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.

[yaofeng]

The previous 95 M50tu for comparison.


The sludge I flushed from the valve train


After cleaning

[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