Okay my 94 Z28 has gave me problems ever since owning it. I replaced the fuel pump and I still think it's something else. While idling my car randomly dies on me, I noticed today that right before the battery voltage started dropping a little and acting funky. So it died at the red light and I started it right back up immediately. Driving a few miles down the highway, probably 5 minutes after dying on me, I went to pass someone and gave it a little more gas, I noticed as my RPMS went up it kinda of stuttered a little. So I let off and then half a mile more down the highway I put it to the floor and gunned it, next thing I know my car just dies. I pull off to the side of the road, and start it immediately again. Any ideas or has this happened to anyone else, and what was your problem? Coil? Wire? Opti? etc...

 

wow, thats a tough one. could be lots of things but it doing its thing once in a while makes it really hard to find. start with basics. check fuel pressure. check every connection you can find. check your grounds, one in front of starter, one under the coil, ground strap going from frame to engine on driver side front of motor, under the kick pad on driver side by the door jamb. check and clean power juncion box wire ends (small red plastic box on passenger side wheelwell by battery) check and clean ground wires to ground junction next to it. check your fuses for any damage or signs of failure. ecm, ignition, gauge fuses for sure. check all connections to coil and coil module. its a start. i think if it was a coil or ignition coil/control module failing it would not start right back up.

 

I had a problem almost like yours. Hearing this it almost sounds like your alternator is going out. Sometimes it will die on you or it will just kill your battery or both.
Check to see how good your battery is next when the car is running check to see how many volts are running to your battery from your alternator should be running about 13-14 volts

 

Thanks for the quick feedback guys. Like one of you said, it could be multiple things, I just don't know if I have the time, patience, or money to figure it out, and it's sad because the car is such a nice and fun car to drive.

But I'll check my battery voltage tomorrow, like I said it gets kinda low sometimes. I've had an alternator go out on a old truck I had before and it just went out all at once. But I'll check on it, I'm pretty sure the battery is fairly new, March of 13 the sticker says.

 

Voltage drop right before the motor shuts off can be deceiving. The thing is these alternators basically stop working if the motor falls below a given RPM. The problem is the RPMs dropping and causing the voltage drop not the other way around. The common issues are dirt in the IAC port, a weak or lazy IAC or an EGR valve that is not sealing and allowing a small amount of exhaust to enter the intake. The “common issues” assume that everything is up to date, Plugs wires, filters etc… All the wear items because many of them could cause the issue.

Small Vacuum leaks can cause issues but as a general rule they cause the RPMs to rise but if the leak is to a single cylinder (intake gasket) it will cause the motor to shake because it throws the fuel mixture off. I have had customers that complained of stalling from it. I never heard of this on a LT1 but it was an issue with the original 80’s TPI system.

If it was mine and everything was up to date I would pull the IAC clean everything, pull the EGR valve clean it and test it for sealing (search youtube for how to) then relearn the IAC per the manual.

If there is ANY other complaint in the drivabilty of the car then the above is not correct. Remember at idle most parts are under very little stress things like coils and fuel pumps tend to bring other issues and rarely just effect a warmed up close loop idle.

 

Okay thanks for the feedback. I noticed today while driving to work that at a redlight, with the brake held in and the car in drive my battery voltage would flutter down a little below the half way point. So I would put it in neutral and it sent the voltage back up some. However on my back home from work the car ran good, no SES light came on or anything. and the voltage was higher than usual and I saw no flutter in it at red lights.

 

You had a SES light on???? dude, that is real important information. You need to see the codes that are stored in the PCM before you do anything else.

 

It might be a long time for a code to pop up. Code readers are cheep and you can get codes read at most auto parts stores. Let's assume that no codes have popped up yet.

I have a '98 so I don't know if my experiences will relate to your problems. I had similar issues and I found it was my throttle body sensor. I had a lot of issues with is before my car threw out a code. Look into throttle body sensor on youtube. There are several ways to test them to eliminate them as the cause.

 

code reader will not work on a 94 and not many scanners will work on it. it is obd1 so even less parts stores have a scanner that will work. heres some info for the op to look at. look at 28 and 29 and whatever else you like here 4th Gen LT1 F-Body Tech Aids
more info on ignition