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As suggested before, swap in the LH ECU from a US 85/86 32v car. Then you can connect a good O2 sensor into it. That will give you much better control of emissions.
Also, you don't mention the MAF. The car as run for the tests was open loop so MAF calibration is critical, did you try adjusting the CO pot on the MAF ?
Ha! You got advice from John Speake about a possible cure through the MAF! I've not seen that information before, really good to know.
Witch Doctor gets rave reviews all over Rennlist, not sure if the quarantine is an issue? But there are other specialists that can also take care of your injectors. There is a car repair shop with a fuel injector lab in Houston that is great, but I can't remember the name. Google?
I think that Greg may have been referring to cats like the Magnaflow when he said the aftermarket cats are not very good. But IDK. I do know they are fairly inexpensive, maybe $175-$250 for the pair?
Are you planning to sell the car or keep it? I ask because most every suggestion to get it to pass smog involves throwing $$$ at it. I would start with simple things like cleaning the injectors (as previously recommended), and a tune up: spark plugs (plain Bosch copper), wires, caps and rotors, and an effective fuel additive like Berryman's. On a budget though, a very basic way to at least take a look at the wires is to park the car in a dark garage at night and open the hood with the engine running, if you see flickering all over the place then you absolutely need new wires. Plugs are easy to inspect, clean, and set at the correct gap. The caps and rotors contacts can be gently cleaned with 600 grit sand paper if not too worn or damaged.
Consider that the 'smells rich' symptom is way more often related to 'too lean to support full combustion' where un-burned hydrocarbons (fuel) pass through and out the exhaust. You smell the raw fuel, bit the reason for it isn't obvious. But... You do have the telltales in the gas readings. CO has a direct relationship to quality of combustion. Higher CO indicates a richer mixture burned. The low CO you show tells you that it's quite lean. The HC number is telling you that raw fuel is making it through. The high NOx number is the result of lean combustion, where there isn't enough fuel to maintain a slow flame front, Instead, it's lean and you have only a partial burn before there's a small local explosion in the chamber that makes a hot spot. NOX numbers spike when you have that hot spot. Those can be caused by timing too far advanced for the fuel you are using, but the CO and HC numbers point to low/lean fuel mixture.
Besides the most-likely dirty injectors that are way typical in cars that sit, look hard at all the vacuum lines and component connections. Unmetered air passing around the MAF by any path will offer the symptoms you see.
Consider that the 'smells rich' symptom is way more often related to 'too lean to support full combustion' where un-burned hydrocarbons (fuel) pass through and out the exhaust. You smell the raw fuel, bit the reason for it isn't obvious. But... You do have the telltales in the gas readings. CO has a direct relationship to quality of combustion. Higher CO indicates a richer mixture burned. The low CO you show tells you that it's quite lean. The HC number is telling you that raw fuel is making it through. The high NOx number is the result of lean combustion, where there isn't enough fuel to maintain a slow flame front, Instead, it's lean and you have only a partial burn before there's a small local explosion in the chamber that makes a hot spot. NOX numbers spike when you have that hot spot. Those can be caused by timing too far advanced for the fuel you are using, but the CO and HC numbers point to low/lean fuel mixture.
Besides the most-likely dirty injectors that are way typical in cars that sit, look hard at all the vacuum lines and component connections. Unmetered air passing around the MAF by any path will offer the symptoms you see.
Totally makes sense. I always appreciate your input, Dr Bob! I've reached out to Witch Hunter again for injector refurb but they seem to be quite underwater during this crisis. Any other recommendations on injector testing and refurb, possibly around the LA area? I've also reached out to Ott's Performance for MAF testing.
You may have missed a reply to your thread by John Speake, it has a couple of suggestions that may be useful to you. John is the specialist that rebuilds the MAF's and LH's that Louis sells, he is located in the UK.
I stumbled across the following writeup on how to pass smog testing. I think that every aspect of it has been presented in this thread, but with much added commentary. Somehow its easier (at least for me) to read and digest the information in a writeup format. You can find it here:
You may have missed a reply to your thread by John Speake, it has a couple of suggestions that may be useful to you. John is the specialist that rebuilds the MAF's and LH's that Louis sells, he is located in the UK.
I stumbled across the following writeup on how to pass smog testing. I think that every aspect of it has been presented in this thread, but with much added commentary. Somehow its easier (at least for me) to read and digest the information in a writeup format. You can find it here:
Aha! Thanks for making that connection. And thank you, John! I'll dig in a bit more on adjusting the CO pot on the MAF. I have no experience with the MAF thus far, other than fixing the harness after rats ate it through. Shark2626, I'll dig into that thread. I appreciate you doing that legwork! Also, to answer your question regarding keeping or selling, I'm not sure yet. The car was rat food when I got it and I had a limited budget (and experience) to get it running. I came in under budget, rehabbed what I could, replaced what made sense, and it seems to run well other than current smog levels and associated issues that create those symptoms.
just wanted to quickly update the thread. I went to RC Fuel Injection in Torrance and had my fuel injectors cleaned. Check out the numbers attached. Big difference! I’m interested to retest after install. I also used some MAF cleaner to see if that helps. If I don’t see a change in NOx, I’ll likely send MAF out for refurb by Louis.
