Ok, I have read a bunch of these same scenario posts, but here is my question that is different. I was driving along and about 5 minutes after I started the car I hit the freeway, got to 70 mph and then the car dies. What was weird is the radio still worked but the speedo and tach went to flat nothing and the check gauges light was sort of really faint (I think it is the check gauges light, the top right red one). No codes as of the first stall I don't think, so then it was still in gear and I coasted to the side pulled it out of gear and stopped. Stated it back up and it went 5 more minutes and then the same thing. This time after I stopped, I tried restarting and it chugged/pinged/backfires a little threw a code (I will read what it was tonight) and then caught and I revved it and it sounded fine and went to idle fine again and I drove on for 2 minutes this time and then same thing, dead. I had it towed home after that. I will read the code tonight, but since it was not thrown the first time, I am sure it is a standard code not related to the stall but related to it chugging. Anyway, what I want to know is, wouldn't the tach and speedo keep running if it was something simple like a loss of fuel pressure? I was thinking electrical at first but most posts point me to fuel delivery problems. Anyone had a fuel problem and had these same symptoms?

Thanks!
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94 Z28 Conv. M6 64,000 Stock

 

If the engine died the tach would not work, but the speedo should work since the sensor for that is in the transmission. It could be fuel related the pump not keeping up with demand. A quick check for fuel pressure would solve that. I agree about the code, chances are that will be related to the stall / starting up scenerio, check it to make sure. The only thing else that can be would be the opti spark taking a dump on you. That at least would throw a code.

How's the charging system working? Low battery, low output from alternator maybe, just check the basics first. Just throwing ideas out there for you.

 

Can anyone confirm what happens when the car dies at about 70 mph and coasts. Should I still have speedo readings and not tach? If that is the case then I am back to thinking it is an electrical problem.

Thanks again!

 

How much gas do you have in your tank? If you are low and hit the pedal hard enough for the car to jerk back it might shift the gas enough to stall the car. Happened to me... lots of chugging for a while with 1/8 tank left and then i hit it hard and it died... sucked because I was out of gas then but the gauge said i still have a fair amount left.

 

Good on gas. Almost full actually. (But I did have that happen in the 94Z I had before this one. The gauge said I had 1/4 but it was empty.) This was happening consistantly and then starting back up, I will get the codes read this weekend and check on some of the things from other posts. Cold here in Ohio, but I gotta get it back running.

 

Check the coil wire for white build-up...seen that cause it to die unexpectedly. Also check any/all electrical connections you can access.

 

I think this is an electrical problem - I have had my engine stall at 50mph and the tach went out, but the speedo kept working with the electrical systems.

However- you were in gear and coasting with your foot off the clutch in 6th gear and the engine stopped turning? Just to clarify that.

Find that code tonight, that'll get you in the right direction. Also be sure to note WHICH light went on. You should know (if not, go look and figure it out... to be sure. Dont guess on that one)

 

my car did that when the opti went, could only get it to drive about a mile, but drove perfect in that time then just died, let it cool for about 15 min start it back up drive it again and it'd die

 

Most people would be upset if it was the opti, but I have done 3 on my old Z and can do them pretty quickly. But on my old one I had code and a distinct bad idle between 1800 and 2200 RPM. Above and below that and I was fine. But I do know people say differnt things, some get a pop and and nothing after that. Some get all around bad stuff. So I havent ruled that one out yet either.

 

Sorry, did not answer the clutch question. It was the same with the car in gear and when it died, it was in 6th gear and my foot not on the clutch and nothing (started to pull car to stop, but not hard), not tach or speedo. Upon seconds later pushing the clutch in and pulling it to neutral, nothing still.

 

Sounds a lot like what happened to me after my top end rebuild, I forgot to put that heat cream on the back of the ICM (little black thing under the coil) and the heat killed it. I lost my tach but not my speedo.

 

Ok, I hope this helps. Here are my codes from free scan. See this site for the screen captures - http://www.tsrmarketing.net/freescan.htm

16 LO-RES FAILURE
36 HI-RES FAILURE
42 EST GROUNDED

I have been reading around here and this I guess would indicate OPTI failure maybe? Any ideas.

 

Post those codes in a fresh thread.

 

Sorry to say that, but codes indicate the opti

 

Thank to all for the help. Changed the Opti and the Coil (water pump too)and all is OK now. I think the Coil was fine, I am betting the Opti was the suspect.

Thanks again to all!

Tim
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94 M6 z28 Conv - SS Hood - 97 wheels - K&N - 66.5K and now a new OPTI