Help me figure out my rough idle and stalling

[Avetiso]

Thought I'd have this taken care of by now, but the problem still pesters me.

Issue: rough idle, often jumps up to 900, or falls to 500 and starts vibrating. Car often stalls out, but it's not a rough stall. Just dies.

Items that have been replaced:

DISA rebuilt
VANOS rebuilt
New NGK plugs
New fuel filter
New VCG
ICV cleaned
Intake boots inspected (still good from what I remember, but having issues raises doubts)
Intake filter is new and freshly oiled
Oil is also new :rofl
Shell 91 gas only

No check engine codes.

73.5k miles. My assumption is fuel pump, but I have no issues with high-end fuel delivery at all, and my revs are always responsive. When I press the pedal, I always get power.

Possibly related: I hear a whistling noise when I'm not heavy on the gas. Pretty sure it's my intake, but I haven't noticed it until now. Might be a vacuum leak somewhere? Haven't checked my CCV hoses. No issues with oil consumption.

Up to this point, I've just thrown money at it because it was good maintenance, regardless. But now, I'm not sure what it is.

[kayger12]

Time for a smoke test. Sounds like a vacuum leak somewhere. Especially given the whistle.

[Avetiso]

Time for a smoke test. Sounds like a vacuum leak somewhere. Especially given the whistle.
Any common places (hoses, seals, caps) that are common culprits? Might try replacing some old hoses before I get a smoke test, and it's good maintenance.

[kayger12]

I'd start with the intake boot since you said you have some concerns there. The F connector on the intake boot would be another spot.

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[Vas]

I would replace the intake boots IMO.

[kayger12]

Tough, though, since you're not getting any codes.

Intake plenum gaskets as well since you're hearing that intake whistle.

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[Avetiso]

I guess I'll order new boots when money comes around. I have my cousin coming over soon; I'll have him give some revs while I poke around in the engine bay.

Really hope I don't have to take my manifold off.

[Mtnman]

The most common thing with those symptoms would be intake boots. Upper or lower. They are cheap. Should be less than $50 for the pair. Lower intake boot sucks to replace, just because of its location, but beside that it is a super easy DIY. At the age of the car (age, not mileage) i would think they would be suspect.

[Avetiso]

The most common thing with those symptoms would be intake boots. Upper or lower. They are cheap. Should be less than $50 for the pair. Lower intake boot sucks to replace, just because of its location, but beside that it is a super easy DIY. At the age of the car (age, not mileage) i would think they would be suspect.
Yeah, well that's the thing. When I was in there, I checked them out, and they looked fine. I'm just doubting whether I saw correctly, or maybe missed a crack somewhere. I guess I'll replaced it regardless, but I'm not convinced that's the issue.

[Vas]

Weird that there are no codes being thrown. How is your maf sensor ? Try cleaning it ?

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[Avetiso]

Weird that there are no codes being thrown. How is your maf sensor ? Try cleaning it ?

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I'll pick up some MAF cleaner tonight or tomorrow. I had P0171 and P0174, but that was waaaay back when I started the car the first time after wiring it back up. Cleared it and it never came back. Been a few months already, nothing. Had an intermittent O2 code thrown, but it went away after DISA repair. No codes since.

I had the issue before I upgraded to an oil aFe, but I'll still try the MAF cleaner.

[kayger12]

Yeah, well that's the thing. When I was in there, I checked them out, and they looked fine. I'm just doubting whether I saw correctly, or maybe missed a crack somewhere. I guess I'll replaced it regardless, but I'm not convinced that's the issue.

Crack in the elbow of the lower intake boot is nearly impossible to see unless you remove the boot and flex the elbow.

[Avetiso]

Crack in the elbow of the lower intake boot is nearly impossible to see unless you remove the boot and flex the elbow.
I guess I'll be replacing those.

Also, just checked out the whistle; it's just the intake.

[Avetiso]

Picked up some MAF cleaner. I will also order new intake boots. $36 + shipping at thebmwpartstore vs $42 + shipping at ECS.

Any other common vacuum leak hoses I should order?

[Lanister]

Be careful with that F connector on the upper boot. They're brittle and can snap. I ordered one with my new boots but it didn't snap.

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[WOLFN8TR]

As suggested I would replace both intake boots and the F connector. The easiest way to remove the lower intake boot is to just cut it off with a exacto knife. Makes it so much easier. Also if you don't have a flex screw driver with an extension get one. That tool is a must for the hard to reach hose clamps.

I got this one on eBay and it comes with a extension and it's a 1/4" drive.

http://img.tapatalk.com/d/14/01/22/qu2abuve.jpg

http://img.tapatalk.com/d/14/01/22/yja2a7a9.jpg

[Avetiso]

Picked up some MAF cleaner. I will also order new intake boots. $36 + shipping at thebmwpartstore vs $42 + shipping at ECS.

