89 240 turbo swap ECU issues

Red block gods I need some assistance for I am completely confused.

This summer I swapped 89 240s b230 with a later 940 b30ft. I got the 940 engine harness wired into the 89 body harness and ran very nice with the NA ECU and ignition module. We swapped the NA computers out for 760 computers and the car would just immediately lean out and stall. There was also a smell of burning electronics coming from the ECU. At first I thought it was a bad ECU since it ran fine with the NA. I had swapped back to the NA computers and have been driving it around for the past couple months with little issues. I wasn't driving it hard in that time since I heard that the spark is a bit aggressive and melts stuff. I finally bought another 760 ECU and plugged it in today and now it runs fine for the first 5 seconds then quickly leans out and stalls. I'm able to keep it alive with quick shots of the throttle to keep it from leaning out. I also quickly found out that the same smell was starting to happen with this ECU as well. Since the only two things im switching out are the computers I decided to keep the NA ignition module in with the Turbo ECU just to see if maybe the ignition module is causing the issue. Still leans out after 5 seconds but with little to no burning smell? And now Walbro fuel pump in the tank primes with key on which it didn't do before. Note for the fuel pump I wired it as if it was the main external pump and deleted the wiring for the in take assist pump.

Any help would be appreciated because nothing is adding up here and I am at a complete loss. Thanks in advance!

We'll the turbo motors use low impedance injectors and if you put those in your harness without the resistor pack then you burn up the injector driver in your ECU.

What injectors you running and do you have the resistor pack in the harness?

Im running 850 turbo injectors in the car. Where would the resistor pack usually be.

Yamsman97 said:

Im running 850 turbo injectors in the car. Where would the resistor pack usually be.

Click to expand...

I think the resistor pack is located on the drivers side inner fender. It looks like this.





But if you don't have the pack installed I think you would of had to install jumpers to get the injectors to fire. Something like this.

https://www.classicswede.co.uk/940_Turbo_resistor_bypass_loom/p1733344_20051234.aspx

or this

http://forums.turbobricks.com/showthread.php?t=226559

850 injectors should be high impedance so the resistor pack is not needed with those. I think they measure around 12ohm or so.

If you did this-- I got the 940 engine harness wired into

And that is a turbo engine harness it should have the resistor pack as part of it and then if you used high impedance injectors, same problem you might have burned up your ECU injecktor driver.

Post what your setup really is.

Sorry guys my bad. The harness is from a 93 240 that originally was from a +t setup. As far is I know I don't think there is a resistor pack in the harness. I have the 940 harness sitting in my garage from when I bought the engine but wasn't installed.

So from what I understand, I don't need the resistor pack for 850 injectors and the 240 didn't come with one. I have the stock ft injectors but in order to run those I would need a resistor pack installed correct?

My setup (just so it's not all mixed up)
93 240 engine harness paired with an 89 body harness
Currently running na injection and ignition computers
Injectors are 850 turbo injectors
Fuel pump is converted to a single walbro 255
Engine is a later 940 b230ft

Yes correct. You'll need a stock ballast resistor pack to run the stock 940 turbo injectors. It's easier to just run the 850 injectors as you are doing.

Are these 760 ECUs LH2.2 or LH2.4?

The ECU I have is a 0280000563. I'm not sure if that's a lh2.2 or 2.4

Yamsman97 said:

The ECU I have is a 0280000563. I'm not sure if that's a lh2.2 or 2.4

Click to expand...

The 563 is a LH 2.4 non-EGR Turbo ECU. You cannot plug an LH 2.2 computer into an LH 2.4 harness. The connector is not the same length and will not fit.

The 5xx series ecu's have several common failure modes with injectors stuck open, the fuel pump relay not staying grounded due to a failed driver and the 5v to 12v level converter failing. They designed this custom chip for it moulded in epoxy that can fail when the epoxy cracks and let's in air.

Start out with checking of the Injectors are stuck open, and if the fuel relay remains on. After that, possibly try another ECU, make sure to pull it of a running car, as they are somewhat likely to fail, especially those with a 'pink' label

Issue solved!

Turns out I just had really bad luck on the two turbo ECUs I had. I ended up getting a 954 ECU from a later 940 turbo and works pretty well now besides having 02 sensor issues but I think it's being caused be either an exhaust leak or vacuum leak. Thanks for the help!