My car goes rum-rum-rum at idle (not any more - sorted!)

Post Fri Feb 10, 2012 6:57 pm

Just as the title says really. Rather than the usual constant purr at idle, mine is rum-rum-rumming constantly. It doesn't pull well at low revs either and although smoother higher up the rev range, doesn't seem to be pulling as well as it should?

Whatsamatterwi'it please?

Post Fri Feb 10, 2012 7:00 pm

http://www.e30zone.net/e30zonewiki/inde ... ake#Idling

Post Fri Feb 10, 2012 9:46 pm

Thanks for the advice guys - I'm planning a full service tomorrow, so I'll check these things over.

Post Fri Feb 10, 2012 9:49 pm

PeteE30Tourer wrote:Just as the title says really. Rather than the usual constant purr at idle, mine is rum-rum-rumming constantly.

Whatsamatterwi'it please?

You didn't buy it from a Pirate, did you ?

Post Fri Feb 10, 2012 9:59 pm

mine does this but i have m50 engine and seems to be ok when i unplug maf so i suspect that for my problem , have you tried this for yours?

Post Sat Feb 11, 2012 1:44 am

gooner1 wrote:
PeteE30Tourer wrote:Just as the title says really. Rather than the usual constant purr at idle, mine is rum-rum-rumming constantly.

Whatsamatterwi'it please?

You didn't buy it from a Pirate, did you ?

Mine must be the cheapskate model,it goes beer-beer-beer!

Post Sat Feb 11, 2012 8:32 am

Har-harrrr Jim-lad! Perhaps it would run better on rum.

I'll report back later with my findings (on fixing the rum-rum-rum, not if it runs better on rum).

Post Sat Feb 11, 2012 8:38 am

If you havent fiddled with anything recently the most likely cause is a split air intake boot from the AFM to throttle body.

You need to remove it to check it.

There are several different ones available from the dealers so make sure you get the right one.

It can sometimes be difficult to get a proper seal on each end of this boot particularly on the AFM if its "dropped" slightly - you need 3 hands - one to hold the AFM in the correct position, one to hold the bellows in the right place on the AFM and one to do up the jubilee clip.

Post Sat Feb 11, 2012 3:55 pm

'Hunting' is the phrase you're looking for

Post Sat Feb 11, 2012 4:26 pm

PeteE30Tourer wrote:Just as the title says really. Rather than the usual constant purr at idle, mine is rum-rum-rumming constantly. It doesn't pull well at low revs either and although smoother higher up the rev range, doesn't seem to be pulling as well as it should?

Whatsamatterwi'it please?

I may have missed the engine some where is the thread?

After checking for simple things as mentioned above, split afm2tb boot, perished blanking plug underneath the TB, perished FPR to inlet manifold pipe, then I'd check the operation of the TPS, possibly it's not registering idle, mine used to rock the whole car side to side at traffic lights before I fixed and reset the TPS!

Post Sat Feb 11, 2012 5:04 pm

As many of you suspected, it was the boot that connects the AFM to the TB and ICV - well and truly split. When I pushed the splits closed, the engine idled correctly. Too late to catch the dealers today, so I bodged it with some black silicon gasket gunk, having cleaned/degreased the boot first.

Checked the blue temperature sender whilst I was at it - performed as it should.

So, pleased with the car running properly again, I treated her to a wash and polish - and fitted the iS lip spoiler that's been sat in my shed for ages. Chuffed to bits now.

Thanks to everyone above who offered their help.