Sauser85

Ok. . I have been on here many times posting about my 97' Z28.. there is still a problem with the fact that very time it warms up, it dies and does not want to restart. . or when you shut it off it does the same thing. . hell. . even when you start it and sometimes just hit the gas to hard it dies then too..when you try to restart just sits there and cranks with no intention of firing. . it's also got great fuel pressure. . now it's been in the shop for about a week. . i know i should do the work myself but i have neither the time nor tools. . anyway they have replaced the distributor, opti, coil, ICM, Crank sensor, and have tried running on the computer and still no sign of codes. .the only code it shows is the random multiple missfire.. and that is from the hotcam that was put in when the motor was rebulit.. if anyone has any ideas please pass them on. . or more questions that may lead to a solution to this problem. . thanks

Green96Z

What brand are these sensors being replaced? They should all be replaced with GM, because over-the-shelf sensors are crap and can break fast. And why are you getting a misfire after a cam install? That's not right, considering it was installed correctly. Were the timing marks lined up on the timing chain sprockets? Was the opti installed correctly (hard to screw this up on 95-97 cars)? Make sure the plug wires are all routed correctly.

dangalla

when it messes up disconnect the MAF sensor and try it again. another sensor to try would be the coolant temp sensor

i would not have replaced any of the parts you say they replaced, i would get the car out of that shop and take it to a shop that has half an idea of what they are doing

Blacksmith

if it's not the opti, it may be the cam is too big for your engine. you can't just stuff any cam into an LT1. i read that all the time in chevy high performance. some guy cams his engine with the wrong spec cam and BAM, car becomes an instant turd.

dangalla

from a hotcam?

Cook Performance

It sounds like the shop you have your car at has part replacers working there. Get your car out of there quick. If they have replaced all of these parts and they have not fixed your problem, you should not have to pay labor, only for the part. I dunno, maybe your car has multiple issues? Is it lossing spark, fuel, injector pulse, all of the above?

dangalla

i cant emphasize this enough, none of those parts should have been replaced for that problem, get your car out of there

Sauser85

well so far i am not paying for anything. . as far as the spark issue, the computer showed the left side cylinders were firing weak. i know this much. and the fuel pressure is steady 41-47 psi.. i have never heard of a problem like this

jasonface

Sounds more like electrical gremlins than fuel delivery issues, especially since you show good steady fuel pressure. I had a friend with weird stuff happening with his '96 TA, and eventually traced it to a bad engine ground. Since your engine was out for a rebuild, first make sure all the ground wires were properly reconnected to a solid ground point. A solid ground connection is critical for the computer to properly function, even if your grounds seem to be connected, you may have an internal short in a ground wire (which was my friends' problem). The Hotcam shouldn't cause random multiple misfires. You say the computer shows left bank is firing weak, so if you can get access to a wiring schematic see if you can identify anything that ONLY cyls 1-3-5-7 have in common (sensors, grounds). When you try to restart, and it shows no intention of firing, are you watching the fuel pressure at that point? If FP is good, check for injector pulse. If you have good pulses to the injectors, then you almost certainly have no spark, which is what I would lean towards considering your weak left bank issue. Does the car run fine cold? I assume you've checked the possible mechanical causes such as making sure the timing marks are properly lined up, valves adjusted properly, plug wires are correctly routed?