Re: M50 Won't start

[pyro]

Well some of you might remember me finding out the problem so bare with me if you remember.

I have a 1991 525i and the engine would flood itself out every time I would crank it. When you remove the fuel pump fuse it will start up and rev until 3k rpm. So I checked fuel pump relay, fuel pump wiring, Fuel pump, and the Fuel pressure regulator (FPR). No work. Then I switched out the injectors. Still no work. Then I finely burrowed someone’s ecu and it started and I drove it for about 20 minutes w/ out problem so I took that out and returned it. (That run was on a known working set of injectors)(From my e32). While waiting for the new computer to arrive I switched the injectors back to the original ones. So hers the bad f*ckin news. Got new ecu online plugged it in ran like a beauty, drove to get gas, then got taco bell, got back in car started it and got back on the road home. While slowing down to stop at a light all of the engine lights went on and I started to laugh then I realized it was something serious and the engine had stopped running. So I quickly shift into park and crank and I get the dreaded smell of a flooded engine. Same frigin problem all over again the car fry’s this brand new computer in the same way it messed up the old one. Same exact symptoms. So now back to square one -200$ and a broken glass that I threw out of anger.

Need help ASAP so thanks in advance guys.

Now I have narrowed it down to something on the car is making the car eat ECU's this is its 3rd one. The second was a rebuilt version of the first one.

[pyro]

I went and checked the resistnace of the injectors and all of them were between 15.7 and 15.9 ohms
and none of them are grounded but one of the pins on the ecu connector has continuty with +12v
im gonna go back out and verify

[pyro]

nm i made a error no +12 v to the injectors. now im realy stumped...

[pyro]

Well I think my testing process is flawed. How should I go about testing the engine wiring harness? I have a digital multimeter and it beeps when you touch the leads together. People say oh check for shorts. Well im unsure on the process to do that.

[Javier]

to the injectors connector (one by one). You should see pulsating light, if permanent on, the output drivers from the ECU are gone, if any one of them is permanently off, its wires may be shortcircuited.

Use an interior light bulb or similar to limit the current to the very minimum, you don't need much to test. If you have one of those led probes, (available at Pepboys) it should do it.

Javier

[pyro]

Ok ill test that tomrow and like you said in your email how do i test if i have weak spark? Also how do i test the ignitiion coils? i did the test that the bently manual says and they are all with in range of how many ohms they stated they should be.

By the way thanks for all of your help unlike the people at bimmerfourms makeing fun of me for not being able to figure this out. Iv asked 2 bmw dealerships and 3 shops and all of them are baffled and i don't have the money to have them look at it for 6 hrs at 110 a hr.

[Javier]

connector pin 4a and the sparkplug connection in the coilpack, it is the high voltage coil, compare readings between coils (have no values to offer you). Also can wire a light bulb between terminals 1 and 15 of the coil connector. You should have a flashing light wile cranking. This will test DME transistor (six in total), as we already know that whatever you have in there is taking out the DME. (Remember coil and injector feeders are not fused, attention to ground shortcircuits).

I feel the problem is more toward the injectors, let us know what the injector operation test turned out to be (Permanently energized?).

Javier

[Bellicose Right Winger]

I can't believe all those DME's are fried. Can you test them in the vehicle that gave you the loaner DME? If indeed they're bad, you need to discover cause before any more get ruined. It could be a wiring issue that comes and goes when you plug/unplug the DME or jostle other wires.

Paul Shovestul

Well some of you might remember me finding out the problem so bare with me if you remember.

I have a 1991 525i and the engine would flood itself out every time I would crank it. When you remove the fuel pump fuse it will start up and rev until 3k rpm. So I checked fuel pump relay, fuel pump wiring, Fuel pump, and the Fuel pressure regulator (FPR). No work. Then I switched out the injectors. Still no work. Then I finely burrowed someone’s ecu and it started and I drove it for about 20 minutes w/ out problem so I took that out and returned it. (That run was on a known working set of injectors)(From my e32). While waiting for the new computer to arrive I switched the injectors back to the original ones. So hers the bad f*ckin news. Got new ecu online plugged it in ran like a beauty, drove to get gas, then got taco bell, got back in car started it and got back on the road home. While slowing down to stop at a light all of the engine lights went on and I started to laugh then I realized it was something serious and the engine had stopped running. So I quickly shift into park and crank and I get the dreaded smell of a flooded engine. Same frigin problem all over again the car fry’s this brand new computer in the same way it messed up the old one. Same exact symptoms. So now back to square one -200$ and a broken glass that I threw out of anger.

Need help ASAP so thanks in advance guys.

Now I have narrowed it down to something on the car is making the car eat ECU's this is its 3rd one. The second was a rebuilt version of the first one.

[Hypr5]

Ok - I've been helping him with this project and trust me - it's a headache.

The DMEs are in-fact fried. No, we didn't test them on other vehicles, but anytime we plug a new ECU in, it works. (For how long.. nobody knows)

I DO think it's either coils, injectors or wiring SOMEWHERE, but I don't think it has to do with wire movement as this last ECU died while we were at a stop. It's frustrating.

The fact that the loaner ECU didn't die and it drove the car for longer than this ECU tells me that it may be injectors (because at the time, there were known working injectors from another vehicle installed).

Whats the likelyhood of injectors causing this sort of problem? Has it been heard of before?

[Bellicose Right Winger]

Lets work backwards from here. What was rebuilt on this DME?

Paul Shovestul

.....The second was a rebuilt version of the first one.