firewall. Or, at least, it will mounted somewhere nearby, with a line from the end of the rail and then connected to the fuel retun line to the tank.
Greg
10-12-2006, 08:00 PM
#14
Burning Brakes
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Wow, thanks for the input!
First, I don't know what an FMU is, fuel management unit maybe? I don't think there is one installed, the FAST instructions I have say:
-Fuel injector upgrade to 30lbs.
-Adj. Fuel pressure regulator installation and tuning
-Computer safety check valve
-Install Vortech FMU (optional, not supplied with kit, not recomended)
Install and tune Air/fuel ratio gauge
-Replace spark plugs
The not recommended part threw me...although
later in the instruction it mentions the FMU and where to install it on the firewall I believe and there is no sign of it that I can see...of course I really don't know what I'm looking for either !
So if anyone could describe it to me I'll go look for it. Could a FMU overcome the mismatch of injector to fuel pressure I apparantly have? this car was run this way for a few years before I got it but the extremely rich scenario seems to be a new development.
Also, am I understanding it correctly that with a SharkTuner this setup could be made to work properly or do I need to change out the injectors before the SharkTuner session.
Who ever DR is I'd love to visit him and have things put right, I'm guessing from the link he's the owner or operator of 928 Specialists (I didn't realize they did anything other than sell parts from a website)
I'll be trying to get a hold of him to see what he can do for my car.
Thanks to all for the help!
First, I don't know what an FMU is, fuel management unit maybe? I don't think there is one installed, the FAST instructions I have say:
-Fuel injector upgrade to 30lbs.
-Adj. Fuel pressure regulator installation and tuning
-Computer safety check valve
-Install Vortech FMU (optional, not supplied with kit, not recomended)
Install and tune Air/fuel ratio gauge
-Replace spark plugs
The not recommended part threw me...although
later in the instruction it mentions the FMU and where to install it on the firewall I believe and there is no sign of it that I can see...of course I really don't know what I'm looking for either !
So if anyone could describe it to me I'll go look for it. Could a FMU overcome the mismatch of injector to fuel pressure I apparantly have? this car was run this way for a few years before I got it but the extremely rich scenario seems to be a new development.
Also, am I understanding it correctly that with a SharkTuner this setup could be made to work properly or do I need to change out the injectors before the SharkTuner session.
Who ever DR is I'd love to visit him and have things put right, I'm guessing from the link he's the owner or operator of 928 Specialists (I didn't realize they did anything other than sell parts from a website)
I'll be trying to get a hold of him to see what he can do for my car.
Thanks to all for the help!
10-12-2006, 08:10 PM
#15
Burning Brakes
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The "FMU" or "RRR" is just different names for the same tool - an adjustable fuel pressure regulator.
The amount of fuel that sprays out of your injectors is determined by (basically) 3 things:
1. How big are the injectors? (How big is the hole?)
2. How long are they open? (Pulsewidth determined by LH brain)
3. What is the fuel pressure?
As "Fuel Management Unit" or "Rising Rate Regulator" are replacements for the fixed pressure regulators that come on the car from the factory.
They allow the fuel pressure to go higher than stock. This allows the injectors to spray more fuel volume in a given amount of open time (pulsewidth).
Make sense?
The amount of fuel that sprays out of your injectors is determined by (basically) 3 things:
1. How big are the injectors? (How big is the hole?)
2. How long are they open? (Pulsewidth determined by LH brain)
3. What is the fuel pressure?
As "Fuel Management Unit" or "Rising Rate Regulator" are replacements for the fixed pressure regulators that come on the car from the factory.
They allow the fuel pressure to go higher than stock. This allows the injectors to spray more fuel volume in a given amount of open time (pulsewidth).
Make sense?