Surging and Unsettled Idel after MPS Rebuild, '74 2.0L D-Jet Options

[914four]

Running down a bucking issue and found my MPS to be leaking. After rebuilding the MPS and verifying a good seal, everything went back together okay. When I started the car, the engine surged up and down and would not idle.

The electrical connector socket on the MPS does not appear to be keyed and using the diagram below from Clay's D-Jet troubleshooting guide it seems I may have plugged in the MPS wire incorrectly. I ohmed the wires from the ECU connector to the MPS socket and made sure the wires are in the order shown in the diagram.

The wires look to be looping back from terminal 7 to 15 and 8 to 10 so that the socket could be plugged in either way and work correctly. Could plugging in the MPS wires incorrectly have damaged the ECU? If not, what should I be looking for that would cause the surging and lack of idle?

[914four]

So far I my car has been running smother than ever and has been a lot of fun to drive. The surging issue was completely fixed with the adjustments I made.

I was able to find a CO meter that measures vehicle exhaust gases. It is a Gunson model G4125. After going through the manual and learning how to operate the gas analyzer I found the CO at idle to be about 10. I set the ECU adjustment to center and started adjusting the MPS down. I was able to get the CO level set to 3.0 at idle speed and simulated have load and full load adjustments close.

During my test drive I found there is a small amount of bucking now.

Should I go back to making small adjustments on the MPS to get this out or is there a better place to make this adjustment?

Kelvin

[pbanders]

So far I my car has been running smother than ever and has been a lot of fun to drive. The surging issue was completely fixed with the adjustments I made.

I was able to find a CO meter that measures vehicle exhaust gases. It is a Gunson model G4125. After going through the manual and learning how to operate the gas analyzer I found the CO at idle to be about 10. I set the ECU adjustment to center and started adjusting the MPS down. I was able to get the CO level set to 3.0 at idle speed and simulated have load and full load adjustments close.

During my test drive I found there is a small amount of bucking now.

Should I go back to making small adjustments on the MPS to get this out or is there a better place to make this adjustment?

Kelvin

CO was 10% when you started? Yeow... I like what you did to set the main mixture on the MPS, but you definitely want to do a part load test.

First thing I'd check on the bucking is to make 100% sure that the CHT female connector is inserted properly in the male connector that's inside the plastic insulator coming off the wiring harness. It's very easy to have it look like it's correct, when it's actually jammed to the side between the plastic and the male spade connector inside the insulator. I had that happen to me and thought I had a bad TPS for about a year before I figured it out. Turns out I wasn't the only one.