Thank you for that bit of insightful technical wisdom. I had done the rotating the throttle test way back when but before I rebuilt the harness. SO here's hoping. I'll clean the resistor pack while I'm at it. I'll also double check the coax cable.

Thanks,

 

If you send me your email address I'll forward a copy of the MY 1990 XJS EDiagram... Super helpful in situations like this. I would try to take some screenshots of relevant to pages but the details get fuzzy in the process. And as we know, its ALL about the details.

As a great mind here says, they are simple cars for complicated people - that last bit is me, lol.... The no fuel problem (small fires my complicate things) should not be impossible to tracks nd fix.

 

Here is my email address- d.michael.litscher@gmail.com

Just to clarify and double check, when I said " I then checked both sides of the fuel injector connector and I have 12 V to ground on each side. Is that right?!" On a single fuel injector connector, each pin in the connector has 12 V measured to ground. Is that right?

 

Yes, both sides have 12v "+" until the ECU grounds one side to trigger the injector.

Cheers
DD

 

Thank you Doug... That info helps me too. Just because.

DMike,,, I sent the PDF... I think the page/diagram you'll wanna look at is 25.1 and 2...

 

Thanks guys, you got me back in the game .

I tried rotating the throttle... no click. I checked the throttle switch and no voltage. Should there be? I'll check the circuit diagram today.

 

Hi Guys, It's been a while since I was disappointed that the new EFI ECU didn't solve all my issues but I'm back at it, here is the status

Fuel

1. I replaced the only hose that wasn't replaced because it "looked good" . Apparently it was the leak that bled off the pressure. I how have the pressure holding at 38-39 psi.
2. When I used an external power/switch to test the injectors they spray fuel.
3. When the ignition is turned on I can rotate the throttle I now hear a "click and the A1 injector fires gas.
4. When I use the Noid light I get the flash on all injector leads. (see video)

Spark - Digital Ignition Circuit

1. I have spark.
2. I checked the gap on the TDC sensor and found that it was close but bigger than .042 so I removed the shims and it measures .025. Is this too small? If so what should I use as a minimum?
3. I rechecked the continuity of the blue and white wires back to pins 1 and 2 on the Ignition ECU ("A" pillar - DAC 5871) and it's good.
4. I check continuity of the white wire running from pin 24 Ignition ECU ("A" pillar) to pin 18 on the EFI ECU (Trunk) and it's good
5. Both the Air Temp Sensor and Coolant Temp Sensor have been replaced.
6. Power resistor was opened and it looks OK so it hasn't been replaced.

Current state of affairs Now when I turn on the ignition and I rotate the throttle I hear the click and the injectors spray in gas. Then when I turn it to start it tries to start with the gas in the cylinders for a bit but then it just cranks so it appears the injectors are not spraying to maintain fuel flow as I crank the engine.

I reviewed some other post so I'm going to do a couple things.

1. Remove TPS and in the plug connect the two terminals then try the start sequence.
2. Short pin 18 connector to ground then measure the continuity to ground on the white wire coming from the ignition amplifier on the LH intake manifold.

Everybody, please provide thoughts as to why the injectors won't fire when engine is cranked.

Best regards,
Mike

 

Hi Mike

Just because the Noid Light indicates that the Injectors are Firing, that does not mean that they are all spraying gas and so it sounds as if you could have some blocked injectors

Did you physically Check that all the Injectors were Spraying with your Manual device or only just the one that you could most easily get to?

If not then Blocked Injectors would be at the Top of my list

The CPS gap sounds ok to me so I would rule that one out at the moment

Also a small possibility that it could be a Failing FPR on 'B' Bank although I 'think' you said you changed that?

Looking on the positive side I think you are now well within an Ace of getting her running!

 

Can on yours Robbo. We aren't all scrubbing our engine bays with a toothbrush

 

Here's what I think I know today.

1. I thought I would test new things of interest before I pulled everything apart to test all the injectors since I cleaned and tested all of them and they worked fine before installation. I had tested the #1 "A" side originally for spray so I decide to test #1 "B" Side and it sprayed fine also. I know small sample.
2. While I was at it I put my pressure gauge in line so I would have gas pressure readings until I get it running, 38 psi.
3. TPS - I actually did this first since it was a complete unknown to me. I watched a video that explained how to find the voltage source and the ground without a schematic and then compared it to the schematic and it matched. I had 5 volts source which seemed good. When I tested the ground I got a number of 161 ohms back to the trunk ECU, and that doesn't seem right.

Question. Does that resistance make sense? I though I'd splice a wire in and run it to the ECU and see what happens. Any options and suggestions?

Thanks,
Mike

 

MY resistance measurement was a mistake it really is in the 5-8 ohm range.

I don't know what to check next, someone pls advise.

Mike

 

How robust does the vacuum back to the trunk ECU have to be. What would be a good value?

 

You should try it from the engine end, not the ECU end. This is somewhat difficult as the balance pipe end is inaccessible. If you can suck that end and it stays sucked all is well!

 

The TPS functions as a voltage divider.
In the car as the wiper moves over the resitance it will give from around 0.4V at the low end to close to 5V at the other.

Just checking the TPS detached from the car wiring, not sure of exact figure but the resitance from end to end would be maybe 5kohm.
As the wiper moves you will see its resistance from wiper to one end move smoothly from around a few hundred ohms to (say) 5kohm
The wiper at the low end tells the ECU the throttle is closed.
The other function is if the throttle is opened rapidly the resultant rapid change in voltage tells the ECU to add extra fuel for acceleration.
In normal cruise the TPS has no effect on fuelling.

 

..and now I know that my TPS is working correctly. Still isn't running.

When all else fails check everything for the third time … starting with the "white wire" .

When I first went through all the lists of things to check the first thing I replaced was a section of the white shielded wire. I soldered all the joints and wrapped shielding around the splice to cover the wire.

Now this time, when I took of all the shrink tubing and tape, the white wire on the left side of the engine seemed to break easily.(Problem # 1??) Once that was fixed I had good continuity from there to the Trunk ECU.

Then we checked the continuity of the shielding over the wire in the same manner. When I checked it right after the original splice, no continuity. Was it because I didn't mechanically connect the shielding? (Problem #2??) I replaced the coax cable and this time I mechanically crimped the shielding across the splices.
If now runs! please see attached video.

Thank you to all the folks that kept me moving and rethinking all the potential problems

So what say ye. What was the real problem ? the core wire broke easily or the lack of mechanical connections at the splices... or both?

How I can move on with my vision of a Group 44 Roadster