Running rich and idling rough

[Racerhoze]

After doing a headgasket/cooling system overhaul, the car starts right up, but seems to idle rough in the 700-800rpm range. Once revved up, it runs nice, but upon returning to idle, it dips down to 600ish rpm and almost stalls, the battery light even comes on for a second when it reaches such low rpms. It also is running extremely rich. I can almost taste gas from around the exhaust pipe, even when it is at operating temp. I used some carb cleaner in the ICV and that did not seem to do a whole lot. I have checked all the vacuum lines for leaks and have come up with nothing. I guess I still need to check the crank position sensor, what exactly should that be gapped to?

[gerizmos]

sounds like what's happening to mine =(

[TouringDan]

sounds like what's happening to mine =(

I've been chasing down a rough running / misfire for a long time now... I just got home with a new cam position sensor that I'll toss in and see what happens. I *thought* it was the ICV, but that wasn't it at all. :mad

So far, I've replaced the crank position sensor, coils, plugs, ICV, fuel pump, fuel filter, the ECU, and, um... some other stuff I can't recall... Nothing worked.

I'll let you know if the cam position sensor does the trick.

[gerizmos]

why the ECU??

and thanks man

[TouringDan]

why the ECU??


One of the only things I hadn't replaced at that point, so thought I'd give it a shot.

[Racerhoze]

Are all your cars running extremely rich? I think after driving this car around a parking lot 4 times, putting on about 7 miles, I have used a quarter of a tank.

[525fourthew1n]

^ Jesus christ... I don't want do throw lame suggestions out, and I don't mean to say that you haven't thought of this, but maybe old/dirty O2 sensors, or MAF? I mean Rich/Stoich/Lean is pretty much controlled exclusively from the input of those devices, correct?

[TouringDan]

^ Jesus christ... I don't want do throw lame suggestions out, and I don't mean to say that you haven't thought of this, but maybe old/dirty O2 sensors, or MAF? I mean Rich/Stoich/Lean is pretty much controlled exclusively from the input of those devices, correct?

Yeah - under that "some other stuff I can't remember" heading - add the O2 sensor and swapped the MAF.

[gerizmos]

qharter tank after 7 miles.. jesus mine isnt THAT rich.. well im getting new 02 sensors anyway so il tell ya if that does anything (itl be done in about a week because i havent even orderedt them yet...but il get back to you all)

[Racerhoze]

Well, I just seafoamed the car, one bottle sucked in a vacuum line, another in the gas tank, with not much improvement in the idle. I think the gas tank sending units are faulty, because it is jumping around from 1/2 to 1/4 to 0 in the tank, so I don't know if those need to be cleaned or what. Is there a way to clean o2 sensors? I don't want to dump any more money in this car than I have to. And I am pretty sure that my car has a AFM not a MAF. I am somewhat stumped at this point. :help

[atl530i]

What about the fuel pressure regulator?? I had one go bad on my Honda (not a BMW but anyway), it pretty much did not open anymore and upped the pressure and dumped all the fuel in the engine. I think I was getting like 8mpg in a car that was supposed to get 30mpg. Just a thought.

[Racerhoze]

Is there a way to check my fuel pressure regulator that does not involve swapping it for another unit?

[atl530i]

You could always get a fuel pressure meter to check it.

[Racerhoze]

damn, I need to make friends with someone who has a shop that can help me and that has tons of tools.

[atl530i]

damn, I need to make friends with someone who has a shop that can help me and that has tons of tools.

It helps. When I was messing with my Honda, I figured it out by process of elimination (ie multimeter). When I took the return line off the fuel pressure regulator, my friends father put a screw in the exit part of the FPR to up the fuel pressure and make the fuel economy worse then a 64 Impala.

[boone.msi]

join the club...

Mine, in now way shows a huge impact on mpg, but it does misfire. I have gotten it from running on 4 cylinders and stalling, to now only missing on 1 cylinder every 60 seconds at idle, still working on it. Me and shrike have just about replaced everything... seriously.

