Swap Issues...

[halfofnothing]

I've recently swapped a complete 2.0 with motronic in my 91 golf. There is no pulse to the injectors. I've gone through all the test points for power and ground at the ecm connector according to the bently and they all test properly. The fuel pump comes on for a split second when i turn the ignition on and i have fuel pressure while cranking. I don't want to just throw money at another ecm if that isn't the problem so any ideas would be greatly appreciated.

[Fourt1thirty]

There should be a wire on each injector that is red/blue (should be... might be red/other color). You should get 12v on that wire when the key is on.

[halfofnothing]

Originally Posted by Fourt1thirty

There should be a wire on each injector that is red/blue (should be... might be red/other color). You should get 12v on that wire when the key is on.

i get 12V across the injectors with ignition, but no pulse while cranking(stays at battery voltage).

[Fourt1thirty]

They're switched ground... the pulse is on the other side and comes from the ECU. If you have power to everything it sounds like the ECU doesn't know you're cranking the engine. Do you have spark?

[halfofnothing]

Originally Posted by Fourt1thirty

They're switched ground... the pulse is on the other side and comes from the ECU. If you have power to everything it sounds like the ECU doesn't know you're cranking the engine. Do you have spark?

i have spark from the coil....i've replaced the rpm sensor, same thing...not getting the ground pulse at the injector plugs or the ecm connector.

[halfofnothing]

do the injectors fire on crank window, distributer window, or a combination of the two?

i think my biggest problem right now is that i'm not sure if the car that the ecm/harness came out of was running at the time or not so i have no idea if the ecm is in working condition so i've been trying to eliminate sensors/harness from the equation. thanks in advance for your input.

[Fourt1thirty]

Everything works on the 60-2 trigger wheel on the crankshaft. There's a single window wheel in the distributor (used as a cam sensor) which is a TDC reference but the car will run without this (limp timing).

[halfofnothing]

so if i test for "crank trigger" at the ecm connector and that's fine i can assume the ecm is toast?

side note...are you familiar with or know where i might find what letter ecm's belong to what year cars?

[Fourt1thirty]

Unless you have an oscilloscope you may have a hard time testing the crank sensor.

ECU codes changed a lot, even within years. What year was your source car?

[halfofnothing]

Originally Posted by Fourt1thirty

Unless you have an oscilloscope you may have a hard time testing the crank sensor.

ECU codes changed a lot, even within years. What year was your source car?

i have an o-scope

the engine is from a 93. the harness and computer are supposedly from a 93 as well...i know for sure it's an obd1 harness. ecu is an AE

[stevethefolkie]

My understanding is that when you first turn the ignition key on the fuel pump comes on - then (after running for a couple seconds) goes quiet until it receives an ignition signal (from the HAL sensor) indicating that the engine is running. If you're getting spark but no fuel I'd imagine that the problem is in either the wiring (to the fuel pump relay) or in the ECU.

You COULD wire the fuel pump to an "ignition on" source of power to provide pressure to the system IF you're getting spark. The only downside to this would be (to my mind) that in the event of an accident that kills the engine, the fuel pump won't "know" to shut down -

Steve

[Fourt1thirty]

Any OBD1 ECU should work.

You can scope pins 1 and 2 on the crank sensor. It's an unfiltered VR sensor so it may be a dirty signal. You should have 500-700 ohms across those two pins (pin 3 is the wire shield). The crank sensor is a tough one. The ECU will ALWAYS throw a crank sensor code unless the engine is spinning (running) at the time it's scanned... even when the sensor is good.

[halfofnothing]

Originally Posted by stevethefolkie

My understanding is that when you first turn the ignition key on the fuel pump comes on - then (after running for a couple seconds) goes quiet until it receives an ignition signal (from the HAL sensor) indicating that the engine is running. If you're getting spark but no fuel I'd imagine that the problem is in either the wiring (to the fuel pump relay) or in the ECU.

You COULD wire the fuel pump to an "ignition on" source of power to provide pressure to the system IF you're getting spark. The only downside to this would be (to my mind) that in the event of an accident that kills the engine, the fuel pump won't "know" to shut down -

Steve

the fuel pump isn't the problem, it's the injectors that aren't firing.

[halfofnothing]

Originally Posted by Fourt1thirty

Any OBD1 ECU should work.

see, that's what i thought....but according to some it has to match the harness if that makes any sense....

i've had four different ecu's in the car and they all do different things, with one the fuel pump won't work, with another the fuel pump will run constantly, with another nothing works, and with the one that's in there now(that belongs to the )the fuel pump comes on like it's supposed to to prime the system, but that's about all it does. i haven't tested spark at the plugs yet so i'm gonna try that tonite or tomorrow. i'm about at my wits end with this one, i've done this swap about five times now for other people and they all went off without a hitch, and of course the one i do for myself has issues...

[Fourt1thirty]

I've run at least three different ECUs in my MK3 ('95), my wifes ABA MK1 ('93 harness) and my roommates ABA MK2 ('94 harness) I did for him... never had a compatibility issue.

fwiw: '93 in ETKA brings up AS which is the replacement for the AE you have.