Just wanted to update again. Retested with cleaned injectors and there was no change to high NOx. We also adjusted the MAF to richen the mixture and there was no change. I’ve now sent my MAF to Louis for a refurbed one to see if there is a change. I suppose the Cat is next (test before and after cat to see if it’s doing anything). Then, I’ll need to consider the US ECU so I can consider utilizing the O2 sensor.
Just wanted to update again. Retested with cleaned injectors and there was no change to high NOx. We also adjusted the MAF to richen the mixture and there was no change. I’ve now sent my MAF to Louis for a refurbed one to see if there is a change. I suppose the Cat is next (test before and after cat to see if it’s doing anything). Then, I’ll need to consider the US ECU so I can consider utilizing the O2 sensor.
Received the refurbed MAF from Louis, adjusted air/fuel via the MAF adjustment screw measuring o2 sensor voltage, and retested emissions. HC was better but no luck on lowering the NOx. I plan to send back the refurbished MAF and re-install my original as it did not do the trick. Thoughts? I suppose it’s Cat/ECU/o2 sensor research time. I’m wondering if time/mileage would help, as well. Through all of the work I’ve done on the car, I’ve really only driven about 30 miles. Also, in the last two weeks, I did the oil pan gasket, oil sender gasket, oil sump tube gasket (and Helicoil), motor mounts, timing belt, oil pump gear, accessory belts, A/C wire repair, leaking transmission cooler lines (with Greg’s kit from Roger), flushed the differential, and topped off the ATF with K&W Trans-X. Got it up to 80mph today and it felt better than ever - even with the lingering emissions issues. Latest emissions results.
Received the refurbed MAF from Louis, adjusted air/fuel via the MAF adjustment screw measuring o2 sensor voltage, and retested emissions. HC was better but no luck on lowering the NOx. I plan to send back the refurbished MAF and re-install my original as it did not do the trick. Thoughts? I suppose it’s Cat/ECU/o2 sensor research time. I’m wondering if time/mileage would help, as well. Through all of the work I’ve done on the car, I’ve really only driven about 30 miles. Also, in the last two weeks, I did the oil pan gasket, oil sender gasket, oil sump tube gasket (and Helicoil), motor mounts, timing belt, oil pump gear, accessory belts, A/C wire repair, leaking transmission cooler lines (with Greg’s kit from Roger), flushed the differential, and topped off the ATF with K&W Trans-X. Got it up to 80mph today and it felt better than ever - even with the lingering emissions issues. Latest emissions results.
Following this thread closely. I am moving to the LA area next week w/ my '83 US and an '86 Euro project car. Neither are smog friendly and I am not looking forward to this process at all. Sunshine taxes begin.
Following this thread closely. I am moving to the LA area next week w/ my '83 US and an '86 Euro project car. Neither are smog friendly and I am not looking forward to this process at all. Sunshine taxes begin.
Let’s meet, compare notes, and share stories! I’m near Culver City, have a spot to work and a couple of buddies who are Porsche mechanics (mainly 1997+ and not too familiar with the 928 but very smart and experienced). I’d love to borrow your US ECU and retest emissions with my o2 sensor actually plugged into something.
Let’s meet, compare notes, and share stories! I’m near Culver City, have a spot to work and a couple of buddies who are Porsche mechanics (mainly 1997+ and not too familiar with the 928 but very smart and experienced). I’d love to borrow your US ECU and retest emissions with my o2 sensor actually plugged into something.
For sure, I think I have another new O2 sensor in my boxes of parts too. I'll be out in Claremont- will PM my cell. FWIW, I also had a serious case of the stinkies on my ’83 which I generally attribute to high NOX. Turned out to either be plugs or coil- changed at the same time. Both were relatively new before I swapped but who knows… completely disappeared after. Went from the Bosch copper to whatever Roger sells (silver I think?), could have been that.
For sure, I think I have another new O2 sensor in my boxes of parts too. I'll be out in Claremont- will PM my cell. FWIW, I also had a serious case of the stinkies on my ’83 which I generally attribute to high NOX. Turned out to either be plugs or coil- changed at the same time. Both were relatively new before I swapped but who knows… completely disappeared after. Went from the Bosch copper to whatever Roger sells (silver I think?), could have been that.
04-17-2020, 05:54 AM
