Trying to help a friend

[yzpilot]

Hey guys. Trying to help out a buddy, and dare I ask a question about a non-Z?? Don't kill me guys. I have a friend on base here that has a beautiful 95 LT1 coupe. He said he has no problems with the car at all until recently. He was driving back from San Diego to the Marine Corps base here and the motor just died. All electical power was still there, and it cranked fine, just the dreaded no start. He came back a few hours later with a trailer, and low and behold it fired right up. Drove it for a bout 10 miles, and same thing. I am thinking a sensor somewhere?? Getting hot and failing? Just want to try and help him out before he starts throwing money at the wrong problems! He said he checked all the grounds according to the manual, and the optispark was replaced about 6 months ago. Any help would be appreciated guys. As I know there are more than a few of you that have a couple non-Z's in your stable as well. Also construction has been started on my paint booth, so I'm excited to get started on doing resto's! First victim will be my Z....many photos to come! It's overdue time to reverse the results of a barn....3 years....a bunch of cats...and a careless Z owner!!!!;)

[mike100]

A paint booth? I have a fiberglass trailer that is in bad need of painting Ha!

I was going to say Opti-Spark, but since that probably isn't it, I will suggest he look into intermittent VATS functionality. (the theft deterrent chip in the ign key).

[ZR-1nce removed]

If he used an aftermarket optispark, I would bet that's it, I went through 3 in my LT-1 before giving up and buying the AC delco one. Good Luck

[LGAFF]

Get the manual out, check the ignition module on the PS head

[GOLDCYLON]

Yep im think OPTI as well.

[yzpilot]

Hey Mike! I was thinking that as well. If I remember right...isn't there a way to bypass that? And yes, converting the garage into my paint booth. I painted for years, mind as well get back into it. So if you need a trailer done...no problem! My phone was crushed last week and I am waiting on sprints super fast service of getting my replacement! But I am definitely still interested in the amps if you still have them. The Z should be back on the road in about 3 weeks! I can't wait!

[yzpilot]

Thanks guys. I need to find out if the opti spk was aftermarket or OEM.

[mike100]

BTW, I still have my factory service manuals from when I had my 95 LT1 if you need to look something up. Didn't seem worth selling them off just to get $60.

[Franke]

If it fails again, can he check for spark at plug wire? Sounds heat related to Opti-spark.

[yzpilot]

Thanks Franke. Thats exactly what I was thinking to do.

[bdw18_123]

I'm thinking Opti as well. I used to have a '93 6-speed LT1 Corvette and I had a very similar issue. Back then, I also initially ruled out the opti as a cause of the failure because I too had replaced the opti a few thousand miles ago at the time.

The Optispark units in the '92 to '94 LT1 Corvettes have such a high failure rate because they do not have an active venting system to remove the buildup of moisture which leads to corrosion and eventual failure of the unit. In the '95 and '96 LT1 Corvettes, GM changed the design of the optispark unit and added the active venting system.

The aftermarket opti that I had purchased went bad because I sealed up the seams with RTV and the corrosive gasses (and condensed moisture too, I'm sure) stayed in and took out the optical portion. But even if you don't do the RTV thing that I did, the opti will sit have a very high chance of failing if the active vent system mod is not done. That opti I bought came with a warranty, so I was able to get it replaced for free. I also purchased the '95-'96 style of opti cap with the hose nipple for the vent hose so I wouldn't have to glue in one like is described in the Corvette Fever article I used (see CF thread linked to below).

Here is a link to a thread where I described my problem in detail and what I did that ended up fixing the "cranks, but doesn't start" problem:

http://forums.corvetteforum.com/c4-tech-performance/2323823-intermittant-no-start-car-has-stranded-me-several-times.html


pcolt94's post in the middle of the above CF thread is a really good one for understanding the role that the ICM and coil play in the sparking system, which helps to narrow down the source of problems with the spark system in the Corvette LT1 engine.

I just edited my last post today in my old thread I linked to above because I never posted the update I promised in that last post.

[Schrade]

If it started up after cooling off, I'm guessing NOT opti-spark.

Opti laser (or whatever the 'light' reader mechanism is), gets fouled by dirt, and occasionally coolant. I don't think a cool-off will allow a fouled opti to read better.

Lotta' snappics here:
http://forums.corvetteforum.com/c4-tech-performance/2069247-merged-fresh-opti-pull-pics-and-ignition-stutter-code-crackers-needed.html
(thread I got CF mods to merge with another CF'er, with identical problem...

http://forums.corvetteforum.com/attachments/c4-tech-performance/47625846d1215271506-merged-fresh-opti-pull-pics-and-ignition-stutter-code-crackers-needed-1coptis.jpg

Did VATS problem get addressed by GM prior to '95?

Sudden shut-off (was he at speed?) seems HIGHLY likely a hot ignition module, which would NOT allow a code to set.

Does he have SES light???????