Makes me wanna cry -- D-Jet torment, 1973 1.7 D-Jet malfunctions... Options

[Mike!!]

Thanks again all,
I have a couple of plans for this weekend based on all the useful information. Starting from the easiest to hardest.

Testing Plan:
Swap a series of resistors in place of the CHT, 100 ohm, 470, 1k, 2.2k, 4.7k. See if that changes anything.
Swap the yellow and white FI trigger leads from the dizzy (Terminals 21 and 22)
Unplug the MPS and see if I can get it back to that super-rich state that made it appear like the engine was running normally while not under load, if so and I can get it to 3500RPM, shoot the timing again to verify
Put the engine at TDC, jacking up the back wheels, and check dizzy orientation, I'll try the old chopstick down the plug hole trick (which sounds really painful) on #1 to make sure I'm not 180
Use a noid light on all cylinders
Pull the fuel injectors and do the glass jar test
What else?

One pf the Porsche Club guys here (he's a 356 guy, has 3, his garage is unbelievable...) but he has one of those super old-skool dizzy testers, I might pull the 123 and take it over to his place and stick it on the tester, the thing is the size of a washing machine, and just see what happens. I don't know if it will be at all diagnostic, but it will be cool.

Does any one have a good idea how to test the TPS? The traces were pretty gouged when i got the car, so I replaced the little circuit board, it looks like it's fine and near as I can tell, it tests out okay. I've calibrated for idle, goes to open when throttle is opened, and I get ten closed circuits on both the left and right track as I run through the motion, but I never figured out what is supposed to happen at WOT? There are five positions on the connector, but only 4 pins and I have conflicting documentation (1.7 vs. 1.8?) as to what those pins are supposed to be, near as I can tell from Bowsby's documentation those pins are blank, 17, 30, 20 and 9, with 17 being idle (closed at throttle fully closed), 30 being ground (common) 20 being accel track 2 and 9 being accel track 1. but is there a WOT pin? But I have another collected piece of wisdom from an unknown source that says the pins are blank, 17 (idle), 12 (common) and unused and 9 (WOT). I checked this up against the old duct taped harness and went with Bowlsby's diagram which matched the OEM harness, but the WOT thing has always bugged me. Is there no WOT just an idle switch? What's the best way to verify the TPS is functioning right, it could have been broken from the get go or I might have screwed up the clockwork when I replaced the slider board.

But what else should I do? AA says they can test all of the fi parts if I send them out, so that'd be the TPS, MPS and ECU, so I might do that if I'm still stuck. But if anyone can think of anything else diagnostic short of rebuilding the engine, I'll try it.

Thanks!

[Ishley]

I’d focus on the 123 first. Pull all the plugs… setup to take a picture numbered how they were oriented as a base comparison point. As mentioned by others… you need to have the gear below the distributor oriented properly. Get the number 1 piston to tdc and go back thru the 123 setup. Focus on timing and spark. Your plugs say you’re getting fuel and the motor runs… albeit rough. Pull the plugs after you make changes and run the car and compare how they look. You will see which are misfiring. You have to have the 123 working right or nothing else matters. Document with pictures.

Once you’re sure you have that right (and it still runs rough) I’d check the injectors. I pull two at once and pull the coil wire. I set cups up and set the injectors in them. I set my phone up and turn on the video to capture (pain to do but you don’t need a helper) Crank the engine a bit and see if the video shows a good spray pattern. If it’s dribbling out on any of them…that’s your problem. The passenger side is harder with all the gizmos… but it can be done. Just make sure there is no spark close to raw fuel.

Avoid trying everything at once. You can’t turn all the knobs and Know which one is showing what. All the FI components should be looked at after you confirm proper fuel delivery and spark.

I’ve been thru this set of issues. Ask questions… you can do this.

That’s what I would do.

[emerygt350]

What ishley said. It is easy to set up the 123 badly. Took me a couple tries and had to call tangerine in the end for help.

[JeffBowlsby]

Test the TPS with a continuity tester (ohmmeter). You’ve replaced the circuit board, so it likely is physically ok. It requires calibration when mounted to set the idle position, that’s all. It had no discrete WOT contacts. The two idle contacts signal the ECU to control idle engine functions, then off idle the engine sensors control.