740i has numerous problems after visit to garage

[jonathanb]

Hey Everyone!

Really excited to get some of the expert advice I've seen on this forum the last few years as a lurker. I've been having a bunch of issues with my 1998 740i after having the car taken to the garage to fix a small dent in the left rear side panel. I'll try to be as clear as possible so here goes:

Current Issues Experienced:

1. ABS Light comes on intermittently
2. DSC light comes on intermittently (At the same time as the ABS light)
3. Infrequent loss of power steering (haven't had this issue crop up yet since spraying my electricals with some electrical cleaner)
4. Intermittent low gas mileage. I know these cars guzzle gas like crazy, but I've noticed that right now I'm getting like 2km/litre of gas. This is based on how far I travel and how much gas is left in the tank, not the gas consumption gauge.
   
   1. Additionally, after getting the car back from the dealer once, I noticed this car could really fly! It seems to breathe power and would take off when I put my foot on the gas super easy. Since getting it back from the garage it just doesn't have that speed right off the bat and worse, it feels like I have to push on the gas farther than normal to even get it to budge.
   
   
5. I've noticed that when the DSC/ABS lights are on, my car sounds "more rough" when I rev the engine than when they aren't on. When they're off and I rev it's like a clean rev, when they're on and I rev it's like a rough gargling rev.
6. Recently had to replace my disc rotors and brake pads, and unfortunately broke the brake pad sensor while I was at it: So now I always have the check brake light and a notice to check my brake linings.
7. I have noticed some sloshing water sounds from underneath the door trim but the inside of my car is not wet
8. I have also noticed a flooded spare-wheel compartment. I assume it's coming from the sunroof (a small seal deteriorated when I first bought it: see lower notes on initial state of the car for more info)

Notes on my garage visit:

• A nice lady (no sarcasm, she was really nice about it) hit my car while trying to park. She dented the rear-left side panel just above the wheel well. She offered to pay for the fix
• I brought my car to the garage and they had a look at it, they put it up on the lift, brought it back down, and for whatever reason, they didn't close the hydraulic cover properly, so when they told me to drive my car out it got caught on the lift cover and left small indentations on the underside of my car (already a bad sign!)
• Nevertheless, I agreed to let them fix the panel, and I asked them if they might also paint my hood while they had the paint going.
• I got my car back and within ten minutes of driving my ABS/DSC light came on.
• So I call them and let them know- they tell me they had nothing to do with it but they'd be happy to work on it

My research on this forum tells me it could be a number of things:

1. Bad ABS module
2. Bad DSC module
3. Bad rear wheel speed sensor
4. Bad Voltage Regulator
5. Bad MAF
6. Bad Battery

So many possibilities! I figured I would take a chance here and see what some of the more knowledgeable members might suggest. Just an fyi; I am a hobbiest, so not totally an expert- but whenever I've worked on my car I've hired a mechanic to help me through the process. Thanks in advance for your help!


More info:
Recent Work on car:

• I recently cleaned the engine bay, got a rough idle on start, turned the car off and started again and all was good after that. A few more starts and no rough idle.
• I recently put some silicon grease over the suspension bushings.
• I recently replaced the front stabilizer bar bushings.
• Recently replaced rear-brake rotors and pads.
  
  • This is when I broke the brake pad sensor.

Initial state of vehicle when purchased:

• The car had had the radiator replaced before I bought it. It currently doesn't sit snugly in the engine bay, but doesn't move around too much and seems to be okay. Hasn't caused any issues thus far (to my knowledge) and the dealership seemed to think it was okay as is. It has always said to check coolant level, which always seems to be at the max- engine temp always seems good.
• Apparently the fuel level gauge had a tendency to show more gas in the tank than there actually was. I read that a few tanks with some fuel system cleaner could help and so far it seems to be accurate!
• One of the (very thin) seals on the sunroof seems to fall into pieces my first few time using it and now no longer exists! This causes my sunroof to rattle up and down going over bumps when it's closed, but seems to be fastened in place when i open it a little bit.

[georgebest]

DSC/ABS: you might get lucky and it's only the ABS sensor, you need to pull codes. Get some kind of diagnostic device or INPA on a laptop. Will be the best investment you ever made on this car. Based on the fact that work was done with rotors and then the issue came up, I'd guess it's an ABS sensor problem.
50l/100km is really extreme consumption, should be around 10-20l/100km. I'm not sure what could be causing that, could be so many things.
Either way, get the error codes and those might help.

[jonathanb]

Okay thank you for the response! Any tips on how to get started with the INPA- Looked around for some instructions and got a bit lost!