will not start

#1

What am I missing?

I can not get this engine to start. I have checked all the electrical at the ECU according to the Bentley manual, main relay, fuel pumps, injectors all click or turn on when tested. there is fuel pressure and fuel at the rail, the coil has juice. I pulled a plug and looked in the cylinder and it looks dry. The motor turns over with the key but never fires.

One issue im having is finding out which plug under the diagnostic plug is for the timing sensor and which one is for the distributor they both will plug into the other.

Another problem may be, I have plug wires for a 90 and a harness for an 87, does the 87 come with a plug that plugs into the main engine harness like the set for a 90?

I have 2 motronic units, one from an 89 and one from an 87 both i cars and have tried both, same results.

Any help here would be much appreciated. Thanks in advance.

#2

I am a confessed parts-swapper. And I’ve had my share of no cranks.

In the land of parts swappers:
Check any grounds that might have been jiggled.
Check the crank position wire to make sure its connection at the sensor is good.
Just for fun, reconnect the main harness at the round connector (fixed one of my many no-starts).

To help others that might chime-in, was the car running before? Or, is this a no-crank after an engine swap?

More impotrantly, what will the paint look like?

Robert Patton

#3

Run through Jim Levie’s list…

The E30 Guru Speaks

#4

HA! Its looking like the BMW racing colors, three large stripes.

I bought the roller with no motor and a fair amount of work already done to the car as far as suspension, steering, and some electrical. The chassis is an 87 as i am assuming the wiring inside is 87 also. It also came with the engine harness from an 87. I pulled a core out of pick and pull from an 89 or 90 (cant remember) with a harness and ECU. I tried to use the harness from the later model but there was a red/white wire that went to the fuel pump relay center that was somehow connected to a ground at the round firewall plug and it toasted the wire. So I put the old harness back on and verified that wire (red/white) doesnt have a plugin point on the older harness. so this time when I turned the key there was no smoke :slight_smile:

So other than the cooling system everything else seems to be from the 87 unless there is something else such as the crank positioning sensor and that extra plug that comes from the distributor that im missing.

#5

probably too basic, but are both the large and small wires connected to the battery? Not having the small wire connected will allow cranking, but no start.
thanks,
bruce

#6

Actually not too basic I realized that I did not connect that wire to my kill switch yet, and thats the first thing im going to do tonight after work. thanks for bringing it up, sometimes its easy to over look the most basic details…

#7

Ok hooked up the small wire from the battery, still no start. But im not getting a spark at the plug either. coil has voltage. going to test the crank position sensor next.

#8

I am far from a BMW expert, but maybe I can help as an ignorant child. There is a resistor near the left front corner of the engine bay, I have not a clue what is does, maybe ballast for the injectors??? But when I was building my car recently I bumped it and knocked off one of the leads and I was same as you, everything else checked out but no fire. Plugged it back in and vroom vroom!! My Jeep has the same resitor in the same spot, disconnect it and same result. I guess they both have I6’s! Is it possible the AMC is GERMAN? Good luck.

#9

any chance you can you send me a picture ?

#10

HA! Its looking like the BMW racing colors, three large stripes.

I bought the roller with no motor and a fair amount of work already done to the car as far as suspension, steering, and some electrical. The chassis is an 87 as i am assuming the wiring inside is 87 also. It also came with the engine harness from an 87. I pulled a core out of pick and pull from an 89 or 90 (cant remember) with a harness and ECU. I tried to use the harness from the later model but there was a red/white wire that went to the fuel pump relay center that was somehow connected to a ground at the round firewall plug and it toasted the wire. So I put the old harness back on and verified that wire (red/white) doesnt have a plugin point on the older harness. so this time when I turned the key there was no smoke :slight_smile:

So other than the cooling system everything else seems to be from the 87 unless there is something else such as the crank positioning sensor and that extra plug that comes from the distributor that im missing.[/quote]
You smoked the harness because pin 20 of C101 on an 87 car is grounded. I don’t know what the pin is used for on an late model car, but if you don’t clip that wire you’ll damage a late model harness when using it on an 87.

Did you connect the three wire connector that pigtails off the 87 harness near the DME to the matching connector in the car? That connector has the tach & econometer outputs from the DME and the Start input to the DME. Without it the DME won’t run. Later cars route those signals through C101.

#11

DAM! That was it that little pig tail wasnt connected. Plugged that in and it started right up and idled perfectly. Thanks for all the help guys!