E30 Zone

had a 2.5 engine rebuild, run sweet for 2 weeks,

now on idle it is a bit jerky.

when i give it gas really quick on and off, it stuters and then revs.

before would rev freely .

also the exhaust note sounds more racey.

whats the problems, all help apreciated

many thanks

When you rev the car doe sthe needle drop down below the normal idle speed, and then take a while to settle down before idling ok?
Without seeing the car sound like the AFM or the idle control valve but like i said without seeing the car could be anything

Describe the idle, low, high, hunting, rough?
Rough idle check:
air filter
blue temp sensor
valve clearances
ignition system
High idle check:
tps
icv
vacuum leaks
blue temp sensor
Low idle check:
tps
icv
air filter
Hunting idle check:
tps
bad wiring to all sensors
icv
big vacuum leak
maybe cps

Also is this intermitant or always there, only when hot, cold or both

it idles fine.

but every 3/4 seconds it grumbles.

left parked will just run the same always

when your driving and change gear the revs go up then down, when the clutch is pressed.

this problem always there. from start to finish

having the same problem mate.blow my head gasket got a rebuilt cylinder head with a cat cam fitted. the the engine struggles when idel the whole car shakes plus it exhaust sounds like its misfireing. no 1 has yet to tell me what the problem is.

check ur idle valve as my car would jump forward at hight revs and the revs would just drop down then re idle after couple seconds

So this is not really an idle problem but a general running issue. Was it sudden or did it just get worse and worse over time. When you say the revs increase as you press the clutch what rpms are you talking about, changing gear at 4000rpm or 1500rpm as that makes a big difference to what your problem can be. The rough idle sounds like it could be a vacuum leak making it run lean which would explain revs hanging on low rpm gearchanges, but if you just rebuilt the engine I would assume all gaskets vacuum hose, breather hose and inlet boot would have been replaced?

Any update on this problem? Have you fixed it or have any new information?