Running Lean

[Hvilshoej]

Hi

I have some issues with my Porsche 911 engine that is probably running lean. It is a 1985, 3.2 sitting in my 1971 coupe chassis.
The exhaust pipe is totally clean, so no deposits and the engine is getting very hot in just a few minutes.
At the right side in the engine bay there is two hoses that are not in use. I believe one of the is a vacuum line - but no clue where it will fit. And the other one is a thicker one that I believe should go the the charcoal canister or the oil tank. I have blocked both of them - hope that is ok.
Any good ideas on how to solve the problem would be much appreciated.
Thanks in advance.

[Hvilshoej]

Update.
It is running so lean that I do not dare to drive it.
The Lambda sensor is not fitted, but that should not cause the problem. More like the other way around, right?

[911obgyn]

Motronic engine uses O2 sensor for maps once engine is warmed up.
Vacuum leaks with idle tweaked so it runs will cause lean running. Baseline CO and idle should be set, not sure how much of the 3.2 wiring is installed. Bentley manual shows jumper to center ICV so you can set idle and mixture with stock system.

[Arne2]

Is the 3.2 a newly installed motor? Have you verified fuel pressures?

[Hvilshoej]

Thanks Arne2 and 911obgyn for your reply.
It a newly installed 3.2 engine in my 1971 chassis with complete 3.2 engine wiring.
The lambda (O2) sensor is not installed - the cable is sitting in the left side in the engine bay with no connection.
The fuel pump is form the previous engine - so not from a 3.2. What would be correct fuel pressure.
The spark plugs are wet and light black. If running lean I believe they should be all white - correct?

[cabmandone]

Originally Posted by Hvilshoej

Thanks Arne2 and 911obgyn for your reply.
It a newly installed 3.2 engine in my 1971 chassis with complete 3.2 engine wiring.
The lambda (O2) sensor is not installed - the cable is sitting in the left side in the engine bay with no connection.
The fuel pump is form the previous engine - so not from a 3.2. What would be correct fuel pressure.
The spark plugs are wet and light black. If running lean I believe they should be all white - correct?

Correct.

If you have an IR thermometer, check the exhaust temps at each port to make sure they're all reading about the same.

[r lane]

If I understand, you are using a fuel pump designed for carbs, which I would guess performed at less than 5 PSI. Motronic wants 3.5 bar give or take on the engines demand. That has to be one issue. Also I have seen frequency valve issues interferring with fuel trim. Bob

[r lane]

Disregard the frequency valve part, getting my systems confused