Topic

Here's the scenario. It's a lovely sunny day, with temperatures in the low 20's. Perfect for a top down run, so off we go on a leisurely jaunt around the Scottish countryside. About an hour into the run, the rev counter blips to zero. Just a blip. Moments later it blips again, then more frequently. It then stabilizes for a few minutes. I put my foot down (right foot), and the needle drops to zero. When I let my foot off, up it comes again. This can continue for a few minutes until the needle drops to zero and stays there. The car still runs sweetly, and the needle stays on the pin until the car has been sitting parked for a while. This has happened a few times and only worries me because it might be the start of something more serious.
Wondering if anyone has had similar experiences, and hopefully found out either how to fix it, or found that it DOESN'T lead to bigger troubles.

Sorry mate I can't see from your sig or your post whether it is an F or a TF. Do you have any problems with the speedo?

MacGeorge;13721 wrote: wrote:

Here's the scenario. It's a lovely sunny day, with temperatures in the low 20's. Perfect for a top down run, so off we go on a leisurely jaunt around the Scottish countryside. About an hour into the run, the rev counter blips to zero. Just a blip. Moments later it blips again, then more frequently. It then stabilizes for a few minutes. I put my foot down (right foot), and the needle drops to zero. When I let my foot off, up it comes again. This can continue for a few minutes until the needle drops to zero and stays there. The car still runs sweetly, and the needle stays on the pin until the car has been sitting parked for a while. This has happened a few times and only worries me because it might be the start of something more serious.
Wondering if anyone has had similar experiences, and hopefully found out either how to fix it, or found that it DOESN'T lead to bigger troubles.

It does sound like a dodgy connection, and I can't see it being the precursor of something serious, but as Clive says, we could do with a bit more information.

David Aiketgate;13728 wrote: wrote:

It does sound like a dodgy connection, and I can't see it being the precursor of something serious, but as Clive says, we could do with a bit more information.

Sorry, I've been off line for a couple of days. The car is a 1999 MGF 1.8VVC, previously tweaked by Mike Satur to 158bhp, 34000 on the clock. Don't think it was re-chipped (doesn't show on the invoice anyhow).

All other electrics seem to be unaffected when the rev counter dies, and I would agree that it could be either a flaky connection in the wiring, or an iffy joint in one of the magic boxes. But where might it be? That is the interesting question. Perhaps its just a resident gremlin who doesn't like the heat..

It's a shame its not MEMs3, otherwise you could have plugged a USB reader into the system and read the revs from the ECU rather than the rev counter. This would have given some indication as to where the problem was.

Not sure if you can get a reader for the earlier models.

CJJ;14135 wrote: wrote:

It's a shame its not MEMs3, otherwise you could have plugged a USB reader into the system and read the revs from the ECU rather than the rev counter. This would have given some indication as to where the problem was.

Not sure if you can get a reader for the earlier models.

Mmmmm! Interesting thought. Unfortunately ( that means I would have to drive the car for about an hour with each piece of test gear just to find out if it worked. That might be a problem (although a somewhat miniscule one).

If there is such a reader, you could just hook it up to a laptop on the passenger seat. If the rev counter starts playing up then a quick glance would tell you what the live data is doing.

It could be a faulty rev counter or a wiring break somewhere... Its a white and black single wire from the ECU to the instrument cluster that powers it, its earthed with all the rest of the cluster.
The loom that comes out of the ECU has been known to rub through as it passes through the ECU holding cage... worth a look?

Andycolm;14144 wrote: wrote:

It could be a faulty rev counter or a wiring break somewhere... Its a white and black single wire from the ECU to the instrument cluster that powers it, its earthed with all the rest of the cluster.
The loom that comes out of the ECU has been known to rub through as it passes through the ECU holding cage... worth a look?

This white/black wire is an issue it would seem. In another thread I mentioned a problem with the EPAS, and IT is also given important data through the infamous white/black wire. I have checked it at the main ECU, and it looks OK (using thexpression loosely.There is a lot of stuff tucked behind that Engine Managent Box). I did check the wire for voltage at both ends, and it seems good, although I didn'tcheck for data (measured about 6.something volts DC, but there must be either AC or square wave data on there somewhere too).

Wishing that a) I didn't have a paying job to do, and b) I didn't have the constant urge to test drive the little monster - even after I didn't do anything to her. (just a little drive to see if anything changed)

I'm a basket case,I know

macgeorge wrote: wrote:

Andycolm;14144 wrote: wrote:

It could be a faulty rev counter or a wiring break somewhere... Its a white and black single wire from the ECU to the instrument cluster that powers it, its earthed with all the rest of the cluster.
The loom that comes out of the ECU has been known to rub through as it passes through the ECU holding cage... worth a look?

This white/black wire is an issue it would seem. In another thread I mentioned a problem with the EPAS, and IT is also given important data through the infamous white/black wire. I have checked it at the main ECU, and it looks OK (using thexpression loosely.There is a lot of stuff tucked behind that Engine Managent Box). I did check the wire for voltage at both ends, and it seems good, although I didn'tcheck for data (measured about 6.something volts DC, but there must be either AC or square wave data on there somewhere too).

Wishing that a) I didn't have a paying job to do, and b) I didn't have the constant urge to test drive the little monster - even after I didn't do anything to her. (just a little drive to see if anything changed)

I'm a basket case,I know

did you find the problem? im having this exact issue now... whenever the car if left idling for more than about 10-15 mins it starts doing this, then leave it for a further 10-15 mins and the power steering warning light comes on and power steering dies... give it some revs and all goes back to normal...