2g gst all of a sudden runs lean

[blackhawkgsx]

Hi today i was working on the 2g gst and got a cel it was for map sensor and the o2 down stream so i replaced them both and the cel went off i drove for about 25 miles every thing was fine then the next morning im driving to work then out of no where at a cruise of 55 mph it goes mega lean on my WB (aem) it went 3 dashes then engine sounded like it was studdering this lasted maybe 5 seconds then went back to a normal afr of 14.7-15.2 and the same thing happens every other minuet or so... As of now im lost

Also noticed earlier that day that turbo has a decent amount of shaft play

Mods include 3" tbe , boost controller ,16g turbo (shaft play) walbro 255, stock injectors, stock fpr , aem wide band , k&n air filter and intake, knock off greddy type rs recirculated, avid racing motor mounts

any idea what might be causing this lean condition

 

[gofer]

Hi today i was working on the 2g gst and got a cel it was for map sensor and the o2 down stream so i replaced them both and the cel went off i drove for about 25 miles every thing was fine then the next morning im driving to work then out of no where at a cruise of 55 mph it goes mega lean on my WB (aem) it went 3 dashes then engine sounded like it was studdering this lasted maybe 5 seconds then went back to a normal afr of 14.7-15.2 and the same thing happens every other minuet or so... As of now im lost

Also noticed earlier that day that turbo has a decent amount of shaft play

Mods include 3" tbe , boost controller ,16g turbo (shaft play) walbro 255, stock injectors, stock fpr , aem wide band , k&n air filter and intake, knock off greddy type rs recirculated, avid racing motor mounts

any idea what might be causing this lean condition

From looking at your posted mods list I would think you'd be doing the EXACT opposite of going lean, seeing is how your running a wally 255 fp with the stock fpr and injectors.
Anyhow, when you replaced the MDP did you make sure you seated that o-ring thats on there. The symptoms your describing suggest a vacuum leak around the TB/IM area...

 

[Gamble97]

From looking at your posted mods list I would think you'd be doing the EXACT opposite of going lean, seeing is how your running a wally 255 fp with the stock fpr

This makes no difference on a fwd. It won't have any affect.
I would clean your MAF and check your plugs, start there.

 

[gofer]

This makes no difference on a fwd. It won't have any affect.
I would clean your MAF and check your plugs, start there.

What makes no difference on a fwd? What won't have any affect?

Your cars running lean so its obvious your fpr is doing its job. Be careful though, I'd suggest forking the cash for an afpr in the near future because soon enough that 255 will overun your OEM fpr causing you to run SUPER rich.

 

[2qik4u]

check your throttle position sensor. it can cause the fuel on fuel off situation you are describing...

 

[blackhawkgsx]

Thanks for the input guys I guess i will start with the maf because i have a code for a iat sensor that comes and goes does any one know where that sensor would be located? some one on here said its inside of the maf im not sure i used the search button and my manual and got nothing. I also had a feeling it might be the fpr but not sure why but in between shifts it goes rich like 11.8-12.9

check your throttle position sensor. it can cause the fuel on fuel off situation you are describing...

you might be on to something after driving in stop & go traffic my idle goes from 750 to 1800 and stays there until i drive on the expressway for at least 15 minuets or shut the car off for about 30 minuets



ohh and please note im running about 10 lbs boost

 

[gofer]

Thanks for the input guys I guess i will start with the maf because i have a code for a iat sensor that comes and goes does any one know where that sensor would be located? some one on here said its inside of the maf im not sure i used the search button and my manual and got nothing. I also had a feeling it might be the fpr but not sure why but in between shifts it goes rich like 11.8-12.9



you might be on to something after driving in stop & go traffic my idle goes from 750 to 1800 and stays there until i drive on the expressway for at least 15 minuets or shut the car off for about 30 minuets

Your IAT sensor is a part of the MAF, if it goes bad you've got to replace the MAF itself.

You said it runs rich inbetween shifts, you are recirc'ing your bov right?

 

[blackhawkgsx]

Yes but its a greddy knock off so i dont expect it to be perfect my greddy was old as dirt and cracked on me

Ok cool thanks for the info i will check in to that you guys have been a major help setting me in the right direction ! as soon as its done thunder storming I will go and check this issue out!

 

[blackhawkgsx]

ok so i checked every thing and i had a cel for cyl 3 misfire so i pulled the plugs and they where black especially 3.. so i replaced the plugs and the car runs fine..... the cel went away but now it came back but seems to be running fine although im only running 12psi and i don't step on it so.......

 

[stefanOst]

ok so i checked every thing and i had a cel for cyl 3 misfire so i pulled the plugs and they where black especially 3.. so i replaced the plugs and the car runs fine..... the cel went away but now it came back but seems to be running fine although im only running 12psi and i don't step on it so.......

Did the same CEL for a Cyl 3 misfire come back? Check the plug for that cylinder again, and if it is black once more, you might have a leaky injector for that cylinder, or it might be stuck open, causing that cylinder to run rich and giving you the misfire.

 

[Gamble97]

soon enough that 255 will overun your OEM fpr causing you to run SUPER rich.

On an AWD yes, on a FWD not really.

 

[topekagsx]

I'd check the ecu also...I was having this same problem and it turned out to be the ecu flaking out on me.

 

[blackhawkgsx]

I think it micht be a combo of my wires they are old and came with my car, some of the insulation on cyl 2 & 3 are kind of shaved off with some of the wire exposed.... Does any one think wiring up the injectors poorly will cause this issue because the guy i got the car from does ghetto wire jobs .... im talking yards upon yards of electrical tape and on some things he had the plastic things you twist to connect wires so i fixed most of that......

 

[gofer]

ok so i checked every thing and i had a cel for cyl 3 misfire so i pulled the plugs and they where black especially 3...

That means your running RICH, lean conditions appear as white on the spark plugs... Makes me think your experiencing alittle 255 fp overun since your on your stock fuel pressure regulator and all your plugs are black. Cylinder 3 might have a weaker spark than 1,2,&4 thats why its gunking up first, but your definitely running rich across the board if they are all black dude.

On an AWD yes, on a FWD not really.

W.T.F. does that have anything to do with it? An OEM fpr is an OEM fpr no matter what platform, GS-T or GSX, its the same part. If your running your 255 fp on the OEM fpr it will be overun which is why you buy a afpr.

I'm not trying to be an ass about it but why would an AWD OEM fpr be overun by the 255 but not a GS-T?

I think it micht be a combo of my wires they are old and came with my car, some of the insulation on cyl 2 & 3 are kind of shaved off with some of the wire exposed.... Does any one think wiring up the injectors poorly will cause this issue because the guy i got the car from does ghetto wire jobs .... im talking yards upon yards of electrical tape and on some things he had the plastic things you twist to connect wires so i fixed most of that......

You definitely want to replace any hack job you find from a previous owner, whether it works or not. Those things can work for years until your taking a cross country road trip and NEED a reliable car. If there are any hack jobs (wires not spliced together and TAPED) it needs fixed... ASAP.

 

[blackhawkgsx]

thanks for all the support as of now i have fixed most hack jobs except the fuse box but that's tomorrow...... the car runs a little better and also spools much quicker and runs stronger although im still running my mega shaft playing 16g

 

[sonik619]

On an AWD yes, on a FWD not really.

Please try to explain to me why the stock fpr would matter if it's awd or fwd.