325i misfire

[andrew1300]

Hi all.
My beloved 325 has started to idle unevenly with revs fluctuating between 500rpm to 1100rpm..Starts off with a little hunt & gradually gets worse. Today i noticed a misfire at around 3500rpm & then it clears if i keep the foot down..
Idle control valve working,air flow meter properly on,checked plug leads ( which were replaced 3yrs ago along with spark plugs )
Feels like it starts on 5cyls at first & then i can feel it smooth out within 5-10 seconds.
Any idea's ??
Thanks

[martauto]

Hi mate, check out the "Wiki" , it`s very good for things like this.

Mart.

[BenHar]

Check for air leaks on the intake side.

You can do this with lighter gas. Spray it around with engine running and if there is a leak the tickover will increase when you spray near it.

Ben

[martauto]

Check for air leaks on the intake side.

You can do this with lighter gas. Spray it around with engine running and if there is a leak the tickover will increase when you spray near it.

Ben

Is it true Ben that Body Spray works as well ??

Mart.

[BenHar]

Check for air leaks on the intake side.

You can do this with lighter gas. Spray it around with engine running and if there is a leak the tickover will increase when you spray near it.

Ben

Is it true Ben that Body Spray works as well ??

Mart.

Anything flammable should work.

Ben

[paultv]

Isolate the missing cylinder on start up...remove one ht lead at a time and find which one makes no difference.

If revs are rising above normal on tick over then there's more air getting in somewhere...so find the leak...could be sticky ICV.....or an AFM issue...clean everthing but also search for an air ingress.

Regarding the hi rpm missing, plug lead failure ( resistor in cable burning out ) grubby distributor cap terminals or AFM track damage/wear.

Good Luck

Paul

[andrew1300]

Thanks guys for the tips..
I’ll start with the plug leads first & go from there. Thanks