soontobered84

Thanks Wally, Lonnie, Rjtw et.al.Time to go figure this bugger out and see what I find

Randy V

Great diagnostic method and write-up Rick.

Welcome to the 928 Forum, hope to see more of you now that you've 'de-lurked'.

Lonnie G.

IT'S ALIVE!!!!
I finally found the problem. It was a ground wire. On pin 5 of the ECU is shown in the wiring as a ground. If you unplug the ECU and measure it was open to ground. Traced wire out and found that it goes directly to the temp sensor II. Took a jumper and tied it to ground. Turned engine over and I had pulses to the injectors.
Boy is that a trill after this long! Hurried and put plugs back in and assembled everything else that was loose. Tried to start it and it turned over about twice and then just sit there and ran.
I still haven't give up the idea of swapping out the Bosch for an after-market controller. But I sure feel alot better knowing that the engine is sound. Took a listen to the injectors while it was running and a couple of them don't snap quite as sharp as the rest. Probably wouldn't hurt to pull them and send them out to be cleaned and tested.
Just wanted to thank everyone that replied and let you know the outcome. Anyway Thanks Alot!
Lonnie

jwarner6

OH YEAH!! almost

Okay, I haven't really touched the car since Thanksgiving. Sorry. But now after buying and reading the Bosch Fuel Injection book (if you don't own it you should) and doing other research I finally have a plan and time to take another Whack. I literally just finished my very comprehensive to-do list and decided it was time to check back in on the Rennlist to see if I might pick up a few tid-bits.

Lo and behold I find this posting on my first search. Why I didn't find it before of course has everything to do with my search terms. Anyway, this posting and the subsequent wonderfully detailed replys nailed my problem to the post.

So without bothering to even start with my list I yanked out the Fuel Injection relay and it's brand spanking new and not the right part number. So 928 gurus, can you point me in the right direction by answering my question as to whether or not this relay might be compatible anyway or if I must have the exact right relay. This relay is Bosch 332.209.159. The '82 928 calls for part number 928.615.119.

Or maybe clarify for me how I might be able to tell it the relay is doing its job. I 'm not quite certain I understand exactly what the Fuel Injection relay is supposed to be doing.

I'll be sitting here waiting in desperate anticipation of your replys!



Jeff

Landseer

My friend, why not jumper the suspect relay?

Do you know how?

jwarner6

Absolutely not certain. Do I do it the same way you jumper the fuel pump relay? Off the top of my head I'm not sure I remember which two terminals that was either. It's been a while but my jumper is still laying on the floor by the fuse panel. I did compare the wiring diagram of the proper relay with the one I have and it looks like I'm supposed to have a diode in the relay and the one I have may have some extra part to the circuit that I don't recognise. I'm a bit concerned now about what damaged might have been caused by that diode not being there.

So remind me. I don't have any relay diagrams handy in front of me at the moment to make a guess. Which two terminals do I jump?

Do you know exactly what the relay is doing? Having just looked at the wiring diagram out in the shop it looks like it supplies voltage to the injectors and possibly the ECU and some other related components. I didn't try to trace them all down but I recognised many of the wire colors etc. from this post.

Thanks for the quick reply.

Jeff

jwarner6

30 and 87 yes?

Landseer

On the 84S cars, there is an 87 and an 87a.
The jumper is from 30 with a three way jumper to both 87 and 87a.


I think on the 82 its 30 to a single 87 connection.

Landseer

Fuel injection relay in position XVI (16)?

Fuel pump relay in position XVII (17)?

What are the symptoms?

Do you know you have fuel pressure from the pump?

Do you know if you have signals to individual injectors?

Grounds clean?

jwarner6

Symptoms are as described before by the other posters. Car starts when the Cold start injector is firing but doesn't appear to be firing the injectors at all. Unlike the previous posts, I believe mine is firing the injectors but possibly almost not at all. In other words, firing them very weakly. If I feed the car ether until it warms up a bit then it will idle on its own and sounds fine but it can't do anything more than idle. I'm just now getting around to the fuel injection circuits etc. and so no the grounds haven't been done yet and I'm hoping that's the big difference. Everything else has been covered nearly to death. Fuel presure, spark, etc are all good. Now I need to focus on the ECU and it's signals.

