Running Rich
02-19-2010, 01:45 PM
#1
Racer
Thread Starter
Running Rich
Last year I was experiencing some black/greyish smoke coming from the exhaust when under boost. More so if I had not driven it hard in a while. I even found some small soot deposits on the rear bumper area.
Obviously I'm running rich. I'm thinking fuel damper or O2 sensor. Car is stock. Any thoughts?
Obviously I'm running rich. I'm thinking fuel damper or O2 sensor. Car is stock. Any thoughts?
02-19-2010, 01:56 PM
#2
Nordschleife Master
O2 sensor, DME Temperature sensor (in cylinder head, has square connector), AFM reading incorrectly, Wrong FQS setting, Fuel Damper, FPR, Injectors all can be suspect...
Check your FQS setting, clean the AFM tracks, replace teh O2 sensor, and a new DME temp sensor are all cheap and easy, damper, FPR are next, followed by injectors.
Check your FQS setting, clean the AFM tracks, replace teh O2 sensor, and a new DME temp sensor are all cheap and easy, damper, FPR are next, followed by injectors.
02-19-2010, 02:07 PM
#3
Racer
Thread Starter
I have replaced the DME temp sensor, injectors were rebuilt and flowmatched, all vac lines have been replaced.
The O2 sensor has some small tack welds at the threads. Perhaps its one of those universal ones or even the wrong one.
How do I check the FQS settings and what does FQS stand for?
The O2 sensor has some small tack welds at the threads. Perhaps its one of those universal ones or even the wrong one.
How do I check the FQS settings and what does FQS stand for?
02-19-2010, 02:14 PM
#4
Nordschleife Master
I have replaced the DME temp sensor, injectors were rebuilt and flowmatched, all vac lines have been replaced.
The O2 sensor has some small tack welds at the threads. Perhaps its one of those universal ones or even the wrong one.
How do I check the FQS settings and what does FQS stand for?
The O2 sensor has some small tack welds at the threads. Perhaps its one of those universal ones or even the wrong one.
How do I check the FQS settings and what does FQS stand for?
FQS is the Fuel Quality Setting there is a black plug on the side of the DME, with a small allen wrench or small tipped screwdriver you can reach through the hole the plug is in (plug MAY be missing, but look for a hole in the side of the DME).
Stock is position 0 then the next 3 positions maintain stock timing but add and or retard fuel, next 3 positions maintain fueling but modify the timing control..
modifications are +3%, -3%, and +6% if I remember correctly... if your DME has been chipped the FQS values may be different... Make sure the switch is turned completely counter clockwise, but don't turn it too hard... this will set it to the factory default position...
02-19-2010, 02:26 PM
#5
Racer
Thread Starter
Someone welded the O2 sensor to the bung in the exhaust pipe. I'm assuming the threads were stripped or it is the wrong one. Probably will have to chase the threads before installing the new one. Any idea on what the thread is?
I am assuming I have stock chips, but you never know. I will have to open the DME and have a look. I can than check the FQS settings as well. Thanks for explaining that to me.
I am assuming I have stock chips, but you never know. I will have to open the DME and have a look. I can than check the FQS settings as well. Thanks for explaining that to me.
02-19-2010, 02:30 PM
#6
Nordschleife Master
Someone welded the O2 sensor to the bung in the exhaust pipe. I'm assuming the threads were stripped or it is the wrong one. Probably will have to chase the threads before installing the new one. Any idea on what the thread is?
I am assuming I have stock chips, but you never know. I will have to open the DME and have a look. I can than check the FQS settings as well. Thanks for explaining that to me.
I am assuming I have stock chips, but you never know. I will have to open the DME and have a look. I can than check the FQS settings as well. Thanks for explaining that to me.
not sure if the factory location will be as easy for them to get to, but it won't hurt to ask..
02-20-2010, 09:44 AM
#7
Rennlist Member
The thing is, though, that the O2 sensor is out of the loop when under boost, so it shouldn't affect the fuel delivery, even if it's bad.
(You said it happens when under boost)
Has this been happening lately, or since you've owned the car?
If this is a new thing, it probably wouldn't be anything related to a chip or the FQS.
Before getting into the DME yourself, check to see if it has ever been opened before (there will be scratch marks around the tabs).
Sometimes on full throttle, the airflow and pressure going through the intake forces engine oil into the combustion chamber, causing the smoke you see. The oil sits in the intercooler and pipes and comes from a gradual accumulation generated by the crankcase vent system.
(You said it happens when under boost)
Has this been happening lately, or since you've owned the car?
If this is a new thing, it probably wouldn't be anything related to a chip or the FQS.
Before getting into the DME yourself, check to see if it has ever been opened before (there will be scratch marks around the tabs).
Sometimes on full throttle, the airflow and pressure going through the intake forces engine oil into the combustion chamber, causing the smoke you see. The oil sits in the intercooler and pipes and comes from a gradual accumulation generated by the crankcase vent system.
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02-20-2010, 01:03 PM
#8
Rennlist Member
I'd get a wideband sensor before concluding you are rich. You'd hate to lean it out and blow the HG just because you were buring a little oil or because condensation was blowing exhaust soot out. If you are suddenly running rich under boost, but not otherwise, you may have a pressure leak in the intake system -- a crack in on of the couplers, bad clamp, bad throttle body seals, etc. They can be hard to find if they only open up under pressure.
02-20-2010, 06:15 PM
#9
Burning Brakes
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The thing is, though, that the O2 sensor is out of the loop when under boost, so it shouldn't affect the fuel delivery, even if it's bad.
(You said it happens when under boost)
Has this been happening lately, or since you've owned the car?
If this is a new thing, it probably wouldn't be anything related to a chip or the FQS.
Before getting into the DME yourself, check to see if it has ever been opened before (there will be scratch marks around the tabs).
Sometimes on full throttle, the airflow and pressure going through the intake forces engine oil into the combustion chamber, causing the smoke you see. The oil sits in the intercooler and pipes and comes from a gradual accumulation generated by the crankcase vent system.
(You said it happens when under boost)
Has this been happening lately, or since you've owned the car?
If this is a new thing, it probably wouldn't be anything related to a chip or the FQS.
Before getting into the DME yourself, check to see if it has ever been opened before (there will be scratch marks around the tabs).
Sometimes on full throttle, the airflow and pressure going through the intake forces engine oil into the combustion chamber, causing the smoke you see. The oil sits in the intercooler and pipes and comes from a gradual accumulation generated by the crankcase vent system.
02-21-2010, 09:39 AM
#10
Racer
Thread Starter
Thanks guys. Car is still in storage, but will likely start with the O2 sensor and go from there. There is a accumulation of oil in the IC pipes etc so it may just be some of that moving through and that is why when I am more frequently on the boost, I don't see much smoke.
The car has been doing this since I've owned it and I burned an axhaust valve at the track last year. I don't want to keep running rich and build up more carbon in the engine and perhaps have a repeat of the burned valve.
The car has been doing this since I've owned it and I burned an axhaust valve at the track last year. I don't want to keep running rich and build up more carbon in the engine and perhaps have a repeat of the burned valve.
