75 csi still running horribly NEED HELP

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Still struggling to get this car to run well. I haven't had a ton of time lately. But here's where I'm at. Brief re-cap: 1975 csi car, motor block and head from 77 530i. All egr eliminated. Both manifolds, exhaust and intake original to car. Car has been dormant 30 years. I am by no means an expert. I don't have any experts near me. I plan to refresh original motor and drive the car for now.

The car runs horribly, I have since re-cored radiator, believe to have good coolant flow. I have tried original injectors, then new injectors. Not much difference in running performance. Timing, ignition,plugs, points, wires believed to be good. Engine compression excellent. It is running so poorly I feel only three cylinders are firing, hard to tell. Easier to isolate one if it were 5 firing. I eliminated the cold start injector and plugged the vacuum hose going from cold injector to the AAV. I did this to attempt to zero in, as the cold start system is of zero value to a running engine (I think). I have about 30psi fuel pressure at the cold start fuel line. That leads me to believe fuel pressure throughout is 30psi as the cold start is near the end of the fuel rail loop. I think the car calls for about 30psi.

Suspects in my opinion:NEED HELP

1) poor voltage coming off injector wire plugs. I am getting less than one volt pulsing at injector plugs. HOW MUCH VOLTAGE IS REQUIRED.? I DO GET ABOUT 12v at cold start injector. BUT LESS THAN ONE VOLT AT CYLINDER INJECTORS. Is that normal? Do I have bad ground? Bad ECU? Or is (.4-.5v) normal.

2) possible but not likely injector harness plugs got mixed up between two of them? Would that even matter as the ECU sends fuel evenly.

3) what do I need to know about the manifold pressure sensor? Could that be malfunctioning?

4) throttle position sensor? I highly doubt that could cause poor running. I suspect that would make for a fluctuating idle if faulty.

5) manifold vacuum regulator pump thing. Not sure of actual name, but it seems to doing its job. If I unplug it car shuts off, and it seems to be pulling vacuum off manifold.

6) injector plug one specific way? The plug will attach to the injectors either way, they prefer one way more than the other, so I plugged them all in the same manner that seem more cooperative. Could they all be in reverse? Is there a specific signal to each injector prong?

7) week coil?

ANY THOUGHTS WOULD BE GREAT. FRUSTRATED IN MASSACHUSETTS.
 
assuming

L jet, 35 psi. Go put in a new fuse as they get corroded. Worth a shot. get the pressure up first. At 30 all sorts of things get wonky.

Low impedance injectors equals low voltage. 4v.

Polarity shouldn't matter.

If some are firing and some are not a simple resistance check will tell you if the coil is blown.

All the injectors fire all the time if I remember right. Go to First Fives website. They have tech articles to help you better understand the system and trouble shoot. Something that's been sitting that long you probably need to do a full resistance check on most everything systematically beginning with pulling the ecu connector and "pinning" the specific wires to the injectors that aren't firing.

It might help to describe if the symptom is surging idle or bad idle on just three cylinders. Surging might be the low fuel pressure.
 
I wouldn't say it's surging, more of struggling to idle. This is a d-jet not l-jet and I believe I read 28 psi pressure is called for. I haven't done any work on it today. I'm first going to apply a jumper wire ground from the neg cable to the grounded injector harness that is bolted to the valve cover, to insure a good ground. Then go to the ECU and clean all connections. I didn't see a fuse in the fuse panel related to injection . Is there a fuse inside the ECU?
 
I also had difficulties to troubleshooting a L-Jetronics issue on a M90, that was running very rough.
. I spent a lot of time on the injection system. After checking the valves clearance the engine run smooth as butter. Worth checking..
Also, what helped:
. Check firing order Firing order = 1 5 3 6 2 4.
. Check condition of the plugs/ plug wires / distributor / rotor cap.
. Disconnect any auxiliary air valve (A/c or air cold valve) to ensure no air leak (plug at the air intake)
. Check that 7th injector (to inject extra fuel when engine is cold) is off once car is running.
. Check grounds on the injection system.
. The injectors are also noisy when they function. By using a large screwdriver as a stethoscope you can determine if it works or not.
Good luck!
 
A few suggestions-

The MPS connector/plug is not keyed. Luckily the wires and plug are numbered.
Make sure the numbers match.
Even if the MPS holds vacuum that doesn't mean it is working properly.
Send it in and get it checked.

The quick test for the TPS is key on and hand on throttle linkage at throttle body.
Depress the throttle linkage quickly and listen for the injectors clicking.

30 psi is good.
 
You need to open the ECU and look for water damage.

Use a hand held vacuum pump on the MPS.
 
I preface this by stating I know nothing about this specific BMW...the E24 has 2 position sensors that are identical with connections side by side and easy to confuse. Reversing them will cause the car to run like crap. Also if it has a MAF sensor, poor contact can cause major issues.


Pull a plug and get a sense if you are running lean or rich.
 
INCHING CLOSER, I appreciate all the feedback. I found the fuel pump relay was flickering due to a corroded fuse. The same fuse also powers up RR lamps. So that was potentially shutting down the pump intermittently. Runs better, maybe even on all six cylinders. But far from running good. Seems to be running rich.
As Sfdon suggested look at the pressure sensor. It does hold vacuum. But if I block the hose connected to the sensor , it runs a bit better. Then if I use a hand pump to simulate less vacuum to the sensor, it runs even better. Now I need to fully understand and test all the components and how they work.
The ECU inside is extra clean and dry. Could the manifold be producing too much vacuum?
 
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