Rough idle

[saace7]

After a short trip to the store, i noticed even with the car warm. When i started it up and idled in the parking lot for a minutes the idle got rough. Almost sounded like i had internal parts going out. I freaked out and shut the car off... I check oil, good. And no odd signs of something catastrophic. I start the car back up and it sounds fine.. Few seconds of idle the car gets rough again... but seems to adjust it self as the rpms went from 600 to maybe 800 and smoothed out... no more rough idle, it doesn't seem to last longer than say 15 seconds or so before it adjusted itself. Sounds like the engine is perfect. There seems to be a little hesitation while driving through the rpms as well... its not "perfectly smooth". With normal driving too.

Now I know the fuel filter is original and i have one coming in tomorrow to change it along with new vanos seals... But besides that, does it sound like the DISA causing the issue? Should that be my next place of inspection if these few fixes don't work?

[Avetiso]

Any codes?

[danewilson77]

Could be running rich/lean. Could have an intake boot crack/tear. ICV could be dirty. Would be nice if you could pull a code.

Even if no SES light is present you may have a code stored.

[saace7]

First chance i get Ill check for codes. No lights are being thrown.

[LivesNearCostco]

I have a similar problem, though can't say if it's the same issue. Sometimes on hot start, if I leave it to idle in neutral with clutch engaged, it does the rough running thing for 15-20 seconds. If I rev the engine, it goes away. If I push in the clutch pedal, it goes away. If I start it cold or drive off immediately, it doesn't happen. Once or twice it threw a CEL but usually there is no CEL.

My intake boots are fairly new. Upgrading DISA with GAS kit did not help (and GAS guy told me it probably wouldn't help before I bought their kit). One indie heard it happen in front of his shop and suggested flywheel or driveline thing, since it stops if I press in the clutch. I've got 172,000 miles on original DMF (2nd clutch), maybe its damping mechanism is failing?

Haven't cleaned the ICV in 2.5 years and never cleaned the throttle body... those are possible issues.

[wertyu78]

It could be all sorts of things. As Dane mentioned, it could be an intermittent vacuum leak. Without a code, it's a lot harder to narrow it down. In these sorts of situations, I just run INPA and check all of the modules(specifically the DME in your case) and it helps me narrow down the possibilities. If you have a way to measure coil resistance and fuel trims, go that route. Otherwise there is always the old fashion way of diagnosing things.


Start by disconnecting a coil pack one by one during the rough idle and see if it changes. If it doesn't then you know if you have an ignition issue.

Disconnect the harness from the DISA valve and see if anything changes there (also a good time to see if your DISA valve is making any noise). If so, I recommend rebuilding it with the GAS kit. It's top notch.

If all goes well there, move the intake boots around and see if you can't notice any difference there.

Disconnect the MAF and see if anything changes.

[saace7]

Also the rough idle isn't consistent. As in it will do it then stop... Doesn't consistently idle roughly... Also, as you mentioned try these techniques with the car running? I guess it would work only during the rough idle it self? Im about to get a scan in about an hour. Advanced does it free and its about 10 minutes from me. Looks like its time to order the actron cp9575 tonight.

[LivesNearCostco]

I don't think the CP9575 scanner will get all the BMW specific codes, but it will pull all general OBD-II codes and let you monitor some real-time data, including live O2 sensor data, plus of course turn off the CEL. Even if I don't rev engine, drive off, or push in clutch, my rough idle stops after a while. I did replace all my plugs and coils about 18 months ago and my VANOS seals 2 years ago but that didn't solve this problem.

Besides possibly being the dual-mass flywheel, sometimes I wonder if it's my CCV, which--if original--has 10 years and 172,000 miles on it.

[saace7]

The guy at advance couldn't get my car to pull up on the scanner. I believe he was using the cp9580... Is this right or is that guy just not capable of using it correctly?

Also, just now my drive to advance, typical small town driving, i had a little rough idle when i first started up, no where near as rough as before. I noticed the pressing of the clutch and turning the a/c on and off changed the roughness... A/c off it was more rough, a/c on it smoothed out... So something to do with the load at idle...this was the beginning of the trip. When i got back home, i idled for about a minute doing the same stuff the symptoms lessened so much that they barely showed. As in seems like nothing is wrong at all. So my problem doesn't seem major but is definitely showing signs that something is starting to go out. If my fuel filter is original at 105k miles i'm assuming the fuel pressure isnt consistent when im at idle the load type on the engine is what caused to be rough or smooth.

[ELCID86]

I used the CP9580 scanner at advance several times on my '02 330Ci.

[saace7]

They sell the cp 9575 for $130 but he told me if i print the amazon page displaying the sale for $100 he would sell it to me for $100 bucks. Im thinking about buying the 9575 real quick and trying to scan it myself... there is not way the cp9580 scanner wouldn't work on a 04 zhp right? I can assume the guy didn't know what he was doing?

I also have pretty bad VCG leak that is getting replaced with the fuel filter and vanos seals this weekend.

[saace7]

After doing a little research I am going to order a BMW specific scan tool. I was looking at the R5/FCX-3 by PEAKE b/c they are only $150.
Or the bavarian technic for enthusiast. its $280 but seems to have a lot of great features.
Also, I have guys at the e46 site saying to use this method: http://forum.e46fanatics.com/showthread.php?t=893444

any input?

[saace7]

Any codes?

SES came on today. I checked it threw. p0174 and p0171 - bank 2 system too lean

[ELCID86]

And the search begins for air leak.


Shawn in VA.
Via thumbs and Tapatalk.

