Fried ECU

[88SubGL]

You probably already know this but at some point, pull your dipstick and see if it smells like gasoline. If it does, you’ll want to change your oil before you run the engine much. I understand that right now you’re just trying to get it to run. 

[davepak]

10 minutes ago, john in KY said:

Is there anything that looks like an old Mopar ballast resistor over by the air filter?  I can't recall if it was the XT or XT6 that used it but am sure one of them for sure.  

Oh dear. I don't know about such ballast thing. I can check tomorrow but as far as I remember I've never seen that near the MAF

[davepak]

7 minutes ago, 88SubGL said:

You probably already know this but at some point, pull your dipstick and see if it smells like gasoline. If it does, you’ll want to change your oil before you run the engine much. I understand that right now you’re just trying to get it to run. 

Oh that's a pro tip yes. I've seen it mentioned before. I checked it and I can't say with certainty that it is fuel laden, but an oil change is in the to do list. To be on the safe side. That and a coolant flush.. 

[davepak]

I've found this more detailed wiring diagram and I see that all injectors share a live B(+) feed from the fusible link also shared with the Fast idle control device FICCD. Thinking that there could be something here. But again, it's only ECU signals for injectors #3 and #4 that are giving me trouble 

[el_freddo]

Well one thing is for sure @davepak - if you like puzzle boxes this is sure to be right up your alley! 

All the best with it. With that wiring diagram cross reference the wire positions at the ECU to make sure someone previous to you hasn’t repinned the ECU plug wires and misplaced a few. 

Cheers 

Bennie

[davepak]

On 12/19/2020 at 6:43 AM, idosubaru said:

Holy smokes.  This is nuts, sounds like a British car.  convert it to carburetor - get an EA82 carb intake and swap it out. it would run and avoid all electrical issues  

Sounds like bleeding injector filled the cylinder with gas and it’s hydrolocked. It’ll probably drain over night or pull a plug and blow/draw the fuel out. 

have you swapped injectors?  I wonder if you should try 4 other injectors or swap the pairs that fire together.  I forget which ones fire together but if 1-3 and 2-4 fire together then swap those pairs and see if your issues “move” from cylinder 3 pair to the other pair. This would verify the injector without needing to buy anything except the incinerated one 

I’m not sure why this happened but maybe the injectors don’t make a perfectly straight run from the ECU to the injectors?

I think the the next step would be tracing that wiring to exactly where it failed. Expose a piece of the wiring by cutting back the wire insulation and exposing the wire but not cutting the wire. Do this at a random point like inside the cabin.  Then test from there to ECU and there to engine to see which side it’s on.   Then do the same thing - test from under the dash to the engine and under dash to previous exposure. 

Seats pulled and you have the testing equipment - this would only take a few minutes.  
 

But the one down side might be that maybe the overheating injector ruined the wiring and the wiring isn’t the causative issue.

does anyone know what all is a part of the injector circuit?

I wonder now whether the pairing of the injectors differs from the location of the cylinders. I mean this:

Location of cylinders:

       Front                 1.      3. 

      Of Engine          2.      4.

Fire batching by injectors?? 

           1 + 3

           2 + 4

If this were to be true, perhaps the contact /resistance in Ohms I'm seeing between ECU wires for injectors #3 and #4 is somehow normal, maybe this means there is a contact between them (#3 and #4) while #1 and #2 are "closed" and the ECU opens these signals in pairs, but not by cylinder location (as I've thought) but by batch firing order instead? Therefore keeping for example : injector #1 and #3 closed while injectors #2 and #4 are "open" / "touching" as part of the firing signals the ECU sends? 

What do you think @idosubaru    @naru2   @john in KY @DaveT  @el_freddo

[idosubaru]

Look up the ECU codes for fuel injectors and then look at the diagnostic section for them in the FSM.  It’ll give the proper wire testing steps and values for that wires. 

Thats where I should have pointed you in the first place! 

[DaveT]

The injectors have to be fired individually.  Spraying fuel into another cylinder while one is at the correct time for ignition would cause massive unburned hydrocarbon emmisions. Unburned fuel would be pumped out the exhaust.

[davepak]

1 hour ago, DaveT said:

The injectors have to be fired individually.  Spraying fuel into another cylinder while one is at the correct time for ignition would cause massive unburned hydrocarbon emmisions. Unburned fuel would be pumped out the exhaust.

Gotcha! Yes, Ill run some more tests this week..have no choice 

[carfreak85]

1 hour ago, DaveT said:

The injectors have to be fired individually.  Spraying fuel into another cylinder while one is at the correct time for ignition would cause massive unburned hydrocarbon emmisions. Unburned fuel would be pumped out the exhaust.

