hoof desease

[yaofeng]

While my 540 is a joy to drive with power available on demand in every gear, the 525 is really pathetic. I havn't been driving it for a long, long time so I lost the feel for its power and torque, or lack there of. It has been my son's daily ride while i was using the 9000 turbo. The 525 has had an engine consuming some oil I replaced it with a 93 M50tu only two weeks ago. While the 93 engine has 170k miles, it is a much stronger engine, IMO. The compression numbers were impeccable. There are 235, 230, 180, 235, 235 and 235. And these were done following engine install when the engine doesn't start because I blew a 80 amp fuse link. The 93 engine has been stting in the corner of my garage for two years. I'd say the numbers are very, very good despite the low number in the middle.

Anyway the 525 has no power in low gears after I replaced the engine. I need to rev the engine close to 3,000 rpm in first to pull away many times. If I start in second the car just sit motionless not responding to the gas pedal. At higher speeds the 525 is okay. People have been suggesting to me to get a chip. But I seriously think something was wrong although no codes were thrown. I know I shouldn't compare to when it is new. But if it were like this 12 years ago no one would have bought it.

What could have gone wrong?

[Ross]

You have one cylinder that is more than 20% off. That isn't impeccable, very, very good or even good. But even with that it should be able to pull below 3000. Something is wrong this isn't typical.
Perhaps sonny boy has been flogging it some.

[repenttokyo]

my car is a 91 with hundreds of thousands of km's and i pull away at 1500 rpm, not 3k....

[yaofeng]

The 93 m50tu idles at a little less than 500 rpm as if the engine is shut down. But it is pathetic in power in the first three gears. The original 95 M50tu has uneven idle and consumes oil but I don't remember it to be as bad although I drove it very little. My son has been using it most of the time. He has moved to the west coast. He is the person who can truly tell the difference. But I just know something is not right.

[bsell]

The 93 m50tu idles at a little less than 500 rpm as if the engine is shut down. But it is pathetic in power in the first three gears. The original 95 M50tu has uneven idle and consumes oil but I don't remember it to be as bad although I drove it very little. My son has been using it most of the time. He has moved to the west coast. He is the person who can truly tell the difference. But I just know something is not right.

So you have a low idle, low power at lower rpms, and just ok power at speed.

This sounds like a vacuum leak, possible low voltage on the engine (weak spark) due to ground problems, or other install-related issue.

Is it possible the cams are not timed right in relation to each other or the crank? A sticky/weak chain tensioner? Just typing out loud as the engine did sit dry for two years...

I don't put much stock or emphasis on 'at speed' behavior unless the power noses over like you have a restricted exhaust or loss of fuel pressure. The engine turning at high speed hides many a driveability problem so behavior at speed can be deceiving.

So do the standard poor running checks for vacuum leaks, weak spark, poor fuel flow/injector spray quality. If things check out, then look into engine computer issues related to the year difference between old engine and newer car and/or the cam timing issue.

Good luck,

Brian

[Ferret]

So you have a low idle, low power at lower rpms, and just ok power at speed.

This sounds like a vacuum leak, possible low voltage on the engine (weak spark) due to ground problems, or other install-related issue.

Is it possible the cams are not timed right in relation to each other or the crank? A sticky/weak chain tensioner? Just typing out loud as the engine did sit dry for two years...

I don't put much stock or emphasis on 'at speed' behavior unless the power noses over like you have a restricted exhaust or loss of fuel pressure. The engine turning at high speed hides many a driveability problem so behavior at speed can be deceiving.

So do the standard poor running checks for vacuum leaks, weak spark, poor fuel flow/injector spray quality. If things check out, then look into engine computer issues related to the year difference between old engine and newer car and/or the cam timing issue.

Good luck,

Brian

Stuck/Malfunctioning vanos unit? (I dont know if the designation tu means it's a vanos engine?)

[genphreak]

Vacuuuuuuuuuuuuuum ;)

[yaofeng]

If I combined all of the comments to the symptom, it forms a very wide net I don't think I have time to go over each, especially now my 540 is running and I am enjoying it every day. I'll probably give it to my younger son to drive so it will not get him into trouble speeding. But thanks to all.

I am sure I checked every hose to be in good shape having stripped the engine almost bare (not separating the head from the block of course). The wiring harness was also switched as the 93 does not have ASC+T and my 95 does.

A few pictures are atached.
http://i21.photobucket.com/albums/b274/yaofengchen/BMW_95_525i/DSC_4805.jpg
http://i21.photobucket.com/albums/b274/yaofengchen/BMW_95_525i/DSC_4825.jpg
http://i21.photobucket.com/albums/b274/yaofengchen/BMW_95_525i/DSC_4817.jpg
http://i21.photobucket.com/albums/b274/yaofengchen/BMW_95_525i/DSC_4826.jpg

[yaofeng]

The previous 95 M50tu for comparison.

http://i21.photobucket.com/albums/b274/yaofengchen/BMW_95_525i/DSC_1643.jpg
The sludge I flushed from the valve train
http://i21.photobucket.com/albums/b274/yaofengchen/BMW_95_525i/DSC_1638.jpg
http://i21.photobucket.com/albums/b274/yaofengchen/BMW_95_525i/DSC_1646.jpg
After cleaning
http://i21.photobucket.com/albums/b274/yaofengchen/BMW_95_525i/DSC_1640-1.jpg

[Dave M]

If you're confident its not a vacuum leak, how confident are you that you nailed the timing ? I recall your work on this engine a while back. Did we discuss timing issues?