I will go ahead and jumper the relay to eliminate it as a possiblilty and then move on from there. My next step is to clean all the grounds I haven't done yet and then look for voltage and pulses at the injectors. I'm also thinking that maybe it might not be getting the tach signal so I'll be checking that as well.

Thanks for the reply.

Jeff

Landseer

I think this car will have the "green wire" that leads from the base of the distributor to the spark box on the passenger fender. It is coax with proprietary ends that get fragile. That basically provides the "when should I fire the sparkplugs" signal, as these cars don't have a crank position sensor that the later cars utilized. Search on "green wire" for info.

I think you should be very certain to clean four grounds in particular. Two located into the firewall, just above the fuse box. One linking the engine block with the passenger side frame rail under the car. And, the hard-to-access ground for the injector harness located on the passenger side cam (valve) cover.

I would also very carefully disassemble and clean the 14 pin connector on the passenger side fender.
It comes apart so you can see the male and female connectors. It further disassembles to allow access to the backside of these connectors so you can inspect the solder joints. Again, search this to dial-in on discussion about what each wire feeds, such as the coils, etc.

Darklands

On a Euro S mj 84 the injection relais is VIII (8).It´s a standard VW piece btw. Hella and cost 8 €.

jwarner6

Yes, the '82 does have the green coax wire. But if the car will idle and attempt to accelerate then doesn't that mean the ignition box is sending the primary spark signal through the wire? I'm hoping that's the case anyway. I was thinking that the signal wire from the spark box to the ECU might be a problem. I'll also have a look for that connector you spoke of. I'm assuming it is connecting the ECU to the engine components.

Thanks for the insightful reply.

Jeff

Landseer

I'm not skilled enough to pinpoint diagnose this like sharkskin and others, but here's some more ideas.

The AFM unit has a cover that can be removed and the rheostat can be cleaned with a pencil eraser. It tells the computer how much air is flowing.

A major vac leak bypassing the AFM can cause in ability to properly read the air (instead, unmetered air).

Since you have idle (I missed that originally) then you might have a fuel supply issue. What's the condition of the tank and supply circuit? Several guys reported clogging of the supply side screens inside the injectors (I think the way to clean is with ultrasonic bath or send to vendor like Witchunter).

You need pressure on the fuel lines, that is regulated near the back of the motor I think, just before return to the tank.

Fuel pump might not be performing adequately. Possible fuel filter clog ( it is between the pump and the injectors ).

It is possible with great care to reverse leads on fuel pump and run it backwards to clear/flush it. I've squirted some WD 40 in, then quickly backflushed by reversing.

Lots of little stuff to track.

Assuming timing is set / need a timing light to do this, may actually be the best place to start.

jwarner6

Okay, back into it now and WOW! what a discovery. The jumper on the fuel injection circuit made no difference but I've got time to get a new one now because of what I just found. That 14 pin connector at the front right inner fender above the ignition module. The harness leading from it across the front of the motor to the started, alt., and other goodies is a complete disaster. It's the first bad looking cable I've come across and boy is it bad. All of the wires on the even numbered pins are without insulation and badly corroded and frayed. Also the wire on pin 1 is bad. I'm amazed that the engne ran at all but having traced them all down in the wiring schematic they for the most part seem to be battery positive leads. Still, considering how bad they are there can't be anything good coming from them. I had an extra harness in a box but it turned out to be amost as bad in some areas and worse in others. So I guess I'll be spending the next few hours removing the harness so I can start rebuilding it. Anyone know of a good source for a replacement harness that doesn't cost a small fortune?

By the way, if you want to catch up on "the rest of the story", you can find it here:

https://rennlist.com/forums/showthre...ferrerid=64040