Car misfiring I think?

I'm honestly not sure what is going on but I will try to explain the problem the best I can. Car is a 1991 525i automatic with the M50 engine. When driving at any speed more noticeable at 45mph or over the car seems to start not firing on all cylinders then it runs fine again. Loss of power and extreme vibration through out the car. I'm trying think how to explain it more clearly but I can't come up with anything. I'm basing the assumption of misfiring off a previous car I worked on with the same problem and all it turned out to be was bad plugs and wires. Which I have changed less then 300 miles ago on my car (plugs and coil packs) . Sorry if I've not explained the problem clearly enough. Feel free to ask any questions you have and I will try my best to answer them.
Any help is highly appreciated.


DARRiN

Sent from Samsung Gem using Bimmer App

just wondering if you have checked fuel filter? how does it work after oil change? sometimes lose of power is also due to o2 sensor playing up .. need to attch a computer for that.
how ur fuel mileage? also have you had a cylinder test done.. what about your fuel distributor cap..

fuel distributor cap???
his car has coils, not a dizzy.

but yes all those things mentioned could be the cause, maybe add vacuum leaks.

DO you get any stomp test codes?

Originally Posted by ebu4

just wondering if you have checked fuel filter? how does it work after oil change? sometimes lose of power is also due to o2 sensor playing up .. need to attch a computer for that.
how ur fuel mileage? also have you had a cylinder test done.. what about your fuel distributor cap..

Fuel filter was changed when plugs were changed, fuel mileage seems the same, had a cylinder test done about a month ago all 6 were over 190. May look into purchasing a O2 sensor.

DARRiN

Sent from Samsung Gem using Bimmer App

Originally Posted by paperplane94

fuel distributor cap???
his car has coils, not a dizzy.

but yes all those things mentioned could be the cause, maybe add vacuum leaks.

DO you get any stomp test codes?

Have looked for vacuum leaks have not located any yet. Have tried stomp test several times with no success.

DARRiN

Sent from Samsung Gem using Bimmer App

would put money on either your CPS or your TPS. i changed both of those on my 525iT and she came right as rain

Originally Posted by Ethrty

would put money on either your CPS or your TPS. i changed both of those on my 525iT and she came right as rain

I changed the crank position sensor not long ago because of a no start issue. Will look into picking up a throttle position sensor.

DARRiN

Sent from Samsung Gem using Bimmer App

I would make sure the TPS is adjusted per the bentley instructions before I buy a new one. They are pretty robust.

I think its spark related. I had similar symptoms once ,turned out last plug well was full of rain water and shorting out the plug. Have you replaced the long boots on the coils? Another guess would be a faulty injector ,this is where the stomp test would come into play.

Originally Posted by luckydog

I think its spark related. I had similar symptoms once ,turned out last plug well was full of rain water and shorting out the plug. Have you replaced the long boots on the coils? Another guess would be a faulty injector ,this is where the stomp test would come into play.

Yes the boots were replaced along with the coils and plugs at the same time. The stomp test would be very helpful right now, but I have tried it several times with no success.

DARRiN

Sent from Samsung Gem using Bimmer App

If the TPS doesn't work you won't get the stomp test to work.

Originally Posted by paperplane94

If the TPS doesn't work you won't get the stomp test to work.

yes. thats a very handy feature accidentally built into BMWs ha. if the TPS is shot, the stop test wont start, thereby diagnosing the TPS lol

I had the same problem with my '91 525i with the M50. It turned out it was a loose coil pack that was just NOT obvious, since it seems there is only one way to install those things. Turns out one of the studs that holds down the coil was loose, since the whole shank came loose instead of the small nut. You can tighten the nut all you want, but if the shank (stud) that screws in to the hole is loose, you get vibration and just enough "looseness" to cause the misfire. I finally got so frustrated that I took it to an indy shop in Portland and they fixed it in less than an hour. Go figure...but it's been running like a champ ever since. Learn something new every day.

Regards and hope this helps,

Christen

Is it a miss under load? Revving? Steady cruise?

Originally Posted by SawheadE34

Is it a miss under load? Revving? Steady cruise?

