BMW E46 Fanatics Forum banner

1 - 20 of 35 Posts

·
Registered
Joined
·
87 Posts
Discussion Starter #1
OK, I'm stumped, and unfortunately, so are the mechanics at the BMW dealer.

I had been getting intermittent lean codes and misfires on all cylinders, which are documented in another thread. Along with that was occasionally almost stalling at idle.

Since it was on all cylinders, and since I had disassembled, checked and reassembled the intake system to check for vacuum leaks, and cleaned my MAF sensor, and I was leaning toward a balky fuel pump.

A few weeks ago, the thing started to have trouble starting. It would crank over just fine, but not fire up. The first few times it happened were on extremely hot days after sitting in the sun. But I'd wait a few seconds, and it would start right up. By this point, the SES lights had gone off from my earlier misfire problems, and the idling problem hadn't been seen for weeks.

So, after it stranded me at work one day, I took it (drove it there, started fine in the morning) into the dealer, and after a preliminary inspection where they eliminated the key security system as the culprit, they told me it was the fuel pump. They had to order the part, and since they couldn't install before the holiday, I said I'd just put it in myself. So yesterday, after driving in to work, I parked in the shade, took an early lunch while it was still not that hot out, and drove 1.5 mi to the dealership. Walked in, paid for the fuel pump, and went back to my car.

Of course, it wouldn't start. :banghead::censor::censor::censor::cry:

So I went back in, explained to the service guy who's been working what's going on, and he said he'd have someone look at it today and replace the pump asap. Didn't really want to spend 3x as much to have a fuel pump installed at the dealer, but whatever.

Well, after work, I hitched a ride over to the dealer to pick up my car, and when I walk in, the service manager give me a sheepish look and says, "It's not the fuel pump."

I say, "OK, what is it? Please say something inexpensive."

"Well, we don't know. The fuel pressure is fine. But it just won't spark at times. We think your car may be possessed by demons."

Now, generally speaking, that's not what you want to hear from a BMW dealer who has been looking at your car with two experienced techs for several hours. He apologized, and even said that he'd get me a rental car. Unfortunately, this being July 4th weekend, Enterprise was out of vehicles. So after a 45 minute bus ride back home, I'm here without a car and the dealership won't work on it again till Monday.

Assuming all the usual easy stuff has been checked and rechecked, what could cause an intermittent starting failure that seems to be somewhat temperature sensitive? The last I saw, the techs had all of the wiring harnesses they could find taken apart, checking for faults. The fuel system is fine. The car just cranks and cranks, but no starting. On occasion, it will fire up for a half second, then die. I've never had it die once I started driving.
 

·
Registered
Joined
·
5 Posts
Not that this is it but my car had the same problem, stalling after 5 or so minutes driving, then starting for 2 seconds, then for a half second.......wait.....then start up and run, then rough......then quit. $239.00 true BMW 1300 cold cranking amp battery and the car runs fine......go figure.
 

·
Registered
Joined
·
873 Posts
I would say oxygen sensor (pre-cat) or battery
O2 sensors have positively, absolutely, nothing to do with a car's ability to turn over and run. The ECU won't even enter closed loop conditions until after the required warm-up period. The car will run without any oxygen sensors whatsoever, as the ECU primarily uses inputs from the MAF and TPS to calculate fuel requirements. The oxygen sensors are just used to dial in the A/F ratios to stoich during warm idle, light acceleration, and cruising conditions.

The fact that the engine consistently cranks just fine also indicates that it is positively, absolutely not the battery.

The best opportunity to diagnose the problem will (unfortunately) arise the next time the car fails to fire up. Do you have access to a fuel pressure tester? If so, I'd suggest keeping it in the trunk so you can hook it up the next time the car fails to start.

It would also be a good idea to carry a voltmeter with you to ensure the fuel pump is getting power the next time the car doesn't start. Have you checked the relay?
 

·
Registered
Joined
·
87 Posts
Discussion Starter #6
Yea, I'm not thinking O2 sensor, because it's not stalling, it's just not starting or running. It runs fine. Perfectly smooth. It just either decides to start or decides not to.

Seems more likely to me that it's electrical, or some computer problem.
 

