1984 325e Starts and Dies Immediately (FIXED)

[subi_life]

Hey guys, so I recently bought a 84 325e 5 speed. When I went and checked it out the engine would start and idle (a little ruff) and the car would die under any load. Would fire back up and idle.

Now when I got it home the car now starts after a few cranks, runs for maybe a second then dies. Doesn't stumble at all. All the electronics still work before and after it dies. I have replaced the main relay, jumped the fuel pump relay and has not changed the symptoms. Intake boot appears to be in good shape. What should be my next plan of action?

FIXED: Previous owner cut and soldered on new injector plugs. Looked to be from a different model since the wires were a lot thicker. They must of shorted out the dme while doing this. I went to pick and pull and got the original injector plugs off of a 85 325e. I also bought a new dme off ebay. I installed the new dme and injector plugs and it started up and held idle. Went and drove around the block and it seems to be running smooth!

Short answer: Installed new dme and it fixed my start and immediately dies issue.

How I found this out: Bought a bentley, and tested everything from the wiring harness connector at the dme to make sure all sensors, grounds, wires were working. Once I knew they were and no vacuum leaks I could narrow it down to the dme.

[325e '87]

Get the Bentley shop manual.

Check the throttle position switch on the bottom of the throttle housing to make sure it works.

Check all the ignition parts

Check the coolant temp sensor, the one with 2 prongs

The Bentley manual will tell you how everything needs to be looked at.

[TobyB]

check fuel pressure,

t

[subi_life]

Thanks for the response. Have a Bentley manual ordered and on its way. I will do some more trouble shooting today. It’s just strange it was idling fine a few days ago and now it wont run for longer than a second. Not sure what went wrong in the tow ride home

[jeffnhiscars]

Vs umm leaks are also a big deal, especially with a car that's sat and the rubber dries out

[subi_life]

I replaced the intake boot and checked all the lines going into/from the throttle body. Also have fuel coming into the fuel rail. Today I am going to check power at injectors. The car dies and adding throttle does not affect it. It dies just as fast with or without throttle input.

[RobDog]

Try unplugging the AFM and starting the car. All my 325e have behaved this way when there was a bad connection between the AFM and the harness plug or the AFM was bad. The car starts fine but turns off like it’s on a timer with the key.

[subi_life]

Try unplugging the AFM and starting the car. All my 325e have behaved this way when there was a bad connection between the AFM and the harness plug or the AFM was bad. The car starts fine but turns off like it’s on a timer with the key.

Unplugged the afm and it didn’t change it at all. Still starts then dies right away. My manual should be here today so hopefully and figure it out.

[subi_life]

Replaced the spark plugs today and also check resistance on both the sensors in the bellhousing. Both sensors had resistance around 1000. Car starts the same exact way but still dying after a second. Checked injectors and they are getting power but not sure if they are pulsing. What would cause the injectors not to pulse?

[jeffnhiscars]

Replaced the spark plugs today and also check resistance on both the sensors in the bellhousing. Both sensors had resistance around 1000. Car starts the same exact way but still dying after a second. Checked injectors and they are getting power but not sure if they are pulsing. What would cause the injectors not to pulse?

If the car sat the injectors could have power but not fire us to being gummed up so it's running on the cold start valve. Exact same problem I had with a non running eta I bought. Swapped injectors and ran great

[subi_life]

It seems my problem is the injectors are not pulsing. They do have power and the car is still starting and running for a second then dying. Today I went through the wiring harness. When I ground pin 14 and pin 15 I can gett the set of injectors to pulse. I can audibly hear them click. Seems like the problem could be the dme? Anything else I should check before I look for a replacement?

[subi_life]

I also checked the resistance on both the cps and speed sensor? I did this through the wiring harness at the dme location so I could know the wiring loom is in tack and both has a reading around 945ohms. I know the car wouldn’t start without the cps but read a thread saying the speed sensor could cause the car to misfire. I am thinking about ordering a new one even though is seems good from the ohm reading.

[Jaxx_]

I also checked the resistance on both the cps and speed sensor? I did this through the wiring harness at the dme location so I could know the wiring loom is in tack and both has a reading around 945ohms. I know the car wouldn’t start without the cps but read a thread saying the speed sensor could cause the car to misfire. I am thinking about ordering a new one even though is seems good from the ohm reading.

What is the "speed sensor"? Are you talking about the differential's speed sensor? It will not cause the issues you are mentioning.

[subi_life]

I am talking about the other sensor right next to the crank position sensor. Not sure what it is called.

[subi_life]

FIXED: Previous owner cut and soldered on new injector plugs. Looked to be from a different model since the wires were a lot thicker. They must of shorted out the dme while doing this. I went to pick and pull and got the original injector plugs off of a 85 325e. I also bought a new dme off ebay. I installed the new dme and injector plugs and it started up and held idle. Went and drove around the block and it seems to be running smooth!