[Hotter]

Hi, I have E92 328i which idles around ~590 and at this idle RPM it shakes slightly. I beleave it started doing that after valve cover and gasket change. When not idling engine stops shaking, even when AC is on it shaks less, because RPM is at ~700. No error codes nothing. So mechanics do not see anything wrong and suggests to adjust idle RPM.
What do you think?
How could I adjust idle RPM?

[JDang]

You can adjust the idle RPM through MHD.

[Hotter]

My engine is N52 328i. I dont see that MHD would list this engine.
Is it possible to do it through INPA or Rheingold?

[gbalthrop]

Originally Posted by Hotter

Hi, I have E92 328i which idles around ~590 and at this idle RPM it shakes slightly. I beleave it started doing that after valve cover and gasket change. When not idling engine stops shaking, even when AC is on it shaks less, because RPM is at ~700. No error codes nothing. So mechanics do not see anything wrong and suggests to adjust idle RPM.
What do you think?
How could I adjust idle RPM?

If the idle speed has dropped and it idles rough SINCE a valve cover/gasket change on an N52 engine, it is likely that you have an air leak into the intake manifold, downstream of the MAF, causing lean idle. Particularly suspect is the PCV Breather hose from the rear of the Valve Cover.

Rather than try to increase idle speed through coding of some type, I would try to identify any air leak and fix that. One method of locating a cracked hose that is not capable of easy visual inspection is (with a COLD engine) spray ether/starting fluid on all hoses/connections to the manifold downstream of the MAF and if the idle speed increases when a certain area is sprayed, you have found the leak.

George

[Sensible_]

Indeed. Fix the cause, not the symptom. But if you insist. ISTA D Rheingold can do this.

[Hotter]

Originally Posted by gbalthrop

If the idle speed has dropped and it idles rough SINCE a valve cover/gasket change on an N52 engine, it is likely that you have an air leak into the intake manifold, downstream of the MAF, causing lean idle. Particularly suspect is the PCV Breather hose from the rear of the Valve Cover.

Rather than try to increase idle speed through coding of some type, I would try to identify any air leak and fix that. One method of locating a cracked hose that is not capable of easy visual inspection is (with a COLD engine) spray ether/starting fluid on all hoses/connections to the manifold downstream of the MAF and if the idle speed increases when a certain area is sprayed, you have found the leak.

George

Well its shaking only slightly, more like vibrating. Only on idle you can feel seat vibrating like phone on lowest setting, so all mechanics are telling me that that's how it should be... Do you think that such small vibration is vacuum leak? I think it might be realy small leak and not sure if its easy to catch such leak... Increase RPM could be the best option for now...

Originally Posted by Sensible_

Indeed. Fix the cause, not the symptom. But if you insist. ISTA D Rheingold can do this.

How could I do it with ISTA D? I was going through it and could not find where to set the value. ISTA D seems more like a manual than the tool where I could set values. Could you tell me where I could set the value?

[Sensible_]

Originally Posted by Hotter

Well its shaking only slightly, more like vibrating. Only on idle you can feel seat vibrating like phone on lowest setting, so all mechanics are telling me that that's how it should be... Do you think that such small vibration is vacuum leak? I think it might be realy small leak and not sure if its easy to catch such leak... Increase RPM could be the best option for now...

How could I do it with ISTA D? I was going through it and could not find where to set the value. ISTA D seems more like a manual than the tool where I could set values. Could you tell me where I could set the value?

It's in service functions, drive, DME, Adjustment of idle speed.

Connect your car first of course.

[Hotter]

Originally Posted by gbalthrop

If the idle speed has dropped and it idles rough SINCE a valve cover/gasket change on an N52 engine, it is likely that you have an air leak into the intake manifold, downstream of the MAF, causing lean idle. Particularly suspect is the PCV Breather hose from the rear of the Valve Cover.

Rather than try to increase idle speed through coding of some type, I would try to identify any air leak and fix that. One method of locating a cracked hose that is not capable of easy visual inspection is (with a COLD engine) spray ether/starting fluid on all hoses/connections to the manifold downstream of the MAF and if the idle speed increases when a certain area is sprayed, you have found the leak.

George

So I talked with one mechanic and he suggested to upgrade DDE software to see if that fixes rough idle, because its cheaper. If that does not help continue looking for air leak. And if still the same fuel injectors...

What do you think about DDE software upgrade? Could I do it my self? Or its too risky to do?
I have DCAN cable. Done few time coding with NCSexpert, but did not tried updating any ECU firmware with WinKFP before.
How do I find correct ECU family for my DDE (MSV80)?

[Sensible_]

Originally Posted by Hotter

So I talked with one mechanic and he suggested to upgrade DDE software to see if that fixes rough idle, because its cheaper. If that does not help continue looking for air leak. And if still the same fuel injectors...

