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325_driver

e46 Rough Idle

33 posts in this topic

Just putting the feelers out first, but going to start looking into specifics, and probably when i'm next down at the work shop see if theres any fault codes.

in the mean time,

When I start my car and the engine isn't warm I have a rough idle (9/10 times), if i put the pedal on the throttle and get the revs above 1000 rpm seems to be ok, but if i let it idle, or like im reversing or idling along in gear it's pulsing between 500-700 RPM, sounds rough as guts.

I'm leaning to think that maybe there are some common vacuum leak places others might aware of that I could start hunting round for? 

Once the car gets running - if i stop the car, the start it (anywhere in the next few hours) it's perfect.

Any suggestions? What other idle problems have others had in the past - Symptoms similar to this?

m54 in a 2002 330ci

 

Edited by 325_driver

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There is a myriad of postulations on this one online.  I've had exactly the same on both M54's I've owned.  In the end I suspect on one of them it was VANOS O rings.  But I'd start checking and cleaning easy things first like unplug and plug in all electrical connectors you can find, Intake hoses/tubes, MAF clean, throttle body and idle control valve, CCV hoses, coolant temp sensor, then VANOS.  I did all of the above with my current M54, and all sweet.

And on mine, the longer it was left without running (days) the more likely it was the roughness occurring and also the degree of roughness...

Hope it helps...

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hmm, 

yeah wonder if maybe something MAF related

might get some WD40 and spend another week showing this car some more love

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Did you mean - in the end you did your Vanos + all the other things and was resolved?

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Yep as above, clean and check,  a smoke machine makes goes along away. I always seem to find leaks from DISA valve o-rings on the few M52\M54 engines ive put the smoke thru.

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39 minutes ago, 325_driver said:

Did you mean - in the end you did your Vanos + all the other things and was resolved?

In the end I think it was just the VANOS (not 100% sure)  but that just may be in my case...  It's a transient issue on cold start so not likely to be the type of thing that would cause issues all the time like a leak or something.

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34 minutes ago, hqstu said:

In the end I think it was just the VANOS (not 100% sure)  but that just may be in my case...  It's a transient issue on cold start so not likely to be the type of thing that would cause issues all the time like a leak or something.

oh yeah - i've been doing some reading about vanos - it is possible with symptoms that it could be it, since it runs on oil pressure related things, with very fine seals and pistons.

Guess i'll start the journey - Check those DISA valves too thanks Eagle

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The M54 retards the cam timing like crazy at cold starts to dump heat into the cats - if the Vanos seals are stuffed (and they pretty much ALL are, unless replaced with aftermarket) it struggles to maintain the timing and also shift the timing to the required angle when you use the throttle.

Our Vanos seals were so bad, the car was super easy to stall when cold (manual, obviously & only 115K on it back then), because it couldn't pull the cam timing back fast enough to make any torque.

You NEED to check the DISA anyway - if it's rattly, it can lunch your engine if it falls apart.

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As above would pay to re-build the vanos. I had the same problems with my e46....rebuilt the vanos unit with all new seals and she ran perfect again. Definitely worth doing a rebuild on.

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Before replacing any parts, or diving into a vanos rebuild... remove parts up to the throttle body, inspect everything along the way for cracks. Clean ICV and throttle body. Inspect CCV hoses while you’re there. 

 

I teplaced my CCV whilst doing this as well. No more rough idle. I will replace the vanos seals when I get back to NZ too, but the CCV difference was enormous and the throttle body and ICV cleaning were clearly necessary in my case.

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On 10/12/2017 at 1:23 PM, Gabe79 said:

Before replacing any parts, or diving into a vanos rebuild... remove parts up to the throttle body, inspect everything along the way for cracks. Clean ICV and throttle body. Inspect CCV hoses while you’re there. 

 

I teplaced my CCV whilst doing this as well. No more rough idle. I will replace the vanos seals when I get back to NZ too, but the CCV difference was enormous and the throttle body and ICV cleaning were clearly necessary in my case.

yeah i think thats the plan - definitely need to have a nosey at that disa valve - looks like something i should get checked over if im going to want to avoid a valve bending situation!

I think you're right though , the only way to do this - is to do it all, might as well. 

Did you have a leak in the CCV pipes? Where are they?

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34 minutes ago, 325_driver said:

yeah i think thats the plan - definitely need to have a nosey at that disa valve - looks like something i should get checked over if im going to want to avoid a valve bending situation!

I think you're right though , the only way to do this - is to do it all, might as well. 

Did you have a leak in the CCV pipes? Where are they?

Ok, here's what I'd do (and what i did do, for the most part...)