[danewilson77]

And the search begins for air leak.


Shawn in VA.
Via thumbs and Tapatalk.

Sux. Hopefully it's obvious.

HTC DNA ON TT4 BETA, WILLIAMSBURG, VA

[BCS_ZHP]

That code is quite often a leak at your upper & lower intake boots. Each boot is about $15-20 from the dealer. While you're replacing, clean your ICV and DISA too. And replacing boots plus cleaning, I'm willing to bet this will rectify your rough idle issue.

[danewilson77]

ICV you can clean, but the disa should be inspected per Germanautosolutions guidelines and ensure that o-ring is intact and looks good.

HTC DNA ON TT4 BETA, WILLIAMSBURG, VA

[saace7]

Thanks for the input. lll be installing my fuel filter, vcg, new vanos seals tomorrow hopefully. Ill start with checking the DISA and intake boots while im doing that.

[BCS_ZHP]

I've cleaned at least half a dozen DISA with no issues. You need to check the vacuum to ensure the flapper is actually working and replace that o-ring. A cheaper alternative for the o-ring is Fel Pro p/n 35489, a rubber o-ring in the cooling system of a 91-94 Ford Probe.

[danewilson77]

I've cleaned at least half a dozen DISA with no issues. You need to check the vacuum to ensure the flapper is actually working and replace that o-ring. A cheaper alternative for the o-ring is Fel Pro p/n 35489, a rubber o-ring in the cooling system of a 91-94 Ford Probe.

Yes. That's what GAS tells you to do.
Absolutely take the advice about the o-ring.

HTC DNA ON TT4 BETA, WILLIAMSBURG, VA

[BCS_ZHP]

So should I be expecting royalties from GAS for my "free" advice? Lol

[Tnhl1989]

I would say get the cable that is useable with inpa and ncs. It's cheaper and more capable of doing a lot more stuff. I still have to read everything else on the thread. Order through amazon.

[saace7]

I would say get the cable that is useable with inpa and ncs. It's cheaper and more capable of doing a lot more stuff. I still have to read everything else on the thread. Order through amazon.

Anyway you could provide a link? :D

[Tnhl1989]

http://img.tapatalk.com/d/13/06/15/zytuvuqe.jpg

Open it up and solder pin 7&8

[saace7]

After changing the fuel filter the rough idle is gone. Though the lean code is still thrown and there is a loss of low end torque i think i have found the culprit.. After cleaning the MAF and installing the intake boot back to the MAF i have found my break!! Right at the top of the intake boot where the clamp is there is 1 inch tare. So ill order that part for replacing. Also i checked my DISA and the flap has nice resistance against it and seem tight. Though the gasket around it might be done. when i closed the flap all the way i heard some kinda of little pop that was coming from the circular part on the end of the DISA. There is a little lever attached from the flap to it. The DISA came out pretty easy, I read before if it does the outer gasket should be changed. sound about right? Looks like Ill have that SES gone soon enough!

[BCS_ZHP]

Sounds like your running the down the right path. If you pull the DISA again to replace that o-ring, I'd strongly suggest the lower boot be replaced and clean the ICV while you're right there. Then you'll know both boots are new and your ICV & DISA are clean, it should run amazing for very little parts cost, plus you'll have piece of mind.

[saace7]

I ordered upper and lower boots. I was planning on cleaning the ICV when i changed the boots. I was thinking about getting the o-ring for Fel Pro p/n 35489, a rubber o-ring in the cooling system of a 91-94 Ford Probe. Which someone mentioned earlier.

[BCS_ZHP]

Yes, that's the way to go. Lower boot clamps are installed when the engine is not in the car so if you have the new lower boot, just cut the old lower boot off to gain better access to those hose clamps. Ask me how I know, this simple step can save you an hour easily, plus less busted/cut knuckles.

[saace7]

I don't think that is the right P/n for the O-ring b/c I cannot find it. Any ideas?

EDIT: Actually I think i just found it. Would this be it? Says it doesnt fit the car i have selected which is a base model 91 ford probe.

http://www.autopartswarehouse.com/sku/Felpro/Water_Outlet_Gasket/FP35489.html

[BCS_ZHP]

I walked into an Advance Auto and gave them that o-ring number, they produced one in a couple of seconds.

[saace7]

Great deal. I actually just check the availability for my local advanced auto store and says it is in stock. I'll ride up there tomorrow and grab one. Thanks for the help!! I'll be back with an update after some more work is done!

[BCS_ZHP]

A forewarning, it will at first appear too small to fit on the DISA but it does. And then before installing the DISA back into the car spray some silicone on the o-ring to help it slide in. Do not use WD40 or any other petroleum based product as all of them help deteriorate rubber faster. And it's going to be tight going in, alternate tightening the nuts to get it to seat evenly, all will be perfect afterwards, you'll be very happy.

[saace7]

Cool. Thx for the tips! Lol save me some frustration when I know its supposed to happen that way. ;)

[saace7]

Great news!!!! Installed the parts today and she is running so much stronger. Cleaned the ICV, replaced outer gasket on DISA, both intake boots, cleaned MAF. She pulls like she used to now! No more slumping to 500rpm when coming to a stop either. Though the SES is still on. I haven't got my scanner in yet to reset it. I assume if it is all fixed properly over time the SES should turn it self anyways. Tomorrow I'll probably do the VCG and vanos seals.

[ELCID86]

Good to hear. Hopefully it will clear in a few days of driving.


Shawn in VA.
Via thumbs and Tapatalk.