Under load, mild to hard acceleration, and steady cruising. Seems to rev fine with no signs of misfiring.

DARRiN

Sent from Samsung Gem using Bimmer App

I have I 92 525i with the m50 motor.. Am having same issue with The loss of power and rough idle. I have so far replaced three coils but.... Two of the bolts came completely out of the coil after reading someone had same issue with bolts and vibration of the coils am I able to just glue the bolt back in then tighten the nut. Or any ideas on what else it could be???
Thx

I have a 1994 BMW 540i just bought it Sunday and its Wednesday i was so freaking happy but on the way home sure enough at about 40-45 mph it freaking shook and scared the hell out of me so i checked and found that the wheel hub bearing was bad im replacing it now but i was looking online to see if anything else could be wrong and i found some good info you might want to try as well not sure if its true but will have to try if the new wheel hub doesn't fix it. and there calling the shake the "Front wheel Shimmy" http://www.unofficialbmw.com/repair_faqs/shimmy.html seems like the cure is on-the-car balance but might want to check your hubs first from what i read the on-the-car balance seems to be expensive but i haven't really looked into it yet. Hope this helps...

The previous owner should of told you the front end was worn out .I would start with front shocks. $400 parts and labor. If still shakes upper thrust arms at least $300 at a shop. maybe you can have it all done as a package deal for 500.

So I have a similar issue, 93 525i, with a manual transmission. Interestingly the problem first arose when the engine was in a 96 325i, I swapped the motor into the 525 and it still has the same problem. All of the vacuum lines are new, and it is using the 525 engine management wiring harness and chip. But because the garage I was using was not going to be available for very long I ended up being rushed, so the coil packs, plugs, and tdc sensor all moved with this engine. I just got done yesterday, but I'm planning on changing these out one at a time to figure out what it is. I'll let you know what I find.

By the way, mine does it once a day, right as it warms up for the first time, then it idles rough, hesitates and vibrates (misfire) free revving or under load, then it stops acting up and runs fine unless I leave it for 10 hours or so.
I did run across an interesting post about the valve gasket failing around the coil pack boots and causing a misfire, but if you remove the coil packs and you have this problem it is blatantly obvious due to the large volume of oil over the boot and plug.

Wow to some of the early posts.. hahaha

Ok,

1) check the plugs, make sure the valve cover gaskets are not leaking onto them and causing an erratic misfire.. typically it is just the rear plug(s) because the slant off the motor its the low point.. This is the number 1 cause of this..



2) Check your MAF (mass air flow sensor) Disconnect the thing and drive, if it runs the same or better it is not working right.. if it runs like a dog it is good usually.. I have had personal experience's with them that frustrated me endlessly.. Do Not buy a china knock off if you replace it..

Also, Vacuum leaks will tend to go away with RPM becuase as RPM/throttle angle goes up, vacuum goes down.. seem like you?

Fuel pump/ fuel filter failing, start's with high RPM loss, being unable to supply enough fuel for RPM.. that seem like you?

Finally do a basic inspection of the front end to rule out front end shimmy, CAB's,Ball Joints and Tie rods LOOSE WHEEL?..ect..


fck jdm / fck honda

Originally Posted by imae34driver

wow to some of the early posts.. Hahaha

ok,

1) check the plugs, make sure the valve cover gaskets are not leaking onto them and causing an erratic misfire.. Typically it is just the rear plug(s) because the slant off the motor its the low point.. This is the number 1 cause of this..



2) check your maf (mass air flow sensor) disconnect the thing and drive, if it runs the same or better it is not working right.. If it runs like a dog it is good usually.. I have had personal experience's with them that frustrated me endlessly.. Do not buy a china knock off if you replace it..

Also, vacuum leaks will tend to go away with rpm becuase as rpm/throttle angle goes up, vacuum goes down.. Seem like you?

Fuel pump/ fuel filter failing, start's with high rpm loss, being unable to supply enough fuel for rpm.. That seem like you?

Finally do a basic inspection of the front end to rule out front end shimmy, cab's,ball joints and tie rods loose wheel?..ect..


fck jdm / fck honda

+1