I have 99' EM1 completely stock, engine runs fine, but when driving on highway like 60-70 mph the engine suddenly dies, no throttle response, after like 5 seconds still driving it suddenly powers again and keeps driving normally, it has done this to me like 2 or 3 times now, no cel at all.. Any suggestions?

 

Check ur Dizzy.......But it could be a few things...thats one for starters

 

Alternator or battery, sounds like to me.

 

Does the engine actually die and must be restarted?

 

I doubt a distributor issue (such as the igniter) would cause symptoms like this, but I may be wrong.

I'd say it's one of two things, loss of ground for spark, or loss of fuel. Either way it's most likely a power connection. Unfortunately I don't know of a sure-fire way to tell. I doubt the fuel pump is going, because fuel pumps generally don't just cut out for a few seconds like that, but it could very well be the ground or power of the fuel pump.

On the flipside it could just as easily be the plug ground. I would sand the engine grounds (3 of them?) very well, and their connecting surfaces, using metal scuff paper, torque them back down nice and tight, see if issue persists.

That's my take on it, anyway, sounds like something is bumping in connectivity. Best of luck, on it.

EDIT:
I'll let you know if anything hits me, but due to the frequency it's very hard to test...and you typically won't get CELs for issues like this, so I wouldn't expect one.

As for the alternator or battery, I would say you're more likely to see issues caused by them at high revs, when you use more watts over the course of a given time period. Highway is pretty low revs.

EDIT:
How often does this happen?

 

well i had this same issue...i had a exposed wire in the dizzy and when it got to hot the motor would shut off...when it cooled down it shut back on...but u are right...it could be other things

 

Thanks for the responses, I just did recently an alternator test to check some VSS issues I just fixed, I disconnected the battery while the engine was running and it kept running.. As for the engine dying it doesn't have to be restarted again I just let go the gas and then 5 seconds later throttle response comes back. I don't know if the engine actually dies because i don't push in the clutch to let it idle, I could check it next time Ron..

 

When the engine becomes non-responsive, do the cluster warning lights turn on? Do you lose electrical power?

 

Eh, if it's coming back on automatically I'd say it's off. Make sure you put it back in gear after you're sure it's off or it won't start again. Also, don't be surprised when the car sounds like it snaps an axle when you let the clutch back out, that's just the RPM going from 0 to 3500 in an ungodly amount of time.

I agree with almotor18, which is why I said what I said about grounds, it sounds like the engine is dying due to a power issue. It could be pretty hard to track down.

Next time it dies make sure your radio is still lit up, make sure you're not losing power to the entire cockpit or we can look more towards the fuse box for a culprit.

 

Thanks a lot guys, I would make sure next time it happens to check all this little details to bring more info to the table..