maroguy1

I took the car out after changing the fuel injectors and it killed and would only run if i floored it. Brought it home and the plugs were fouled. Adjusted the fuel pressure from 50 psi to stock 38 and the same thing the plugs are covered in gas and it barely runs. I am lost. Now the fuel in jectors are slp 22lbs. I had 19 lbs on it and it ran fine. It is a 357 vortec heads with a mild cam.

jfreeman74

Your computer thinks you still have 19 lb injectors. That is why you are running so rich. You have to reprogram the eprom to 22lb injectors.

Viprklr

iTrader: (5)

Not necessarily so. I had less mods on my 355 with 24lb accells on stock 19 lb programming and didn't have his problem. I ran rich but definitely had no driveability or fouling problems.

thirdgen88

I agree with freeman.. When I put my E-tec TPI together with SLP 25lbs injectors, just for fun I tried to see how it'd run with the stock 350 chip (for 22# injectors).. It wouldn't start.. Changed the injector constant and the cylinder volume size (cyl volume not as critical since it only was from 350 to 355), and it started... Ran very rich at that point (after tuning now all is well), but at least it ran...

PS: not only does your computer think you still have 19# injectors, but if I'm not mistaken, that would mean it also thinks you have a 305... time for a chip..

thirdgen88

Also, Viprklr, since you have less mods (stock heads, cam?), that may have been the reason you were able to squeeze by without changing programming (although I'm sure it doesn't run very well like that)..

Viprklr

iTrader: (5)

I'm just speaking from personal experience.
Also, I would think that me having less mods at that time would have accentuated the rich condition.

Firebreather

No computer programming should be necessary by going from 19 to 22#. Maybe the AFPR is wasted

1bad91Z

iTrader: (1)

Computer tuning IS necessary!!

The only other thing it "could" possibly be is you have one or more injectors stuck open. Make sure you can wiggle (slightly rotate) all injectors back and forth. If you cant, then they are too tight and the injectors might be in a bind causing them to stick open. Also, you need to immediately change the oil. Chances are too much gas has seeped passed the rings and into your oil. This will thin out your oil and you could spin a bearing.

You DO need a PROM chip programmed for your motor.

Firebreather

Well, I have 24# injectiors in my car and last week went from 19 to 22# in a Formula and everything was ok. None of us have reprogammed computer. Stuck open injector/s or bad AFPR is my guess. A bad ignition system could be the problem as not all the mixture is burnt properly. That happened to me once. No SES??

jfreeman74

I disagree. Right now your ECM is using a larger pulse rate for the 19# injectors. When you use 22# injectors with the same pulse rate you are dumping a lot more fuel into the intake because the injectors are staying open more. The purpose of the constant is to lower the pulse rate and allowing the injectors to open and close normally. Right now your 22# injectors are staying open more than they are staying closed which causes you to run rich.

jfreeman74

The car may run but I would be willing to be if you take it to a dyno where they check A/F ratio you are running rich.

maroguy1

Ok thanks for the replies, I fixed it this weekend and found it the instrument cluster blew the gauge fuse. I will probably need a new one. I changed the fuse dropped the fuel pressure put in a custom burned chip and it runs pretty well. Have to fine tune it though. Thanks for the replies.