3.2 Motor won't start. Please help!!
 

Motor ran fine in my 914 until I changed the fuel lines on the motor and installed stock 915 flywheel for my new 916 trans. I ran through all the bentley book tests.
-Fuel pressure is around 39 lbs
-Voltage readings all correct on DME
-Unplugged spark plug #1 cable and got spark on external spark plug
-Resistance looked good on Reference Sensor and speed sensor
-During start I get 3.7VAC on Speed sensor
-During start i get between .133VAC-.157VAC on reference sensor
It sounds like it wants to start. Click on link below to listen to motor.
https://dl.dropboxusercontent.com/u/28794322/Motor.m4a

Any ideas??

Appreciate any help at all!!!

thanks,

Steve in Laguna Niguel, CA.

Did you by chance reverse your speed and reference sensor wires? When I installed my engine the P.O. had marked the harness and sensors wrong and had them on wrong. I swapped them and it started.

Thanks!! I just tried switching the sensor wires and now it doesn't fire at all.
I am leaning towards the reference sensor pin on the flywheel. I initially broke it off but a local shop welded it back on and swared that it was good.

I don't think it's your reference sensor now that I read your post again. If you have spark, the speed and reference are working. How did you test fuel pressure, by jumping the fuel pump? If you've got spark while cranking you need to move onto fuel and air. My guess is fuel.

Have you tried disconnecting one or two injectors and then tried to start?

Check the brown bundle of ground wires on the drivers side of the intake...

This engine is fuel injected? Do you have a noid light?

Thanks everyone for the help!! I bought a fuel pressure gauge and attached it to the test fitting. It shows 39 lbs, when I try to start the motor. I will try disconnecting some of the injectors today and see what happens.

The ref sensor is used to enable the fuel pump once started, not the spark.

You say you swapped the speed and ref sensors and that it won't start at all. But it wasn't starting at based on the audio clip of your first post. How exactly did it sound different to you.

Bentley says you should have a ~2.0 V sine (AC), but your reading seems low.
The Flywheel is new and you suspect the reference pin.
I think you are on to something here - all relatedto the ref signal and fuel starvation.

The wrinkle is your fuel pressure which ok, but the pressure may have gotten up from the ignition switch.

I would try jumpering the DME fuel pump relay ON temporarily to see if it fires up.

The engine is a totally stock fuel injected 1984 Euro 3.2 motor. The grounds are good. I also tested the grounds and voltages on the DME connector, per the Bentley manual. I need to google noid light. I used a DVM from radio shack for the measurements. It has a nice beep connectivity feature.

Interesting. After I switched the sensor connectors the starter turns over, but it doesn't sound like it's trying to start like in the recording. I also have a switch on the starter solenoid. I used this switch with the DME relay disconnected to get the oil pressure up, before trying to start the motor. It sounds the same as that. I will switch the connectors back and try disconnecting some of the injectors. I have a fuel pressure gauge on the test fitting. It shows 39 lbs while starting. Maybe that's left over pressure from when I jumpered it. I will force the pump on and try again.

All excellent suggestions. I won't be able to work on it until this afternoon. I will report back tonight. Thanks everyone for the help!!!

Maybe Sal or Ingo will correct me if I'm wrong but I think the DME uses both the Reference sensor and the Speed sensor to determine the engine is turning and then starts to generate both spark and fuel injection pulses.

Any chance some contaminants got in the fuel hoses?

This would make more sense (both spark and fuel) - I shouldn't have discounted the "spark control" . I know the engine needs to be turning for the chip to allow the DME/Fuel pump to be ON, but I don't know enough about how the 8051 is programmed. Both the reference and speed sensors get buffered by an IC (S100), and then go to the 8051. How the chip uses that for spark control, I don't know.

I've seen though, that sometimes if the speed/ref sensor signals are there, the FP doesn't turn on. Maybe it is because no FP power was easier to diagnose - that led me to that thought. (and the fact / smoking gun that the flywheel was recently changed, and the OP did mention good spark on #1).

That stuff aside, my bad if I threw anyone off track - espec'ly fetus. I would love to know more about the DME.

+1 fuel contamination (b/c of the fuel line work too)

I am also interested in the DME electronics, From what I've learned from the FRWILK website the reference sensor is used one time and then the DME counts teeth off the flywheel. FRWilk also says there is some crude frequency synthesis to get the angular resolution required for spark timing between teeth (see DME math)

Sal Carceller has disassembled the code and maybe he knows.

That's exactly correct, i.e. the ref sensor is only needed to determine TDC for
starting. Once the engine is running the ref sensor can be disconnected.
The DME ECM always knows when TDC re-occurs by counting the speed sensor
teeth. This is a good test to determine how good the speed sensor's signal is.
If the engine eventually dies, the speed sensor is weak.

It runs!!!!!!! But I don't know why. I put everything back the way it was. Traced the sensor wires to make sure they were going to the correct sensors. Tried to start the motor again, same symptom as the recording. Then I disconnected two of the three injector plugs on the distributor side. The one in back was being a butt head. Then I tried to start the motor again and it started!!!! Then I shut the motor off and plugged in the middle injector plug. Then started the motor again. It ran a little better!!! Then I shut the motor off again and plugged the #1 injector back in again. I thought it must be the #1 injector, but the motor started right up again.
Has anyone seen this before? I guess next step is to reseat all the injector plugs and wiggle wires to see if I can make it happen again. I did go to Harbor Freight and bought a noid kit, but I didn't need it so far. Motor runs great so far. Now I just need to adjust the clutch and tweak my home grown 916 shifting linkage and get insurance for the car. It's been apart for over 2 years, with fixing the hell hole and installing the 916 trans.

Thanks again everyone for the help!!! I was ready to tow it to a shop, but I am tight on funds right now and didn't know how I was going to pay for it.

This is cool. Thanks rick-1 and mysocal911.

This is great - although I agree it would be nice if you knew exactly what the prob was so you don't get a surprise later. Congrats on getting this far.