You would be surprised.  Emissions standards in the 80's were less stringent than they are today.  Our ignition systems are batch fire, and IIRC, so are the EA MPFI systems.  Batch fire of the injectors can also aid in cylinder cooling, but yes, will contribute to higher emissions.

Edited December 21, 2020 by carfreak85

[davepak]

7 hours ago, idosubaru said:

Look up the ECU codes for fuel injectors and then look at the diagnostic section for them in the FSM.  It’ll give the proper wire testing steps and values for that wires. 

Thats where I should have pointed you in the first place! 

Yes, Ill try that, especially now that I have seen the location of the ECU pins for the injectors

[el_freddo]

I’m 99% sure many vehicles until late into the naughties were batch fired injectors - that’s why the sequential injection became a catch cry of many car company’s advertising campaigns. 

EA are definitely batch fired. Which ones I don’t know. 

Cheers 

Bennie

[davepak]

2 hours ago, el_freddo said:

I’m 99% sure many vehicles until late into the naughties were batch fired injectors - that’s why the sequential injection became a catch cry of many car company’s advertising campaigns. 

EA are definitely batch fired. Which ones I don’t know. 

Cheers 

Bennie

The next thing I will do (probably after the holidays) is to redo the entire wiring from the engine that feeds into the engine connector number one. That'll be injectors, thermosensor, oil pressure, radiator fan etc. I'm beginning to suspect the culprit might be associated with the live B+12V coming from the fusible link that feeds all injectors but somehow it is shorting with the injector #4 ECU pulse. This could answer a fusible link that kept blowing a while ago and I thought it was the alternator circuit. 

I reason this now as I have seen that the wires from ECU to the engine bay are fine despite being under a smelly carpet and after having tested them for circuit and resistance. 

[idosubaru]

18 hours ago, davepak said:

Yes, Ill try that, especially now that I have seen the location of the ECU pins for the injectors

I looked In the FSM. You probably know this. Yes there’s power feeding the injectors directly *and* if pulling one connector - power can still back feed from another injector from the fusible link.  

I’ll post pics later when I have internet access and if I can figure out why usmb isn’t allowing me to attach any images over 0.000026 kB.   It says my limits is so small that I can attach a usable image. 

[davepak]

1 minute ago, idosubaru said:

I looked In the FSM. You probably know this. Yes there’s power feeding the injectors directly *and* if pulling one connector - power can still back feed from another injector from the fusible link.  

I’ll post pics later when I have internet access and if I can figure out why usmb isn’t allowing me to attach any images over 0.000026 kB.   It says my limits is so small that I can attach a usable image. 

Hmm this is something to consider then. My plan is to open up all the wiring from the injectors to the main engine connector and inspect them. The section from ECU to the main engine connector was fine. And Ohm tested. I figure is more likely that from the injectors (including the harnesses) to the main connector there could be a problem since this section is widely exposed to wear and tear. I know about the file limits. *sigh* so I tend to convert the pics to very low resolution to say 110 kb and the like. Otherwise it wouldn't let me upload anything! 

[idosubaru]

35 minutes ago, davepak said:

Hmm this is something to consider then. My plan is to open up all the wiring from the injectors to the main engine connector and inspect them. The section from ECU to the main engine connector was fine. And Ohm tested. I figure is more likely that from the injectors (including the harnesses) to the main connector there could be a problem since this section is widely exposed to wear and tear. I know about the file limits. *sigh* so I tend to convert the pics to very low resolution to say 110 kb and the like. Otherwise it wouldn't let me upload anything! 

Each injector wire is actually connected to another injector wire.  Both of them. if you PM your email I can email you the FSM section. USMB isn’t allowing me attach  

If you have the FSM  grab the largest book 2 & 3 (they call the book “section 2 & 3”)

Its on page 77

in Section 2-7.

Edited December 22, 2020 by idosubaru

[davepak]

12 minutes ago, idosubaru said:

Each injector wire is actually connected to another injector wire.  Both of them. if you PM your email I can email you the FSM section. USMB isn’t allowing me attach  

If you have the FSM  grab the largest book 2 & 3 (they call the book “section 2 & 3”)

Its on page 77

in Section 2-7.

Yes. The FSM I've got them all. I'm looking at "injector connector" and their colors and designations. I'm once again suspecting something in these wirings. Perhaps a not known wire that affects the injectors and might be affecting the feed of the battery from the fusible link. I have injector harnesses and plenty of wiring. The plan is to fabricate a new section for the injectors while checking the wires running along those wires. Maybe the fast idle solenoid, maybe the positive feeds from the battery.. 

Thanks for the input once again. I feel I'm gonna get this darn issue one way or the other! 

