Low power at low rpm (below 2200 rpm or so)

[alex 1993 525i auto]

Thanks,

I went trough all this before (1st for Vanos repair, 2dn for cyl head removal) and I have the special tools etc. and I did follow the procedure exactly and the car started fine right after and has been running well since.

This made me realize that maybe the secondary chain tensioner went kaput? Which may explain the no power, noise, metal rip on the CPS magnet?

BTW the 3rd link didn't open-up for me. If you can let me know what's about.

Thanks
Alex

[632 Regal]

BTW the 3rd link didn't open-up for me. If you can let me know what's about.

Yeah I see that, do an advanced search for vanos only in the title.

I believe your thinking is off a bit, the intake cam advances at low RPM not higher RPM. So by default it should be advanced which is not your symptom right now. Visual inspection for sure especially with noises coming from up front.

[genphreak]

Better triple check for vacuum leak in the intake boot... or elsewhere. Anything you've touched or could have gone bad. Esp. underneath the intake manifold- maybe there's a split? Are you saying it conk outs (or stumbles) if you rev the engine in neutral?

I've seen this happen where the ICV hose connector, that connects to the intake manifold just where it is hard to get to, has come loose (or clip broke so it just works its way out). By far the most common problem on these. If you don't already know this is nicely seated and clipped in, well its the most likely culprit. The ICV hose(s, there are 2 or more) is also known to split, or crack so you have to check that too, and it is deeper and harder to get to. Some remove the intake manifold- the seals are re-usable so its not a bad option even if just troubleshooting.

Other thing to triple check is the hose to the Fuel Pressure Reg, that could cause this stuff. I've had to replace many of these on M50s, they perish, split crack and fall off- sometimes all of the above, LOL!

[alex 1993 525i auto]

Update:

Tonight after work the car almost failed to start. After cranking 30 sec. or so it then started and went as before. Later at home I checked the idle speed control valve with my multimeter to see if it could be wrong.

The idle speed actuator coil resistance values were off. They showed 12, 11 and 24 ohms (between terminals 1-2, 2-3 and 1-3). In the Bentley it says the readings should be 20, 20 and 40 ohms respectively (+/- 10%). But the numbers match with resistance specs of an M60 (12, 12 and 24 ohms +/- 2, 2 and 4). Other tests were fine.

Any idea about that? i.e. the resistance values are off, they fit with the ones from an M60 (just happens like that?), car stalls when I quickly depress the pedal to the floor or lacks power when I quickly accelerate from low speed/take-off), then it almost failed to start tonight? (It has been raining Yesterday but not today, this morning it was fine).

I'm not sure about the ICV ohm readings if it shows my ICV is bad. I didn't think a bad ICV can prevent a car from starting. (I checked tonight and it starts when I unplug it, but the idle is very bad of course). When I disconnected the smaller breather vacuum hose, idle was higher at first but it looked like the valve was reacting, like if it was adapting after a 30 sec.

I'm in doubt if all that can be Vanos related now. I'll check anyways at some point when I have time, my valve cover gasket is due for replacement (is leaking oil, I'll check at same time).

Thanks for reading,
Alex

[alex 1993 525i auto]

Just found that the resistance readings are good, there is a mistake in the Bentley, you can check this very detailed post:

Idle control valve, need resistance specs

Would'nt hurt to clean my ICV I guess. I'll post if it makes any difference.