Random stalling while coasting after fmic install.

DJ23GSX · 06-29-2008, 02:15 PM

First things first
My bov is recirculating and a 25psi boost leak test showed only one tiny leak

Here's the problem. I took the car out for a cruise last night after the fmic install and it stalled on me 3-4 times while coasting in neutral. After a good pull i'd put it in neutral to slow down and the rpm's would catch perfect at 750 but after say 10-15 seconds of coasting and idling perfectly fine the rpms fall to around 400rpms then the car dies. This only happened about half the times i coasted in neutral the rest of the time it was fine. The car idles perfect other wise and runs excellent under boost and around town. I didn't have this issue before i installed the fmic and i'm kinda leaning towards a tuning issue but i'd like some other advise of other places to check that i might have over looked.

While the car was down for the fmic i also put in 650's cleaned the tb spotless brand new o2 sensor and ported 2g housing. My ecu was also rebuilt a few months ago. My bfp is 40psi.

So far i've had to add 8% on the safc to get the low fuel trim to 100 but that didn't help the stalling. That seems a bit hight to me on a 2g maf and 650's but then again my intake temps were hovering around 112* while standing still. I didn't have a chance to trim my cold air box yet to fit around the filter. I also have a 4 pipe plumbed from the fog light location up the filter so the intake temps drop dramatically once i'm moving even without the filter box.
I also unplugged the isc and the idle raised up to about 1200 rpm's and i tested it with an ohm meter and everything checked out fine.

Someone point me in the right direction please.

Thanks

->PrOjEcTGS<- · 06-29-2008, 02:23 PM

Well, looks like you are adding too much fuel. If I read it correctly your at +8 on the LO setting? I have 650's and a 2g MAS and I am around -10 on the LO just for my idle speed. My guess is that you are just insanely rich and it's flooding it out. When you installed the injectors, did you reset your ECU? When you reset the ECU it will put all the trims back to 100. Then you let it idle till it warms up to temp, and then once your LFT is starting to adjust itself, then make the proper adjustments to get it back to 100.

DJ23GSX · 06-29-2008, 02:41 PM

Quote:

Originally Posted by ->PrOjEcTGS<-

When you installed the injectors, did you reset your ECU? When you reset the ECU it will put all the trims back to 100. Then you let it idle till it warms up to temp, and then once your LFT is starting to adjust itself, then make the proper adjustments to get it back to 100.

Yes i reset the ecu and zeroed out the safc and let it warm up to temp before i touched any safc settings. i also noticed that the higher my intake temps climbed at idle the more fuel the ecu was adding hence my low safc setting at +8% to get it back down to 100.

redtsi252 · 06-29-2008, 02:46 PM

Did you find any leaks anywhere else?

iugrad92turbo · 06-29-2008, 02:50 PM

I had a similar probllem it was a vacuum leak.

DJ23GSX · 06-29-2008, 03:01 PM

Quote:

Originally Posted by redtsi252

Did you find any leaks anywhere else?

only leak was on on of the lines going to the thermostat housing. I actually think the plastic piece they connect to is cracked.

->PrOjEcTGS<- · 06-29-2008, 03:23 PM

Yea it definitely sounds like you have a vacuum leak or leak pre turbo and post MAS. Since there must be air coming in past the MAS and making your O2 sensor believe you are lean in essence making your ECU richen things up. Because your corrections are about 20% richer than you should be on the LO side. Something is wrong with your metering. Are there any holes in your intake to the turbo? That would suck in more air than the ECU would see? Those do not show up on a boost leak test. Also what do your other fuel trims look like. And what are your other settings on the SAFC as far as hi throughout the RPM band? What were your settings on the SAFC before the injector install?

DJ23GSX · 06-29-2008, 03:43 PM

Quote:

Originally Posted by ->PrOjEcTGS<-

Yea it definitely sounds like you have a vacuum leak or leak pre turbo and post MAS. Since there must be air coming in past the MAS and making your O2 sensor believe you are lean in essence making your ECU richen things up. Because your corrections are about 20% richer than you should be on the LO side. Something is wrong with your metering. Are there any holes in your intake to the turbo? That would suck in more air than the ECU would see? Those do not show up on a boost leak test. Also what do your other fuel trims look like. And what are your other settings on the SAFC as far as hi throughout the RPM band? What were your settings on the SAFC before the injector install?

I've always seemed to have to add fuel at idle in this car even with the old 1g maf and 560's. There are no visible holes in the intake pipe itself and the 2g maf has all the honeycombs still in. Like i stated before i was watching the logger while idling and the higher the intake temp climbed the more fuel the ecu was adding. I was seeing 114* intake temps at the maf. My other fuel trims didn't move from 100 yet i've only driven it probly 10-15 miles since the ecu reset and fmic install. It makes sense that i would be sucking in unmetered air since my idc's at 18psi topped out at 86% on 650's and a s16g. I have to pull the intake/filter out later to fix my headlight motor i'll take a better look at it when i do.

->PrOjEcTGS<- · 06-29-2008, 03:56 PM

Have you looked at the reading your getting from the Coolant Temp sensor that feeds the ECU (not the gauge)? People have had problems with their fuel trims if that is bad. Also, possibly you have a restriction in your fuel line. Maybe you have a dirty fuel filter. Which would make it run lean making the ECU richen things up. I'm just trying to throw out possibilities for you man! I have pretty much the same setup as you except I have a 190 not the 255 and a NT FPR. But it's probably a metering issue.

DJ23GSX · 06-29-2008, 04:22 PM

Quote:

Originally Posted by ->PrOjEcTGS<-

Have you looked at the reading your getting from the Coolant Temp sensor that feeds the ECU (not the gauge)? People have had problems with their fuel trims if that is bad. Also, possibly you have a restriction in your fuel line. Maybe you have a dirty fuel filter. Which would make it run lean making the ECU richen things up. I'm just trying to throw out possibilities for you man! I have pretty much the same setup as you except I have a 190 not the 255 and a NT FPR. But it's probably a metering issue.

I did a fuel filter last summer and i put less than 5k miles/year on this car and i've logged the coolant temp sensor and it seems to read fine.

knochgoon24 · 06-29-2008, 04:38 PM

Quote:

Originally Posted by DJ23GSX

I was seeing 114* intake temps at the maf.

Sounds like you need to make a cold air box type thing.

http://www.dsmtuners.com/forums/articles-intake-exhaust/157149-2g-turbo-high-flow-intake-cold-air-box-0-a.html

DJ23GSX · 06-29-2008, 05:52 PM

Quote:

Originally Posted by knochgoon24

Sounds like you need to make a cold air box type thing.

http://www.dsmtuners.com/forums/articles-intake-exhaust/157149-2g-turbo-high-flow-intake-cold-air-box-0-a.html

Thats exactly what i made it just needs a bit more trimming to fit properly. I made it out of sheet metal not cardboard thought. Next time i drive it i will keep an eye on the airflow hz reading either on the logger or safc to see if they do anything wacky when it stalls.