A mile or so after starting out to a restaurant this evening the car intermittently seemed to "cut out" a few times -- at one point setting off a flashing dash and (I think) blinkers! Car really bucked at that point for 15 seconds or so, then settled down.

Drove the 3 miles (I think 3 episodes) and had dinner (1.5 hours). After dinner, started car and it seemed to idle rough and low for 30 seconds or so, and one time stumbled slightly on the ride home.

Got in the garage and checked for codes. There were none.

Some other info --

• LT1 M6
• misty evening tonight
• drove in rain last night and car felt a little rough (very subtle). Never had any problems in rain before
• checked battery cables and they seemed very tight -- did not remove or retighten, however
• several weeks ago, cruise control stopped working one day -- and worked the next -- has worked since except for one highway stint last week but worked when restarted that day
• car has ~120K miles
• no mods
• no water pump leaks; original opti

Anybody ever have these symptoms and come up with a fix??? Sure could use some advice so I don't throw money at this thing which I certainly can't afford at this point!

Thanks

 

I would start with checking the fuel pressure and inspecting the plugs and wires.

Other than that, original opti at 120K....

 

When was the last time you changed your fuel filter? At night, in a dark garage, with your vette running, pop the hood and look at your plug wires for spark gaps. Its a place to start....good luck.

 

I'll be the odd man out and disagree - you have a bad ground someplace.

If it's flickering the dash lighting and the Signals, and the Cruise is acting up at times - well, it isn't the fuel filter...

I would start with the connections at the battery (yes, loosen and re-tighten them), then at the engine block, then the Frame lead, then the harness grounds on the back of the heads, etc. Right down the list including the hard to find one (I forget the harness identification #..) near the drivers side door post on the inside.

Then the main firewall connector behind the battery, etc. Somewhere in there you will stop it from happening...

 

Could be anything for ignition to a faulty fuel pump.

You need to go through each system and figure it out.

1st thing to do is pull the codes.

 

Thanks folks -- a few observations re some of the comments might narrow it down a bit:

"pull codes" -- did that last night: no codes

"pop the hood and look at your plug wires for spark gaps" -- did that last night after posting and doing a forum search: no spark gaps.

Also, had car out today (still slightly misty) and nothing happened. It seems slightly on the rough side but no idle surging or anything like that. So, it's wait and see for it to act up again (I'll try to be even more attentive to the specific symptoms). But, in the meantime I will follow rons85's advice to painstakingly go through the ground connections -- this weekend most likely. I can find their locations in the Helms manual, correct?

Thanks again -- what a great forum

 

Many years ago I was driving along in my 92 and it went completely bat****. The gauges went wild, the tach just froze. It still ran, but ran like ****, and then as quickly as it had come on, it went away. It did it to me again when I hit a pretty bad bump in the road. The only thing I could figure that would cause as many instant problems was the ECM. I replaced with with an advance auto parts reman and have never had a problem since.

 

Yes, the ground points will be identified and their locations listed (and in most cases shown in diagrams) in the Helm book.

I say "in most cases", because... For the '85 (at least) one of the ground points in the Instrument cluster circuits is G201. This is stated to be located "behind I/P, near LH side of steering column". It is the Only ground point that does NOT appear (that I've been able to find) in a diagram anyplace in the manual.

In reality, that ground point is randomly placed (apparently) Somewhere on the drivers side of the car. On My '85 I found it to be hiding behind the plastic interior trim close to where the lower door hinge attaches to the body structure. Note that this is nowhere Near the steering column

Since That was a pain to reach (required the lower trim surrounding the door opening to be removed) I re-located it to the base of the A pillar where the little support bracket for the dash panel is screwed on.

Doing that, and probably "fixing" what must have been a "no ground" condition at that point, cured the inoperative cruise control in My car, and also eliminated the tendence of the cluster illumination to blink out, once in a while (becoming more frequent, which is what sent Me on the big ground hunt in the first place...).

That ground point Should be redundant. It's one of two ground paths that are provided for the LCD panel (the "front" one of the two large circuit cards in the dash cluster) and the Cruise circuit board (which is "piggy backed" in the cluster assembly). While I had that cluster out (and apart) during this exercise I went ahead and soldered a wire to the "finger" connection (the ground lead) between the two cluster boards and ran That New wire to the relocated G201. Shouldn't have needed to Do that, but it's now Surely grounded. And the problems I was trying to fix are gone.

 

I'm assuming it did not throw a code when it happened to you? I've been wondering about the ECM for some time -- just call it a weird instinct...