Erratic e34 performance

[hoffmeister]

Hi all

Just wondering if someone all shed some light on this problem. My 525i (1995) has had this lack of power at odd times. It had syruppy smooth pickup when I bought it about 18 months ago but now seems to labor at odd times. How shall I describe it -'old engine' sound and very little pep. Used to think this was due to the weather (hot country, Malaysia - 30 deg C common on most days) as cars esp. contis here generally run well in the mornings and evenings or when it rains. I keep a strict maintenance schedule with synthetic Elf every 8K km change. Recently serviced the cooling system,so no overheating. Oddo says 180K km. could it be the tranny?:( Appreciate any views on this. Cheers.

[Russell]

When were the plugs, fuel filter and air filter last changed? Trany should be serviced as well every 30,000 miles. All of these will make a difference in performance if neglected.



Hi all

Just wondering if someone all shed some light on this problem. My 525i (1995) has had this lack of power at odd times. It had syruppy smooth pickup when I bought it about 18 months ago but now seems to labor at odd times. How shall I describe it -'old engine' sound and very little pep. Used to think this was due to the weather (hot country, Malaysia - 30 deg C common on most days) as cars esp. contis here generally run well in the mornings and evenings or when it rains. I keep a strict maintenance schedule with synthetic Elf every 8K km change. Recently serviced the cooling system,so no overheating. Oddo says 180K km. could it be the tranny?:( Appreciate any views on this. Cheers.

[KenB]

Mine had similar symptoms, after changing plugs and filters there was no change. The problem was intermittant also. Sometimes nice and smooth, other times felt like I was dragging weight but no roughness like it was mis-firing or anything. It turned out to be a weak coil, because of the age of them (around 120k), I just replaced them all since I got them cheap from BMA. (at that time around $35 each). This may not be your problem but something to look at.

[hoffmeister]

When were the plugs, fuel filter and air filter last changed? Trany should be serviced as well every 30,000 miles. All of these will make a difference in performance if neglected.

Thanks, but these were changed two services ago. Somehow the intermittent problem seems to occur more often now.

[hoffmeister]

Mine had similar symptoms, after changing plugs and filters there was no change. The problem was intermittant also. Sometimes nice and smooth, other times felt like I was dragging weight but no roughness like it was mis-firing or anything. ...

Ken, very similar symptoms. But how did you work around to the coil - the ignition coil? Well, it may well be the electrics. I remember when I changed the battery some months ago, the car ran beuatifully for a couple of days and there was a light feel to the accelerator pedal before the old problem surfaced again. At that time I thought that leaving the battery disconnected for an hour has reset the ECU.
Thanks for sharing the info. I will check out the coil.
Rgds.

[Russell]

If one or more fail, It may damage the ECU. You may want to check for oil around the plug wells. That can cause coils to misfire. You may need to change your valve cover gasket if theres is oil.

Good luck


Ken, very similar symptoms. But how did you work around to the coil - the ignition coil? Well, it may well be the electrics. I remember when I changed the battery some months ago, the car ran beuatifully for a couple of days and there was a light feel to the accelerator pedal before the old problem surfaced again. At that time I thought that leaving the battery disconnected for an hour has reset the ECU.
Thanks for sharing the info. I will check out the coil.
Rgds.

[1995 525i]

Ken, very similar symptoms. But how did you work around to the coil - the ignition coil? Well, it may well be the electrics. I remember when I changed the battery some months ago, the car ran beuatifully for a couple of days and there was a light feel to the accelerator pedal before the old problem surfaced again. At that time I thought that leaving the battery disconnected for an hour has reset the ECU.
Thanks for sharing the info. I will check out the coil.
Rgds.

Not sure if my situation was similiar but my injectors were clogged and that made for spotty performance. After new plugs, having the injectors cleaned (professionally, not with an in the tank solution), new few filter and oil filter it drove much better.

Michael

[KenB]

After doing the spark plugs, checking ignition wires, changing filters and fuel injector cleaning (professionally) I just decided to take a chance and replace them (all 6) since they had over 120k miles. I had also been in contact with another member here that helped me decide to do the coils. Plus, through reading archives here I decided that was the next logical step and it was easy to do myself and was not too expensive.

There is a way to check the coils resistance with a meter but someone else here would have to tell you how and what the specs should be.

[hoffmeister]

OK, my DIY knowledge/skill is rather basic. I think most of the maintenance items mentioned here have been checked/cleaned except the ignition coils at the plug wells - since no misfiring so far.
Reminds me of of something that did happen several days ago after the last service. I gunned the car in S mode and there was a loud pop sound from the engine. Stopped the car immediately to check the engine compartment (and the windshield for tragic remnants of a large bug or bird). Nothing looked amiss visibly and engine restarted and ran smoothly enough afterwards.
Any ideas for simple diy testing before I take the car to a professional mech? Thanks.

[Russell]

Is it possible there are vacumn lines/hoses that are od/cracked that could leak. Another thought on vacumn leaks, is the dipstick in and the oil cap on tight?

Not sure if any of these things are bad, but I do know that a vacumn leak can cause a loss in power.




OK, my DIY knowledge/skill is rather basic. I think most of the maintenance items mentioned here have been checked/cleaned except the ignition coils at the plug wells - since no misfiring so far.
Reminds me of of something that did happen several days ago after the last service. I gunned the car in S mode and there was a loud pop sound from the engine. Stopped the car immediately to check the engine compartment (and the windshield for tragic remnants of a large bug or bird). Nothing looked amiss visibly and engine restarted and ran smoothly enough afterwards.
Any ideas for simple diy testing before I take the car to a professional mech? Thanks.

[hoffmeister]

Russell (and others)
Thanks for the pointers. I suppose there's a host of things to be checked/repaired. Will give an update soon. Cheers.

[Felixdacat]

Hoff,
It sounds like it could be one of the coils, or it could be one of the plug wires. If you push on the gas and it made a pop sound, that is the fuel not burning properly, and back firing in the intake. Also check to see how much residue is built up in your throttle body. This could also delay the proper burning of fuel. Not enough air, or too much air.
Good luck.....

[hoffmeister]

Hoff,
It sounds like it could be one of the coils, or it could be one of the plug wires. If you push on the gas and it made a pop sound, that is the fuel not burning properly, and back firing in the intake. Also check to see how much residue is built up in your throttle body. This could also delay the proper burning of fuel. Not enough air, or too much air.
Good luck.....
Felix

I had the throttle body serviced mid last year. Hmm...the pop sound I heard is probably the result of the backfire in the intake as you say? No obvious defects in the coils and plug wires on a visual check. Meanwhile the intermittent sluggishness presists. Will definitely see the mech this weekend. Thanks and cheers.