rough idling

[panzershreck]

just got a 90' BMW 525i, engine is really rough in idle... checked the oil to see when the last time the guy got an oil change and it really needs to be replaced, could this be the problem with the idling (note that according to the previous owner, the timing belt had not been replaced/recalibrated at the 100,00mi point, he lost his owner manual so i dont know if this is true either, but oil problems would be alot more convenient than fooling with the timing belt)

[Will308]

Does your car have the M-50 engine? Sometime in 1990,1991 the engine was changed from the old design to the M-50. I have a '91 w/M-50 and have been chasing a rough idle problem for some time now. Mine's erratic, the rough idle doesn't happen all the time. Sometimes it idles smooth as glass. I changed the idle control valve under a TSB. It seemed to help. It doesn't idle roughly as often as it did before I changed it. You might want to take it to a dealer and have them check it out to see if they can determine the problem with their diagnostic equipment.
Good luck and keep me posted as to what the problem is.
Thanks,
Will

[panzershreck]

well what i do know now is that the oil filter and oil seriously need to be replaced as well as the air filter

im ordering the service manual today so hopefully sometime this week i'll be able to replace that and see how the engine does after that (engine might just need to having timing belt re-calibrated a little faster which is why it might be erratic)

[stuie]

I am also experiencing problems similar to wil308. From cold the engine "Hunts", but this does not happen every time. Also when driving down the motorway(freeway) doing say 70mph constant, the engine will suddenly splutter and cough. The only remedy I've found is that i have to turn off the engine and restart!

The engine will also stall approaching junctions as I change down the gearbox. This is dangerous as the power steering goes and the brakes aren't as useful.

I have had the oxygen sensor replaced, the fuel-tank vent valve, and the air mass meter and the problem still happens. The car has been on the BMW main dealers computer and guess what - it reports nothing wrong with it.

This has been happenning for 18 months now and I'm getting desperate to resolve this as I have almost crashed on many occasions.

If anyone could shed any light on this I would be very grateful.

[Will308]

Stuie,
It's dejavu all over again! The dealer replaced my DME about 6 years ago. It solved the hunting throttle problem. I'd go into a freeway off ramp, at about 50mph, lift my foot off the accelerator and the engine would surge up and down.
The tradeoff was this rough idle problem. Ive been trying to get it resolved for some time now and like you everytime I take it to a shop, they find nothing wrong with the codes. I don't have the sputtering you described. Just the rough idle when the car is stopped. Hope this might help you.

[kidwired]

I always start w/ the basic and enexpensive stuff.
get a can or 2-3 of carb cleaner and spray all air and vacuum lines, including the boot. if RPMs pickup you have a vacuum or unmeasured air leak.

also check the basics, fouled plugs, dist cap and rotor burnt or scored?

[tommy50]

Originally Posted by stuie

I am also experiencing problems similar to wil308. From cold the engine "Hunts", but this does not happen every time. Also when driving down the motorway(freeway) doing say 70mph constant, the engine will suddenly splutter and cough. The only remedy I've found is that i have to turn off the engine and restart!
The engine will also stall approaching junctions as I change down the gearbox. This is dangerous as the power steering goes and the brakes aren't as useful.
I have had the oxygen sensor replaced, the fuel-tank vent valve, and the air mass meter and the problem still happens. The car has been on the BMW main dealers computer and guess what - it reports nothing wrong with it.
This has been happenning for 18 months now and I'm getting desperate to resolve this as I have almost crashed on many occasions.
If anyone could shed any light on this I would be very grateful.

why not come and join us at the e36coupe forum. there are plenty of experienced 5 series and x 5 series people on there and they've allways been a great help to me. i have a 535i se 1990 and every problem i've had has been solved through this site. you can get there via this link.
www.e36coupe.com

good luck and give us a try. you have nothing to lose.

[Will308]

Originally Posted by kidwired

I always start w/ the basic and enexpensive stuff.
get a can or 2-3 of carb cleaner and spray all air and vacuum lines, including the boot. if RPMs pickup you have a vacuum or unmeasured air leak.

also check the basics, fouled plugs, dist cap and rotor burnt or scored?

Been there, done that. Really has everyone that it's been to, perplexed.
Plugs look great( Bosch Platinum), Individual coils( no rotor, dist. cap ,etc.).
Latest problem, CHECK ENGINE light came on. First time ever since I've owned the car.( 182,00 miles). As mysteriously as it came on it went out. No change in engine function while it was on. Fault code showed bad O2 sensor. plan on replacing it.
Replaced one of the coil packs and all of the boots w/ new to see if that would help. So far no difference, I'll be changing the location of the new coil to see if it makes a difference.
If anybody knows what it could be, I sure would like to know!
Thanks,
Will

P.S. Did you ever get the hunting problem fixed?