AAN Engine transplant into VW T3 Transporter

[Truckasaurus]

Awesome van, looks good.

[RS2]

ECU pins 42, 51 and 54 relate to the ECU talking to the Autotrans computer and therefore should not need to be hooked up.

http://forums.quattroworld.com/s4s6/msgs/21009.phtml

Your symptoms above sound like you do not have a good signal from the G4 crank position sensor, G28 engine speed sensor and G40 cam position (Hall) sensor (as I discussed above) because the computer does not seem to know where the cylinders are and therefore refuses to send the "go" signal to the injectors and/or coils.

That said, I am not clear as to how you know you have spark. How was this determined? If it was on turn over (on the starter) you are close to getting this thing started (just the ECU/injector control issue).

I pulled the coil pack cluster out, stuck a plug in each tube and cranked it over while watching the plug, with the plug earthing out on the rocker cover... I had good sparks at regular intervals.

I'll check the engine speed sensors tonight re resistance and connections. What does the ignition get it's trigger from?

MG

[RS2]

At work currently so not at the van to check on this but going back to basics...

Looking at this photo which I took when I was still marrying the Porsche gearbox to the AAN, it looks like I might have the G28 and G4 sensors in the wrong place





Will check this when I get back tonight just to confirm and hopefully it'll fire up! Nothing's ever that simple but you never know.

MG

[UrS4boy]

At work currently so not at the van to check on this but going back to basics...Looking at this photo which I took when I was still marrying the Porsche gearbox to the AAN, it looks like I might have the G28 and G4 sensors in the wrong place. Will check this when I get back tonight just to confirm and hopefully it'll fire up! Nothing's ever that simple but you never know. MG

The order of the connectors on the connector rack in your case, should be blue, green, grey, black, white, white, black with the G28 engine speed sensor with the grey plug end connected to the grey harness connector and the G4 crank position sensor with the black end connected to the black harness connector beside the grey harness connector.

As far as I can tell from that photo, it looks (?) like the G4 crank position sensor, the one closest to the front of the engine is connected to the proper black connector and the G28, the one directly over the teeth on the flywheel ring gear is connected to the proper grey connector. But, hey, do check them.

The fact that you are getting spark indicates to me that the ECU is getting the proper G40 cam sensor, G4 crank position sensor and G28 engine speed sensor. Otherwise, you wouldn't get any spark.

This leaves you with a fuel injector issue. I know you have somehow hardwired the fuel pump into your ignition system. As I have suggested before, with the AAN, the Fuel Pump relay is an important part of the ignition system because it supplies the main power to the injectors, as discussed here:

http://forums.quattroworld.com/s4s6/msgs/22583.phtml

Also important is the Holding Relay (part of the ECU) since it supplies power to the injectors before the fuel pump relay is energized during starting. It might have failed (you would need a second AAN motronic ECU to try out). Info on the holding relay is found here:

http://forums.quattroworld.com/s4s6/msgs/102009.phtml

Related to all this is the fact that the way the injectors are controlled by the ECU is the ECU takes the 12V to ground when it wants the injector to open, i.e. with the ignition on, you should have 12V at the injectors (via the holding relay before engine start and then via the FP relay after start). I am not sure if you tested this. Here is some injector wiring info:

http://forums.quattroworld.com/s4s6/msgs/90802.phtml

One last fundamental question, do you have fuel pressure in the fuel rail with the engine cranking? (Not sure if you tested for that).

Good luck.

[RS2]

Thanks for that.

I'm currently using the van fuel pump and just switching that on with the ignition so it's running constantly. Yes I have pressure at the fuel rail, as stated earlier, I earthed out each injector individually and had a good spray pattern on all.

I've also wired the feed which would normally come from the Fuel pump relay to S17, S72, S73 and S75. Again, this is on with ignition.

I'm triggering the starter manually with a Snap-on starter test switch direct from the battery. Maybe this is my problem?

I haven't got the sensors plugged in the wrong way around but they may be bolted into the block in the wrong order... will check in a bit.

MG

[UrS4boy]

Thanks for that.I'm currently using the van fuel pump and just switching that on with the ignition so it's running constantly. Yes I have pressure at the fuel rail, as stated earlier, I earthed out each injector individually and had a good spray pattern on all. I've also wired the feed which would normally come from the Fuel pump relay to S17, S72, S73 and S75. Again, this is on with ignition. I'm triggering the starter manually with a Snap-on starter test switch direct from the battery. Maybe this is my problem? I haven't got the sensors plugged in the wrong way around but they may be bolted into the block in the wrong order... will check in a bit. MG

First thing I have to say (nothing to do with the starting issue) <nanny rant on> is the way you have things wired up, bypassing the intended function of the AAN's J17 fuel pump relay (as controlled by the AAN Motronic ECU) is inherently dangerous. In an accident, (a rear-ender in your case), with the ignition still on but the engine stopped (due to damage), potentially with a fuel rail ripped off the engine, your fuel pump would continue to pump fuel until you turned the ignition off - leading to a high risk of fire - especially if you were incompassitated in the accident. <nanny rant off>

Back to the non-start, if you have the ignition to "ON" when you manually trigger the starter, I don't see why that would be a problem. Except <nanny rant on> that you are bypassing the load reduction relay - putting more strain on the battery. But <nanny rant off> that shouldn't be a real issue at this particular point in the swap.

I am running out of ideas.

