94 z28 needs help
Thread Starter
Teching In
Joined: Apr 2004
Posts: 7
Likes: 0
From: IL
94 z28 needs help Hi all, I have a 94 z28 w/t-56 and it ran like a top until..... I pulled the thermostat out and started it up. The OBD1 shut the car down after a few back fires and it has run like poop ever sence. I have sence then put new wire new plugs new optispark unit (the whole thing) and even tried to use hyptech programmerlll to fix the problem. When I say poop what I mean is the car runs very rich and and has horrible smelly exhaust along with that a lack of 50-75hp. I watched a tech use an $8,000 snap-on scanner and showed me that the car is running perfect down to every last sensor, which is a crock cause under a load it miss fires and runs even richer. Ihave sunk around $2,500 on this stupid problem and im getting ready to sell the car if I cant fix it with in the next $1,000.
Mods includ
4:10 rear
MSD coil
Hypertech P3
JET piggy back stage ll
K&N air filter
Pro50 shifter
underdrive pullys
Note I have pulled all the mods but gears and pullys for testing on scanner
PLEASE help any suggestions are greatly welcomed
thanks
Mods includ
4:10 rear
MSD coil
Hypertech P3
JET piggy back stage ll
K&N air filter
Pro50 shifter
underdrive pullys
Note I have pulled all the mods but gears and pullys for testing on scanner
PLEASE help any suggestions are greatly welcomed
thanks
If it's running really rich and like poop, you really need to find out what's going on with the PCM. The only real way to do that is with diagnostic scan tool (or a laptop and scanning software). The scanners only show half the battle - they don't datalog so that you can dump it to a spreadsheet and plot the results over a time period. Need to look at the Ltrims (BLM) especially.
Are you running an HPP and a Jet at the same time?
Are you running an HPP and a Jet at the same time?
Thread Starter
Teching In
Joined: Apr 2004
Posts: 7
Likes: 0
From: IL
I put a new hypertech 160 thermo back in to get the car to start, and yes I am running both the JET and the hpp and to tell you the truth iv tried running the car with just the JET and then w/ hpp and then just hpp and saw nor felt any difference in any of the senerios
I also run a hollow cat with flowmaster cat-back
I also run a hollow cat with flowmaster cat-back
Teching In
Joined: Apr 2004
Posts: 2
Likes: 0
Check to make sure you catalytic converter is not plugged.
My car ran great for a while and then progressivly got worse. Tried several things to see why it ran like crap. Had the cat pulled and it was really plugged.
Car goes GREAT now.
Ron
My car ran great for a while and then progressivly got worse. Tried several things to see why it ran like crap. Had the cat pulled and it was really plugged.
Car goes GREAT now.
Ron
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Originally Posted by jasonsz28maro
or do you think my PCM could have been ruined when the car shut down?? Hoow do I find out?
No, but pull the fuse on the PCM or disconnect your battery for at least 20 minutes to reset the PCM and put it back into learn mode.
Car could also be running "too" cold. You want about a 180 coolant temp. once it's warmed up. Use a scan tool as the factory gauge is inaccurate. I have a '94 as well. You could be sticking in the cold start enrichment mode if you don't allow the coolant temp to get warm enough.
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(shameless plug) Diagnostics?
http://www.akmcables.com - my web site
I wouldn't run both Jet and HPP at the same time. Either / or, but not both. Of course, my real opinion of both of them...
A PCM reset happens after a second or two. No need to wait 20 minutes. On a 94Z, it's the PCM BAT fuse that's in the driver's side of the dash, just inside the door. I believe it's one of the lower right fuses. Back in the way-early days of LT1Edit (almost 5 years ago), anytime I read or programmed my PCM, I had to reset the PCM by pulling the fuse.
http://www.akmcables.com - my web site
I wouldn't run both Jet and HPP at the same time. Either / or, but not both. Of course, my real opinion of both of them...
A PCM reset happens after a second or two. No need to wait 20 minutes. On a 94Z, it's the PCM BAT fuse that's in the driver's side of the dash, just inside the door. I believe it's one of the lower right fuses. Back in the way-early days of LT1Edit (almost 5 years ago), anytime I read or programmed my PCM, I had to reset the PCM by pulling the fuse.
