M52 running problems when hot

Post Mon Sep 03, 2012 11:14 pm

When the engine is cold it runs fine with rock solid idle and pulls smoothly,
as soon as its up to temp after say 5-10 minutes it starts acting up, for instance when pulling up to a junction as soon as i dip the clutch and take it out of gear the revs go up and down quite badly to the point its stalled a few times, this lasts for about 3-5 seconds then it will idle perfect apart from every few seconds i will hear a light dull 'pop' from the exhaust.
If i rev the engine it does it again.

It also seems to be using more fuel, probably as low as 17mpg as opposed to the 22-25mpg i was getting before.

Whether its just me but it does seem to have lost a bit of power, not a massive amount but it just doesnt feel as perky as it used to.

As said this only does it when its up to temp so could the fault be related?

Thanks (in advance)

Post Tue Sep 04, 2012 1:39 pm

Faulty lambda..?

making it over fuel and pop,

it might act ok when its cold because it needs that little bit extra fuel to warm it up,
but once its up to temp it should knock the fuelling back a bit....??

Post Tue Sep 04, 2012 3:07 pm

Is there a way to test the lambda, ie with a multimeter?

Post Tue Sep 04, 2012 8:35 pm

If the lambda sensor is working and doing it's job keeping the mixture correct, the signal wire from it should switch between zero and one volt at least twice a second.
If this is happening the lambda sensor and its associated feedback loop are OK. If it's not happening, this does not necessarily mean the sensor or loop are faulty, since a permanently weak or rich mixture outside the range that the lambda system can correct, will also stop the sensor from switching.

Post Tue Sep 04, 2012 11:01 pm

So where do i start?

Post Wed Sep 05, 2012 8:25 am

Plug it into a puter innit

Drive over if you want mate

Post Wed Sep 05, 2012 10:30 am

I've had this recently, been going crazy to figure it out! Won't be a few weeks till I can get diagnostics on it so let us know if you fix it.

Post Wed Sep 05, 2012 11:41 pm

DanThe wrote:Plug it into a puter innit
Drive over if you want mate

Probably be next week some time, im up to my neck with tiling the bathroom at the min.

You got any E36 front legs/brakes in stock?

Post Mon Sep 17, 2012 9:46 pm

Any results on this Lee? I changed my lambdas and it solved the slight misfire pop and cured it overfuelling but the idle issue remains.

Post Mon Sep 17, 2012 10:01 pm

does it stall?

Post Mon Sep 17, 2012 10:18 pm

If I let it, yes

ICV seems OK but might swap it out for another one I have.

Post Wed Sep 19, 2012 7:49 pm

Finally got to the bottom of it - just had to reset the adaptation values. Can't believe it was so simple.

Post Wed Sep 19, 2012 8:35 pm

No i havent really had time but it doesnt seem to be acting up so much, still not right but ill post up when i get round to it.

Post Fri Oct 19, 2012 9:45 pm

Only a month late.

Nipped over to Dans yesterday to plug it into the puter. Came back with no faults!

So next step, today i removed the ICV to clean it up, the little shutter inside was not seized or tight but i cleaned it anyway but noticed when i shook it it felt loose inside like something was not right, it wasnt the shutter flapping about it seemed more like inside the ICV itself.
So i dug another ICV out off my old engine, cleaned that out and compared the two together, the iffy one id took off definatly didnt sound right.

Anyway ICV swapped over and now the idle is rock solid!