·
Registered
Joined
·
87 Posts
Discussion Starter #7
The best opportunity to diagnose the problem will (unfortunately) arise the next time the car fails to fire up. Do you have access to a fuel pressure tester? If so, I'd suggest keeping it in the trunk so you can hook it up the next time the car fails to start.

It would also be a good idea to carry a voltmeter with you to ensure the fuel pump is getting power the next time the car doesn't start. Have you checked the relay?
Yea, the dealer tested the fuel pressure when it wasn't starting, and it was fine. They've 100% eliminated the fuel system by doing that. The problem is in the ignition, it's not sparking.

And, yea, I have had my trusty multimeter in the car for a week or so, and the volts are fine, until I crank it too much for too long. Once the car starts, it charges the battery right back to normal.
 

·
Registered
Joined
·
27 Posts
I'm not mechanically astute, but I had a very similar problem. Mine ended up being the fuel pump but my shop suspected at first it was the crankshaft sensor. It's my understanding that this could cause problems like what your experiencing. Was that ruled out?
 

·
Registered
Joined
·
6 Posts
I had the very same problem with my 01 330ci. It would start fine, then at some extremely inconvenient point (when is it not inconvenient?), it would choose not to start - once right after I filled it up. Mine seemed to have more problems when the tank was close to empty, but I don't recall that it had much to do with sitting in the sun.

I replaced the fuel filter first ($70), then the relay ($18, but a real pain in the ass to get to for a big guy), and then the fuel pump ($330). I was really hoping it wasnt the fuel pump, but after replacing it I have had zero problems starting. This sure sounds electrical, although I agree that it couldn't be the battery. I was getting the odd O2 lean codes on an intermittent basis too. That seems to have disappeared as well with the new fuel pump.

I know this is a long shot, but what about the integrity of the wire harness between the relay and the fuel pump? (I think long shots start to count immediately after the dealership uses the word, 'demons')
 

·
Registered
Joined
·
87 Posts
Discussion Starter #11
Well, The dealer cleaned the wiring harness for the DME, reinstalled and tried it all day yesterday in 90+ degree heat. It started for them all day. They called me around 1:45pm to pronounce it 'probably fixed' and I went over after work to pick it up. I paid the cashier for diagnostic time, returned the key for the loaner Ford Exploder they got for me, and waited for them to pull my car around front. If you've been following this, you know what happens next.

I wait 5-10 minutes, then the dealer service manager comes up with my key to say it won't start. They think they've done everything they could except replace the DME, which is a $1300 non-returnable part because the car has to be reprogrammed.

I got the Ford Exploder back and drove home last night. And here we are. I'm still getting unsatisfactory, fuzzy answers to questions I'm asking them, like "is there fuel pressure when it doesn't start?" and "is it missing a spark or missing fuel when it doesn't start?"

I mean, I have to trust the BMW techs on some level, but shouldn't I have answers to these questions before we replace the DME?
 

·
Registered
Joined
·
80 Posts
I'm just beginning to see this problem on my 01 325i... No engine codes, though. No stalling once running, just cranking without starting (only two incidents so far, but it's a matter of time).

First time i kicked the tire, rolled it back down the driveway, and it was fine three minutes later... Car had been sitting overnight; not terribly hot. No real clues to the problem.

Second time it was worse, 90 degree heat and car had been sitting 30 min. It fired a few time, then no more. So I tried and tried, sure the battery was soon to be toast. Behold a solid knock knock on the fuel tank did the trick...


My mechanic warns strongly against running the e46 down to empty on fuel (which i sometimes do), as it won't cool the pump and can lead to premature failure... (this may relate to what classic said). However, he also says a '99 is the newest pump he's had to replace.


Next time it happens i'm going straight for the pump - that's just the demon i think haunts *my* car. Will let you know...

Hopefully I don't end up in a Ford for the weekend!
 

·
Registered
Joined
·
103 Posts
When it doesn't start, unplug the MAFS. See if that does anything.

I had MANY random issues with my car ever since I bought it. It would have a hard time starting, would stall out while driving, misfire, and even bad performance. The MAFS finally died and I replaced it. Ever since, the car runs fine.

Give it a try.
 

