ok, i have a built bottom end boosted gsr. it has been tuned and ran great making 300 hp. now, for some reason, it has had issues. when it is first started and driven for a while it still runs normal. however, after getting on it a few times and getting it nice and warm it starts running like crap. It leans out to about 17-1 when trying to drive, and idles in the 15 to 16-1 a/f. there are no cels so i'm not sure what the cause is.

things i have tried:
new tps
new iat
differnent 3bar map
fuel filter (pressure is staying where it should)

i am going to try coolant temp sensors next.

any ideas? help!

 

n e body?

 

What tuning system are you using?

Have there been any part changes since it last ran well?

All the same tank of gas, or different gas from different stations?

boots gauge reading correct?

On idle hood open, does it sound like a miss or that one cylinder is not firing or partial?


i would pull plugs, see if one is very lean and then check or swap out that injector. my only guess really

 

all plugs look the same. unpluged one injector at a time and each raised a/f ratio from 17 to 20 at idle. so i cant limit it to one cylinder. it has to be sensor, fuel, or ecu related. i'm running out of sensors to change, its got constant fuel pressure.

next things to try: diff. ecu and clean injectors.

any other suggestions?

 

Check for fuel pressure under a load. What are the O2 readings? Look for vacuum leaks....

 

no stock o2, just wideband. no vacume leakes (20inHG on boost guage). i'll liik into the fuel pressure.

 

fuel pressure good. could crank sensor in dizzy cause this issue?

 

Carburetor needs to be readjusted?

Vacuum lines need to be replaced/repaired?

There is something called a PVC valve on our vehicles, each time we have needed to replace one the car/truck was having similar issues as yours.

 

carburetor? really? hope that was a joke :/