Wtf...missfire problem

[llll1l1ll]

Alright, my car misfires (I'm guessing that's what it is. Like, the car will buck and hesitate when I have the throttle at a certain position. The mpg will also go down to zero. This makes me think its the throttle position sensor) and its been doing new things lately. Now, the tach and the mpg gauge will just randomly stop working and the car will feel like it has no power. It only does this for a second or two at a time, every once in a while when it runs. Plus, a completely different problem happens. Sometimes while I'm driving, the check engine light will randomly come on, but the car feels completely normal. Wtf. Anybody have any ideas?

[chesster6969]

Main Relays? Fuel pump or fuel filter?

[PJ325i]

I'm getting something similar also. . . .

For me I'm about to replace the fuel pump, fuel relay, and temp sensor.

Least expense fix first ;)

I'll report my findings.

[bimmerlover]

I had a really bad misfire problem at low rpms in my 318 recently. I put in fuel cleaner and changed the fuel filter.. and no problems since. It's a possibility.
Don't know about your check engine light or gauge problems though. :(

[randomtask37]

i had the same thing, although it doesnt sound like it was as bad.

i just used fuel injector cleaner. worked like a charm.

[PJ325i]

I've tried fuel injector cleaner and such. . .it didn't help. . .

I just replaced the fuel relay.

It idles a bit better and starts right up. I think I'm going to replace the filter and pump anyway. 200K and counting. . . . .

[DaN]

I read a problem similar to this a while back, it turned out to be the coolant temp sensor was intermittently going to open, or infinite resistance. The dme unit thinks the engine is frozen, and it changes the fuel map accordingly.

It will be hard to find, but when you get the symptoms get out and check the resistance of the cts, lol. Or just replace it.
My guess...

[llll1l1ll]

Hmmm... I'll try these suggestions! Thanks everyone!

[grlaneriejr]

what engine do you have?

on my m10, I had this problem a while back. it was something called the fuel pump crossover relay. try this,
start the car and pop the hood. find your big relays under the hood (mine were right by the air cleaner). slap them a couple of times. if the engine runs worse (or better, depends on what it's doing right then), it's those relays.

If it is, the only one I could find was going to the dealer w/ the relay in hand and ordering it. Don't remember cost, though.

Hope it isn't that. the relay was expensive.

hope this helps

[KenC]

what engine do you have?

on my m10, I had this problem a while back. it was something called the fuel pump crossover relay. try this,
start the car and pop the hood. find your big relays under the hood (mine were right by the air cleaner). slap them a couple of times. if the engine runs worse (or better, depends on what it's doing right then), it's those relays.

If it is, the only one I could find was going to the dealer w/ the relay in hand and ordering it. Don't remember cost, though.

Hope it isn't that. the relay was expensive.

hope this helps

Slap them? Literally hit them with your hand?

I have an M10 now and I think I have a similar problem. When driving (in any gear) between 1500-2500rpms the engine will buck and hesitate. Is this a misfire? The fuel filter was replaced not too long ago.

[llll1l1ll]

I have an M20B25.