EFI Relay problems from hell

This site may earn a commission from merchant affiliate
links, including eBay, Amazon, Skimlinks, and others.

SalishSea said:
As I understand it the IGT signal is a series of very short pulses from 0v to less than 1v. A meter might not recognize them as a continuous signal and give you a reading.
Click to expand...

It's at my buddy's shop. From what I understand, it's a continuous pulse put of about 5V. However, the measured value is 0V. He also had a spark tester hooked up. Like I said, the problem was/is intermittent. When it starts, there's a readable value, and visible spark via the tester. We've gone through every single other point, Ohmed out all the wires, and traced every thing via the wiring diagrams. He's pretty positive it's the computer. Additionally, they were able to induce the no start condition by tapping the computer/ Make it start by tapping the computer.

Correlation might not equal causation, but it's all I've got to go on at the moment. I have a huntron scanner at work, and can put passive signals through circuit cards. Gonna try that on Monday, and checks ICs on the board, as well as check the board under the microscope for cold solder joints, cracked runs, etc.

Getting tired of driving my Passat, so I hope the computer is the answer. Lol
 
I seriously doubt the ECU is faulty and it wouldn't go intermittent like that.
More likely you have a wiring issue where the ECU harness passes through the firewall. It is a known chafing point on all 80 Series. If you feel that this is mechanical in nature (knocking on the ECU), then you're looking for a connector or continuity problem.

The igniter is also suspect. If shorted internally it will load down the pulses coming from the ECU, and those pulses can't be accurately monitored with a multimeter in any case. You need an oscilloscope to actually see what is happening. You're not looking at DC in this particular circuit.
 
IGF and IGT are the modified pulses that originate from the pick up coils in the distributor. The ECU adjusts them for proper ignition timing. If the pick up coils or the wiring from the distributor to the ECU (which is all part of the same harness through the firewall) are intermittent, the output pulses from the ECU will be too.
 
Last edited:
jonheld said:
IGF and IGT are the modified pulses that originate from the pick up coils in the distributor. The ECU adjusts them for proper ignition timing. If the pick up coils or the wiring from the distributor to the ECU (which is all part of the same harness through the firewall) are intermittent, the output pulses fro the ECU will be too.
Click to expand...

I'll check it out! Thank you
 
Last edited:
jonheld said:
I seriously doubt the ECU is faulty and it wouldn't go intermittent like that.
More likely you have a wiring issue where the ECU harness passes through the firewall. It is a known chafing point on all 80 Series. If you feel that this is mechanical in nature (knocking on the ECU), then you're looking for a connector or continuity problem.

The igniter is also suspect. If shorted internally it will load down the pulses coming from the ECU, and those pulses can't be accurately monitored with a multimeter in any case. You need an oscilloscope to actually see what is happening. You're not looking at DC in this particular circuit.
Click to expand...


John, what is the part number for the correct igniter? Are the igniters from 3FEs in FJ62s compatible?
 
Randoliof said:
John, what is the part number for the correct igniter? Are the igniters from 3FEs in FJ62s compatible?
Click to expand...
I don't know the part numbers off the top of my head. I know the ignition coils are different, not certain about the igniters. The ECUs are different as well. The distributors are the same as is the AFM and most other sensors.
That said, if the connectors mate it should be able to be used for troubleshooting purposes. I know the plug gaps are different, so the output of the 2 coils is different, but it should still run.
 
jonheld said:
I don't know the part numbers off the top of my head. I know the ignition coils are different, not certain about the igniters. The ECUs are different as well. The distributors are the same as is the AFM and most other sensors.
That said, if the connectors mate it should be able to be used for troubleshooting purposes. I know the plug gaps are different, so the output of the 2 coils is different, but it should still run.
Click to expand...

So if the igniter module is bad/intermittent, there won't be any reading on the IGT (black/green?) wire out of the computer?

There doesn't appear to be an chafed wires going through the fire wall, and the truck isn't starting; we have 0 volts on the IGT wire. Short of taking an O-scope from work, is there a way to definitively say it's the igniter or the computer? The distributor is clean, actually looks new under the cap (I've only had this cruiser two months or so). The connector from the distributor to the harness (red, white, yellow) Ohms correctly, ~190 Ohms. I cleaned the computer plugs and connectors with electronic connector cleaner, no help. The only spot that's not right is the IGT wire with no voltage.

My buddy (the mechanic) hooked up a spark tester, and one of the times the truck started, he said everything was correct, and that there was voltage on that wire.

I'd like to spend $30 on the igniter vs 200 or so on an ECU, but I don't want to jump the gun like I did with the EFI relay.
 
FWIW, I had similar issues with my 80 back in 2009. I posted on mud. I'm 99% sure it was Jon that figured it out at it was my igniter. I ordered a used one and have been running it since without issue.

I would contact Jason at CruiserYard.com (@arcteryx on here) for a used one and if it is determined you need to replace your ECU then that as well. Jason is a good dude. I have dealt with him and he is a solid dude. Even if he lives in Texas... :flipoff2:

But listen to Jon. He knows his sh!t man.
 
LS1FJ40 said:
FWIW, I had similar issues with my 80 back in 2009. I posted on mud. I'm 99% sure it was Jon that figured it out at it was my igniter. I ordered a used one and have been running it since without issue.

I would contact Jason at CruiserYard.com (@arcteryx on here) for a used one and if it is determined you need to replace your ECU then that as well. Jason is a good dude. I have dealt with him and he is a solid dude. Even if he lives in Texas... :flipoff2:

But listen to Jon. He knows his sh!t man.
Click to expand...

Thanks for the info! Glad to hear that this is an issue that's been dealt with before!

I'll contact him Monday, even though he's in Texas. Lol. I'm pretty sure this is the issue. I might have explained it poorly, but I think this is it. God I hope so.
 
LS1FJ40 said:
I would contact Jason at CruiserYard.com (@arcteryx on here) for a used one and if it is determined you need to replace your ECU then that as well. Jason is a good dude. I have dealt with him and he is a solid dude. Even if he lives in Texas... :flipoff2:
Click to expand...
Jason @arcteryx is the man. He's helped me out numerous times and can be relied on to get you known good parts at a decent price.

FWIW, I think I'm on my 3rd igniter. The original lasted quite a while, it was replaced with a used coil/igniter combo which lasted several more years, and was replaced again about 3 or 4 years ago.
 
Last edited:
The real problem with the EFI relay are the connectors on the pins under the relay box. One of the wires on the relay pins has slipped down and is causing the relay to "chatter" or not work! I have a 91 and what I did that solved the problem is to push the wire(s) up to where they should be then secure the wire bundle so no wires could slip down again. I used a cable tie, around the bundle pulled really tight. That was 10-11 years ago and I have not had any problems since. It's tricky, take your time and don't break any wires.
 
I'm not going to curse anything by saying "my igniter has been no problem since Jon helped me figure it out 6 years ago..."
 
You must log in or register to reply here.

Share this page

Back
Top Bottom