Please, help me troubleshoot my car

[napuli]

I don't know what is wrong with my car? Sometimes the car drives like new, but once in a while it starts acting up kind of inconsistantly. Sometimes is hesitation when you accelerate from a dead stop, sometimes it feels like the rear brakes are stuck, sometimes the engine dies, etc. I though that maybe I had a bad alternator or battery. For example, at idle, if you turn off the head lights the dashboard lights get significantly brighter and the fan turns faster. Thing is that I took the car to my mechanic to replace the control arms and brake pads and I asked him to also check the alternator and battery. He told me that the alternator and battery were OK. Assuming that he is right, what then? Any ideas? It has been raining alot so I am thinking that it maybe an electrical short. The SRS light also comes for a little bit after starting the car and then goes away after a few minutes. The car starts great everytime and the battery seems to be OK so I am thinking that is something that only happens when the car is running. What do you think I should do?

[cdnalpina]

When was the last time you (or was) the fuel filter replaced? Almost sounds as though it is starving for fuel. Conversely, it could be starving for air. Make sure your air filter is clean and that you don't have any debris, like wet leaves, clogging any of the ducting to the airbox.

The lights one is interesting. I would have guessed an alternator as the symptom you describe is a classic tell tale. If the alternator is good, then it would say that your headlights seem to be drawing a huge amount of current. Does anything else, like rolling down the windows, turning on the radio, etc cause the same dash dimming? Perhaps put a voltmeter across the headlight wires and see what the current draw is when they are on. If it seems reasonable (and I am not sure what reasonable is), then I would seriously question whether the alternator is good...

As for the SRS light - in my (Mom's) Alpina B10 3.0 Allrad, it has dual airbags and we determined that the passenger airbag is not functional via a scan. In my research, if you have an SRS lgiht that stays on for a minute or so it means that one (or more) of the airbags are inoperative. Not sure if the same applies to the 540 but it would be somethig to look into...

Good luck and keep us posted as to what you discover. It will surely help someone else at some point in time.

Cheers,

[napuli]

I am with you regarding the alternator, that is why I ask my mechanic to check it. I think I better check by myself. The fuel fiter is new but it is also possible that if my voltage is droping significantly that this may also be starving the fuel pump from getting enough electrical juice. The housing for one of my headlights is broken? I am starting to wonder if this maybe part of the problem? The piece that is broken is the dome that actually holds the bulb in place. The PO fixed this with tape and I thought that this was just a cosmetic problem that I could put on the bottom of my project list.

My mistake!!! The lights do not dim...only the OBC computer display dims...lights on-OBC dims...lights off-OBC gets brighter to compensate for daytime ambient light.

I took the car for a drive. It was still hesitating during acceleration. I got on the freeway...same problem even at 60-70 mph. Got out of the freeway and drove around. After a little bit the problem was completly gone. Got back on the freeway again and the engine was smooth like glass at all speeds. I drove for about 30 min...no problem at all.

I am stupid!!! I checked again and the ony light that gets dimmer is the light for the OBC display. Lights on = night mode, lights off = day mode, which means brighter.

I took the car for another test drive and I was still having the same problem...hesitation during aceleration. In fact, I thought i was going to get T-bone when I took a quick left turn and the car decided to nearly stop on the middle of the intersection. I continued into the HWY to see if it will go away at HWY speeds. no luck, even going 60-70 I could still feel the hesitation. I got out of the HWY and drove around a bit more and then back on the HWY. After driving around for about 30 minutes the problem when away.

[sander06]

I'd say it's a fuel starvation problem. Dirty filter, dirty injectors, fuel pump... You need to let a mechanic see it.

[gricey]

Are you getting any CEL codes

Could be intake manifold gaskets. They cause similar symptoms. Check for Vacuum leaks.

[napuli]

I have a new filter, new injectors, new spark plugs, intake manifold resealed w/mew gaskets, PCV plate, etc, valve cover gaskets replaced, etc.

No CEL codes.

What has not been replaced is the fuel pressure regulator, fuel pump, fuel pump relay, and ignition coils.

I would take it to my mechanic if I knew that he could identify and fix the problem, but I think that with your help I maybe able to do a better job and save me some money.

What is strange is that this doesn't happen all the time. For example, if I drive the car six times it will only maybe happen once. Also, the problem seems to go away after driving for a little bit. This makes me think that it maybe a water problem. What I mean is that after a little drive the water dries and the problem goes away. I had a simmilar problem in a VW were I actually had to dry a relay with a hair drier to get the car going in the mornings.