535i miss problem

[bmw325is]

I have a 1991 535i 5 speed. Over the past year i have had a problem with the engine having a slight miss between 3200 and 3500 rpm, usually under load in almost all the gear. It just seems to kind of skip for a second. Doesn't lose all power or anything but just misses for that.

Also this doesn't always happen but the frequency goes up greatly when the engine is running in the higher end of the temp (still at a reasonable tempereature)

Have replaced the fuel injectors, spark plugs and wires. Anybody else had this problem or have any suggestions on what it could be?

[bmw325is]

Still have the miss anybody have any ideas?

[blackparis]

I have a 1991 535i 5 speed. Over the past year i have had a problem with the engine having a slight miss between 3200 and 3500 rpm, usually under load in almost all the gear. It just seems to kind of skip for a second. Doesn't lose all power or anything but just misses for that.

Also this doesn't always happen but the frequency goes up greatly when the engine is running in the higher end of the temp (still at a reasonable tempereature)

Have replaced the fuel injectors, spark plugs and wires. Anybody else had this problem or have any suggestions on what it could be?

Not sure if it will fix the problem but never hurts to throw a coolant temp sensor @ these M30s... Local Parts store 20-30$

[Went4it]

Hi,

I think it's a miss-take to throw parts into a car because they are cheap. I would rather wave a voodoo stick over the car, that's free and would have the same effect. Besides, one can easily test the coolant sensor to see if it works.

I have experienced the same miss in my '90 535iA. It feels as if the electronic ignition just shuts off for a millisecond, during heavy acceleration. Your post reassures me this has nothing to do with the transmission, because yours is a 5 speed.

I suspect the DME (computer control) or possibly the coil. The DME might be overreacting to the mass air flow sensor, and think the car is in a runaway condition, briefly shutting off the ignition. I don't know of any good remedy. I would suggest wiggling or removing the connector at the mass air flow sensor, to try to improve the electrical connection.

I doubt it is the coil, because it would most likely quit altogether.

Tom

[blackparis]

Ive had coils go and just not rev beyond a certian point.... And I have had them completely die... but not just skip @ a mid rpm and keep going...

Yes ya can test the coolant sensor but I do not know the specific Values of the sensor and I do not have a bently manual in sight of my computer... One good determination is if the car starts up and runs ok (but rich) in open loop and bad once it gets into closed loop...

As far as wiggling the VAF goes test that too! quite easy and again I cant remebr values but all it does is change resistance when the door is opened and closed.. Should go up linerally not all spikey, resistance jumping up and down....


Well good luck Again! Let us know after you test those....

P.S. If ya donthave a bently manual I highly recomend getting one, Or I can send ya full instructions Once I find mine!

[323I Junkie]

THe cap and rotor can cause these issues

also, a dirty crank reference sensor can do the same