Turbo Engine rebuild 20HC85

[Jeff Turbo]

Every car with an ECU has a different configuration for that model. Just because they look the same doesn't mean the internals are the same. Early turbos had 2 ECUs, one fuel one ignition from memory, later all in one .I don't have the knowledge to put all into one ECU but many specialist companies do I assume and will build you a custom programmable ECU complete with connections

[Jeff Turbo]

I have found the part numbers for an engine loom but I don't think it will help you much as all are probably no longer available
Early HAM3650
Mid HAM3868
Facelift with the silver ECU is YSB10028

[Juanmacandel]

Hi Jeff, is that part number for the wiring harnesses? I think that if someone had an old harness and could offer me the connectors, I could rebuild the wiring

[Jeff Turbo]

Hi Jeff, is that part number for the wiring harnesses? I think that if someone had an old harness and could offer me the connectors, I could rebuild the wiring

Yes that's the engine wiring harness part numbers for turbo. First two part numbers are for the black ignition ECU, facelift is for the facelift silver ECU as that's a completely different connection.

[Juanmacandel]

Hi, after a long time working on the car, I finally managed to start it. Since it’s a turbo adaptation, I thought of using a MEMS ECU from my 1992 carburetor and cutting the crankshaft and ignition coil signals to wire them to the turbo ECU. Before this, I want to start the car in a 'naturally aspirated' configuration — by this I mean I have the fuel pump, coil, ECU, and all the sensors from the naturally aspirated carburetor. The car starts with the carburetor vent valve tube open, not connected. I don’t have that valve, but if I try to block that outlet, the car stalls and won’t start again. When it does start, the car runs terribly: if I touch the accelerator it stalls, and the idle is very unstable. From what I think, it should work like a turbo carburetor. Is there something I’m missing? Any way to tune it roughly so it works halfway decently? As soon as I have some time, I’ll post the photos of the process.

[Jeff Turbo]

It's good that you're making progress. You will need both ecu's that fit a turbo as it adjusts the timing when on load/boost. Using a normal ECU will not make the car correctly as the timing will be wrong.
I have put a link up on Matt's thread for a turbo ignition ECU near Poland and it's cheap. I think they also have a fuel ECU listed so try those

[Jeff Turbo]

And try this company

[Jeff Turbo]

This is in Italy

[Juanmacandel]

Thanks for your help, Jeff, as always. Since I don’t have the old wiring (with two ECUs), I have to make a hybrid. I have both the turbo ECU and the unified ECU from the newer models. Why wouldn’t it work to use the original carburetor’s fuel ECU and the turbo ECU for ignition?
I want to make it run as naturally aspirated, just to check that everything is correct up to that point, but it doesn’t run properly. I’ve read that it’s possible the crankshaft sensor is faulty, based on the symptoms it has. Something that surprises me is the ventilation outlet: I can’t block it, otherwise the car stalls and won’t start.

[Jeff Turbo]

Ah I see you have the mems ignition ECU for later cars, I will have to do some research about the fuel ECU as I think it's different for those. If you block the vent valve pipe the car runs poorly ? A normal ECU has different internals, the turbo ecu adjusts the timing differently

[Juanmacandel]

That’s right, if I block it the car won’t even start. So I understand it has to remain open to the air if it’s not connected, right? Right now I’m only using the MEMS ECU.
My idea is to take the crankshaft signal (along with the other sensors) to the turbo ECU, so that it controls the ignition coil.

[Jeff Turbo]

A vent valve should be open when the ignition is off and closed when the ignition is on, so blocked so air does not get into the system.. if you've blanked it off then that's how it should be to drive etc

[Juanmacandel]

So I don’t understand why it stalls and won’t start when I block that carburetor tube. Could it have something to do with the float adjustment? How is that done? Is there any other adjustment that should be made with the carburetor off the car?

[Jeff Turbo]

So I don’t understand why it stalls and won’t start when I block that carburetor tube. Could it have something to do with the float adjustment? How is that done? Is there any other adjustment that should be made with the carburetor off the car?

With the carb, did you rebuild it and set it up using the manual for clearances etc? From your picture you do not have a swirl pot from the fuel pipe in to the carb also does it have a fuel regulator as I can't see that?
Post 59-60 in this thread https://maestro.org.uk/forums/forum/...-montego-turbo

[Juanmacandel]

I have the gas separator and the fuel pressure regulator for the turbo, but for now I want to run it naturally aspirated, without any of that, to rule out problems step by step. I rebuilt the carburetor with the HU gasket kit for turbo, but I haven’t adjusted it. What needs to be adjusted? Float height? Idle? Choke? In the manual I only saw how to adjust the mixture, and I’m not too sure about that.