Rennlist - Porsche Discussion Forums - Need help with 16v swap in 951

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Need help with 16v swap in 951 - wiring

Ok so I have a 1987 944S that was wrecked but still ran and drove and I decided to buy a 1988 951 roller to swap everything into.

I am pretty much done with the swap now but I can not get it to start, no tach bounce and no fuel. If I jump the DME relay then I get fuel but still no bounce. I have been troubleshooting it for a while now but I think the problem is somewhere in the 16v wiring that doesn’t line up with the 8v chassis.

So for swap wiring all I did was wire in the ICM (including pins 1 & 14 on the 14pin connector). I have found out by reading today that I need to swap over the fuel injection ballast so I’ll do that tonight, but is there any other wiring I need to do on this swap?

somewhere I read this: “the 944S DME needs an additional power source wired through the Fuse box.”
and i have not been able to locate any more info about this.

So Chaxce; did you get it figured out. I am educatiing myself and buying parts to swap an 87-88 M44/40 16v into an 86 951 roller. I have the engine, engine wiring harness DME and flywheel. I need help with the wiring and the ICM Amplifier? I am confused about how that is set up. It sounds screwy to me ICM in the distributor and another in the forward engine bay that is not wired in the engine harness accept to go to the DME with a shielded wire? I hope you found out whats going on with your no start.

The 16v cars moved the ICM out of the ECU because it generates a ton of heat and had potential to ruin the circuits in the surrounding ecu. The ecu sends a low amp ground signal to the ICM which grounds the ignition coil and gives you spark at the distributor. The signal wire is ground shielded to prevent interference in the signal.

here is a good page that compiles a lot of the harness connector changes year over year.

https://members.rennlist.com/tholyoa...wap_wiring.htm

The ICM is wired into the chassis harness if I remember correctly, and most engines only come with the engine harness, so you have to DIY it. It was a while ago since I did this but IIRC the non-16v coil wire is also part of the chassis harness and you can reuse the #1 pin wire by moving it's orientation in the 14pin connector. You then disconnect the signal wire at the coil, and run it over to the ICM input signal, then a new wire runs from the icm to the coil. With this setup you're running un-shielded, but it worked for me.