I asked the question in my build log but I think people don't check that or come back to it often so I wanted to touch base on this issue, and it may help others if it happens to them.


So the car is idling rough, but revs and drives perfect! It gets a "lean" spike on the wideband and the revs spike about 500-800 rpms about every 5 seconds and it will stay alive for about 2-3 spikes before stalling out. When I first cold start it, it does run a bit longer because of the richer mix for the start up. After baout 15 seconds from start up dead cold, the car then dies.

Back story:

When I had intake vacuum leak after the maf but before the turbo, it idled fine but add gas and it died. Obviously because the leak. Since that, the ONLY things I have done are clean the MAF, replace the tube with the hole causing the leak, and reconnect my secondary air pump. What I have done so far is try unplugging (power) the secondary air pump that just made it worse. I don't think the MAF cleaner would have screwed my maf, especially since the maf doesn't have too much of an effect on the idle.

Thoughts? I can drive the ca ron the highway and give it the littlest gas and there is absolutely no idle problem. I noticed I did overfill the oil a touch by maybe a quart if that but I dont think that was the issue.

 

gets worse when you unplug the SAI? shouldn't have any effect
try running the car with the MAF unplugged, and of course check for any more vacuum/air leaks
also, what year is it?(egas or cable)

 

i unplugged the maf and it ran and didn't die. Crazy thing is I cleaned the maf again, hooked everything up and now it drives and idles just fine. It is a bit lean but drivable. It is in the 15.5 AFR's which seems way to high for me. I start building boost and it goes to 16.5. again these just seem way to lean for me. So now it is idling with a maf cleaning and a reset on the battery. No engine lights, nothing, just lean AFRs. Ill check for another leak somehwere.

Also, does the maf have to be at a certain angle or upright verticle position? My sensor cable plugs in on the bottom side of the pipe and im wondering if it would have an effect. It shouldn't but im just curious.

 

ya 15-16 AFR's are WAYYYY SCARY, don't get into boost until your back into the 11's, maybe 12's.
It won't be an air leak, should be pig rich on boost if it had one.(unless its between the MAF and turbo)
MAF shouldn't be affected by angle at all.
Just to clarify, no CEL when running with MAF unplugged or after cleaning it and it plugged in?
Might be a split fuel pump hose...

 

Position of the MAF in the airflow can have an effect, I have clocked MAFs and observed a change in the AFR reported. It is related to turbulence in the intake tube and how the heated element in the MAF reacts to it. I am sure the tuner has a recommended position to set it at. When the engine is running in closed loop (using the O2 sensor) the AFR should ditter around 14.7 so you are a tad bit lean but not bad. The 14.7 AFR is what the Catalytic converter needs to do its chemical process of oxidation and reduction on exhaust gases.

I agree with Rob post above, I would NOT boost anymore until you add fuel to your fuel map. It should be in the low 12s , upper 11s to avoid detention and to be near the max power AFR (12.3- 12.6 for a turbo). Running a bit richer gives you some margin and cools the mixture a bit more. Another component that can effect AFR is fuel pressure, if it was running correctly before this happened, I would check it first.

 

I drove it around yesterday out of boost with the MAF plugged in and it threw a code finally. Ill pull it and see what it says and go from there. Thanks!

 

Goodstuff, keep us updated

 

Sounds like it needs a throttle adaptation and a handover. Whats the fuel trim like?

 

any updates?