Sputtering at idle

[MOTRSPRT]

My 1998 recently turned 100K miles and has slowly had an increase in sputtering while just sitting at idle. Instead of the smooth engine idle, it will slightly sputter. There is no sputtering or hesitating during acceleration at all, and the throttle is still responsive when blipped from idle.

If I could narrow down search terms to find just what I want, I would do that. After reading through a bunch of other posts unrelated I decided it would be quicker to pick your guys' brains.

Any idears?

[joe91985]

check out the idle control valve cleaning, should be a DIY somewhere on here. I'm sure it's reffered to as the ICV.

[MOTRSPRT]

Is this the DIY you were referring to:

http://forums.bimmerforums.com/forum/showthread.php?t=322651&highlight=icv+diy

I will give this a try tomorrow and will clean my TB as well...

[Brent 930]

It could be the ICV or a vacuum leak. Personally I wouldn't go through all the trouble of cleaning the ICV with the age of the car now. Just buy a new one and replace it. Even if that isn't it, it's still a good thing.

As for a possible vacuum leak, check your hoses and replace any in question.

[///M LIFE©]

Most likely a vacuum leak. I had the same thing and found out a pipe was cracked.

[MOTRSPRT]

Well, just got around to the DIY for cleaning the ICV. It certianly wasn't very dirty, but a few squirts of throttle body cleaner and it was again sparkly as new. Reinstalled everything (there's more to move around for those of us with a supercharger) and took the car for a drive. My biggest concern was the sputtering I could hear in the exhaust while the car idled. After I returned home, I listened for the sputtering. I found there was still some sputtering at idle, but in a reduced amount. The biggest improvement, however, is the smoother driving and gear transition especially from 1st to 2nd gear. The car used to jerk around (not stumble or sputter) for a second or so no matter what rpm I shifted. This problem has been eliminated--probably from the slightly increased idle the car gained.

So, I'm now back to the drawing board with my idle sputtering. Most of the hoses I've inspected are in decent shape. Is there any way I can check the spark plug coils one by one? Can I just unplug one at a time to see if the sputtering changes or goes away? My plugs are probably 2.5 years old. Maybe I should change them out?

[Razziel24]

I had the same symptoms on my eurospec M3 a few months ago, I replaced the TPS, and the problem was gone.

[MOTRSPRT]

I forgot about that. What I was considering was checking to see if the TPS can be adjusted, and if so maybe mine is out of adjustment?

[mmark.]

Why don't you do a tune up?
100k miles and Spark plugs that are 2.5 years old?....lack of maintenance. With supercharger to boot.
Read the maintenance booklet.

m

[xman11]

My plugs are probably 2.5 years old. Maybe I should change them out?

Definitely change them.

http://forums.bimmerforums.com/forum/showthread.php?t=856515

[MOTRSPRT]

Definitely change them.

http://forums.bimmerforums.com/forum/showthread.php?t=856515

Sometimes I overlook Mr. Obvious :( I will pick up some plugs tomorrow, most likely NGK BKR7E copper plugs. Hopefully, this will cure my problem and maybe even improve my fuel mileage.

[MOTRSPRT]

Update:
Bought some NGK BKR7E plugs today and gapped them down to .030" from .032". Removed the old NGK iridium plugs whose gaps were .042" and really looked worn out. Installed the new plugs, buttoned everything back up, and took my car out for a test drive. The car definitely picks up a LOT better now and the power seems much more linear without a flat spot. Overall, the driving is much nicer now. HOWEVER, the original reason for starting this thread is still haunting me. The car still sputters at idle. I wonder if a fuel injector is beginning to go out? Any idears?

[str8bucking]

start up the car,(open the hood) while car is on, remove the plug from the MAF and see of it goes away,and plug it back it you will see a big differents with it on and without it, most likely if the idle gets get a little better is the MAF
(try to clean it out)

[I3MW]

Update:
Bought some NGK BKR7E plugs today and gapped them down to .030" from .032". Removed the old NGK iridium plugs whose gaps were .042" and really looked worn out. Installed the new plugs, buttoned everything back up, and took my car out for a test drive. The car definitely picks up a LOT better now and the power seems much more linear without a flat spot. Overall, the driving is much nicer now. HOWEVER, the original reason for starting this thread is still haunting me. The car still sputters at idle. I wonder if a fuel injector is beginning to go out? Any idears?

yeah I have the same problem, although its not really a big deal, I changed my plugs about two weeks ago and while I'm glad I did it, it made now difference. I will end up cleaning my ICV also. Would love to hear a definitive solution...

