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You're lucky with that smog shop- technically they can fail you just for having that mbc and for missing the intake snorkel... and probably the KN filter.
You're lucky with that smog shop- technically they can fail you just for having that mbc and for missing the intake snorkel... and probably the KN filter.
They are wonderful people.
The intake snorkel is installed. I was cleaning the car and it just so happened to be off while snapping a picture.
For Sure make sure your air filter is clean! My brother spent retarded amounts of money trying to get the 944T to pass emissions in SoCal. New injectors, new O2 sensors, new catalytic converter, new spark plugs, then different spark plugs, Went to various shops to try to get it passed. Imagine that! not a single shop thought of cleaning the K&N air filter!! His HC's were always high. He finally called me to take the car to Idaho where maybe I can "fix it". First thing I did was to look through the filter. It was dense with debris. Cleaned it and it passed very nicely here in Idaho! Now my son drives it. He loves it!!
I went back for a smog test with stock klr/ DME chips and a new o2 sensor. This time I was able to pass the 2500rpm test but FAILED the CO at idle.
Smog guy says something is dumping fuel into the car. I’m bone stock engine now minus a manual boost controller. There is a boost leak somewhere I can’t find yet. Idles just fine.
A boost leak is a vacuum leak under vacuum. A vacuum leak means un-metered air is entering the system, so less fuel is supplied. This causes a lean idle, not a rich idle. However if the vacuum leak is causing your fuel pressure to be higher (less vacuum equates to higher fuel pressure at idle), then it could cause rich AFRs. FPR references vacuum/boost.
Check your fuel pressure. With stock chips you need a 2.5 bar static pressure.
Make sure the idle switch is active, maybe your TPS needs adjustment?
Was the engine hot when the idle test took place? You do not want the cold enrichment active during the test. Best to keep the car running (after a long drive) before running the test.
Originally Posted by Chapman951
I went back for a smog test with stock klr/ DME chips and a new o2 sensor. This time I was able to pass the 2500rpm test but FAILED the CO at idle.
Originally Posted by Chapman951
Smog guy says something is dumping fuel into the car. I’m bone stock engine now minus a manual boost controller. There is a boost leak somewhere I can’t find yet. Idles just fine.
Just talked to a Porsche mechanic and he said the catalytic converter is more than likely the culprit. The honey combs in the cat are not doing their thing at idle but are at 2500rpm.
A boost leak is a vacuum leak under vacuum. A vacuum leak means un-metered air is entering the system, so less fuel is supplied. This causes a lean idle, not a rich idle. However if the vacuum leak is causing your fuel pressure to be higher (less vacuum equates to higher fuel pressure at idle), then it could cause rich AFRs. FPR references vacuum/boost.
Check your fuel pressure. With stock chips you need a 2.5 bar static pressure.
Make sure the idle switch is active, maybe your TPS needs adjustment?
Was the engine hot when the idle test took place? You do not want the cold enrichment active during the test. Best to keep the car running (after a long drive) before running the test.
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Hi John.
I don’t have a fuel pressure gauge. Something to look into.
I will look into the tps also.
i ran the car for 30 minutes prior to the test at highway speed and let it idle for 15 minutes before it went in for inspection. Basically I never turned the car off.
What are your new CO numbers?
Working properly, the O2 sensor feedback keeps the mixture BELOW 1% CO.
If your readings out the tailpipe are richer than 1% CO, your engine is running too rich whether the cat is functioning or not.
I can't find a real conversion chart anywhere, but from memory, the 14.7:1 stoichiometric A/F ratio the ECU is aiming for is something like 0.6% CO...
Keep looking for the cause of the rich mixture. The cat might be toast too, but that's not really the source of the problem.
The CO reading at idle was 0.44
The CO readings at 2500 came in at 4.23, 2.09 and 1.86. Apparently there was an idle fluctuation that occurred. Perhaps that’s why there was a 4.23 reading.
I will pull the spark plugs next and do a visual inspection.
FQS is at 0 setting and a new o2 sensor was installed less than a week ago.
Your text says idle CO was .44%, but the notes on the report sheets say 'idle', and show the 1.86%/2.09%/4.03% numbers...
Something is sending the mixture too rich, way beyond what a cat could be expected to clean up.
Time for some real diagnostic work... Might be time to take it to a pro?
06-01-2019, 10:54 AM