Anyhow, I can't explain why most of your comp results are good, but the lack of power certainly fits a timing bug.

Dave

[yaofeng]

No. Not this engine. I discussed the original 95 M50tu engine two years ago. This engine I left it in the corner of my garage until about three weeks ago.

I never had the chance to get comprerssion because it was not installed. I wasn't sure I got the timing correct either after almost taking it completely apart. That's why when I faced with the no start (because of a blown 80 A fuse) I did compression.

Tell me, if it is you, do you have any doubt after putting together the camshaft, chains and valves, then lower the engine and find the compression are 230 to 235 in every hole except the number 3 hole you get 180 that you did not get the timing right? Give me a reason you think timing is incorrect when you have these compression numbers.

[Dave M]

No. Not this engine. I discussed the original 95 M50tu engine two years ago. This engine I left it in the corner of my garage until about three weeks ago.

I never had the chance to get comprerssion because it was not installed. I wasn't sure I got the timing correct either after almost taking it completely apart. That's why when I faced with the no start (because of a blown 80 A fuse) I did compression.

Tell me, if it is you, do you have any doubt after putting together the camshaft, chains and valves, then lower the engine and find the compression are 230 to 235 in every hole except the number 3 hole you get 180 that you did not get the timing right? Give me a reason you think timing is incorrect when you have these compression numbers.

Thats the puzzling part to me and why I said I can't explain the comp results. I recently missed the timing on a vw golf and it idled low and ran with no balls, just as you described. I adjusted the timing one tooth at a time until I hit it right.

Sorry I can't provide more insight,

Dave

[yaofeng]

First of all, to clear the idle speed out of the way. When I said the 525 with the 93 m50tu idles like the engine shuts down, I meant it idles so smooth if I didn't see the fan I would thing the engine is not on. Yes, it is this quiet.

This morning i did a little bench marking. On a level surface in first, the car started to move around 1,200 rpm. To really accelerate in first, I need to rev the engine to 2,500 rpm.

What are your numbers? I am only interested in the 525 numbers. So far I don't think I have rev'ed my 540 beyond 2,500 in any gear.

[BuckNaked]

The 540 by nature is a high revving engine. It needs to run a good 10 minutes at 4,000 rpm once in a while, just to clear it's throat. Get her up to temperature and jump on the thruway and do 65 mph in 3rd to the next exit.
I love the voice at 6,000 + rpm, it's addicting.

[Ferret]

http://i21.photobucket.com/albums/b274/yaofengchen/BMW_95_525i/DSC_4817.jpg

Call me crazy, but looking at this photo, I'm sure I can see the intake cam is visibly out of time...

The square lobes at the back of the camshafts dont look like they're dead parallel... or is that a perspective trick of the camera or a vanos trick?

[yaofeng]

Your're crazy.

[whiskychaser]

http://i21.photobucket.com/albums/b274/yaofengchen/BMW_95_525i/DSC_4817.jpg

Call me crazy, but looking at this photo, I'm sure I can see the intake cam is visibly out of time...

The square lobes at the back of the camshafts dont look like they're dead parallel... or is that a perspective trick of the camera or a vanos trick?
Looks way out to me too. But I'm sure its not. Er...is it?:)

[yaofeng]

Looks way out to me too. But I'm sure its not. Er...is it?:)

Are you crazy too?

http://i21.photobucket.com/albums/b274/yaofengchen/BMW_95_525i/DSC_4822.jpg
http://i21.photobucket.com/albums/b274/yaofengchen/BMW_95_525i/DSC_4821.jpg
http://i21.photobucket.com/albums/b274/yaofengchen/BMW_95_525i/DSC_4820.jpg

[Ferret]

Are you crazy too?


You're welcome.

We were actually after a shot of the back end of the cams, the two square blocks that you're supposed to use to set up your timing.

[Paul in NZ]

Are you crazy too?



you should read a book called
"how to win freinds.....
Is the 525 an auto....could it be the trans and NOT the engine?
My 535 moves off at idle.....

[yaofeng]

you should read a book called
"how to win freinds.....
Is the 525 an auto....could it be the trans and NOT the engine?
My 535 moves off at idle.....
It's five speed.

[Ferret]

It's five speed.

Slipping clutch then?

[yaofeng]

The clutch I replaced about 18 month or 5,000 miles ago. It has more than 95% left when I replaced the engine last month.

[yaofeng]

The 540 by nature is a high revving engine. It needs to run a good 10 minutes at 4,000 rpm once in a while, just to clear it's throat. Get her up to temperature and jump on the thruway and do 65 mph in 3rd to the next exit.
I love the voice at 6,000 + rpm, it's addicting.

I'd like to know the benefit of running the engine at 6,000 rpm in third other than contributing more than my share to the green house effect and making my wallet thinner going to the gas station more often. The 540 is already a gas guzzler compared to my other cars getting only 20 mpg or so. I did 265 miles today going to New York. Haven't enjoyed driving so much for a while. The highest I rev'ed the engine to is 2,800 rpm or so in 6th, at 90 mph.