No Power, Running Super Rich

[bigfeller]

I bought a 1978 633 CSi in the summer. It’s a one owner car that was parked in 1993 and hadn’t run since.

Towed it home, drained the tank, changed all of the fluids, filters, belts, hoses, etc. It runs, but very badly. No power at all. Feels like it has about 30 hp. Running super rich.

We have replaced most of the fuel system hose, the fuel filter, the fuel pump, cleaned and checked the fuel rail, pulled, cleaned and tested the injectors. I installed new spark plugs, plug leads, distributor cap, rotor, and ignition coil.

Still runs terribly. Doesn’t want to start, finally does, runs for a bit, fouls the plugs with excess gas, stalls, and then dies.

Compression is good in all cylinders (150-155 psi). We have checked the cam timing, the ignition timing. I replace the coolant temperature sender, bought and tried another ECU, bought a rebuilt Bluestreak AFM. Still nothing.

I have taken it to two different mechanics shops, and we still have not been able to source the problem.

At this point, my only remaining guess is the crank position sensor, or the spark control unit. Am I missing something obvious?

[Ralph in Socal]

Coolant Temperature Sensor. It's blue or white/tan inserted into the thermostat housing. Sensor may be bad or signal is not getting to the ecu. Check signal to at the ecu connector to make sure sensor output is getting there

There are 2 different coolant sensors on the thermostat housing. One is for the ecu the other is for the gauge reading on the dash

Ralph

[bigfeller]

I replaced the temp sender (the long one that plugs into the blue and white wires to the ECU) with a brand new OEM BMW part. There's another one with a red plastic cap on it but it's not actually connected to anything.

This is it:
https://www.flickr.com/photos/29157481@N07/53203828740/

[Ralph in Socal]

Not sure which one that is with a red cap. There are 3 sensors I'm familar with- thermotime sensor/switch, Coolant Temp x2 as described before. Thermotime has a 7 second ON status if the engine is cold and that triggers the cold start valve. Unplug the cold start injector valve (csv) to see if the Thermotime switch has failed. You can also disconnect the CSV fuel line to see if that is feeding too much fuel when it's not supposed to.

Your car doesn't (shouldn't) have a crank position sensor except for the BMW Inspection Connector. I'm not well versed on that spark control unit. A friend had issues with one and I provided a known good replacement. Years ago so memory is spotty on his specific symptoms. I do have several used ones if you want to try swapping it out. Pic below is from E12 Repair Manual

You should have the stand up disrributor the has advance and retard function and maybe also centrifugal advance. Make sure you're getting proper timing advance when running

Ralph

20230917_224829.jpg (1.19 MiB) Viewed 568 times

[emac]

Fuel pressure regulator on fuel rail? I had one go bad causing too much pressure and very poor running except with wide open throttle.