edco

I recently rewired the ends on all my fuel injectors, Temp II and the front knock sensor. Everything is available from Eagleday.com I purchased my fuel injector pre wired pigtails from an eBay Vendor "Same as a Ford Injector plug" for $2.00 a piece. I had a short in one that prevented the car from starting.

I checked all the injector plugs and they were all bad, along with my Temp II and front Knock sensor. Exposed wires like the photo below, Eagleday had everything in stock and with the pigtails for the injectors from eBay and new boots and the 3 prong AMP connector kit for the Knock sensor the repair was $ 85.00 for parts

Porsche928DT

Well I just finished inspecting all the connectors and not a one is in bad shape. Heck all the rubber boots slid back easily and weren't damaged. If your thinking "he's lucky" think again. This pretty much narrows it to the LH Brain may be bad . I'm going to check with the Noid Lite or Power Probe thing Zues+ was reffering to when I get my hands on one. If anything good came from this at least I noticed the hose from the throttle housing to the Y intake manifold/brake booster has a split in it so that will have to be changed.

John Speake

If you measure across several injectors still connected (in parallel) you are only going to get a couple of ohms resistance - almost zero if the meter is on a high range.

Do you get +12 on the injectors when the engine is cranked ? Does the tach flicker when the engine is cranked ?

Porsche928DT

It took me a while to realize that John. I'm such an idiot lol. Ill see what I get with cranking like you mentioned.

Porsche928DT

Hmmm no tach movement when cranking. What does that mean?

sharkmeister85

I'm thinking no signal from your TDC sensor. But I'm no expert.
Glenn

Porsche928DT

That's what I'm thinking but then I wouldn't I have no spark either, which I do have? Theres also the EZK but then that brings up the same point I just made.

Porsche928DT

Oh and to be a bit more specific I get a slight twitch from the tach when turning key to the on position but no movement when actually going past that and cranking.

sharkmeister85

Again, no expert, but there are relays for the LH and EZk I think? Could one be acting up?
Glenn

John Speake

I thik you have spark, as the engine runs when you squirt starter fluid into the intake (don't get it on the platinum wire/sensor assembly !)

The flywheel sensor sends rpm signals to the EZ-F and you get a spark. The EZ-F sends modified rpm pulses to the LH ECU. Until it get those pulses the LH won't energise the fuel pump relay.

The tach also receives the same rpm pulses from EZ-F to LH. That is why I asked you to check this.

Relay 25 is the LH relay IIRC. Are you getting +12v on the injectors when the engine is turning ?

Porsche928DT

I know all the relays work but no I am not getting +12V at the injectors as well as the fuel pump is not engaging. So then why would the EZF unit not send out an RPM signal. I checked the pin 16 on the EZF connector to the pin 1 on the LH connector/tachometer wire and there is no problem there.

One idea I have is that maybe the Flywheel sensor is wired wrong. The 22 yr old connector on the sensor was disintigrated when I removed it just leaving the three pins. When I put the new connector I figured they go in the order that they were lined up in from sitting in the same spot for so long as well as the wire colors matched the wire harness wire colors so I doubt that is it as well as I don't think I would get spark if it were wrong.

WICruiser

Not getting 12v to the injestors and the pump not engaging both sound like relay issues but you say that they are all working so the next thing to check is the areas that these relays power when they are switched - pump - EZF - LH to see if the power is really getting there. For sake of being sure I would replace the relays with jumpers so that you can measure the voltage at the relay terminals and then down stream.

ZEUS+

It would be better to use carb clean through a vacuum hose. When you get it to run with a different fuel supply(carb clean), see if the tach works. You previously said you had fuel pressure and now you dont. Try disconnecting O2 sensor and jumper power to injectors and pump. A shorted O2 could take that circuit out.

John Speake

I helped a guy fault find a Euro S2 that is similar in electrics to your car. The tach did not move, but he had spark, just the same as you.

He also measured the path from 16 EZf to pin 1 LH was OK. I then told him to check the resistance to ground from that wire. He found a short. It should be several thousand ohms. He found in the end that someone had fitted a relay in what should have been a blank position on the fuse/relay board.

Also, remove the kick down relay, this also takes a feed from pin 1 of the LH.

And check that you have the 12v supply to the LH relay, as others have suggested above.

Lorenfb

It's a very simple effort (10 minutes) to diagnose/troubleshoot the LH no-start case:

1. Check for +12 to the LH unit - pins 4, 9, 35.
2. Check for grounds - pins 5, 17
3. Check for +12 at the injectors (either pin).
4. Use an LED test light to test for a EZK signal on pin 1.
5. Ground pin 18 (back of connector) momentarily while cranking will check injector wiring.
The engine should run momentarily.
6. Ground pin 20 and the fuel pump should run.
7. Ground pin 21 and you'll hear a power relay (XXV) close.

Hopefully a charger wasn't used without disconnecting the battery, as this can potentially damage
the LH unit.