MAF sensor cleaner works then doesn't. - United Bimmer Community

**gldfshkpr** · 01-28-2008, 11:17 PM

I've been trying to diagnose terrible misfire during idle. I'm suspecting all the usual culprits; crank case valve hose, crank case valve, dirty MAF, vacuum leaks down stream MAF, idle control valve, bad gas, bad ECU, hmm... what else.

Anyhow, after checking for obvious hose leaks, I figured I'd clean the MAF. After cleaning it the car idled great! It was closer to 1000 RPMs and smooth. After about 10 minutes of driving, (warmed up) the symptoms returned and my low idle (500-600 RPMs) with misfire returned.

To summarize;
1. Engine started after 1 day sitting in garage. Rough idle present, misfire city.
2. Cleaned MAF; car runs great after initial startup and runs great for 10 minutes.
3. Car is at normal operating temp and runs like crap with the misfires.

It really seemed like the MAF cleaner helped, temporarily. I'm no closer to figuring this out. This is my daily driver. I'm about at my wits end and desperately need this resolved. Any help is appreciated, even a bump!

133,000 on motor.

witeshark · 01-28-2008, 11:22 PM

Any cracks in the intake tube to the manifold? That's what caused my car to do exactly that

**gldfshkpr** · 01-28-2008, 11:28 PM

Nope. The boot has a few 1000 miles on it. That's it. It's fresh.

**Antiburn** · 01-29-2008, 06:15 PM

Maybe you just need a whole new mass air meter. They do go bad and cleaning it wont fix the problem. Only way to really tell is to get the propper diag equiptment hooked up and get a true fault read out. Then you will know the exact problem of your idle.

**gldfshkpr** · 01-29-2008, 09:57 PM

Quote:

Originally Posted by Antiburn

Maybe you just need a whole new mass air meter. They do go bad and cleaning it wont fix the problem. Only way to really tell is to get the propper diag equiptment hooked up and get a true fault read out. Then you will know the exact problem of your idle.

At $438.59 I hope not! By proper diagnostic equipment do you mean a voltage meter? I need to test my ICV as well. I cleaned it with the same result as the MAF sensor. Car idled great until it warmed up to operating temp. Then the RPMs dropped to 600 with misfires. I also have a Fuel Sys 2 CL-Fault, whatever that is.

**Maxi** · 01-30-2008, 01:53 AM

I have same like this prob. in my 325i, it's RPMs around 500-600 only, and much emissions ( no smoke, just bad smill ) from the exhaust coming. No vibration in the engine every thing seems fine with hoses.
the car performance is seems fine, I'm not sure about it. but I feel there is somthing wrong with that low RPMs and that much exhaust emissions, which seems to be caused by misfire.
I'll replace the sparkplugs and see the result.

Tell us if you solve your prob.
Thanks,

johnnybayonne · 01-30-2008, 10:33 AM

Hey! gldfshkpr, Did you try searching some other forums like,
http://forums.bimmerforums.com/forum/index.php

http://www.bimmerfest.com/
When I bought my car it had a problem code for a leaky emission tank! I counld not find it for anything, so I just kept searching the all BMW forums! Then I found somebody with a thread that had the same problem!!!
On the other hand when I installed my struts & springs I damaged 1 of the speed sensors. There was no way of telling which one it was, so I bit the BULLET & brought it to a bmw dealer shop just to get a diagnosis, they charged me 1 hour labor, which was $125.00 & told me that the left front speed sensor was not working. They wanted to do the job for $350.00. I DECLINED, paid the $125.00 & bought the sensor on-line for about $80.00 bucks & did it myself. So you have some options!!!