[RS2]

First thing I have to say (nothing to do with the starting issue) <nanny rant on> is the way you have things wired up, bypassing the intended function of the AAN's J17 fuel pump relay (as controlled by the AAN Motronic ECU) is inherently dangerous. In an accident, (a rear-ender in your case), with the ignition still on but the engine stopped (due to damage), potentially with a fuel rail ripped off the engine, your fuel pump would continue to pump fuel until you turned the ignition off - leading to a high risk of fire - especially if you were incompassitated in the accident. <nanny rant off>

Back to the non-start, if you have the ignition to "ON" when you manually trigger the starter, I don't see why that would be a problem. Except <nanny rant on> that you are bypassing the load reduction relay - putting more strain on the battery. But <nanny rant off> that shouldn't be a real issue at this particular point in the swap.

I am running out of ideas.

Hi, no problems re nanny rant. I completely agree with everything that you've put regarding safety etc. The reason I've wired things up this way at the moment is that I've never heard this engine running and before I get into huge amounts of work fitting it to the van, I want to hear it run. Even if it's only for 30 seconds... I want to make sure that there's nothing obviously wrong with the engine. I have carried out a compression test and every looks to be ok.

Once I have it running, I'll be re-wiring as per factory. At present, the engine loom is hanging over the back of van with wires all over the place, screwed together in horrible connector blocks but again, this is only temporary.

I'm also running out of ideas. I checked earlier this evening and I did have the crank senors in the correct places. With the fuel rail getting full pressure and the injectors not being brand new... they're leaking a little so that small dribble of fuel is allowing the engine to splutter a little each time I try something new and crank the engine over.

I know that several people have said that the Auto signals aren't needed for the ECU to make it run, but... in the schematic above, there is a wire which goes from the gear selector to the Engine ECU, B12... whatever B12 is. I thought it might a connector but can't find any reference to it. Why would it go to the ECU if it wasn't needed?

MG

[UrS4boy]

Whoa. I thought the engine was IN the T3 already. As a result, I have to ask, is the ECU grounded to the engine properly? Without the ECU grounded, the injectors cannot be properly activated. In particular, you need to have a ground from T14/55, T19/55, T24/55 and T30/55, as described here:

http://forums.quattroworld.com/s4s6/msgs/21009.phtml

[RS2]

Right... tomorrows job will be to double check all pins again from the ECU plug inc all earths mentioned above.

I'll get to the end of this at some point.

Yes the ECU is earthed (body) but can't remember atm about the rest you've just pulled up.

MG

[UrS4boy]

Right... tomorrows job will be to double check all pins again from the ECU plug inc all earths mentioned above. I'll get to the end of this at some point.
Yes the ECU is earthed (body) but can't remember atm about the rest you've just pulled up. MG

Grounding/Earthing the case of the ECU does nothing. You have to have grounded/earthed the pins that I listed (through the harness), to engine (intake manifold) and from the engine THEN back to the negative side of the battery (normally this is done through a strap from the engine to the body and from the body to the battery). I think this could be the problem/solution.

[UrS4boy]

If you look on the lower right corner of the diagram below, you will see that pins 10, 14, 19 and 24 all ground (earth) to the cam cover/head or intake manifold (which in turn is grounded to the block and the block to the chassis and the chassis to the negative (-) terminal on the battery.

10 = O2 sensor = wouldn't stop the engine from starting
14 = injectors, definitely would prevent starting
19 = ECU, various sensors = might be an issue
24 = other sensors = might be an issue.

So the bottomline, is the harness needs to be grounded to the head/intake manifold (there should be two brown wires all ready to go) and the engine block needs to be connected directly or indirectly to the (-) terminal on the battery.

[RS2]

The bolt on earths onto the cam cover and intake manifold are bolted on as per factory. I will however, remove them and clean them up. There are two earth straps, one from the engine to the van and the other from the gearbox to the van.

I need to check up on the earth which is connected close to the ECU but will also check all the earth pins.

Thanks again,

MG

[RS2]

Back again ...

Ok so have checked all earths, all have good continuity. It's trying to fire as the injectors are slightly weeping.

However, I did decide to check the output from Pin 3, Fuel Pump Signal from the ECU. Nothing from it when cranking. This may suggest that my G40 sensor isn't supplying the ECU with a pulse?

I think I read somewhere about pooring water down inbetween the sensor and cam wheel? or am I going mad...

MG

[UrS4boy]

Back again ...Ok so have checked all earths, all have good continuity. It's trying to fire as the injectors are slightly weeping. However, I did decide to check the output from Pin 3, Fuel Pump Signal from the ECU. Nothing from it when cranking. This may suggest that my G40 sensor isn't supplying the ECU with a pulse? I think I read somewhere about pooring water down inbetween the sensor and cam wheel? or am I going mad...MG

And the earths/grounds are connected electrically to the same battery that is running the engine during starting?

Weeping injectors could just be leaking injectors not signs that the ECU is actually trying to activate them. Pulling the fuel rail and injectors and then carefully sitting the rail and injectors on five glass jars that you can monitor during the start attempt would be better proof.

No out put from Pin 3/55 to the Fuel pump (normally) indicates to me that the ECU is not getting a good signal from the G28 engine speed sensor (the one that lives adjacent to the flywheel ring gear). The ECU is looking for at least 13 RPM (by counting teeth) before it fires the J17 Fuel Pump relay (normally).

You might still have a G40 cam sensor issue. Pouring water down the back of the cam belt cover is typically only effective when the car has been running and then refuses to restart after shutdown (and heat soak). The water seems to revive the cam sensor (at least temporarily - it is failing and needs to replaced). In your case, I doubt that the water trick would help (but hey, try it). You would be better to check the signal with an LED as explained at Paul N's website and also Marc S.'s EFI Express website (as a link out his new cam sensor pffering).

Start with the G28 sensor.

[RS2]

Ahah ok, I'll see if I've got another G28 kicking around or maybe swap the G28 and G4 over? I presume that that would create other faults if the G28 is dead?

Weeping injectors.. that's all they are. They're not being fired by the ECU.

MG