What do you think about DDE software upgrade? Could I do it my self? Or its too risky to do?
I have DCAN cable. Done few time coding with NCSexpert, but did not tried updating any ECU firmware with WinKFP before.
How do I find correct ECU family for my DDE (MSV80)?

I don't think it's necessary. And will probably cause you a lot of grief if you are new to it. If you brick your DME then things will be very costly.

I personally have never heard of an BMW software update that corrects a rough idle.

This all points to a mechanical problem.

[gbalthrop]

Originally Posted by Sensible_

Indeed. Fix the cause, not the symptom. But if you insist. ISTA D Rheingold can do this.

Originally Posted by Sensible_

...I personally have never heard of an BMW software update that corrects a rough idle. This all points to a mechanical problem.

Reminds me of the old saying:

"If your only tool is a hammer, everything looks like a nail."

George

[Hotter]

Originally Posted by Sensible_

I don't think it's necessary. And will probably cause you a lot of grief if you are new to it. If you brick your DME then things will be very costly.

I personally have never heard of an BMW software update that corrects a rough idle.

This all points to a mechanical problem.

Well for example this post:
https://www.e90post.com/forums/showp...09&postcount=7
I think updating software should be positive thing improve over all performance or reset adaptations which could be causing rough idle... But yes, I also believe that its most likely air leak or other hardware issue...
Also its a bit scary to update it myself, I dont want to brick ECU.

[6ixSpd]

INPA can program a higher idle speed as well and it is retained. I did this on my car after noticing a slight increase in NVH with new motor mounts.

[DaanBMW]

Confirm INPA can do it. If I recall correctly it only can be done with car running.

[P14kle]

Originally Posted by 6ixSpd

INPA can program a higher idle speed as well and it is retained. I did this on my car after noticing a slight increase in NVH with new motor mounts.

How is this done please??

[6ixSpd]

Originally Posted by P14kle

How is this done please??

After starting your car (engine must be on) and connecting to it:
In INPA, load up MSV80.
F9 System
F8 LLABG
Add the # of RPMs you want to increase/decrease your idle speed by in all parameters.
F9 Program to save the changes.

Hope this helps.

[P14kle]

Cool. Will give it a try next time I get the chance.

Thankyou 😎

[Hotter]

Originally Posted by 6ixSpd

After starting your car (engine must be on) and connecting to it:
In INPA, load up MSV80.
F9 System
F8 LLABG
Add the # of RPMs you want to increase/decrease your idle speed by in all parameters.
F9 Program to save the changes.

Hope this helps.

This has worked. Would like to find real cause though...
I noticed that when vibrating on tachometer RPM is showing ~550 and at the same time on INPA it shows ~650, does INPA and tachometer use the same source to get RPM or maybe that indicate the problem?

[Hotter]

When idling and vibrating on tachometer RPM is showing ~580 and at the same time on INPA it shows ~660, here is a photo:



Does INPA and tachometer use the same source to get RPM measurement? Could this indicate the problem? Am I onto something?

Aslo I viewed "Systemtest smooth-running check". It seems that "overall DFT 0.5 motor reference" is sometimes outside of green zone:



What does "DFT" stand for? What does this "overall DFT 0.5 motor reference" mean? Could this indicate where is my problem?

[nsjames]

yes, but the kombi module has it's own graduations for the needle, and it also smoothes the input so the needle doesn't jump around.

it means your engine is running roughly.

find the vacuum leak and stop dicking with your DME.
either smoke test the manifold or wave an unlit propane torch around all the intake/lines until you here the idle drop.

[Hotter]

Originally Posted by nsjames

yes, but the kombi module has it's own graduations for the needle, and it also smoothes the input so the needle doesn't jump around.

it means your engine is running roughly.

find the vacuum leak and stop dicking with your DME.
either smoke test the manifold or wave an unlit propane torch around all the intake/lines until you here the idle drop.

Do you know what "overall DFT 0.5 motor reference" indicates? Is it for sure vacuum leak?
I will bring car on Wednesday to mechanic, I will tell to check for vacuum leak.

[nsjames]

no, it's telling you exactly what you already know, that the motor runs roughly at idle, which is why you wanted to raise the idle, which happened coincidentally to doing the valve cover, which involves removing a bunch of vacuum lines, that are probably now leaking and causing your rough idle.

Does that adequately surmise your situation?

The root cause of all of this is something that happened when the valve cover was serviced. Your car most likely has a vacuum leak.

Everything that you've seen, felt or heard since that point is likely related to the exact same issue. There is no software or coding solution. Your car has a mechanical issue.

[nsjames]