Major loss of power. Troubleshooting tips please

[RIPDOTCOM]

Well about a week ago my 525i started to exibit a major loss of power. it would start up fine and eventually when it warmed up I would lose a major portion of power. At first I thought it was the Transmission going into limp home mode but I can manually shift into 1,2,3 and The gears change fine in auto (albeit very slow since my 0-60 times are slower than a yugo) or manual. I have simply lost all power. The engine was idling fine until today and the best way to describe it is "chuggy" When i rev it I get some backfiring. It does not rev smoothly. Here is a list of the things I have done.

1: Removed 1 Cat and running open Exhaust (same problem only much louder)
2: Cheaned the shift switches with electrical cleaner.
3: Changed air filter
4: Reset ECU
5: Cleaned Throttle Body
6: Checked Battery and Alternator voltage (looked fine)

I have recent plugs (2 months old) so i doubt they are bad although I am not ruling this out. I have not changed the O2 sensor as I do not have any codes denoting that the O2 sensor is bad. I am leaning toward a bad TPS at this point but I hate to keep throwing money at it unless I can track the problem down. This is not my primary car so i dont need to get it running immediately but It would be nice to have it running properly.

[Exact-Oh]

This sounds exactly like what mine is doing. I posted a thread here earlier today. Only difference is mine is throwing and O2 sensor #2 code. Mine runs fine for a few miles, then can't get out of it's own way. I can't pull out into traffic like that... until I clear the codes, then it's fine for a few more miles. Check out my thread and what I did to mine to troubleshoot.

[632 Regal]

what plugs are you running?

did you check fuel pressure yet?

[Exact-Oh]

Since the problem happens only after the car warms up (closed loop operation), I would doubt that plugs or fuel pressure is the culprit. That's when I would start checking computer sensor problems, or back to that converter... when plugged converters warm up, they restrict more flow.

[RIPDOTCOM]

Running bosch platinum Plugs and the cat is completely bypassed (open Exhaust :( loud as hell)

[Exact-Oh]

The only leads I got for mine so far (like I said, mine is doing the same) are to check for vacuum leaks around and at the back of the intake manifold. The oil seperator/pcv were brought to my attention, which causes a vacuum leak in the intake. Remove the decorative covers from your intake and spray carb cleaner around the intake manifold gaskets and behind the intake... if you hear the engine RPM increase at all... you have a leak. I suggest fixing your exhaust first though.

[RIPDOTCOM]

The only leads I got for mine so far (like I said, mine is doing the same) are to check for vacuum leaks around and at the back of the intake manifold. The oil seperator/pcv were brought to my attention, which causes a vacuum leak in the intake. Remove the decorative covers from your intake and spray carb cleaner around the intake manifold gaskets and behind the intake... if you hear the engine RPM increase at all... you have a leak. I suggest fixing your exhaust first though.


Gonna change the plugs tomorrow and get a "Y" pipe made to skip the cats. Might do a ghetto temp fix fo rthe exhaust until i track the problem down. Will also check for vac leaks, keep em coming.

[bullyd]

my m20 done the same when i first got it (my first post i think) and i changed the crankshaft position sensor, the lead runs close to a pulley and had rubbed a hole in the insulation, i dont know why but it was fine when it was cool and only played up when the engine was warm?? AND i had it plugged into a scanner that gave no sensor code faults,i know nothing about electrics and dont why it only happened when warm but just worth a check as its free,

[632 Regal]

DING!!!


Running bosch platinum Plugs

[Alexlind123]

Hmm...my bosch platinum plugs are doing quite fine...

[RIPDOTCOM]

Update

1: Cleaned the AFM
2: Replaced Fuel filter
3: Changed plugs

Same problem.

[RIPDOTCOM]

Is it possible that I have a bad CPS?

[RIPDOTCOM]

Just a quick update. i was thinking fuel pressure but i cant test it until I tap the line but I put in in "N" and tried to see how high I could rev it. Takes forever to climb up but it looks like about 4000-4500rpm is the max and when i let off the gas pedal at around 4000-4500 the car simply stalls out. Looks like its starving for fuel, Replacing fuel pump tomorrow if I can find one. . Any thoughts on my idea?

[Anthony (M5 in Calgary)]

Just a quick update. i was thinking fuel pressure but i cant test it until I tap the line but I put in in "N" and tried to see how high I could rev it. Takes forever to climb up but it looks like about 4000-4500rpm is the max and when i let off the gas pedal at around 4000-4500 the car simply stalls out. Looks like its starving for fuel, Replacing fuel pump tomorrow if I can find one. . Any thoughts on my idea?

If nobody else will say it, I will: Keep throwing parts at it and you may eventually stumble on the actual problem. You may be money ahead having it diagnosed by a pro.

[Jose]

The only thing I can think of right now, is the blue temperature feeler is malfunctioning giving the ECU the wrong temp info and therefore injecting too much fuel, or a bad crank sensor, although the last one should be seen in a system read out.

[RIPDOTCOM]

My mechanic did a system readout and discovered that it has a bad knock sensor. Could this cause the problems I am having?

[Jose]

Jup, it could. Start changing that one and reset the ECU again. Failes a lot on the M52 2,3 litres engine.