Hi all you D-jet Gurus out there..

Heres the problem I have ,hope you can help.

73 1.7 stock car.
Hasnt run in many years I assume , I Bought it with everything removed and off the top of the motor. all the parts looked cleaned and (maybe?) checked or reconditioned. they may have just been wiped clean and put in bags? who knows?
Ive just got the whole thing back together and ready to start.lt Cranks over, fuel pressure, good spark..would almost catch , but not quite fire.
Through checking spark plugs and swapping injector plugs around, worked out I was only getting fuel out of one injector.
Confirmed this by pulling injectors, then operating throttle with ignition on, which allows the enrichment circuit to fire the injector, and you hear a series of clicks from injector.
Only one out of the four injector plugs seem to make the injector click.when i swapped the plug onto another injector that clicked fine and sprayed fuel,indicating injectors are fine.
SO next i checked and cleaned injector wire ground points and checked continuity to ground to the wires, and they all behaved the same, seemingly fine.
so where im at is working out if its possible that the computer is fritzed and only firing the one injector, or if its a fault in the loom.

I guess my question is.. does the signal to fire the injectors come out of the brain as four seperate wires, or two then split to the two banks, or a single terminal and split in the loom somewhere? a diagram of the connector pins would be a great start.. I guess stripping the loom out is next and checking for any breaks/poor connections.

You're saying you only get one injector plug to fire even though you can swap injectors onto that plug and get them to fire? Injectors are "fired" in pairs by the trigger points, located inside the distributor. The ECU controls the duration of the "pulse" that keeps the injectors open. So if you're getting one injector firing, you should get at least two (they fire 1&3 and 2&4 together), assuming grounds and wiring harness are ok. You did check the multi-point ground on the back of the engine case, right?

Verify that you really are only getting one to fire:

You can try a noid light to see if the injectors are actually getting signal.

You can also check continuity on the ECU wiring connector between poles 12 and 21 and 12 and 22. You should get alternating continuity as the engine is cranking.

You can also pull all the injectors out and stick them in little glass jars while you crank engine to see which one(s) are actually firing based on fuel accumulating in jar.

If you're still convinced only one (or two) injector is firing, pull the dizzy and clean the trigger points and make sure the connector is plugged into it correctly.

If you're trying to get a car running that hasn't in a while, I'm a big fan of sending the injectors out for cleaning (Mr. Injector is a good option). It's a cheap way to eliminate a major troubleshooting issue, even if it sounds like this may not be your specific issue.

Thanks beatnavy,

yes Im positive only one injector plug is delivering a signal to fire the injector. pretty confusing!
checked and tightened the ground points to the case, and every other connection on the loom. replaced a few slightly corroded terminals, but overall the loom seems good, still pliable and soft .
I dont have a noid light, but will get one.

I guess I'll pull the distributor and check the trigger points first. then take the loom out and check all the continuities and resistance.

If the car has been sitting for a while it is probable that the injector pintels may be frozen.

Have the injectors all cleaned and tested and in tandem check the connections and signals at the ecu and through the harness for good measure.


My .02.

1 of 4 wouldn't be trigger points, or at the least trigger points are not your only problem. You should individually test every d-jet component otherwise you will be chasing your tail trying to get it going. Sounds like you need to start with the wiring harness but also be sure to test your MPS and head temp sensor as both of those are good at casing all sorts of issues.

Test every pin from the ECU connector out. Even if it tests good you may still have faulty connectors so you may want to find a 2nd harness to test with.

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Thanks this is all great stuff!

to clarify, the injectors all operate correctly, i swapped them over one by one onto the operating connector and they all spray what looks to be a good pattern, no leaking .

yup im going to go through every component and test.
I guess thats the price of buying a car with stripped incomplete engine, and no idea when it last ran ! I guess i can count my luck in that it has good compression and oil pressure ( at crank speeds anyway!)

If all your injectors work when tested on your one good plug, then even if the injector driver circuit for one injector group was bad, you'd still have one operating injector group (two injector plugs). From how you describe it, I suggest that you have a wiring fault in the harness, which could be due to an open wire, faulty injector plug, faulty ECU plug, or faulty multi-point ground. It should be a straightforward process to check all of these with a multimeter. If everything checks out good, then you have an ECU fault in one of the injector groups.

Take a look at my page (in my sig file) for descriptions on the ECU and system connections for D-Jet if you need more help.

