D-Jet Conversion not going as planned., Car starts but will not run. |
|
Porsche, and the Porsche crest are registered trademarks of Dr. Ing. h.c. F. Porsche AG.
This site is not affiliated with Porsche in any way. Its only purpose is to provide an online forum for car enthusiasts. All other trademarks are property of their respective owners. |
|
D-Jet Conversion not going as planned., Car starts but will not run. |
slapshot |
Oct 18 2024, 03:08 PM
Post
#1
|
Member Group: Members Posts: 109 Joined: 11-June 23 From: Utah Member No.: 27,409 Region Association: Rocky Mountains |
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? |
slapshot |
Oct 21 2024, 11:08 PM
Post
#2
|
Member Group: Members Posts: 109 Joined: 11-June 23 From: Utah Member No.: 27,409 Region Association: Rocky Mountains |
I inserted a noid light on each injector wires, except the cold start injector, and they all lit up during crank. Does this indicate that the 123 distributor trigger wires are communicating to the ECU and the ECU is working properly?
Just noticed that you stated early in the thread that it looks like someone used the Tangerine kit to rebuild your MPS. If that's the case, the diaphragm is likely fine since the kits haven't been around for that long. More likely that the rebuilder wasn't able to get the MPS case to seal properly as it can be tricky to do. I did open the body of the MPS and yes the diaphragm on the top is brass and looks like the one on the tangerine racing website. Maybe they all are brass, I don't know. Its definitely been rebuilt. When I put my ear up to it with vacuum, it sounded like it was leaking through the top vents. I taped them off and check and it is. With the tape, the vacuum just barely leaks at all. no calibration necessary, make sure that you have good dwell and timing and fuel pressure as you crank the car, and that the trigger points are plugged in to start, we can work through this but many variables to deal with since it is a fresh installation. (you can also spray some brake clean into the throttle body to make sure that it keeps running to totally eliminate the ignition system I have a 123 distributor so no dwell to mess with. Trigger points are plugged in. Starter fluid in the TB seems to just flood it. I agree, lots of variables. I'm 99% sure my timing is spot on since it was before I started this conversion but I'm getting to the point that I can't assume anything is correct. I have a fuel pressure gauge in line between the two fuel rails and the pressure is at 28. You won't damage the engine. Adjusting the inner screw clockwise will lean out the mixture, counter-clockwise will richen the mixture. It's farily sensitive, which is why I only suggested 1/4-1/2 a turn, but you won't break anything if you go further. Note that you need the Tangerine Racing adjusting tool so that you don't also turn the outer screw that the inner screw sits in (not the outer screw you're talking about which is more commonly referred to as the full-load stop screw). I'm not sure I follow on what is the full-load stop screw. Is that just the outer allen wrench nut? Here's a pic of the top of mine. Attached thumbnail(s) |
Lo-Fi Version | Time is now: 28th November 2024 - 04:50 AM |
All rights reserved 914World.com © since 2002 |
914World.com is the fastest growing online 914 community! We have it all, classifieds, events, forums, vendors, parts, autocross, racing, technical articles, events calendar, newsletter, restoration, gallery, archives, history and more for your Porsche 914 ... |