94 Camaro LT1 A4 Motor is stock. 163xxx miles. I had not driven it in a while (at least a month) It started and was driving well. I stopped to top off the gas. Restart took a little cranking (which is unusual for this car). Drove a few more blocks and the engine died.

Battery is strong. Cranks fast..

Fuel pressure gauge attached to the rail reads a little over 40psi

No indication of leaks around the opti. (Opti, wires, and plugs have about 40K miles on them)

I checked the fuses for the PCM, and fuel injectors..

I was alone and couldn't think of a way to check for spark.

Does anyone have a troubleshooting flow chart for a no start condition for the LT1?

I have Freescan and a cable, but didn't have them with my toolbox tonight. I'll probably try to scan the PCM first thing in the morning.

Any suggestions of what to check and how to check it?

Thank you,
Steve

 

Idle control valve?Water in the tank?My02.

 

Update,

I'm following the Opti and Spark test on Shoebox's website.
http://shbox.com/1/4th_gen_.html#opti_test

I have good voltage from ICM harness terminals A and D to Ground.

Test for AC pulse when cranking from terminal B to ground does not give me any pulse. Voltage stays at 0.

So it sounds like that points to the Opti, harness, PCM, or wiring.

 

Scan it. You may find codes for the Opti low res pulse (no SES light, shuts down fuel system) or a proble with the IC Module.

 

I scanned it using FreeScan and my AKM cable. The PCM was communicating, but it did not display any codes.

While I was trying to diagnose things, I had removed and checked many fuses including the pcm fuse. If I cleared any stored codes by pulling the pcm fuse, would that code return once I try to crank the motor?

Thank you so much for your advice

 

If its DTC 16 for the Opti, it will set while you are cranking. I suspect the codes for short and opens in the ICM circuit will set as well. If you don't have the pulse on the white wire to the ICM, you probably don't have the pulse signals from the Opti.

 

Thanks, I'm getting my Z towed back to my house where I have all my tools. I'll continue trying to diagnose it there. I agree, it sounds like I'm not getting pulse signals from the opti..

Thanks again!

 

Check the Opti harness connectors for corrosion and damaged pins.

 

Update

I didn't have time to follow up on the suggestions for a week or so, but I finally did last night.

I did check the connections for the opti harness, ICM, and coil. All were free of corrosion and appear to be good.

Since it's now parked in my garage I started over re-checking things I had checked.

Fuel pressure 40 + PSI

I have good voltage (12 V DC) from ICM harness terminals A and D to Ground

CHANGED Test for AC pulse when cranking from terminal B to ground DOES give me a pulse when I test it with my analog multi tester on the 10V AC range. My digital tester just reads 0. (I had previously assumed I wasn't getting pulse because I was testing with my digital multi tester)

PCM Scan shows no codes even when I've been cranking the starter.

Ignition, pcm, and fuel injector fuses are all good.

I tested for spark from the coil to ground and I do not get spark.

Even after cranking for 10 seconds or more, I don't smell gass. (kind of expect to smell gas but I could be wrong here)

I read in the opti diagnostic sticky that I can test the coil by measuring resistance across the coil. Does anyone have a picture or drawing showing the proper test points on the coil?

Is there any way to test the ICM?

Thanks as always for your help.

 

i think your on the right track, icm or coil. i carry a spare icm in my center consol.

 

Coil testing.

Many auto parts stores can test your ICM.

 

i have always had great success with this write up http://www.mainstreamtopics.com/foru...p?showtopic=78

 

Thanks Shoebox! My coil's resistence measured about 7.5K Ohms from each of the 4 terminals. No obvious opens. I'll pull my ICM and see if any of the local parts stores can test it.

Thanks, I followed the diagnostic and got to the point where it instructs me to test for pulsing ground at the white/black wire(93-95) at the coil coming from the ICM.

This test failed, no ground pulse while cranking. But I want to make sure I have my test set up correctly.

negative probe connected to the white/black wire in the coil connector.
Positive probe connected to the pink wire in the coil connector.

This appears correct according to the electrical diagram on page 8-21-1 of my helms manual.

I do have 12V from the pink wire to ground.

From my testing, it appears that the ICM is the failure point. I'll take Shoebox's advice and see if a local parts place can test it for me.

Thanks again,

 

Just wondering if you got your car running. My camaro recently started sputtering, backfired, then died. All my test results are the same as yours except I put a new icm on, but still no start. I'm thinking it could be the rotor on the opti...even though its brand new from thepartsladi with about 50 miles on it. I just recently dislocated my shoulder and don't know if I'm up to pulling the darn opti again lol.