1987 3251 engine swap, now rev counter doesn't work

[vecky]

hi guys
i'm new to the forum, i hope you can help me out.
i've swapped my old 1987 325i engine for a 1990 325i sport engine.
i also was told to swap the main wiring harness and ecu.
now the engine works fine but the rev counter and fuel consumption gauge has stopped working.
i checked all the fuse's and looked for any loose wires, but everything seems ok, i've had a mechanic look it over, and he seems to think that there a slight difference between the 87/90 wiring looms.
has anyone experienced this problem, or has anyone got any wiring diagrams(picture) that can help me.
any ideas guys?
thanks for your help in advance.

[Speedtouch]

See the Zone Wiki guide:

http://www.e30zone.net/e30zonewiki/inde ... tronic_1.3

"What wiring does need doing is for instrumental purposes only and is easiest to carry out on the ECU plug end. There are two wires you need to cut on the ECU plug and then connect to the C104 plug which will now be unconnected following the removal of the old loom. The easiest thing to do is cut the matching plug from the old loom and plug it into the loose plug in the car. Then you need to connect pin #1 (Blk/Blu) on the C104 to pin #6 (Blk) on the ECU, the second connection to make is to connect C104 pin #3 (Wht) to ECU pin #32 (Wht/Blk), C104 pin #2 is not used."

[Grrrmachine]

Why did you swap the engine in the first place?

[vecky]

the reason why i swapped the engine was that the old engine was a bit cammy, when a friend said he had a great engine sitting around and i could have it for nothing, long story short, i no longer have the 1987 loom, would anyone know where i can get my hands on an old engine loom, so i can cut the the correct plugs off of it.
because the car sat in my garage for about a year after the engine swap, the fella that did the work had chucked away the old engine loom....i'm not a happy bunny
can anyone advise me on a good auto electrician who could help me out in the london/essex area.
thanks for your advice guys

[Kedge]

No need for an auto electrician, just follow the steps above it is dead easy and just two wires.

[Brianmoooore]

No need for an auto electrician, just follow the steps above it is dead easy and just two wires.

And running the facelift engine on the pre facelift management would be a retrograde step.
The advances in the electronics compensated for the de tuning of the facelift engine.

[vecky]

Thanks for your advice guys, the problem is I no longer have the old loom, the newer loom is fitted and works well, except for the rev counter/consumption meter. Is there a way of getting around the problem without the old loom.
Otherwise I'll have to try and get hold of an old loom.
Can anyone advice me where the best place is to buy an old loom?

[Brianmoooore]

Extend the two wires from the plug now hanging from the instrument cluster loom to the C101 engine socket, next to the fusebox, OR find the two wires in the engine loom near the ECU plug, cut them, and connect the two ends that go towards the plug to the wires of the redundant plug.