LowSquire, Brad (pbanders) is "the man" when it comes to D-Jet. Bookmark that page in his signature (or go here http://members.rennlist.com/pbanders/djetparts.htm) and read and re-read to learn about D-Jet. Can't tell you many times I've referred to his site for guidance to get and keep my car running...

But for your specific issue, I agree, sounds like wiring issues. The harnesses get beat up over years of heat and other abuse. If you get to that point, Jeff Bowlsby on this site fabricates new wiring harnesses.

How about some high resolution pics of your engine bay? Also, there are some good folks in the Austin area. Reach out and someone will come help you.

Thanks for all this, yup I'll read that site again, and keep testing and rectifying any problems. I have a week away on another OT car related adventure, but I'll be back into the 914 in a fortnight. Will post some pics then. It's funny, but being an ex Porsche tech nearly twenty years back isn't helping much! Amazing how little I remember..

Someone has to say it

d-jet is pretty straight forward but - issue arise mostly with respect to basic component failure , - since replacing my wiring harness with one from Jeff. B. , my main issues have been related to MPS failure and retuning rebuilt units.

once you test it all out and check the circuits for continuity - check MPS for leak, - when I bought my car I tested spark- good, tested compression good, if I sprayed starter into the TB it ran - MPS was bad - check your fuel lines and pump, filter- midht want to clean your tank if car has sat for a long time- once I did that the car fired right up!!

Good luck!
Phil

I'm in Austin, also have a D-Jet 1.7, and would be glad to help. I do have a Bosch Jetronic Service Manual with lots of info (most of this is also on Brad's site). Let us know when you get back to working on the 914.

Mark

+1 for the recommendation to get a new harness from Jeff. Probably the best money I ever spent on my car.

re: getting dead/neglected cars back to life - with regard to the D-Jet, I recommend using my site or other resources to test every single component individually (including the wiring harness and the relay board) for basic functionality. The MPS and the ECU are the hardest to test without specialized equipment, but there are basic functionality checks you can do on the MPS (e.g. coil resistances and vacuum integrity), and the ECU's are incredibly tough and rarely the cause of problems - though it's never a bad idea to have a spare. Once that's done, I strongly recommend a new set of vacuum hoses, and a careful check to make sure they're all connected correctly. Lots of resources out there on this, and some stuff on my site, too. I also recommend that you do not disconnect or discard system components like the thermostat/cooling flaps, PCV valve, TS1 sensor, etc., as recommended in various places, as it's likely you'll have problems.

Once you've done all those tests, and you're sure the compression is good, valves are properly adjusted, there are ZERO vacuum leaks in the intake manifold, your throttle body doesn't have tons of slop, your dizzy shaft doesn't have tons of slop, timing/dwell are correct, strong spark is present at all four plugs, fuel pressure is correct, yada yada yada, the engine should work. Best of luck and happy wrenching.

Pull the wiring harness off of the car to test it out. It connects to the ECU with the big connector, to the relay board at the four-pin connector, and to all of the components (temp sensors, injectors, trigger points, MPS, etc.) along the way. Use the pin numbers on the wiring diagrams, or use Jeff B's diagram above, to see which ECU pins should connect to which component.

Use your continuity tester (or ohmmeter) to check that the wires actually connect. Wiggle the wires when you check to look for intermittent connections.

--DD

Okay I'm back and had a chance to spend all day Sunday on the car, and it's fixed and running! I pulled the loom and ecu and checked every wire and all the values, nothing wrong there( phew ) ,last week I sent the injectors away to mr. injector, they came back perfect, and wasn't any problems with them really, just a couple maybe ten percent low on flow , but came up perfect after cleaning. Totally can recommend his service.
then I checked the injector trigger points and found dirty, rusty points , so cleaned them up and got it all back together, and it started right up! Had bad tappet noise so let It cool off, did tappets and set timing as best I could. Fixed a few little electrical probs and have driven it about eighty miles so far. It's sweet running and I'm actually amazed at how well it all works and drives considering the driveline was a total unknown. Got lucky I guess!
I'll post a couple of engine shots here,nothing amazing, just a stock Djet 1.7
but start a new post 'introducing' the car on the board.
Cheers everyone who replied and helped out!

Ben.
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Looks good, very good work at getting it going. Just gotta be methodical and make sure everything is actually working (charging, ignition, mechanical, fuel supply, fuel injection, etc.).