1987 325es crank no start

[Fryedchicken34]

Hey guys I bought another guys project a few weeks ago and have been trying to figure out a crank no start problem. I think it’s related to a bad ground since I can’t find a ground near the right strut tower. The car will run on starter fluid if I jump the dme relay but won’t fire injectors. If anyone’s dealt with something similar, I would appreciate any suggestions. Also if someone could tell me where I should be grounding the dme, or where the right strut tower ground is supposed to go, I would appreciate it!

[82eye]

there is a whole series of diagnostics to go through to solve for poor running and no start conditions. it's important they are done in the right order or you may miss the issue. the faq/diy subforum has them listed out.

start here : M20B25 DME Diagnostics
then have a look at this one : Engine Management Diagnostics

those are i car specific but the e car should be similar enough for you to work it out.

[Fryedchicken34]

there is a whole series of diagnostics to go through to solve for poor running and no start conditions. it's important they are done in the right order or you may miss the issue. the faq/diy subforum has them listed out.

start here : M20B25 DME Diagnostics
then have a look at this one : Engine Management Diagnostics

those are i car specific but the e car should be similar enough for you to work it out.

Thanks, I’ll work through these this weekend. I already tried the diagnostic flowchart but didn’t make any progress. Do you happen to know where the dme gets grounded?

[82eye]

there is an e car specific diagnostic here - e-car diagnostics
pretty sure the ecu grounds back to the g103.

[reelizmpro]

For a crank no-start on an ETA, I would check the main and fuel pump relays. Bypass them by jumping 30 and 87 (on the harness) to test. Once the fuel pump is confirmed working, you can check the main relay the same way. If neither of these are the issue, then I would check the flywheel reference sensors. There are two of them...one should have a white zip tie style tag on it and the other has nothing. If you see a 3rd sensor with a red zip tie, it is for diagnostics and not used by the DME to run the engine. Each has 3 pins, resistance between 1 and middle pin should be around 800-1000 ohms IIRC. I am going through this same issue right now with my white M3. One of my reference sensors has been hack spliced together by the PO and the connector literally crumbled as I disconnected it. I took a measurement anyway and got nothing. I'm actually about the replace them both right now after this post. Hopefully it's something relatively simple for you as well. These sensors are nearly 40 years old unless they've been changed previously.

[Fryedchicken34]

For a crank no-start on an ETA, I would check the main and fuel pump relays. Bypass them by jumping 30 and 87 (on the harness) to test. Once the fuel pump is confirmed working, you can check the main relay the same way. If neither of these are the issue, then I would check the flywheel reference sensors. There are two of them...one should have a white zip tie style tag on it and the other has nothing. If you see a 3rd sensor with a red zip tie, it is for diagnostics and not used by the DME to run the engine. Each has 3 pins, resistance between 1 and middle pin should be around 800-1000 ohms IIRC. I am going through this same issue right now with my white M3. One of my reference sensors has been hack spliced together by the PO and the connector literally crumbled as I disconnected it. I took a measurement anyway and got nothing. I'm actually about the replace them both right now after this post. Hopefully it's something relatively simple for you as well. These sensors are nearly 40 years old unless they've been changed previously.

reference sensors have good readings. I also tried a new set. Bypassing the main relay gives me spark but no fuel. starts on starter fluid when main relay is bypassed but not with a new relay(this is why I think it’s ground related). Bypassing the fuel pump relay gives me fuel to the rails but injectors don’t fire. And I don’t have injector pulse(checked with a noid light).

[Fryedchicken34]

I will also note that the previous owner was gutting the car so a lot of stuff like the icv, brake booster, ac has been removed.

[Fryedchicken34]

there is an e car specific diagnostic here - e-car diagnostics
pretty sure the ecu grounds back to the g103.

I’m pretty sure this ground is missing. I need to find a picture lol

[reelizmpro]

This is from the 87 325e ETM. Looks like the ground is on the intake manifold. Perhaps it's where the diagnostic bracket mounts.

[82eye]

is there a ground point on the passenger shock tower?
it would help if you had an etm for the e car. i am not sure where there is one any longer. we lost all the resources for it i knew of.

[packratbimmer]

On ETA cars, always bypass the on board computer (OBC) harness during diagnostics. The big green module box near the steering column can be bad and cause a no start situation. Bypassing it behind the radio area is a pain, but worth it. Obviously, if one has a known good OBC relay, that would be an option too.

[Fryedchicken34]

Ok guys I’ve made progress. Thanks for the help. The car starts and runs with the relays in place and the cold injector, but the fuel injectors still aren’t firing and there’s no pulse to it. Cps is good since the car doesn’t start without them, or with them switched. The obc is jumped, and I have 12v to the injectors, they’re just not being grounded. Im gonna order a new ecu to rule that out, in the mean time open to any suggestions y’all may have.

[82eye]

Ok guys I’ve made progress. Thanks for the help. The car starts and runs with the relays in place and the cold injector, but the fuel injectors still aren’t firing and there’s no pulse to it. Cps is good since the car doesn’t start without them, or with them switched. The obc is jumped, and I have 12v to the injectors, they’re just not being grounded. Im gonna order a new ecu to rule that out, in the mean time open to any suggestions y’all may have.

injectors fire when the ecu sees a rotating engine signal from the cps. if the cps is bad you won't get injectors.

[Fryedchicken34]

injectors fire when the ecu sees a rotating engine signal from the cps. if the cps is bad you won't get injectors.

Understood, will give an update when it’s done.

[reelizmpro]

I wanted to post this here for posterity. Applies to Eta's, M3's, etc with sensors on the bellhousing.

• The Top Dead Center (TDC) Sensor connector is the left-most of the three connectors. There is a small red wire tie on the wires on each side of the connector. The sensor is mounted on the left side of the bell housing, about 6 inches above the other 2 sensors. • The Cylinder Identification Sensor connector is the middle connector. This connector is grey, and the sensor has a small grey wire tie at the top (connector side) and bottom (sensor side) of the sensor. The sensor is mounted in the left side of the bell housing, in the lower hole, marked ‘B’.
• The Engine Speed Sensor connector is the right-most connector. The connector is black, and there are no wire ties marking the connection or sensor. The sensor is mounted in the left side of the bell housing, in the upper hole, marked ‘D’.
• To test the Cylinder Identification Sensor or the Engine Speed Sensor, test the resistance of pins 1 and 2. Pin 1 is on the right (as mounted in the car), and 2 is in the middle. The resistance should be 960 +- 96 ohms.