jims95z28

Just got my Camaro back together after performing the following mods:

• LE2 cam/heads
• Trick Flow 58 MM TB
• 32# Delphi injectors
• PCM Tune

On the initial start-up, the car fired right up and idled. On the initial test drive, the car ran OK with the exception of the idle being a little buggy. I did a couple of WOT runs shifting at 6300 rpm and it ran great! Cruising back to the garage after about 5 miles on the highway (60 mph, sixth gear), the car started backfiring, losing power, and stalling. It would restart, but would barely run. After getting towed back to the house, I began to diagnose the fuel and ignition system using info found on this site. Fuel pressure was good, spark was good, and all voltages at the optispark and ICM harnesses were within spec. Also used a noid light to verify injector pulses from the PCM. Now the car just cranks and occasionally will pop like it wants to start. I swapped in a spare ICM and coil that came off a running car, but no change. The opti has about 100k miles on it and I installed new Delco cap and rotor about 1000 miles ago. I also went back and verified that the valves were set correctly and nothing was bent or damaged.
Any suggestions on where I should look?
Thanks,
Jim

Jaxem

iTrader: (3)

Compression test?

jims95z28

After I wrote the post, I started to consider a head gasket failure. I'll be checking the compression tomorrow. It's going to be a challenge getting the fitting into all of the spark plug holes. Gonna be a bummer if the heads have to come back off.

hrcslam

Did you loctite the rotor screws in the opti?

LT1FirebirdSLP

iTrader: (2)

Sounds like what happened to my car a few hours ago. I'm actively putting my 24x shopping cart together.

In short... it sounds like your opti is done for. FWIW, my motor was completely rebuilt less than 5,000 miles ago (looks brand new, squeaky clean) and I've developed a very slight oil leak on the front of the timing cover. These opti's seem to be so sensitive that even the slightest bit of debris will cause them to stop functioning.

The only other thing you can check is for whatever reason, a hot opti is always less happy then a cool one. If you let it sit overnight, and try to fire it again, it may run for a short while and then die again. If that is the case, it would confirm my suspicions.

The problems you describe in short seem to depict a complete failure of your optispark. Additionally, you've troubleshot all the likely culprits already so unless you have some bizarre 1 in 1,000,000 issue, its probably time for a new opti. Or, do some research on a 24x kit. After a few hours of research, it seems like the up front investment is worth it to stop the endless hemorrhage of money on optis.

jims95z28

The compression test showed no problems - readings were between 155 and 170. That's a relief. Can't remember whether or not I used Loctite on the rotor. I've looked into the 24x conversions but I'm kinda invested in the OBD1 platform with cables, data logging and programming software. I do have a spare Opti that was working when I took it off another motor, so I may try that just to verify that is the problem. Any other diagnosis I can try before I start pulling it apart?

KyleW707

Did you double check the dowel pin length on the cam? If it was longer than spec, it can put too much pressure on the opti and ruin it

jims95z28

The dowel pin in the new cam was the same as the factory cam.

StealthFormula

iTrader: (35)

I had an identical issue in the past, I assumed it to be the opti but turned out my fuel pump bit the dust. These cars can be a PITA to diagnose.

jims95z28

Are there other fuel tests to run besides pressure and bleed down? My plugs were gas soaked when I pulled them for the compression check so I'm pretty sure I'm getting fuel.

KyleW707

if the plugs were fuel fouled, I'd be looking at the coolant temp sensor. When it goes bad, it tel the pcm it is -40 and it will dump a ton of fuel to compensate for what it thinks is a cold start. Unplug the sensor in the water pump and see what happens. You can also pull the fuel pressure regulator line off and see if it has fuel in it. If it does, the diaphragm inside has torn and you need to replace it

LT1FirebirdSLP

iTrader: (2)

I think your wet plugs further indicate a dead optispark. Sounds like your fuel system is operating correctly and when you are cranking, you're dumping fuel into the cylinders but with out spark, your essentially just fuel soaking the cylinders because of the lack of combustion. Try a spark test on one of the cylinder wires if you want to confirm.

jims95z28

Got it running - the optical sensor was bad in the distributor. The inside of the distributor was dry but there was some sign of oxidation on the steel parts. I had another distributor with 150K miles on it that came off a running motor. Pulled that one apart and the inside was spotless and it had the Mitsubishi sensor. Put everything together (with Loctite) and it fired right up. It's idling better too. Need to find another backup now.

I've owned this car since new and it's the first time I've had optispark problems.

Thanks for all of the input.

Purple Poncho

iTrader: (1)

OP, did you try the spark test? I'm having similar problems.

jims95z28

I did, but I just checked it on cylinder #1. Had a nice blue/white spark. Between that, the injector pulse indications, and all of the proper voltages at the opti and ICM harness, I thought it was something other than the opti. Just got back from a test drive and it's running pretty good.

moehorsepower

iTrader: (3)

The spark test is unreliable, I had a problem once where the car wouldnt start, I pulled the #1 plug to check for spark and firing order, the plug would fire on the compression stroke and had a blue spark, after all checking, I replaced the opti and it fired right up...I believe there is a procedure on ShoeBox where he has steps to test the opti..

jims95z28

I used Shoebox's procedure to verify voltages, resistance, and continuity at the ICM, Opti harnesses and coil. All tested within spec. It wouldn't run until I swapped out the optical sensor in the distributor.

Purple Poncho

iTrader: (1)

Car fired up great for 18 years. Problems started last summer. Left the #2 plug wire off and had trouble starting..obviously. Put it back on and all is well. Few weeks later hard start strikes. Only when cold. Warm all is good. Drives great, no problems. No codes.
Park it for winter storage and no start at all. Fuel pressure looks normal, plugs are wet with fuel and I see spark on the plug. Will investigate further. Hope it is not the Opti but I have a Versafueler and bigger injectors.....maybe fuel pressure regulator but FP looks good...seems like the spark is getting drowned out.
Dunno, sorry for the thread hijack.

jims95z28

If you've checked everything else, it might be the optical sensor. My understanding is you need an oscilloscope to check one with any amount of certainty. I've got it down to where I can swap one out in about 2-3 hours.