aprotogerellis

A bit of help diagnosing this one please as I don't know where to start (or rather I could start from anywhere!)

I was driving on the motorway yesterday for about half an hour and everything was fine. At some point I accelerated from 3rd gear (full throttle) and after a couple of seconds of acceleration the car very very suddenly stopped accelerating (as if I'd suddenly stopped pressing the gas).

I quickly pulled over and saw that the idle was being a bit erratic (moving up and down). I gave it a couple of squeezes of gas which raised the revs for a second or so and then the engine just died (to my untrained ear it sounded like it just didn't get any fuel).

Yes, the fuel tank is almost full...

I looked around the engine bay, couldn't see anything, started the engine fine and drove another 30 minutes back home without any issue whatsoever.

I thought it may have been the immobiliser that kicked in because I accidentally pressed the button but when I tried it out you can't actually set it off in that way.

So I really don't know where to start looking...

Any suggestions welcome!

Alex

KuHL 951

Sounds like a loose reference sensor connection, loose wire somewhere, or failing DME solder joint. My 83 used to die when I hit the brakes hard at high speed. The motor mounts were just bad enough to move the ref sensor connector and stall. Wire tied the connector together and it never did it again.

Kool

^+1

aprotogerellis

Ok, checked (visualy) the ref and speed sensor and they seemed fine. Cables all where they should be, all in good condition. I removed and cleaned the connectors but I have a feeling it isn't this...

Anything else I can check before I start ripping out the guts of the car?

KuHL 951

If you are sure the ref sensor conector is fine I would pull the DME relay and tap it a few times and plug it back in. If that doesn't work try the DME relay bypass method in Clarks. It would help also if you posted the year and model. I still think it's something electrical that popped loose or failed. Does the tach bounce when you crank it?

aprotogerellis

Oops, good point - shows I haven't been around here for long.

Its an '86 turbo...

DME relay sounds plausible I've got a spare so I'll just replace it.

The problem though is that the issue has only happened once (yesterday) and since then the car's behaving fine... so I may fix it or not, only time will tell..

Thanks!

KuHL 951

Sorry I missed the part where it ran fine after the problem. Replace that relay and spray CRC contact cleaner on the sockets of all your relays. If there is any resistance from dirty contacts things get hinky under higher loads like WOT. Are you sure it didn't just go into limp mode from overboost?

aprotogerellis

OK, now I'm really shoring my newbie-ness... not sure what "limp mode from overboost" is!

I've had the car for a year now and taken it to the track a couple of times and nothing like what happened yesterday has happened before - especialy the whole fluttering and dying bit at the end...

Thanks a lot for the help...

aprotogerellis

OK - reading up on overboost on Clark's... got a lot of checking to do...

Rip It

Sounds like a TPS (throttle position switch), also in Clark's. If its only happened to u once u probably will have to wait for it to become more persistent. Hard to fix something when its not broke.

aprotogerellis

TPS eh?... mind sharing the rationalle? I'd imagine that no matter what happens to the TPS the engine won't die (it may slow down or lurch like it did but it won't die completely like it also did)... missing anything?

Mike C.

I'd throw a can of dry gas in just in case it was water in the fuel.

pjburges

+1 one for the reference sensor. Mine did that erraticaly and it was extremely annoying. Took awile for me to figure it out because everything went back to "normal".

Rip It

TPS eh?... mind sharing the rationalle? I'd imagine that no matter what happens to the TPS the engine won't die (it may slow down or lurch like it did but it won't die completely like it also did)... missing anything?
You are absolutely 100% correct, I made the mistake of trying to help you on the cheap. You probably should go out and buy a new DME. Good luck.

Wipeout

Maybe he just wants to understand why you think it's the TPS because of his (potentially flawed) understanding of how it works.

Why don't you help him to understand by telling him "why" instead of the flippant answer you provided.