If you're savvy with cars and wrenching in general, this will be an hour, or two at most (I did it in four and it was my first time ever doing this) I'd remove everything up to, and including the throttle body (this will include air intake, upper and lower boot, DISA valve, ICV and throttle body itself. Check all hoses, rubber boots, etc for tears and cracking. Clean ICV and throttle body. Inspect CCV (in my case, I bought the CCV kit from FCP Euro and instead of just inspecting it, I went in knowing I'd replace it anyway) Inspect your DISA valve.

Having bought the CCV kit up front and taking the bet that since everything else in the car had been neglected anyway... I went full in on the CCV hoses and they pretty much disintegrated in my hands, so good thing I had the parts to replace! My ICV was near stuck, my throttle body was black with grime. 

I ended up replacing upper and lower boots, throttle body gasket, ICV grommet, and vacuum hose from the fuel filter that goes into the F connector on the upper intake boot. (All of which came with my kit from FCP Euro, minus the $2 hose I bought extra)

I still intend to do my VANOS rebuild (and valve cover replacement...) but the urgency is a lot lower now that my idle and random power loss problems are gone.

The DISA rebuild kit from FCP Euro is $50 and I'll get it eventually. My gasket is pretty shot, and that should be an easy job anyway. :)

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did you also clean the MAF sensor with some WD40?

I've read that aparently the sensor it's self can clog up with grime

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3 hours ago, 325_driver said:

did you also clean the MAF sensor with some WD40?

I've read that aparently the sensor it's self can clog up with grime

Did not. I was warned off spraying anything into my maf. 

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Certainly not WD40 lol

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2 minutes ago, Eagle said:

Certainly not WD40 lol

Hoping some one would pick up on that :P

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You can spray MAF cleaner into the MAF....

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On 10/14/2017 at 1:58 PM, 325_driver said:

did you also clean the MAF sensor with some WD40?

Lol that's a definite no no...... an electrical contact cleaner is best, a few bucks for a can that'll last years. Use throttle body cleaner for the throttle body and everything else.

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So been doing some tests - Leading me to believe CCV system being the culprit - some where.

DISA valve looks ok - no o ring leaks, flap is firm and holds under the diaphragm.

The CCV replacement kit is relatively cheap - might as well order in that + some extra vacuum hoses / throttle body stuff and do it all.

Any other small air intake pipes that can cause issues that anyone might know of / to be aware of?

Edited by 325_driver

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2 hours ago, 325_driver said:

So been doing some tests - Leading me to believe CCV system being the culprit - some where.

DISA valve looks ok - no o ring leaks, flap is firm and holds under the diaphragm.

The CCV replacement kit is relatively cheap - might as well order in that + some extra vacuum hoses / throttle body stuff and do it all.

Any other small air intake pipes that can cause issues that anyone might know of / to be aware of?

I ordered the FCP kit, plus bought a can of throttle body cleaner and a short length of vacuum hose. If your upper intake boot is shot, you’ll need that in addition, and if you’re taking off the intake manifold you’ll need new gaskets for it, also, if you take he manifold off, you might as well buy the coolant hoses that go under there and replace those too. I did not find replacing the CCV system with the manifold on hard and I am a newbie with this stuff. 

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4 hours ago, allan said:

Check out the condition of No 15, 17 they are rubber plugs at the back of the manifold

http://bmwfans.info/parts-catalog/E46-Sedan/Europe/325i-M54/R-N/oct2000/browse/engine/intake_manifold_system/

Note there was a plug like this on my CCV unit itself. I’ll find a diagram when I’m in front of a computer for you, but same kind of plug as those. This did not come in the kit and I had to find mine as it had snapped off and I had to hunt for it...

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1 hour ago, Gabe79 said:

Note there was a plug like this on my CCV unit itself. I’ll find a diagram when I’m in front of a computer for you, but same kind of plug as those. This did not come in the kit and I had to find mine as it had snapped off and I had to hunt for it...

did you buy vacuum hose from FCP or do you buy like generic vacuum hose?

haven't had a detailed look at their supply - never sure if they supply it as a specific part sometimes or whether it's just a generic like 7mm wide hose

Edited by 325_driver

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On second inspection i think the DISA does have play Has anyone done a rebuild on a DISA valve before / pretty straight forward? I might do it anyway when i do the CCV system + ICV clean.

I also heard 1 noise like this once - and i saw some errors on the Testing Computer saying mis-fires that lead me to believe that maybe DISA play is causing some misfires on start up, and the popping noise being a mis-fire.

It's not a rattle, it sounds like a pop
 

Is that a valid arguement? That DISA (since it controlls air intake) could lead to mis-fires?

 

 

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