E46 n42 318ci, rough idle, revs by itself

[elboffor]

So i bought this car a month ago and it has a few issues.

The main one I'm tackling at the moment is rough/speradic idle, and now an oil leak.

When I got it, the car ran fine.
I bought torque and an odb reader and noticed some codes, thats when i started digging (wish now i had lived in ignorance)

The car was underpowered at low revs and thowing codes that pointed to the vanos solenoids.

I bought new o rings and set about cleaning them and changing the o rings.

I noticed however that the cable for the intake was plugged into the exhaust solenoid. And the intake solenoid was not plugged in at all.

Hazzaaar i thought, easiest fix on the planet. I plugged them in correctly, did an oil and filter change for good measure and started her up.

The idle now has a slight misfire on idle but when it reaches full operating temp it exhibits some very strange behaviour, the car revs itself slowly up to about 1800 rpm and then drops back to about 1000. This doesnt always happen when you go to idle, but it does most of the time ( i look like an idiot revving at lights for a race or something).

I have also noticed that now on start up i get smoke from the manifold from the right hand side (uk drivers side) which appears to be oil leaking from the rocker cover gasket (valve cover to my american friends).

In an attempt to fix the idle situation i have changed the MAF and air filter (no change), also the boot that goes to the throttle body. Cleaned the throttle body also (still no change).

So the issue still remains.
If the engine is warm or completely cold, i can run the car fine with the MAF or vanos solenoids disconnected and there are no more issues, not even the oil leak!

If the car however has had a short run and not reached full operating temperature then it won't start afterwards correctly (idles at 500 and dies) unless i plug all the relevant parts back in and clear the faults, butthis puts me back into the idle and oil leak situation.

No faults are showing when everything is plugged in but it exhibits this strange behaviour :/

I plan on changing the cvv and asociated pipes and also the rocker cover gasket. (Just waiting on parts)

Any and all help would be appreciated to resolve this peeps, i really dont want to have to go to the stealers for them to charge me mucho monies to play about at and most likely still not fix.

Thanks

[dworthy]

Welcome to the Forum!

With the rough running, that would point more to a vacuum leak in the system.

Do you still have the old MAF? What brand did you buy? Have you tried to clean the old MAF using MAF cleaner?

Something else I had noticed that happened to a similar car, but it was a TI - There was oil in one of the DME connector, check that too as that car had a funky rev problem.

That rocker cover could be causing your vacuum leak, get it replaced as well as the inner profile gasket.

I have seen either of those vanos solenoids go bad, but it was showing a code. Can you watch live data with Torque? I don't use it so I don't know, but you want to see what the DME is requesting and what is actually happening.

[elboffor]

Thanks for the reply.
A vac leak was my thought tbh.
I cleaned the old MAF with circuit cleaner and the replacement was an oem bosch. Exactly the same issue.
Having investigated a bit more however and i have found a crack in my rocker cover near coil 1 which is pissing oil out into the well around the coil and dripping off the side and is the cause of the smoking.

New cover has been orderred and will be fit
I did notice however that one of the bolts had been snapped and the head is missing near the centre not the edge.
Most likely done by the same fool that used gasket in a tube instead of the propper rubber/plastic gasket and over tightened the plug at the front causing the crack.
Undecided about whether to bust out the dremel to try and get the bolt out or hope the new gasket seals fine without it :/

Will respond here with my findings either way.

Also pulled the air return pipe from the cvv to the intake and it has oil on it so the cvv is eother clogged or mullered so im still going to change that.

[elboffor]

From a quick google, the dme connector is for the auto gearbox. This is a manual, unless im missing something?

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Also i responded in full but its gone to mod to authorise the post :/

Looks like i got a crack in my cover so orderred a new one that should be here early next week.

Debated super glying it but its a hell of a crack (about 4 inch)

- - - Updated - - -

Also, thanks fir the reply
Its much appreciated

[dworthy]

No worries mate, as being new sometimes your posts has to be reviewed.

Just replace the rocker cover, as it is only plastic and the old one will just continue to break.

Yes open the Electronic Box, next to your brake booster, and you will find the DME in there. It will have a black plastic cover with 4 Torx screws holding it in place.

[elboffor]

Cool, will do one thing at a time (process of ilimination) to be honest the engine bay is clean as hell, doubt its got contaminated but after the cvv n cover thats next on the hit list.