Running very rich and stuttering BAD

[Skate4life_066]

hey guys i picked up a 1g today. i started it up and it started fine, but then i took it for a spin and it wouldnt rev past 3000 and it sputters really bad and runs really rich. i left it running and got out and put a paper towel in front of the exhaust and it turned black almost completely. the car idles almost perfect with little studdering. i am not getting any CEL. i took the plugs out and looked at them. they are completely fouled but do not have any oil on them. the bov is vented. i was looking at the vacuum lines to make sure they were all connected right and i noticed that the dude that had the car before me has the boost guage vacuum line t'ed off into the vaccum line that goes from the intake manifold to the FPR sensor and then to the FPR. now i thought that the FPR needed its own seperate vacuum source (but i wasnt sure). so i was thinking that the FPR could be stuck open or something and thats why its running so rich. besides the boost guage, the car is all stock with all vaccum lines hooked up. i havent done a boost leak or compression test yet but i will this weekend. do u think i should take that boost guage vacuum line off and run the line from the intake manifold straight to the FPR? please help me. thank you

 

[bling5tatus]

Won't rev past 3k? Maybe a tps? Did you do a boost/vacuum leak test?

 

[AndrewD5418]

Take a look if the mass is connected.

 

[Skate4life_066]

no i havent gotten a chance to, im going to this weekend. yes my mass is connected. I took the intake pipe off to check shaft play and hooked everything back up tight and secure.

 

[4Motion4g63]

Is it hard to start?

 

[AndrewD5418]

Maybe the mass is dead then? Big boost leak?

 

[chanley talon]

Sounds like it needs new plugs and wires to me !

 

[Skate4life_066]

the car is very easy to start, as a matter of fact its consistent with taking 2 cranks to start. i pulled the plugs out one by one while the car was running and the wires are good because it was sparking across the valve cover. each time i took one out u would be able to tell that the engine was running on 3 cylinders so i dont think its the wires or plugs. im still thinking its the FPR.. any other suggestions? thank you for the ones you gave guys.

 

[RSTurboFWD90]

Take a look at the ECU capacitors for leakers.

 

[MY 1G DSM]

CHECK the ecu like RSTurbo said also What is the BASE timing At....If you have a Timing light check it out ...

 

[Skate4life_066]

i know this might be a newb question but as you see by my "reputation" i am a newb....anyways, what am i looking for when i look for "leaking caps"? i will go pull it now and take pics and u guys can see if they are leaking if u want cause ive never had experience with leaking caps. would leaking caps cause the car to run like that? thank you for the feedback

 

[MY 1G DSM]

You should be able to tell If you pull the ecu If there leaking just take the cover off and look buy the end of the board buy the wiring harness If they leak they eat at the board.....Do you have timing light? I resontly replaced a freinds ecu to fix a similar problem The caps were Bad but the Timing was also Off and it was choking on timing....

 

[MY 1G DSM]

I have picture of a ECU that had leaking Caps From My 90 GSX that I could post if you still can't tell were to look

 

[Skate4life_066]

ok i took it apart and looked where my1gdsm told me to. there is a little bit of white residue....is this from leaking caps? no i dont have a timing light but im sure i can get to one, and yes i would love it if u posted pics of yours that was leaking

 

[Skate4life_066]

i have 2 90 awd's so im going to take the ecu out of the one that runs good and put it in the one that doesnt to see if thats the problem today.

 

[Eastwood95]

It sounds like a boost leak. Do the boost leak test first man. You need to check all of your couplers and intercooler piping for cracks/holes/leaks. Once you start boosting, the intake air is escaping somewhere before it makes it into the engine, so the fuel doesn't have enough air to combust with. The unburnt fuel is escaping through the exhaust.

Why has no one mentioned that yet?

Anytime you have black smoke (unburnt fuel), and stuttering, a boost leak is most likely the culprit.

 

[TuRBoTaLooN]

nobody noticed that he said he's venting his bov without a blow through setup?? if he's venting, that air is not getting back into the intake pipe after the MAS. The car thinks there is more air so it adds more fuel. however, that extra is not getting back into the motor, but it's still getting that extra fuel. hence: running rich.

 

[Skate4life_066]

yeah but ive vented my bov on all my cars and thats never been a problem... thank you eastwood i will check it out.

 

[TuRBoTaLooN]

yeah but ive vented my bov on all my cars and thats never been a problem... thank you eastwood i will check it out.

I'm sorry, maybe I am wrong. But if you do not have a blow through setup and are venting your bov on this car, then your ecu is NOT reading the correct amount of air. How do you compensate for that?

 

[Skate4life_066]

3 inch maf?

 

[TuRBoTaLooN]

3 inch maf?

that will work. i didn't see it in your profile so I assumed you had the stock mas.

 

[Skate4life_066]

yeah the car is bone stock. thanks for the input though.

 

[GVR4592]

nobody noticed that he said he's venting his bov without a blow through setup?? if he's venting, that air is not getting back into the intake pipe after the MAS. The car thinks there is more air so it adds more fuel. however, that extra is not getting back into the motor, but it's still getting that extra fuel. hence: running rich.

Only between shifts and at idle, it won't affect wot.

 

[nc90awd]

definatley sounds like a boost leak. I would check all the turbo/intercooler hoses and clamps.

 

[Eastwood95]

1G's are pretty finicky when it comes to venting. I haven't seen many that can do it without major idle issues. As the wiseman said, it will really only affect between shifts and idle, which doesn't seem to be his problem.