M60 rough idle

[nearle]

I just purchased a 540i auto, my second e34. I got a rough history of the car, but very few records so it is hard to tell what has been maintained.

I have done a search through the threads and have some ideas about what might be the cause of the problem, but wanted to get an idea of what to do first.

The problem: heavy vibrations at idle, O2 sensor code.

My question: What are some good ways to diagnose this without running out and buying a bunch of expensive parts?

so far I have taken the covers off to check for oil around the plugs. There was just a small amount toward the rear. The rest looks dry. I guess I should take the plugs out to see how they look. I believe they were replaced within the last few years / 40k miles but theres no way to know for sure.

I'd like to check for leaks. Does anyone have a diagram or can explain where to look for vacuum leaks?

Thanks in advance.

[winfred]

almost certainly it's the pcv plate on the back of the intake, you can squirt around the intake with carb cleaner and see if the idle changes, slim chance it's crappy plugs or a failing maf but if it runs good other wise it's probably not a maf, we just had a couple threads on doing the intake job and someone will probably post them up if you can't find them

[compmore]

check your intake gaskets.i also had a rough idle and did plugs o2 sensors etc but still had probs.since i had the intake gaskets done in now idles and runs
like a dream.
good luck


geoff

[MBXB]

Search for Gearhead's post from last week.

[Tiger]

Agreed

[Tiger]

So Winfred... you said "what snow?" Guess you should have kept your mouth shut... LOL. I heard there was a massive whiteout at Flagstaff, AZ that caused a massive Highway 40 accident.

[tim s]

it turned out the cats were blocked shut.
i found this out after replacing the intake gaskets, pvc plate, & 02 sensors.
tim s.

[shogun]

this might help
http://forums.bimmerforums.com/forum/showthread.php?t=542733&highlight=OSV

[winfred]

huh?! i am in loserana so bring it on i dare it to snow :D


So Winfred... you said "what snow?" Guess you should have kept your mouth shut... LOL. I heard there was a massive whiteout at Flagstaff, AZ that caused a massive Highway 40 accident.

[Tiger]

Mmmm... Maybe I got you mixed up with BillR... since when did you live in Lousiana?

[MBXB]

At this point in the life of the car, most rubber hoses, gaskets or o-rings would have hardened and not seal properly.

[winfred]

for the last 19 years:D


Mmmm... Maybe I got you mixed up with BillR... since when did you live in Lousiana?

[nearle]

Thanks for the advice. Any tips on how to get the pcv plate off would be appreciated.

Sprayed MAF cleaner around the pcv plate. No changes in idle speed but I did get a strange sound kinda like a very quiet air horn for a few seconds each time I really dowsed the rear of the intake manifold.

[pgrindstaff]

Thanks for the advice. Any tips on how to get the pcv plate off would be appreciated.

Take a look through this thread (http://www.bimmernut.com/forum/showthread.php?t=34672&highlight=intake+manifold). There are a few good links in there to other threads that have instructions for getting to the pcv plate. Also, if the information isn't all there try searching for "Intake manifold" or "PCV". Those should give you what you are looking for. Another thing to check is an S-shaped hose on the pcv plate. Mine developed a hole and caused my problems. While you are in there you might as well replace all of the other gaskets as well to save you from having to do it later.

[nearle]

it turned out the cats were blocked shut.
i found this out after replacing the intake gaskets, pvc plate, & 02 sensors.
tim s.


How do you check if cats are blocked?

[winfred]

honking is good confirmation, heres a couple pics of one
http://members.cox.net/wdixon27/v8%20plate.jpg
http://members.cox.net/wdixon27/v8%20plate%202.jpg
don't forget the gasket on the throttle body as they are usually cracked on the bottom, the torx bolts are tight shallow headed and strip easily, i remove them with a hand impact driver



Sprayed MAF cleaner around the pcv plate. No changes in idle speed but I did get a strange sound kinda like a very quiet air horn for a few seconds each time I really dowsed the rear of the intake manifold.

[nearle]

How do you check if cats are blocked?