[m52bro]

my 96 328is sputters at idle too.. it sounds like a pop in the engine right? and recently my performance is not what it used to be.. im thinking their related.. are you having any performance issues? im thinking its my feul injectors.. but the icv could be doing it also.. or the vanos..or the MAF.. or the throttle body..or the spark plugs..haha the list just keeps going on and every problem has the same symptoms....

[I3MW]

my 96 328is sputters at idle too.. it sounds like a pop in the engine right? and recently my performance is not what it used to be.. im thinking their related.. are you having any performance issues? im thinking its my feul injectors.. but the icv could be doing it also.. or the vanos..or the MAF.. or the throttle body..or the spark plugs..haha the list just keeps going on and every problem has the same symptoms....

I think you have a different problem, do you have a cel? It's not your VANOS, have you changed your plugs? Does the problem still occur if you turn it off and come back to it quickly? In my case it never caused performance issues and it didn't sound like a pop in the engine. Have you checked for a plain old vac leak?

My car used to have a rough idle for a bit after just turning it on. Changing all the PCV related items helped a lot. The car is still a little rough for a few seconds on really cold starts but I think that's normal, especially for E36s.

[m52bro]

no cel..no vacuum leaks i got it checked.. spark plugs i changed about a year ago should i change them? what about coils? or feul injectors? what happens sometimes is i shift from first to second and the acceleration just dies..i take my foot off the gas and hit it again and itll accelerate..and sometimes when i accelerate it just feels like somethings holding it back..i got a conforti cai with the spongy filter about 2 months ago..i dont think it could be dirty..or am i wrong? WHATS HAPPENING TO MY M52:[

[I3MW]

no cel..no vacuum leaks i got it checked.. spark plugs i changed about a year ago should i change them? what about coils? or feul injectors? what happens sometimes is i shift from first to second and the acceleration just dies..i take my foot off the gas and hit it again and itll accelerate..and sometimes when i accelerate it just feels like somethings holding it back..i got a conforti cai with the spongy filter about 2 months ago..i dont think it could be dirty..or am i wrong? WHATS HAPPENING TO MY M52:[

Go back to your stock airbox and see what happens. Does your idle always stay more or less the same? I don't mean the rpm number but whatever issues your having with it - they don't go away as the car warms up correct? Start with whatever cheaper, easy, and logical. Take the intake out of the equation. Who checked for a vac leak? When?

[bondovw]

Check the ohms on your spark plug boots!

[resqav8r]

start up the car,(open the hood) while car is on, remove the plug from the MAF and see of it goes away,and plug it back it you will see a big differents with it on and without it, most likely if the idle gets get a little better is the MAF
(try to clean it out)

Had the same problem as my 3.5" MAF (540) was flowing too much air so it had some pre detonation and iratic idle. Called DINAN and confirmed the MAF is too big so I got a new stock E36 3" MAF (one of those cheap sub $100 ones from the internet) and it ran perfect for one 6mile drive ... now it won't hold idle, RPMs just drop till it just dies. Unplugged the MAF and it idles fine (albeit at 1500rpm) ... to me it sounds like that cheap MAF failed already?

Does that sound possible?

[tbert122]

I have the same problem. The car sputters only sometimes at idle. With a tap of the throttle it usually clears up and goes back to a normal idle. I recently changed all my coil packs because I got a misfire while on the track. Since I have changed the coil packs I have had two additional misfires while on the freeway. I simply restart the motor and it runs fine afterwards. I am starting to think the random misfires and random rough idle are linked together.

Besides the rough idle and rare misfires, sometimes after doing a tunnel blast the car with idle high (2k) for a few seconds then slowly drop to its normal idle.

Would love to hear what you guys think! The car is a 97 m3 with 158k. I am starting to think maybe a bad injector.