View Full Version : Throttle body, and making it run right.

05-17-2004, 02:31 AM
Well, I need your help. I've got a '91 318i, and i've been tinkering around with what I can in the car.

I disconnected the entire air hose off of the throttle body, and covered up the crankcase breather hose that connects to the airbox, so that there is no vacuum leak.

When I turn the car on, I get a check engine light, and the car doesn't want to idle. But the best part of it is driving down the street and having that aggressive intake roar at 4,000 and above RPM.

My question is, how can I get the car to run correctly without the airboot connected? I want to have the car idle, and be able to drive regularly without having the side effects of VERY sluggish acceleration at lower RPMS (3,500 RPM and under) and having the car jerk around while the sensors try to adjust.

Please help!

05-17-2004, 02:42 AM
i didnt quite understand all of that...but i think what you're looking for is a maf to afm conversion..something like this??

Mass Air Conversion kit

Complete mass air flow conversion kits are available for several models. This is a serious horsepower upgrade for an air flow meter based BMW. Air flow meters are highly restrictive and are frequently the cause for a poor running car. These MAF kits not only improve horsepower, but also provide the means to fine tune performance while preserving drivability. Each kit includes the ARC2, ARM1, mass air flow sensor, wiring harness and complete instructions. Air filter assembly not included
May be legal for racing vehicles only, be sure to check your local laws. Model Body Year Item Price
325i (m20), 318is e30 87-92 126845 $895.95

05-17-2004, 03:26 PM
Here, i'll take pictures within the day and show you ...

05-17-2004, 03:50 PM

05-18-2004, 04:49 AM
Wondering what the fuel economy will be without an airflow sensor connected will be, i'm running a small airfilter off of the thorottle body, wondering what the negative effects are?
Positive effects: quicker revs, tires chirp when throttled hard
Negative: Idle is 'hunting', under 3,000 RPM when gas pedal fully depressed car lugs, decelerates, almost like flooding engine, strange.

05-18-2004, 05:11 AM
i couldnt even get mine to run at anything above idle witout it...i cant see how you can drive around without it hooked up????

05-18-2004, 03:02 PM
Yeah, w/o the airflow sensor connected my car runs alright without, under load it's a little jerky at lower RPM's, but at the higher RPM band it's incredible.

05-18-2004, 03:11 PM
I get a 'check engine' light while doing this ... the code is '1234' which is 'Speedometer Relay etc' Why would it do that?

05-19-2004, 02:31 AM
I presume you have no idea what the AFM does, otherwise you wouldn't waste your time removing it and complain it doesn't run properly with out replacing it with a less restrictive form of fuel metering device, MAF or the more desireable MAP sensor.

05-19-2004, 03:33 AM
I'm aware what the AFM is, i'm wondering why I get a speedometer error code, and what are the side effects with running w/o an AFM on.... jeez.

05-19-2004, 04:46 PM
Dude, the AFM tells the ECU how much air is going to the engine therefore it adds the correct amount of fuel. If you don't understand or want to run without it buy yourself a carburated car.

05-19-2004, 04:50 PM
I wouldn't do this to my car

05-19-2004, 07:47 PM
thats the most insane thing I have ever heard....its like taking off your radiator and asking...why does my engine over heat? The ECU requires the signal from the air meter...otherwise its running in failsafe mode, where it will only meter fuel based on O2 sensor, engine temp, and throttle position...without the afm the car dosn't know how much air is going in, and it also dosn't know the intake air temperature...why not just get an MAF conversion as suggested by others.

05-21-2004, 03:15 AM
That ... still doesn't explain why i'm getting a speedometer error code.

05-21-2004, 03:23 AM
Originally posted by robbieosterman
That ... still doesn't explain why i'm getting a speedometer error code. put the afm back on...do you still get it then???i'm willing to bet you dont...*no-no*

05-22-2004, 01:35 AM
I did, I only used the car w/o the AFM for almost an hour total, just curious to why the computer reads speedometer error