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Car suddenly running extremely rich

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marcmsj

15+ Year Contributor
1,414
14
Dec 20, 2004
Laurel, Maryland
I was doing a few 3rd gear pulls on the highway last night and during one of the pulls, the car jerked a bit so I let off the throttle. While I was cruising, I noticed that the car was running extremely rich. My air/fuel ratio gauge was almost pegged at the richest value and it didn't want to seem to go into closed loop while cruising. I pull over and didn't really find anything out of the ordinary. Car was running so rich that it would just stall.

Fuel pressure is where it's supposed to be, fuel pressure is ocillating with vacuum as it should. intercooler pipes are nice and tight, and no vacuum lines are disconnected. Any ideas on what it could be? I had to turn my afc settings to -20 all across the board and it's still sitting at .89v while cruising. all fuel trims are at 81.9%.

i'm open to suggestions....
 
There could be a couple of things

I hope your in FLorida or something because there is like 1 1/2 feet of snow here in ma, cars run crazy shitty in that weather

-Maybe an o2 sensor went out
-Is you CEL on? Even if its not, check to see if any numbers came up.... doesnt neccesarily have to come on
-are you recirulating the BOV?
-double check the MAF harness
-Check the ground wire on the battery
-Do a boost leak check
-Check your spark plugs to see if they are bad (gap them at .28)

Hope this can help you find your problema.

-PAUL
 
thanks for the reply but I pretty much checked all that already.

all the maf sensor's signals are getting to the ecu so that's not a problem. O2 sensor is relatively new (about 2000 miles on it). Plugs looked fine but I have a new set that's gonna go in sometime this weekend.

as for the snow, the roads are fine down here now. we only got around 4-6 inches in some places.
 
well, being as though this happened so sudden i would assume that rather than a part went bad, there is an electric problem somewhere, so you have the fuel pump, fuel line, fuel filter, fuel rail, then injectors, now for controlling these things what do you have? a upgraded ECU, safc 1, a-fpr, you checked the a-fpr, did the mas sensor or the coolant temp sensor come loose? I think a boost leak would help find the answer though.
 
looks like my upper intercooler pipe was disconnected from the intercooler... :coy:

i thought i had checked that but aparently i didn't check that well enough.. that's what i get for trying to work outside at night in 20 degree weather.

either way, problem solved. thanks guys.
 
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