Ok my buddy from work has put a lot of money and a lot of time into his 1993 Z28 automatic, Ill tell you all of his mods and then his problems. Ive been reading in this section and know someone can help. Mods are:

255 lph fuel pump
1.95 1.50 valves fully ported and polished heads and intake
3 angle valve job
comp cam 218 224 .495"/.503"
slp cold air kit
58mm throttle body
bbk shorty headers
flow master catback no cat
csi electric water pump
ac delco plugs
he has both stock injectors and 30# injectors, has prob with both
has aeromotive fuel pressure regulator and stock, prob w/ both

The problems hes having is the plugs foul out quickly, they turn black and smell like gas,
smells like un burnt fuel in exaust,
run ok at low rpm's with no load runs ok at high rpms with no load
it bogs down under any load,
and it pops out the pvc valve

Well those are his problems and he has put a lot of time and money in the car and cant figure out the problem, he dont have a computer but Im a member here and know you guys on here cand figure this problem out. Thanks

 

is he throwing any ses light.sounds like hes running rich.id check for any leaks from the exhaust and your o2 sensors.does he have datamaster or freescan?

 

sounds alot like the problems i'm having right now after a cam install. read through my thread...it should be on the first page of lt1 tech right now. it offers all the possible solutions. i have not actually found one to fix my car yet though.

 

I think he does have the ses light on, he said a friend came over with a scan tool and said there were three sensors bad but none of them o2's but the guy said he didnt think they would be the problem. Ill talk to him tomorrow and find out for sure. Would something that simple be the problem? The car wont even do a burnout. Thanks for the fast replies and keep em coming

 

Has he done a compression and leakdown test?? I was having similar issues, fouling plugs, running extremely rich, OK at idle and up high, but it bogged/hesitated under load. I had two bad cylinders that had BAD leakdown.

Just food for thought. It's always good to know.

 

Leakdown? Excuse my ignorance, but could you explain a bit more?

-Dustin-

 

93? how about some tuning

 

I am interested as well as to what could be causing the problem. Let us know what tuning he has....that is crucial, especially since you said he had injectors, etc.

O2 sensors can do a lot of crazy stuff too....Too lean, too rich....they are not expensive to replace, so go ahead and do those, if problem persists you did not use much time or $

 

First check to see what those three codes were for, and fix the problem at hand.
Replace the stock Knock Module with an LT4 Knock Module to eliminate false knock, if your friend hasn't already. With all those modes I’m sure the stock knock module is reporting false knock.

Your friend really needs an aftermarket tuning kit like LT1 Edit, PCM4Less, anything other then the stock tuning. Remember the computer is the brains of the operation and is meant to run at stock conditions for economy.
Don't confuse the brain, it won't know what to do and try to protect its organs...

Hope this helps.

 

Any other suggestions, or would a vaccum or exhaust leak and bad sensor do that much damage, the sensors were deffinatley not o2's though.

 

k... lemme rephrase, you have a 93 there, no MAF sensor, the computer doesn't know wtf is going on, therefore you REALLY need tuning.

 

Sorry man, I didnt know what you meant, I dont have the 93 I have I 99 that im still learning about. Ill tell my buddy to take that thing and get it tuned.

 

MAP sensor? CHeap and quick to do? Does it do it cold AND warm temps? if it does rule out o2s.

 

intake or exhaust leak.

Check the header bolts, they might be backing out. I doubt its the tune. o2's should be fine, unless the power is back at full throttle. The PCM doesnt use the o2's to calculate AF ratios at WOT.

Did it just happen after the install? I got 5 bucks on manifold leak.

 

Well guys Ill let you know after the weekend, pay day is friday and he has already bought a new intake gasket because after telling him what everyone said he was looking under there and noticed the back of the intake had a leak. This weekend he is buying all new vaccum hoses, the sensors that are bad, and anything else that he might see that may be leaking.