·
Registered
Joined
·
87 Posts
Discussion Starter #15
OK, well I bit the bullet yesterday and told them to replace he DME. They answered all my questions. No spark and no fuel when it's not starting. They tried swapping in new fuel pump and ECM relays, and that did not do the trick. When it's not starting, there is no voltage at the fuel pump, so it's not that causing this problem. They tested the integrity of the wiring from the DME to the fuel pump and elsewhere where they could, and found no problems when it wasn't starting. They indicated a reflash of the DME wouldn't help (I found an old service bulletin about stalling under no load with old software versions) because it already has the newest version.

What's happening is that there is probably a loose solder joint somewhere on the DME circuit board that is exacerbated by heat. When that thing shakes loose, the whole system shuts down - no spark, no fuel, no nothing.

So it's once more weekend in the Exploder.


And there goes a couple months rent. Its been a while since I spent $1300 on a new computer. And this one doesn't even come with a nice monitor, or any cool games (ok maybe a really fun driving game).
 

·
Registered
Joined
·
873 Posts
It's a crying shame when the computer on a 7 year old car has to be replaced, especially when the price is so terribly overinflated. I can only hope that this permanently fixes your problem.

I realize it's a little bit late for this, but have you investigated the possibility / feasibility of having your old board repaired? It'd sure beat seeing a $1300 peice of electronics wind up in the trash can because of a loose soldering connection.
 

·
Registered
Joined
·
1,260 Posts
My car just died today. It acted up one other time, but after sitting, started up. Sure enough, fuel pump kicked the bucket. My indy guys came and picked me up, we put her on a flatbed and 30 minutes later, new fuel pump was in. Total cost $385 with labor and tow. Damn. That was the most expensive lunch I've been on in a while! Anyway, this SEEMS to have fixed my dipping idle when I push the clutch in!!!! Going to monitor and test some more, but this makes some sense. I'll keep everyone posted, but probably start a separate process.
 

·
Registered
Joined
·
87 Posts
Discussion Starter #19
Good News!

Holy **** I got good news today for a change. So I bit the bullet, they ordered the unlocked DME and were going to install it yesterday and have my car back to me that evening after I got off work.

Around lunch, the dealer called and said they were going to start the install, and that they wanted to keep it till the next day to check it out and make sure everything was working. Sure, I said, what's one more day in a Ford Exploder, if you're paying for it.

Well today, I got no call through lunch time. I was getting nervous, but I didn't want to call and find out it still didn't work. Finally, around 3pm the service manager called.

"Well, it's not the DME," said John the service manager said. As I was about to let a few expletives fly, he added, "but we found the problem. We did some more digging and testing before swapping the DME, and found a fault in the wiring between the DME and the ignition. When you put the shifter in reverse, it is knocking some wires around and causes the fault. We replaced the wiring, fixed the problem, and are now charging the battery back up."

"So you didn't have to use the unlocked DME?"

"No, your total will come to about $382, and we'll credit back towards that the fuel pump [~$320] that you bought the other day and never installed when we thought that was the problem."

:pimpin:

So, instead of forking over $1,200 more today, I'm forking over about $60. So I told them to fix the rear brakes as long as it was there at the dealer (doesn't really need new pads - old ones are cheapos installed by the previous owner that rattle).

I don't know whether the reverse-gear ground fault caused it every time (and I never tried taking it out of reverse gear) or what, and it doesn't make a whole lot of sense to me because I don't know exactly where the wires run, but whatever.

It fits. Thinking back, sometimes the car would start, then immediately die when I started moving. However the few times I recall that, I was starting to back out of a parking space. Wires from the ignition get cut, car doesn't see the key code and shuts down the party.

I'd like to see exactly where the fault was, but that will wait till I pick the car up. I will likely need a new battery now because we've run it down so many times over the last week, but I'm happy to do that.

:thumbsup:
 

·
Registered
Joined
·
80 Posts
Good to hear man! Let us know if it really helps.

I had two more failed starts this week - both times I was able to consistently fix it by "knocking" on the fuel tank. I would suspect fuel pump wiring or connection, but it's only a problem on starting. No idle issues, problems once it's running, or in reverse...
 
1 - 20 of 35 Posts
Top