[E34N]

I guess it's that time of the year for our cars... I just recently started getting the same symptoms. Code 1222... CEL... idles VERY rough (almost dying after start up)

I'm going to start checking things one by one tomorrow.. we'll see what I can contribut to this thread...

[Racerhoze]

Well for those who didn't see any of my other threads, I bought this car with a warped head/blown HG and have just gotten it running, so it is not as if something went wrong all of the sudden, its just been that way since Its been put back together and I have no idea how it ran pre-overheat.

[bmwpower]

To test the FPR, pull off the vacuum hose. If the idle gets even worse after pulling the hose, the FPR should be good.

I, too, pulled my head off after a blown HG. Idle is worse now, too.

How is your timing chain? New?

How are your wires?

One thing I haven't checked is the O2 sensor. Dumping a bunch of coolant into the engine and burning it off could have a negative affect on the O2 sensor.

Have you checked overall vacuum? What did it read?

[TouringDan]

Vac reads 20# at idle

[bmwpower]

Vac reads 20# at idle

Is that within spec? I don't have my book near me...

[Cressidom]

Hullo gents...

sounds like the same crap I'm going thru..fuel pump died on me this past Friday...got one from a chop shop..better shape than the one which died..car performs better...but still missing or hesitating at times.

Sometimes stars easy..sometimes cranks longer...and occasionally a popping sound...

Cheers
Dom

[TouringDan]

Is that within spec? I don't have my book near me...

Yes - it's supposed to be between 19 - 24.

[Racerhoze]

To test the FPR, pull off the vacuum hose. If the idle gets even worse after pulling the hose, the FPR should be good.

I, too, pulled my head off after a blown HG. Idle is worse now, too.

How is your timing chain? New?

How are your wires?

One thing I haven't checked is the O2 sensor. Dumping a bunch of coolant into the engine and burning it off could have a negative affect on the O2 sensor.

Have you checked overall vacuum? What did it read?

Which vacuum hose am I pulling to check this? Is it the one right above the fuel rail? My timing chain is original, but I did get a new guide rail and tensioner :stickoutt. I guess I should check the resistance of my wires because I am pretty sure those are original as well. I am thinking it is probably an o2 sensor. Are those a replace only type thing? or is there a way to clean/repair them.

[gerizmos]

someones gotta try just gettingt a new 02 sensor... that way i can know if that helps at all =)

[bmwpower]

Which vacuum hose am I pulling to check this? Is it the one right above the fuel rail? My timing chain is original, but I did get a new guide rail and tensioner :stickoutt. I guess I should check the resistance of my wires because I am pretty sure those are original as well. I am thinking it is probably an o2 sensor. Are those a replace only type thing? or is there a way to clean/repair them.

Yes, the hose attached to the FPR.

Yea, when I pulled my head I didn't change the chain either. It was close to it's limit of stretch. I'm thinking this is not helping.

Sometime before this, my wires went bad. I had a miss at idle. I must have changed everything before I changed the wires. Turns out the wires bench tested fine, but when I checked the resistance AND moved them around a little bit, there was break in the wire somewhere. You might want to check the wires, too. Check them while you're moving the wire around for best results.

You can try to clean the O2...if you can get it out in one piece. Bad positioning thanks to BMW. See how bad yours is, clean it up carb cleaner.

[Racerhoze]

is carb cleaner good for o2 sensors? what about brake cleaner?

[bmwpower]

is carb cleaner good for o2 sensors? what about brake cleaner?

Now that you mention it, I believe I used electrical cleaner last time I took mine out. CRC brand to be exact. I don't know for a fact that carb cleaner will hurt it. It's environment is a little different than, say, the AFM environment where I definitely would use an electrical cleaner.

[bmwpower]

is carb cleaner good for o2 sensors? what about brake cleaner?

