M42 issues....please help!

[EN318isPDX]

I always thought that the fuel pump was either good or bad? not intermitantly working?

I will test the fuel pressure though and see

Well my fuel pump never made any noise. The filter fell apart and carbon built up and clogged it. The computer managed to run on the 13psi fuel pressure. Fairly amazing. I took pictures of my old fuel pump check my cardomain.

http://www.cardomain.com/ride/2911926/3

I always thought that the fuel pump was either good or bad? not intermitantly working?

I will test the fuel pressure though and see

[EN318isPDX]

I have a 1991 318is with 238k. I had alot of similar issues when i got the car. I found that the TPS and AFM are easy to test with a multimeter. AFM aint cheap (around 300 for rebuilt) so i tested mine and it was easy and it had no issues. I replaced my fuel injectors thinking i wasnt getting enough fuel, or one could have been dripping. hardly any improvement with new injectors. Tested TPS. When i opened the throttle above 90% it went 0 on multimeter. Replaced that... Still not fixed. Tested fuel pressure coming out of the tank and my car was running on 13 psi of fuel. All the vacuum hoses and sensors helped but it all came down to the 13 psi of fuel pressure. New fuel filter and fuel pump really made the new injectors work right and it feels like my M42 tripled in HP

[E30nate]

/\ thank you, I was trying to figure out what is power and ground, are they the same color? as in like red and brown?

thx

Taking it to a shop today or tomorrow

i dont know which one is which. you can probably look in your bently manual or somewhere online.

you can check the voltage to each wire also.

/\ thank you, I was trying to figure out what is power and ground, are they the same color? as in like red and brown?

thx

Taking it to a shop today or tomorrow

[E30nate]

you can test the afm with an ohmmeter. find out what plugs are signal/ground, and move the door inside at an even rate. if the ohms go up or down gradually, it is good. if they are all over the place, as in low, then really high, and no in between, it is bad.

/\ thats right, cause you said your old one quit right? They wont run like intermitantly will they?

Had 3 people tell me to do a stage II tune up as I have never done one and see what happens.

[smonkbmw]

if it was the fuel pump it wouldnt run at all.

Luckily today at the picnic I got 450$ tune-up so hopefully if i can get it there they can take a look at it?

Does anyone think it could be the fuel pump?

[Gray S.]

I replaced my fuel filter when I had my issue and that didnt solve it, so your friend is right on the money!

E30groupie used his codereader and didnt see anything but a blip.

No engine light flashes.

My friend who is a moterwerks advisor/master mechanic at the dealership said he would bet 100$ it is a fuelfilter or AFM

[DCColegrove]

It can be a sticking AFM or a Pump it is hard to tell here on a thread.

Does the MIL (check eng light) flash when this happens?

Are you able to read the codes?

[Gray S.]

I wouldnt buy a brand new AFM until I knew that was the problem. I just picked up a used one off of Bavarian Auto Recycling for 50 bucks since I did wanna shell out hundreds for an AFM if that wasnt going to fix my issue. Just swap in one that you know is working correctly, then decide if you wanna shell out for a new one.

it has new plugs and I will look into replacing it with a known working AFM. I will also look into borrowing some plugwires that work fine.

Jeff: Curt plugged that Codereader in, something very quickly popped up and then it was gone again so the codereader was almost no help. -thanks Curt-

I am wondering if it would be something like the TPS because when the car is sitting it is 100% fine. I drove it for 10 min after reseting the codes and it starrted acting up again. Sputter and stalling with my foot in the gas.

I have 230 to fund fixing it so until i know what it is I wont be getting anything. I was going to replace things like air/fuel filter and such just a routine maintanance.

Do you guys think it could be the fuel pump at all?

Just looking at a bunch of possible scenarios.

thx for all the input

http://www.koperformance.com/online_ordering/make_n_model_search_catalog4.php?make_select=BMW&year_select=1991&model_select=E30318M|||70f23384c1acbedcaf5727021c405148&model_select_text=318i%20M42%20%28E30%20chassis%29&3flag=Y&group_id=F2&group_text=Fuel/Air%20Intake%20System&group_log=4493792&cat_select=822&cat_text=Air%20Flow%20Sensor&cat_log=4436856

Does anyone know if the AFM is worth my time if infact it really is the problem? Has anyone used that one? thx

[Gray S.]

You sound like your having the exact same problem I was when I first got my m42. I would be cruising at part throttle constant speed and the car would start bucking and sputtering, let off the gas it would stop, give it gas and it would start again.

It did this periodically, would do it for a day then not for a few weeks. I took it to BMW and they diagnosed a bad AFM. I replaced the AFM with a known working one and havent had the issue since, that was 4 or so months ago.

It also might be a combination of that and your old plug wires or your ignition system needing a tuneup.