Help! Oh no...Opti Spark failure possibly?

[MCNE]

Hello,

It's been a while since I've been on the forum. I've had very good luck the vette over the last few years now with about 70k on it.

Anyway down to the issue. Driving along today with the wife and the vette just stops...like the ignition was turned off while driving. Pulled over and the car would not start but it was turning over. After I pushed it into the shade I tried starting it one more time and bam its running. Running, but rough as hell. Well it didn't last a block and down it went again and would not start from that point on. Had it towed back to the house.

Need some assistance troubleshooting this problem. It will turnover just fine but it’s almost like it’s out of gas which it is not. My first thought was the darn opti-Spark has reached the end of its life. Did not recently wash of get the car wet at all. In fact if its going to rain I don’t even bother driving.

Thoughts?

1996 Black Vette with 70k. All original with the exception of the mufflers and the rims.

Thanks,

MCNE

 

[gmjunkie]

First thing I'd do is check and see if it has fuel pressure!
Should have 41-47 lb as soon as you turn the key on with in about second or two!! If you have to turn the key off and back on a couple times to get it.The pump is going south!

 

[MCNE]

Ah yes good idea! I'll see about picking up a fuel presure gauge ASAP. I have the service manual so I should be good on where to connect it.

 

[Schrade]

Codes.

 

[sstearns2]

Another easy thing to do is to Ohm check the fuel injectors.

Scott

 

[Itshakes]

Try replacing/inspecting the coil wire--on both ends--look at the boots carefully. The coil wire on our '96 was damaged on the Opti end, the boot was split, and was shorting on the water pump.
This is a simple repair.

 

[MCNE]

Codes.

Where is the best place to get a scanner for the codes? I was planning to just go to the local autoparts store due to time. I'm moving in about three weeks so I need to get the vette fixed so it can be shipped.

 

[Schrade]

Where is the best place to get a scanner for the codes? I was planning to just go to the local autoparts store due to time. I'm moving in about three weeks so I need to get the vette fixed so it can be shipped.

Auto X-Ray just went on eBay for $29. I missed it :cry.

Stick a paper clip in the ALDL socket; see what comes up:

Gotta' agree with ya' on that one uh huh. (not really confusing tho')

From here...

Sequenced Code Recovery - 1994 through 1996:
In 1994, Chevrolet went to a 16 pin ALDL connector in preparation for the federally mandated change to the much more capable OBD-II (On Board Diagnostics - Version 2) system.
As with the 1990-1993 model, you can display codes on the speedometer but the pins to be shorted are different:

Beginning in 1994, you short pin "12" to pin "4" and once again turn the ignition switch to "On" without starting the engine.
The speedometer will display any codes using the same protocol as the 1990-1993 model but there are some changes in the designation for the modules plus additional modules are added:
Module "1" is still the CCM module.
Module "4" is now called the PCM module (Powertrain Control Module) because automatic transmission computer control was added to Engine Control Module in 1994.
Module 7 (on the 1996 model only) is the RTD module. (This is the Real Time Dampening module which replaced the Selective Ride Control module in 1996).
Module 9 is the ABS/ASR module number from 1994 through 1996.
Finally, Module "A", the DERM (Dynamic Energy Control Module --- the air bag control module) will be requested to show any codes.
Just like the 1990-1993 display, you read the codes on the speedometer and read the module number on the trip odometer.
Again, you can cause the codes to repeat by turning the ignition off for five seconds and then back on.
Turn the ignition off and remove the short to restore normal operation.

 

[MCNE]

This is what I get when I shorted those contacts:

H31-38...1 below with nothing else
---
9 ---
A ---
1.0

That's it. Not sure what this means if anything. Also if it would still be beneficial to have a scanner to troublehoot with.

Additional info: Tested the fuel presure and I'm getting nothing. Trying to track down the fuses to check them under the hood.

Thanks!

 

[Schrade]

This is what I get when I shorted those contacts:

H31-38...1 below with nothing else
---
9 ---
A ---
1.0

That's it. Not sure what this means if anything. Also if it would still be beneficial to have a scanner to troublehoot with.

Thanks!

H (history, not C (current)) 31 CCM module is LCD circuit fault. H38 is LCD - CCM circuit fault; circuit open or shorted to ground.

By 31-38, do you mean you have ALL, 31, 32, 33, 34, 35, 36, 37, 38???

Then you have just '---'. It showed a '4', before this? Or '7'?

M9 looks clear, A DERM is clear too, 1.0, diagnostic display test over.

 

[Schrade]

Double check these to make sure they are CCM codes, not PCM codes. CCM codes come up after '1' displays, PCM codes come up after '4' displays...

 

[MCNE]

I got H31 with a number 1 below it. This happened all the way through H38.

 

[Schrade]

I got H31 with a number 1 below it. This happened all the way through H38.

1 below it? Corresponding to WHERE in this diagram?

 

[MCNE]

Here is a picture. Although now the codes are different.

H54...Fuel Enable Failure?

 

[Schrade]

Here is a picture. Although now the codes are different.

Module 1, CCM codes.

You didn't say if you have ALL 31 - 38? (all are CCM - LED circuits)

54 MIGHT explain the motor shutdown. Fuel enable circuit, and it uses CCM PCM coms link to enable the injectors.

BUT, just before you found the 54, did you allow the diagnostic display to complete, and did you turn off the ignition?

To make sure, clear all CCM's here

Then do diags again, and see if 54 returns cold.

 

[MCNE]

H54 did not return. C12 was the code.

 

[Schrade]

All codes are cleared until closed loop.

The H31 - H38 ( you still didn't say if you DO have ALL of them), are all CCM - LED circuit links.

This could be a loose harness connector in the back of the dash LED panel, or, POSSIBLY, a shorted CCM ground (although I'm not sure of that). Check the harness connector first. Spray LIGHTLY some petroleum/lube on the connector pins to stop oxidation at the contact, then re-connect.

Then drive, and see what happens. Earlier I said closed loop. Wrong. Closed loop doesn't affect this circuit. 'Tard

Can't think straight when I gotta' get a grub on.

 

[MCNE]

Not a problem thanks for the help. No I do not have all of the codes any longer. After the reset I only get C12 so H31-38 are gone. As well as H54 now. The car wont start so I can't drive it. Based on the test I tried earlier tonight I can't get any pressure on the fuel test gauge. Looking like I need to troubleshoot the fuel system...oh boy.

 

[Schrade]

No fuel pressure?

Do you hear the pump prime the rails when you turn on the key?

FP fuse good?

Check FP relay. Check for 12V into FP relay. Got volts? Check to see if 12V will ground out through the circuit. Someone here will know where the relay is.

Start there for fuel diags.

 

[MCNE]

I can't hear anything most of the time but the darn battery was getting really low. Where is the FP relay located? Been searching for it to test. looking in the book now for it as well. FP 10a fuse tests fine no opens.