To answer my own question, I found this in the "rough idle and ultimate shimmy guide"

If the converter is plugged, it will create a restriction in your exhaust system. The buildup of backpressure will cause a drastic drop in engine performance and fuel economy, and may even cause the engine to stall after it starts if the blockage is severe.
The easiest test for converter plugging is done with a vacuum gauge. Connect the gauge to a source of intake vacuum on the intake manifold, carburetor or throttle body. Note the reading at idle, then raise and hold engine speed at 2,500. The needle will drop when you first open the throttle, but should then rise and stabilize. If the vacuum reading starts to drop, pressure may be backing up in the exhaust system.

[nearle]

The previous owner confirmed that he had not changed the PCV plate so I ordered the PCV plate and gaskets for the front and rear. Is it possible/smart to do this job without taking the manifold off?

[nearle]

At this point in the life of the car, most rubber hoses, gaskets or o-rings would have hardened and not seal properly.

This is the truth. I have found a coolant leak coming from the coolant level sensor not sealing and a power steering leak from the fluid reservoir cap . Replace, replace.

[winfred]

possible but a royal pain in the ass and if you strip one of the dozen of so really tight shallow headed torx you are really in for fun, plus the lower gaskets can leak as they are just as old and oil hardened as the front and rear plenum gaskets


The previous owner confirmed that he had not changed the PCV plate so I ordered the PCV plate and gaskets for the front and rear. Is it possible/smart to do this job without taking the manifold off?

[632 Regal]

reset cures most everything til winter where i know i should have fixed the gaskets the prior season



Do the Shogun Reset?

http://www.bimmernut.com/forum/showthread.php?t=2806&highlight=shogun+reset

[nearle]

OK, I've replaced the intake manifold gaskets including the PCV plate, PCV gasket, and throttle body gasket. I also cleaned the fuel injectors and replaced the spark plugs.

I still have the rough idle. Also, when I blip the throttle the revs hover around 2k and take 3-4 seconds to return to idle speed.

The next things I am thinking about checking are: catalytic converters, ignition coils, and O2 sensors...

[nearle]

Diagnosing Catalytic Converter functioning (Please Help):

I crawled under the car to poke around. Tapped the cats with my finger. One has a dampened sound while the other has a resonating ping. Hmmm.

Idled the car for a few minutes then went underneith to check the temps at the cats. Nothing too hot (225 F at inlets), but then the car had not been running for that long. Both cats seemed to have roughly the same temperatures at the inlets and outlets. The temperature difference from inlet to outlet was on the order of 100 degrees F. Seems normal right?

I just hooked up a vacuum gage to the intake. It was reading steady around 14-15 in HG (seems low). When I reved the engine the vacuum increased to around 20 in and held. I read somewhere that it was supposed to return to idle levels. Can someone knowledgeable in this area help me?

[jofusfarr]

Use carb cleaner to spray around the various connections at throttle body - one will go to the brake booster, the other to the charcoal canister. Spray there too. Listen for idle changes.

Once vacuum leaks are ruled out, check fuel pressure.

Does the car suffer from any hesitation on acceleration or perceived lack of power?

[MBXB]

Do the Shogun Reset?

http://www.bimmernut.com/forum/showthread.php?t=2806&highlight=shogun+reset

[Rusty Bavaria]

If it's a late production 540 it will have the air pump, smog control stuff on it. Make sure that your air pump valve isn't leaking exhaust into your intake...a nice simple two minute fix that took 3 months and $$ to figure out on my late production 530.

I didn't replace the failed valve just plugged the hose to the intake, well Ok I didn't the mechanic who figured it out did after I almost drove the car off a cliff in frustration.

Jim

[nearle]

It turns out that there is still a leak at the intake, with all new gaskets. One is on the driver's side (left) and one at the PCV plate. I sealed the **** out of the new PCV. Any suggestions?

Is it possible that there is a leak at the oil pipe connections under the manifold? That is the only part that I had trouble with at installation. I have heard people say to push the pipe aft with a flathead. I did not do this.