Brake cleaner should work as well.

[Racerhoze]

Alright, well, looking at realoem and having been under the car... is there any trick to getting the o2 sensor out? I don't remember seeing it, so I assume that it is on top of the exhaust.

[bmwpower]

Alright, well, looking at realoem and having been under the car... is there any trick to getting the o2 sensor out? I don't remember seeing it, so I assume that it is on top of the exhaust.

The easiest way is the drop the mid pipe. I believe that's what I had to do. The O2 is on top of the pipe. You can to get it out without dropping it, but like I said, mine was a PITA to get out, so I dropped the pipe. Fun.

[Racerhoze]

The easiest way is the drop the mid pipe. I believe that's what I had to do. The O2 is on top of the pipe. You can to get it out without dropping it, but like I said, mine was a PITA to get out, so I dropped the pipe. Fun.

Damnit. I wish I knew somebody with a lift.

Edit: Has anybody been able to remove the sensor without dropping the exhaust?

[bmwpower]

Damnit. I wish I knew somebody with a lift.

Edit: Has anybody been able to remove the sensor without dropping the exhaust?

If you want to drive to NJ... :)

[Racerhoze]

If you want to drive to NJ... :)

Well I do want to visit my brother who lives in Oldbridge sometime :stickoutt Though according to my nav, it would be... really far.

[camper1159]

I had the saame problem, turned out to be the cylinder head temp sensor.

When i did all the work, i accidentally broke a wire. The DME then thought the engine was ice cold, and richened up the mixture to the point the exhaust pipe smelled like the gas tank.

New wires and new CH sensor. It ran like new.

Check it out...

[Racerhoze]

I had the saame problem, turned out to be the cylinder head temp sensor.

When i did all the work, i accidentally broke a wire. The DME then thought the engine was ice cold, and richened up the mixture to the point the exhaust pipe smelled like the gas tank.

New wires and new CH sensor. It ran like new.

Check it out...

Where is the cylinder head temp sensor? Is it the one close to the firewall?

I unplugged the vacuum hose to the top of the fuel pressure regulator with the engine running, and it still had the same responsiveness and the same rough idle... does this mean that the FPR is my problem?

[bmwpower]

Where is the cylinder head temp sensor? Is it the one close to the firewall?

I unplugged the vacuum hose to the top of the fuel pressure regulator with the engine running, and it still had the same responsiveness and the same rough idle... does this mean that the FPR is my problem?

It's up at the thermostat housing. Not sure which one he's referring to:

http://www.realoem.com/bmw/showparts.do?model=HD23&mospid=47408&btnr=11_1118&hg=11&fg=35

You may not see a problem with the FPR in your case as it seems your car is running terribly rough already. Even my car, which runs really rough, I can tell a difference with the hose on or off.

The thing to do would be to check the fuel pressure, to see if it is indeed regulating it. My gut is telling me that it's probably bad.

[Racerhoze]

It's up at the thermostat housing. Not sure which one he's referring to:

http://www.realoem.com/bmw/showparts.do?model=HD23&mospid=47408&btnr=11_1118&hg=11&fg=35

You may not see a problem with the FPR in your case as it seems your car is running terribly rough already. Even my car, which runs really rough, I can tell a difference with the hose on or off.

The thing to do would be to check the fuel pressure, to see if it is indeed regulating it. My gut is telling me that it's probably bad.

Yeah, I could tell 0 difference with it on and with it off, even revving it, it was the same, is there a way to clean it? I am very cheap and am trying to fix everything free style. Also, when I was nearing 1/4th of a tank, the guage was being kinda funky bouncing around from 0 to 1/4th. But now that I filled up the tank, it has been staying at full. But I think that is just a bad sending unit, and not related to the idle.