Any other common vacuum leak hoses I should order?
Bump. Any other hoses I should order? SAP? CCV? Or do they not leak commonly?

[Avetiso]

As suggested I would replace both intake boots and the F connector. The easiest way to remove the lower intake boot is to just cut it off with a exacto knife. Makes it so much easier. Also if you don't have a flex screw driver with an extension get one. That tool is a must for the hard to reach hose clamps.

I got this one on eBay and it comes with a extension and it's a 1/4" drive.

http://img.tapatalk.com/d/14/01/22/qu2abuve.jpg

http://img.tapatalk.com/d/14/01/22/yja2a7a9.jpg
I use a tiny little wrench. It's slow, but it works.

[derbo]

Im surprised you have no light. My immediate thought if the boots check out okay, I suspect to look into the sensors. Intake Cam sensor, Exhaust cam sensor or crank position sensor. But these 3 should throw a code.

[Avetiso]

Im surprised you have no light. My immediate thought if the boots check out okay, I suspect to look into the sensors. Intake Cam sensor, Exhaust cam sensor or crank position sensor. But these 3 should throw a code.

Yup. No codes. It's really weird. Plus, fairly low mileage for sensor failure, but of course, still possible.

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[Smolck]

Wonder if your long term fuel trims would show anything? Just spitting out ideas.

[Tampa330i]

I just had a problem with my disa that gave similar symptoms. Rough idle big time with vibration and would occasionally stall(only when rolling at idle). One day last week it started feeling like some misfires happening. Checked codes and yeah, misfires on multiple and lean codes, then cleared codes. I started it the next day and it felt like nothing was wrong, then the rough idle came back within a few minutes. I have no smoke tester, so i took a lighter over near the disa area and around the intake boot looking for air. Determined it was leaking right on the disa unit itself near where the little vacuum pump on the backside. Without the smoke I couldn't tell if it was the seal on the disa or something inside it so I ended up taking it to a shop for the smoke test. Sure enough, smoke right out the back of the disa. The plastic flap part that goes inside the manifold was completely broken off at the base and being held in by only the metal end pin. Replaced disa, problem fixed. I'm not sure what goes into a disa rebuild, but have you pulled it out to make sure that's still in good shape?

[ryankokesh]

Trying to think outside the box here... Any way it could be a fuel pump relay going bad? I think you'd have issues starting it if that were the case, but just a thought.


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[johnrando]

As you're checking things, how's your battery and connections? You'd be surprised....

[Avetiso]

My DISA was rebuilt, including a new seal, so I doubt that's the source of a leak.

Ryan, I have had some difficulty starting, but very rarely. Maybe like 1/30 starts.

JR, I guess I'll give that a look. Thanks!

[ryankokesh]

My DISA was rebuilt, including a new seal, so I doubt that's the source of a leak.

Ryan, I have had some difficulty starting, but very rarely. Maybe like 1/30 starts.

JR, I guess I'll give that a look. Thanks!

I guess it wouldn't hurt to swap the fp relay with the horn relay. Takes about 15 mins. Probably not the answer, but who knows.


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[Avetiso]

Popped a P2240 today. It came up between 3000-3500 rpm going uphill in 6th, about 80-85mph. I always experience stuttering in that RPM range, might be related.

It's for O2 sensor.

[derbo]

Crank sensors?


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[Avetiso]

Crank sensors?


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That's my guess now.

Checked intake boots, vacuum line from boot to CCV, and that tiny line that comes out of the F connector. All good. Not even gonna replace good parts.

Any other ideas before I try a crank sesnor? I could try the one off my parts car, but I'm not sure if its considered a wear item.

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[Lanister]

Crank sensors?


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Dew eet

[derbo]

Camshaft sensors + crankshaft sensors is where I would imagine there might be some issue as well. Have you check the fuel pressure coming out of the rail?

[Avetiso]

Camshaft sensors + crankshaft sensors is where I would imagine there might be some issue as well. Have you check the fuel pressure coming out of the rail?
Any way to know which? I don't have money to just replace them and hope for the best. :(

[derbo]

Crank sensors usually will throw a code though. Do you have a DIS laptop that is working?

[Avetiso]

Crank sensors usually will throw a code though. Do you have a DIS laptop that is working?

Nope. Still need to buy an ssd and have bp set me up remotely. Is it one of those codes that doesn't throw a cel?

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[Avetiso]

Stalled again today. Tried to start it right away, and it was cranking for like 3-4 seconds. Really long. Then it sputtered up to life.

Pretty sure one of the sensors is being weird, but I'm not sure which.

[gmurphy]

Stalled again today. Tried to start it right away, and it was cranking for like 3-4 seconds. Really long. Then it sputtered up to life.

