I have a 1995 Camaro Z28 with 150,000 miles. In the last couple of months when I started the car it would idle rough then after about 10 seconds it would smooth out. Now the car fails to start. When I start the car it turns over but does not fire. If I keep on the ignition I can roughly rev the motor, but once I let go (disengage the starter) the car stalls.
So far I have changed the fuel filter, checked fuel pressure and checked for spark. I checked for spark by buying one of those $10 in-line spark light testers from Kragen. I am suspecting either the opti-spark, coil, or plug wires. Does anyone have any advice or suggestions for diagnosing the problem. Thank you for your time.

 

Do we assume since you said you checked for spark and you suspect it's either opti, coil or plugs wires, that means you didn't see spark?

The answer to where to look depends on where you DIDN'T see spark. If it's at the coil but not at the plugs, obviously the problem is either the coil wire to the opti, the cap or rotor, the plugs wires or the plugs. But keep in mind there are 8 plugs and wires. The chances of a few of them going at the same time are slim.

If you don't have spark at the coil, then you check for voltage, ground and trigger to the ICM. Depending on what you find then, test accordingly.

Also you said you checked fuel pressure. How? With a gage or some other method? Remember that pressure is only half the equation. You still need pulses to the injectors.

One last interesting fact. If the trigger signal to the ICM were a problem, you would have no spark at the coil, obviously. The PCM would set a DTC42 which inturn then shuts down the injector pulses. But the SES will NOT turn on.

A DTC 16 due to lack of low resolution signal from the opti to the PCM will also not set a SES light. But that would shut down the fuel pump so if you have pressure, that is not the likely problem.

The point is, even if you don't have a SES, you may still have DTC's so the first thing to do is scan it. If you don't have access to a scanner, do the above checks.

Make scanning it the second thing to do. The first thing to do is check the voltage from the positive cluster to the engine block with a multimeter while someone cranks the engine over. Be sure it does not drop below 11 volts.

 

Speedy,

Thanks for all the info. Took some more time and individually tested the plug wires, when I came to find out that one of the wires had been chewed thru. Dang squirrels like plug wires I guess. Have any suggestions on good wires and plugs. I was thinking of NGK and taylor wires. Thanks again.

 

One plug wire is not going to keep you from starting the engine. It will run like crap and back fire possibly but it will start. You probably have another issue.

I just bought but have not installed what I think are THE best wires available. The Granatelli's.
http://www.granatellimotorsports.com...kplugwires.htm
They have actual stainless steel wire for as close to 0 ohms as is possible. But they come at a price, a big one. And if you continually have a problem with critters, no amount of wire on the inside is worth that.

Why don't you try a regular set of wires and try putting steel mesh sleeving on them for a while to see how they hold up against the critters.
Then decide if you want the expensive ones later. Just a thought.

 

Well I purchased some cheap Jeg's 8 mm Red Hot Pow'r Wires and will give them a shot this weekend. I agree that it should start even with one plug down. I checked the fuel pressure with a gauge at the shraedar valve and have 40 psi when the system is pressurizing. The in-line wire tester lights up for each of the other plug wires that survived the critter hostilities.

I am thinking about buying some Granatelli wires for my 2001 Silverado HD. I read an article in Super Chevy that dyno tested a 5.3L V8 Silverado with the wires and they gained 7 rwhp.
Will post again after installing the wires this weekend.

 

Well after a solid day of work, I changed the plugs and wires. I also drained all the gas in the tank (by using fuel pump relay) and put fresh 91 octane in it. Engine continues to turn over and I am able to rev the engine while starter is engaged, but once I left of the ignition car dies. After many tries, i did get the car to start and had it idle for about 10 minutes. During this time it idled fine! I shut off the engine and tried to restart, but it just cranked as before. I have 40 psi pressure at the fuel rails with no bleed off. I have spark at the coil and plugs. I have swapped batteries and tried a jump start.

Anyone have any suggestions?

 

Could it be your loosing contact at the ignition switch? Perhaps it makes contact as long as you hold it there but looses it as soon as you let go.

See if you have voltage at the coil and the ICM with KOEO.

 

Thanks Speedy,

I will try checking the voltage at the coil with KOEO. While cranking the motor, I placed a plug in the coil wire and get good spark.

 

Finally think I have narrowed in on the problem. It appears to be the ignition key cylinder or the igntion switch. When I turn over the ignition the key starts, but it dies after I let the ignition go. By keeping the key turned over to a position in which the starter is not running and yet not where the car dies.
I am thinking that this is the cylinder as opposed to the switch. Any suggestions will be helpful?

 

There's a write up on Shoe's website for replacing the ignition switch.
http://shbox.com/ignsw/ign_switch_repl.html

 

Thanks for all your help Speedy!

 

did u ever get this figured out or fixed?oing the same thing....

 

I will be replacing the switch this weekend and will keep you posted on the outcome. I figure it is either the switch or the key cylinder.

 

Well I replaced the ignition switch and the car starts-up and idles fine, but now I can't get the key out of the ignition. The cylinder does not want to go all the way back to lock the steering wheel. Also, it seems that the auto trans shifts into Drive fine, but it does not engage into reverse.

I am thinking that in must be something to do with my parking cable that goes into the ignition switch.

 

Adjusted the A4 parking cable per Shoebox's website and everything seems to work fine now!