[Rono174]

this thread is great, almost everything listed is similiar to whats going on with my 94 530. When I idle at a traffic light, my rpms drop then go back up over and over again until i drive the car for awhile. Few of my friends tell me my car might be running rich too; and as for the engine, you can hear a very faint ticking which is starting to make me worried...

[danielesach]

Is this the never ending story of the rough bimmers??!!! I am having the same prob with a rough idle. The thing I dont understand I when I replaced my plugs it ran great but then it started running bad and gets worse and worse. Is this because the fuel is too rich and fowling the plugs? I dont know. I will continue to follow this thread for possible help......Thanks guys..........

[Racerhoze]

My cars idle has seemed to improve slightly now that I have the bad gas out of the tank, but it still seems to idle pretty crappy. Also I have been getting 14-15 mpg on this most recent tank.... which sucks.

[Dat Aus]

EXACTLY what was happening to mine a few weeks ago. i had the air flow meter replaced along with new 02 censors, and had fuel lines cleaned. ever since then, been running the best it ever has since i bought it

[turbochess]

hi, let me join the rough idlers club from Istanbul, Turkey. With mine the rpm at idle does not change, it is rather constant at 900, however the engine still shakes violently. It even shakes the car a little.
I have cleaned the icv and the maf, there seems to be no vacuum leak (at least none i can see).

Can this be caused by a malfunctioning flywheel?

[ballplayer7373]

Look's like I found the thread I needed. Just got the 535i a week ago and it ran great on the 600 mile trip down from NorCal, but as of yesterday driving around town it died on me in a parking lot and almost stalled a couple times at the light, runs really rough under 1000rpms, seemed a bit better above that. Started it up today, and running even rougher at all rpms, almost dies just sitting in park. First thoughts were that it might be starving for fuel so bad filter or pump, but after reading all your problems not sure. Did any of you guys end up resolving your issues, or was there an agreed upon solution found? Any help would be awesome

[E34N]

Look's like I found the thread I needed. Just got the 535i a week ago and it ran great on the 600 mile trip down from NorCal, but as of yesterday driving around town it died on me in a parking lot and almost stalled a couple times at the light, runs really rough under 1000rpms, seemed a bit better above that. Started it up today, and running even rougher at all rpms, almost dies just sitting in park. First thoughts were that it might be starving for fuel so bad filter or pump, but after reading all your problems not sure. Did any of you guys end up resolving your issues, or was there an agreed upon solution found? Any help would be awesome

Most of the times, people will have different fixes. All suggestions should be looked into.

[bmwpower]

I will be putting my new oil pan gasket on tomorrow night. Bought a new dipstick, too. The only thing I really haven't tried is a new AFM or ICV. If the oil pan doesn't do the trick, it be nice if I could find an AFM or ICV that is from a known good idling car to test out.

Has anyone actually bought a new ICV or AFM...would really hate to have to do that.

[ToppedOut525i]

little off topic.. but racerhoze the wheels you got on that 330i look amazing :buttrock

[Racerhoze]

little off topic.. but racerhoze the wheels you got on that 330i look amazing :buttrock

Thanks! They are Z4 3.0 sport package wheels. Here is what they look like clean.

[hindsight]

Seems like a very common problem with these cars. My 91 525i (M50) is ruinning like crap after cooling system refit. After testing the coils to see if they were all firing learned that my 2 and 5 coil are not sparking. The coils are fine (moved to other cylinders and they fire) so I'm thinking it's the DME or ignition contol module. I really don't want to just start ordering parts if I can avoid it. It ran perfectly until I took apart the cooling system and replaced the thermostat and pump. Any body know a way to test which part of the ignition system may be causing the problem?

[tortexal]

I have an AFM for sale left over from my MAF conversion for a 535i if anyone needs it. But youd have to reuse the plate that comes with yours (4 screws) the plate is needed for the maf conversion thats why its not w/ the AFM anymore.

[ToppedOut525i]

Thanks! They are Z4 3.0 sport package wheels. Here is what they look like clean.


nice....