Interesting issue.

Fri Oct 22, 2010 12:56 pm

I'm having a really bizarre experience with my car atm that's kinds hard to explain.

Basically the car revs but intermitantly the drive isn't there. It's a rapid on/off sensation as if I'm rapidly dipping the clutch in and out. The engine revs like it should though and it seems to run perfectly fine the majority of the time but occassionally I'll have this odd issue.

Has anyone got any ideas please?

TIA

Ant

Fri Oct 22, 2010 1:24 pm

Could be a failing ignition coil or loose engine earth strap, causing intermittent sparks.

Fri Oct 22, 2010 2:46 pm

Would the engine still rev normally if it was a dodgy spark? It's an M40 btw if it makes any difference.

Fri Oct 22, 2010 3:38 pm

or look at the DME relay, located on the bulkhead on your car, they can work loose and cut power to the ECU. what does the tachometer do when the mis fire happens?

Fri Oct 22, 2010 4:18 pm

The rev counter behaves as normal, as if it's reving through the range as normal. The speedo also seems normal but does not tie in with the rev counter (if that makes sense) so, if my revs are at what I should be doing at 40 in say second I'm actually traveling at more like 20.

Fri Oct 22, 2010 4:36 pm

Are you talking of the infamous 'kangarooing' phenomenon, where it judders when coasting along in traffic?

Many E30s do this - there's a thread about it.

Fri Oct 22, 2010 4:47 pm

Coasting as in not in gear? if so no, mine only seems to do it when in gear with my foot on the accelerator.

Fri Oct 22, 2010 4:49 pm

distributor?

Fri Oct 22, 2010 5:21 pm

Banjo1981 wrote:Coasting as in not in gear? if so no, mine only seems to do it when in gear with my foot on the accelerator.

No, I meant just driving along slowly in traffic in say 2nd or 3rd gear, whereupon it will develop a juddering/shunting, making it awkward to drive smoothly.

Fri Oct 22, 2010 6:00 pm

I had this issue on a 316i years ago found out it was a leaking slave cylinder ended up changing the clutch as it covered it in brake fluid.

This only happened when the clutch was hot ie when in stop start traffic.

Fri Oct 22, 2010 6:07 pm

Speedtouch wrote:
Banjo1981 wrote:Coasting as in not in gear? if so no, mine only seems to do it when in gear with my foot on the accelerator.
No, I meant just driving along slowly in traffic in say 2nd or 3rd gear, whereupon it will develop a juddering/shunting, making it awkward to drive smoothly.

Ahh. Then no, it's a seperate issue to that.