I have a 1994 Camaro Z28 that is having a problem. I know it's electrical but I don't have any idea what it is. Last week I went for a drive and on the way back home (cruise control 70 down the interstate) the car started messing up slowly at first but getting worse. Along with this problem, the tachometer was jumping around a lot. The engine wasn't actually doing the said rpms either. If I gave it the gas the tachometer would jump really fast and pretty much max out and then jump back down when I let off, but the motor wasn't, it was acting like it was going to die and eventually did and I had to pull over. After that it wouldn't start but had the check gages and service engine soon light so I had to pull it home on a trailer and let it set a few days. A few days ago I went out and it started right up. Now it won't start again. Please help. I need this car to work...

Check the Alternator first--- also check with the guys on 4th gen site they know alot about that stuff

The alternator is fairly new and the battery stays charged really well. No problem lights on, wipers on, radio on at a stop idling.

With key on , can you hear the fuel pump run? If it will run , can you get it to some place like autozone that will put the scanner on it and look for codes. Is this the LT1 or LS1 type motor? If its Lt1, the optispark could be saying good bye.

I already tried to code it and it didn't come up with anything. The motor has just been rebuilt and almost everything is new including the not so awesome, really expensive optispark.

can you hear fuel pump run?

check for a bad ground at the injector harness...the computer might also have a feedback ground reference from here...check the grounds for the computer as well, but being the motor is freshly installed, i`d bet it was the former rather than the latter...also check the connector plugs to make sure they`re tight...let us know what happens...

Thanks. Also for zdld17, yes, the fuel pump does run.

Hope he hurries back! The news is on but I can't leave this thread! Gotta get a life.:o

check for a bad ground at the injector harness...the computer might also have a feedback ground reference from here...check the grounds for the computer as well, but being the motor is freshly installed, i`d bet it was the former rather than the latter...also check the connector plugs to make sure they`re tight...let us know what happens...

That's very good advice.

Use star washers on the terminals, and clean the surfaces.

It's amazing what a flaky ground will cause on those.

I checked the grounds and their all good. The car still will not start. Any other suggestions? I really appreciate your advice.

I've seen similar problems happen on a couple different cars first turned out the computer got wet; in this case the computer was under the driver’s seat and got loose. Once on the floor it was fare game to water. I have also seen an air temp sensor caused this exact problem, in this case the ground surface was bad, but it did exactly what you described happened to you and it took a couple days before going bad. :confused: The sensor I'm talking about was right off the air filter on this car. The guy had painted his engine bay and painted the grounding surface of the sensor took a couple hours to find it being as it was all together. Cleaned the surfaces and rebonded them worked like a champ. That one didn't show on the scan either. I don't know if this helped any, but good luck

Thanks. I'll look in to it.

Let's see, a shot or two of starting fluid in the computer box oughtta do it just like I used to do to my dizzy cap years ago when it got wet!!

Probably NOT......................

pdq67

Let's see, a shot or two of starting fluid in the computer box oughtta do it just like I used to do to my dizzy cap years ago when it got wet!!

Probably NOT......................

pdq67
So,,,,,,, pdq, you enjoyed the fireworks show, did you?
In the rainy northwest we use WD40.:yes:

Fred,

I've sprayed Starting Fluid in my damp/wet dizzy caps many times through the years, but I always let them air dry out at LEAST 5 minute's to keep fireworks from happening!!

I'd go so far as to sniff them to make sure they were air-dried!!

No, I was just bi-chin' about how EASY it is to fix a point dizzy vs an ECU!!

pdq67

PS., years ago when I as driving a beater dizzy equipped car, I kept the following in it at all times...

Jumper cables;
Starting Fluid;
Quart of oil;
Jug of antifreeze all mixed up; and
a small toolbox full of handtools..

You never know.......

I checked the PCM, even replaced it with one from another z28 with same results. I also tried a coil and ignition control module from another z28. I did find today that the car is not starting because it is not getting a spark. I checked for voltage on the coil wire to the distributor. It was about 12 vdc, definitely not even close to the voltage needed for a spark. So, the signal is getting to where it needs to be, but the coil is not stepping up the voltage near enough, however, I checked the coil in accordance with the haynes manual, which said the coil was still good, plus, I know this because of the known good coil and ignition control module I used. Help!!!

maybe a bad hall effect sensor in the distributor???

My "old" 87 Silverado with TBI acted like the fuel injection died but it was because the distributor pickup and module went bad. The computer didn't see any point in squirting fuel if the engine wasn't turning over. Just something to bring a different perspective.

yeah, the hall effect sensor tells the comp when the engine is spinning and when to fire the plugs(the module that is)

I decided that I'm going to go ahead and replace the opti. I'm on opti #2 about to put it together. How can I make it so that it doesn't form any moisture inside. My water pump did not even leak at all on my last opti, but somehow, when I took it apart there was moisture inside. Is it condensation? How can I prevent this? Replacing this opti is sure getting old.

does the starter turn the engine over???
I checked the grounds and their all good. The car still will not start. Any other suggestions? I really appreciate your advice.

Yes. The car starts now. I found a faulty connection (the one that goes into the distributor, imagine that). Now I'm just having the rpm problem that I talked about in my first post.