Pretty sure one of the sensors is being weird, but I'm not sure which.

Sorry I haven't read all the way through this thread but it isn't the fuel pump is it?


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[Avetiso]

Sorry I haven't read all the way through this thread but it isn't the fuel pump is it?


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That's the other thing I'm thinking about. I'd love to just replace it for PM but I don't have the money to do that right now.

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[gmurphy]

That's the other thing I'm thinking about. I'd love to just replace it for PM but I don't have the money to do that right now.

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I'm in the same boat no joke haha.


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[tkundhi]

Sounds like you need to scan for codes. I bet there are faults that will point you to what is going one. You can have many faults before the SES light comes one.

No need to throw parts at it. That is the expensive has to proceed.

t.


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[Smolck]

I just recently cured a sudden rough idle on my ZHP. Turned out to be the 02 sensor had gotten overheated by my headers (bad bung location) and it was frozen up. I verified this by reading real time data of the fuel trims and 02 sensor function. Car drove fine until I stopped. Then it would buck and kick and lope like an old drag car.

This may not be your issue, but certainly worth looking at the trims and 02 sensor data.

[Avetiso]

I just recently cured a sudden rough idle on my ZHP. Turned out to be the 02 sensor had gotten overheated by my headers (bad bung location) and it was frozen up. I verified this by reading real time data of the fuel trims and 02 sensor function. Car drove fine until I stopped. Then it would buck and kick and lope like an old drag car.

This may not be your issue, but certainly worth looking at the trims and 02 sensor data.

Thanks for the info! I'm waiting to set up a diagnostic laptop before I move forward.

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[tkundhi]

Avetiso, is the problem on cold smart, warm start or both?


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[Avetiso]

Avetiso, is the problem on cold smart, warm start or both?


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It can happen at any time the car is running and not engaging a gear. Cold or warm start/idling.

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[tkundhi]

Occurring at cold start points to something other than the O2 sensors. On cold start the car is in open loop. The O2 sensors are not involved with controlling the fuel mixture. It stays in this state until some other sensor (probably coolant) switches it to closed loop. Also by cold start, I do me cold like in the morning after the car has sat overnight.


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[Avetiso]

Time to bump this. For the roughly one hour I had my coding computer set up, I read the car for codes and no codes besides my oxygen sensors showed up. No crank or cam sensor codes. Next on my list are O2 sensors for replacement, but these symptoms aren't associated with bad O2 sensors for the most part.

To recap my problem: At idle, car will often sputter and die. No codes. Car can be either warm or cold, makes no difference. Happens more often after opening clutch as I roll to a stop.

DISA, VANOS, intake boots all good. New plugs. No vacuum codes.

Read the rest of the thread if you want the most details. I still can't figure this one out, and I don't want to throw money at sensors if that might not be the issue. Any ideas?

[Hermes]

^same issue on the E21, but I know it's worn bearings. I doubt your bearings are at fault, and it doesn't have a traditional style distributor... have you tested your compression yet?

[Avetiso]

^same issue on the E21, but I know it's worn bearings. I doubt your bearings are at fault, and it doesn't have a traditional style distributor... have you tested your compression yet?
No. Didn't think I would have any reason to at my mileage. Engine runs fantastic besides this issue. You honestly think it could be bad compression?

[Hermes]

Not likely, but it could be worn piston rings. Make sure to rev your car near redline once each drive so the rings fully heat up and seal properly.

[Avetiso]

Not likely, but it could be worn piston rings. Make sure to rev your car near redline once each drive so the rings fully heat up and seal properly.

I do that for the most part. I am plenty rev happy.

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[Avetiso]

Bump. Anyone got any ideas?

[Vas]

Maybe run some sea-foam through the intake . That stuff works pretty well in regards to cleaning up carbon build up.

[Pip]

I'm rehashing stuff but the whistle became apparent when I installed afe so not sure if you still have that on, but you could check to see is the whistle goes away after installing OEM. Other than that I can't help because it seems like you've covered everything I would do with plugs, fuel filter, new filters, clean MAF, etc. :( hopefully someone will have a creative idea.

[Avetiso]

Maybe run some sea-foam through the intake . That stuff works pretty well in regards to cleaning up carbon build up.
Not sure that'd help this issue, but it's worth a try, even if just for other benefits. I've heard good things.

I'm rehashing stuff but the whistle became apparent when I installed afe so not sure if you still have that on, but you could check to see is the whistle goes away after installing OEM. Other than that I can't help because it seems like you've covered everything I would do with plugs, fuel filter, new filters, clean MAF, etc. :( hopefully someone will have a creative idea.
Intake is OEM. :( Still thinking about the crank and cam sensors but no codes or any indication of which it could be.