[idosubaru]

I would look over that section i posted rather than the larger diagram.  It’s really simple - shows the couple connectors and ECU and fusible links feed and exactly the test sequence to use.  I would start at the very beginning of the test and work your way through each step. 

[davepak]

59 minutes ago, idosubaru said:

I would look over that section i posted rather than the larger diagram.  It’s really simple - shows the couple connectors and ECU and fusible links feed and exactly the test sequence to use.  I would start at the very beginning of the test and work your way through each step. 

Got it. Will take it from there. I'll post the updates 

[davepak]

10 hours ago, idosubaru said:

I would look over that section i posted rather than the larger diagram.  It’s really simple - shows the couple connectors and ECU and fusible links feed and exactly the test sequence to use.  I would start at the very beginning of the test and work your way through each step. 

You know what @idosubaru Im gonna have to take your offering on that diagram as I dont see it exactly as you described it. I'll PM

[davepak]

On 12/22/2020 at 6:54 PM, davepak said:

You know what @idosubaru Im gonna have to take your offering on that diagram as I dont see it exactly as you described it. I'll PM

This is where I am at the moment. @john in KY @el_freddo  @DaveT @idosubaru Checking all wires in the engine bay. I found a torn exposed wire related to the alternator and a couple of "orphan" wires. At one point the car blew the fusible link perhaps associated to the starter or the alternator. So the fault could be there. Even the alternator could be the culprit, it could be shorted somehow now that I think about it. The injector harnesses look fine although I will put new harnesses and verify that they aren't shorting each other afterwards. 

 

Edited February 2, 2021 by davepak

[idosubaru]

Good that might be a start.  With how quickly your stuff is burning up I’d be checking that power/fusible link side of the injectors circuits really good.

That white wire looks like maybe rubbed through as if it sat against a running pulley or belt. 

Edited December 23, 2020 by idosubaru

[davepak]

9 hours ago, idosubaru said:

Good that might be a start.  With how quickly your stuff is burning up I’d be checking that power/fusible link side of the injectors circuits really good.

That white wire looks like maybe rubbed through as if it sat against a running pulley or belt. 

The rubbed / torn wire is  position "A" from the alternator to fusible link #4 (1.25). And it was strangled by position "L" that heads to the "Charge" indicator on the digital meter out of the alternator. Might not be a culprit but for sure does not look good. I found wire "S" that heads to fusible link #2 (0.85) from the alternator is disconnected. I will fix the connector properly the next time I have a chance.

[davepak]

On 12/23/2020 at 8:55 PM, davepak said:

The rubbed / torn wire is  position "A" from the alternator to fusible link #4 (1.25). And it was strangled by position "L" that heads to the "Charge" indicator on the digital meter out of the alternator. Might not be a culprit but for sure does not look good. I found wire "S" that heads to fusible link #2 (0.85) from the alternator is disconnected. I will fix the connector properly the next time I have a chance.

Happy holidays to you all! 

@idosubaru @john in KY @DaveT @el_freddo @naru2

This is where I am now :

I fixed the alternator's wiring by adding the line labeled "S" that stands for "voltage sense" this was cut and left on the side. 

I reattached the wires I had cut suspecting they were shorted. These wires were all fine all along. 

I prepared 4 new injector harnesses by cutting the old ones and soldering the new ones then using heat shrink on their solder joints. 

I fired it up. 

It started. 

But with a clanking noise, I let it run for a good 10 minutes. And then I noticed it smoothed out, at first it was like a wave, it would run ckanky  then I would hear the typical EA82 purring. In the end it really seem it got a lot better. I noticed injector #4 still leaks fuel, but at a lower rate. When putting a long screw driver it sounded as if that injector 4 was clicking. 

The computer (damaged after a short when attempting to find the injector pulses) works good enough to run the ignition and distribution and in fact, it gave me code 42. Very clear 4 long pulses and 2 quick ones. Reading about it, it is related to "Injector"  stuck open or closed. Which makes all the sense considering all the issues with injector 4. Perhaps that injector is faulty despite thought of being fine otherwise. 

However, reading on USBM, someone mentioned that code 42 refers to "Idle Switch" this would be consistent with the car's behaviour now. After the auxiliary air valve was released of keeping the idle still, the car couldn't maintain an idle any longer. The suspicion now is that the pin in the ECU that controls the iddle switch is fried. (Most expected) 

With all this, I'm calling it a massive improvement! The next actions include an oil and filter change, a swap and test of the injector #4. Waiting for the new ECU that is on its way. And fixing the relays for the radiator fans. Yes, I eliminated the fan clutch and placed 2 radiator fans. However I need a separate relay for the now main fan. It drags too much current for the current auxiliary radiator fan. 

I'll keep the updates coming

[davepak]

 

 

Edited February 2, 2021 by davepak