Ignition Hassles }{ LT1 Ign Sys

[lt1firebirdslp]

Read below for the full deal.

Year: 1994
Make: Pontiac
Model: Firebird
Engine: LT1 V8 5.7L
Transmission: M6

Symptoms: Car just started to have a "seizure" while I was driving. RPMs were not stable. Tach would bounce wildly up and down from 500 RPM to 5000 RPM. The engine sounded like it was missing. I was trying to get it home, and it was backfiring and all. I get the car into my driveway and its idling absolutely crazy. Missing, speeding up, popping. Finally it just died. When I went to restart it, the engine would roatate but would not start. I left the car for about 10 minutes. The car started right up with a very mild flucuation in the idle.

Codes (DTCs):

16 Ignition System Problem
Loss of Low Resolution Pulse Signal

36 Ignition System Problem
Loss of High Resolution Pulse Signal

42 Ignition System Problem
Electronic Spark Timing Is Grounded

84*Output Driver Module Fault
Skip Shift Circuit

*-The skip shift code has always been there since I have gotten the car. Skip Shift Eliminator.

Verdict: I'm 99% sure this is the 4th OptiSpark I will have to replace in this car. The engine has 148,000 miles on it and leaks oil like a siv. Most likely I will have to pull the engine and just rebuild it. But for now I just want peace of mind that it is the optispark. Any advice comments etc would be great. Thanks guys!

[1bad2k2ta]

I am not that familiar with LT1s, but everything you stated leads me to believe it is the Optispark.....I would bet a paycheck on it.

[AAron]

94s in the camaro arnt the most reliable. i would look at one of the replacement optis

dynaspark or something like that, i lost the web address

[Alex94TAGT]

Few thoughts:

1) Don't worry about the DTC 84.

2) The DTC 42 is typically a problem associated to the Ignition Control Module (ICM) mounted behind the ignition coil, or otherwise the wiring running to/from the ICM. However, I'm going to assume for now that it's being thrown simply by default of the DTC 16 & 36 codes, so ignore it for now.

3) The DTC 16/36 codes are the most important. The optispark distributor has two functions -- primary and secondary. The Primary circuit consists of a photo emitter & optical sensor, which reads slots on what's referred to by electricians as a 'chopper wheel'. This is essentially a cam positioning sensor, and it has both a high and low resolution pulse.

Long story short, the PCM isn't reading the optical signal from the optispark. Without that signal, the coil wont fire, the injectors won't fire, and the fuel pump won't prime.

So, either the optical sensor is shot within the optispark, or there is a fault in the optispark wiring. If you have a digital voltmeter, I can explain which wires to probe at the PCM to check for continuity in the harness. I would also recommend that you inspect the harness for corrosion. If you're on your fourth optispark, it's very possible that the problem isn't the opti -- it might just be a wiring fault.

Beyond that, if it IS indeed the optispark, you may have some underlying problem causing it to fail (installation issues, moisture/coolant leaking into the housing).

[94m6hardtopz]

my buddies was eating opti sparks like candy, the pcm was shorting them out. also check the fuel pressure just to make sure, but its more then likely ignition related. if the opti is getting oil on it thats not helping. ive got a 94 and put an opti on at 72K. they arent the POS everyone makes them out to be.

[lt1firebirdslp]

Wow lots of good info. I know for fact that my crank hub seal (lowest seal on the timing cover right behind the crank pulley is leaking like a siv) is leaking. The whole bottom half of the opti is drenched in oil. My guess is the oil eventually just made its way inside of the opti. I dont know if I should rebuild or reseal the engine. Im going to need to do an oil pan gasket, timing cover gasket, etc. I just redid the whole upper half of the engine about 20,000 miles ago new intake gaskets etc. That works fine it seemed to have just made the bottom leak more. Any suggestions would be great. Ill try to post some engine pics to let you guys see what im seeing.

[94m6hardtopz]

hows the pcv valve, if its plugged then its possible resealing the top made the bottom leak more. if the motor is in good shape id just do a reseal.