Author Topic: Progressive Loss of Power - Died (Read 3595 times)

TNM42 · « **on:** January 29, 2011, 08:50:36 PM »

Alright guys, I think my car has taken a crap.

I was driving down the interstate last weekend to work when I noticed on a slight grade that my '91 318is was having difficulty holding speed. I had to give it more and more throttle just to stay with traffic.

Within a mile or so, the power had dropped so much that I could barely hold 55 with the car nearly floored. The next exit at this point was mine, so I decided to limp to the office. After I got there I popped the hood and took a brief look around. And didn't see any leaks or notice any coolant in the oil.

The car was idling a little rough, but nothing terrible at this point. After the car sat for a minute, I restarted it to circle the parking lot. It felt normal through 1st and 2nd gear but then got much worse, losing the ability to even do 10mph in first gear and died all together. I noted a tinny rattle in the last few moments before the car died.

I was meeting coworkers to head out of town and didn't have any more time to look around and haven't gotten back to it yet. At this point my fear is that i've got a slew of bent valves. Any other possibilities? Anything I should look for when I get back to the car?

Please put my mind at ease and tell me its something simple/cheap. Fuel pump maybe?

DesktopDave · « **Reply #1 on:** January 29, 2011, 09:18:06 PM »

Check the coolant level. If that's OK, chances are pretty good your motor is tight. A compression check would determine that 100% though. Probably not a bad idea to have it checked out. You can pull the cam cover and spin the motor to see if the cams are still lined up. That's a bit of trouble though, I'd do some simpler stuff first:

First thing I'd do when I got back to the car is to do a stomp test. If you don't get a CEL (and the light isn't burned out) you might have a bad DME. Take a printout of the codes just in case.
After you get the codes, try to test the fuel pump. Mine is loud enough to hear when the car is at idle, you should have no problem hearing it prime with the motor off.
If you don't hear the FP, I'd pull the FP relay and jump the socket with a bit of wire & the key on position 2. If you can hear the pump sloshing fuel to your rail & back out the FPR you can be pretty sure the pump is good. If the pump tests OK, but it still won't start the car, you might have a bad or dirty crank sensor. To eliminate that as a cause, test the resistance on pins 1 & 2 on the plug. Should be about 680 ohms.

TNM42 · « **Reply #2 on:** January 30, 2011, 11:12:58 PM »

Thanks so much for chiming in so quickly, Dave. I got to spend a minute on the car late tonight.

After doing a stomp test, I get code 1222 which from what I'm reading indicates an overly rich/lean condition for more than 10 seconds. So my fear of valve damage doesn't seem to be ruled out as I was hoping, just yet.

I'm also able to hear the fuel pump kick on when I turn the key. I attempted to start the car, and it has a hard time idling. The tinny rattle is present at idle, and seems to speed up when the engine is lightly revved.

After it ran for a bit, I put the car in reverse to see if I could move it further back in the parking lot out of everyone's way. It wouldn't back out of the spot without dying, so I left it off and just pushed it back in.

Any ideas? Anything I can rule out easily? I'm kind of nauseated thinking about the damage I may be facing.

B318M42W · « **Reply #3 on:** January 30, 2011, 11:41:40 PM »

maybe a clogged fuel filter causing low fuel pressures and lean conditions? might be a good idea to replace it if it wasn't done recently and save a fuel pump by doing so

no idea for the tiny rattle...

TNM42 · « **Reply #4 on:** January 31, 2011, 12:01:04 AM »

Thanks for the input, B318M42W. The fuel filter is a possibility, although I did change it about 500-1000 miles ago along with the plugs, wires, and air filter.

Just to clarify, I'm not sure if I'm spelling it correctly, but when I say "tinny" I mean that it has the sound of light or thin metal clanking (a short "i"), not that it is small. It actually was easily detectable this evening. Sorry for the confusion.

B318M42W · « **Reply #5 on:** January 31, 2011, 12:21:30 AM »

How does it run when it dies? sputter like it's out of fuel? (to see how it sounds, just remove the pump relay and start the car. it should run for about 5-10 seconds then die. My guess is that if it acts/sounds just like it's outa gas, very strong possibility it's fuel delivery. (it might get enough fuel to idle, but not enough to rev/move the car. just give it throttle and see how she reacts!) Good luck!

DesktopDave · « **Reply #6 on:** January 31, 2011, 06:40:50 AM »

You might also want to check resistance on the throttle pos sensor and AFM. If they're wrong, the car will idle well but not rev.

To put your mind at ease, I'd verify that the cams are still in time. Pull the cam cover & check them. There are many pictures on the site for you to review. I know the weather isn't great, but it might save you a lot of work later on.

As for the rattle, that sounds a bit ominous. Unless it's a heat shield. If the idler gear bearing on the timing chain has gone, or the tensioner has slipped past it's mechanical limits (chain dragging inside the case), or a guide has disintegrated, the cam chain won't be in time any more and you might also have those symptoms.

colin86325 · « **Reply #7 on:** January 31, 2011, 09:03:42 PM »

Does it sound like the rattle could be from your exhaust system, as in a clogged catalytic converter?

mr.vang · « **Reply #8 on:** February 01, 2011, 12:05:56 AM »

similar to mine problem. when i'm low on fuel it starts to act like that. i replace a new fuel filter and it went away.

doitover · « **Reply #9 on:** February 01, 2011, 04:07:03 PM »

good suggestion.

Also, I wouldn't assume that the fuel pump is OK because you can hear it.

Quote from: colin86325;101061

Does it sound like the rattle could be from your exhaust system, as in a clogged catalytic converter?

TNM42 · « **Reply #10 on:** February 01, 2011, 08:15:31 PM »

Thanks for all of the great information guys.

The car will idle roughly for quite a while, occasionally dropping to a low RPM and then catching itself right before it dies, but will die quickly when I attempt to add load.

I don't think the rattle is coming from the cat, only because I just had a new cat-back system welded on in December. Could it have gone bad that quickly? It was a generic cat and not a BMW unit...

I should be back to town on Sunday, and it the weather will cooperate I'll have a little time to give it a closer look. I'll try to pick up a multimeter as I head over there to check a few things.

Keep some suggestions coming! I'll cram as many checks as I can into the time I'll have!

doitover · « **Reply #11 on:** February 01, 2011, 08:49:33 PM »

When my fuel pump went, it was still pumping gas, just not enough to run.
I happen to have a fuel pressure gauge and it was clear from testing it that it wasn't able to make enough pressure.

I think I've read that you can get a pretty good idea by disconnecting the hose and letting gas run into a bucket. Fuel pressure gauges aren't terribly expensive though and one would help diagnose the regulator if that happened to be be problem.