D-Jet Conversion not going as planned., Car starts but will not run. Options

[slapshot]

I am converting back to D-Jet and my car will start but dies right after. It will not rev up applying throttle. I have a 1975 914 2.0. It was running great with Weber 40s prior.

The D-Jet system is from a 1974 2.0. All the parts came in visibly good condition. TPS calibrates good, AAV tested good, Thermo sensor good, air intake temp sensor good, and a new cylinder head temp sensor. The only test that I think is failing is the vacuum test on the MPS. It leaks. Video of testing the MPS.. The MPS has also been rebuilt at some point. The original part # has been removed. There's a good chance it is not calibrated for my car. I have all new vacuum hose and fuel pressure is between 28 and 30.

I don't have any tools to calibrate the MPS. Should I try turning the inner screw on the MPS to see if it helps? Or should I send it to someone to have it rebuild again and recalibrated? If the later do you have any recommendations on who to send it to?

[JamesM]

I am converting back to D-Jet and my car will start but dies right after. It will not rev up applying throttle. I have a 1975 914 2.0. It was running great with Weber 40s prior.

The D-Jet system is from a 1974 2.0. All the parts came in visibly good condition. TPS calibrates good, AAV tested good, Thermo sensor good, air intake temp sensor good, and a new cylinder head temp sensor. The only test that I think is failing is the vacuum test on the MPS. It leaks. Video of testing the MPS.. The MPS has also been rebuilt at some point. The original part # has been removed. There's a good chance it is not calibrated for my car. I have all new vacuum hose and fuel pressure is between 28 and 30.

I don't have any tools to calibrate the MPS. Should I try turning the inner screw on the MPS to see if it helps? Or should I send it to someone to have it rebuild again and recalibrated? If the later do you have any recommendations on who to send it to?

The MPS is one of the most critical components of the system, if not the MOST critical to have correct and working. That being said the leak in you have in the video shouldnt be enough to cause the behavior you are describing. Of course not having a critical leak doesn't guarantee its not still bad, mismatched, or miscalibrated. It would be helpfull to hear what it sounds like when attempting and failing to rev but a couple things come to mind:


First, A rebuilt MPS with the numbers ground off is absolutely suspect. I would suggest you are just chasing your tail until you have confirmed you have a known good, matched MPS. Also while these are not incredibly difficult to "rebuild" the ONLY way to properly calibrate them is with a good matching MPS in hand to clone the adjustment with and I wouldn't assume whoever rebuilt it did it correctly, likely the opposite. Setting the inductance values based off numbers someone else gives you will at best get them in the ballpark, but most likely wont be correct.

Second, what is the advance curve you have set on the 123dizzy?

You said it will start but not hold idle and die. Is this without stepping on the gas at all or do you have to floor it? does flooring it prevent it from dying once started?

Sputtering and starting only when floored and not revving could be a sign of a broken connection to the head temp sensor as well. I would absolutely start with the MPS but if you get past that you may want to check continuity of the CHT end to end, starting with the CHT pin at the ECU connector though to the engine block.