**gldfshkpr** · 01-30-2008, 12:34 PM

Quote:

Originally Posted by johnnybayonne

Hey! gldfshkpr, Did you try searching some other forums like,
http://forums.bimmerforums.com/forum/index.php

http://www.bimmerfest.com/
When I bought my car it had a problem code for a leaky emission tank! I counld not find it for anything, so I just kept searching the all BMW forums! Then I found somebody with a thread that had the same problem!!!
On the other hand when I installed my struts & springs I damaged 1 of the speed sensors. There was no way of telling which one it was, so I bit the BULLET & brought it to a bmw dealer shop just to get a diagnosis, they charged me 1 hour labor, which was $125.00 & told me that the left front speed sensor was not working. They wanted to do the job for $350.00. I DECLINED, paid the $125.00 & bought the sensor on-line for about $80.00 bucks & did it myself. So you have some options!!!

I hear ya. I visit all those forums daily plus http://www.318ti.org - You and I think along the same lines. When I first bought the car in Nov '07 the first thing I did was take it to a Indie BMW/Mini shop in my town. I had them do the Inspection II and give me a list of repairs they wanted to make. I told them I wanted it like new. They came back at me with $2400 worth of repairs. I now have a list of things to do! Motor mount, RSMs, control arms, etc. No one can love your car as much as you. Besides, I don't have a disposable income. Thanks for the support! I'll let you all know how this turns out.

I've cleaned MAF and ICV. Next move is to replace the fuel filter on Saturday. I'll be sure to let you know the outcome.

**Numark318i** · 01-30-2008, 03:56 PM

I have read that if u temporarly disconnect the MAF sensor, and the car runs fine u know
its that. That is how they diagnose it

**gldfshkpr** · 01-30-2008, 04:38 PM

Quote:

Originally Posted by Numark318i

I have read that if u temporarly disconnect the MAF sensor, and the car runs fine u know
its that. That is how they diagnose it

Oh that sounds excellent. Do you mean disconnecting the electrical connection? That's a snap. Are you sure about this? I wouldn't want to damage anything.

**Numark318i** · 01-30-2008, 04:41 PM

u disconect it. Make sure u only run it for a min or two only. And no Erving. All it does is tell the ecu to make the default air/fuel
mix

**gldfshkpr** · 01-31-2008, 09:25 PM

Quote:

Originally Posted by Numark318i

u disconect it. Make sure u only run it for a min or two only. And no Erving. All it does is tell the ecu to make the default air/fuel
mix

Numark, I disconnected it and the car ran really badly. I guess that means my MAF sensor is doing something. Cleared the mass air volume code and reconnected MAF. Still runs really badly, worse than before. These cars are killing me with their computer on-top-of mechanics. All in the name of emissions.

Saturday I'm replacing the fuel filter. I'll go for a nice drive and see if I can get the MAF to talk nice to the computer again.

I love my car, I really do.

**Numark318i** · 01-31-2008, 09:42 PM

maybe bad O2 sensor? It might be running to rich hbecause thats bad?

**gldfshkpr** · 01-31-2008, 09:52 PM

Quote:

Originally Posted by Numark318i

maybe bad O2 sensor? It might be running to rich hbecause thats bad?

Sensors are @ 30k. I'm also running some Sea Foam through everything and see if that clears up some issues. I've heard nothing but positive results with that. O2 Sensors are one of my last resorts. I'll test them before I replace them. Thanks for your replies. It really helps to have this community for support.

As much as I love my wife, she just can't engage in car talk.

**rainman73** · 02-10-2008, 04:48 PM

Quote:

Originally Posted by Maxi

I have same like this prob. in my 325i, it's RPMs around 500-600 only, and much emissions ( no smoke, just bad smill ) from the exhaust coming. No vibration in the engine every thing seems fine with hoses.
the car performance is seems fine, I'm not sure about it. but I feel there is somthing wrong with that low RPMs and that much exhaust emissions, which seems to be caused by misfire.
I'll replace the sparkplugs and see the result.

Tell us if you solve your prob.
Thanks,

MAXI have you changed the plugs already? I have the same problem although mine stays at 600 rpm but does skip every 30 to 45 secs. and Im also planning to do a plug change