AU 4.0L 1 - 6 miss.

[Bob Valdez 136]

Will a bad cam sensor cause a 1 & 6 miss in a 4.0L AU engine? We have tested/tried/replaced EVERYTHING that could otherwise cause it. Dad's car stopped one day. They replaced the coil pack, found the ECU to be red hot, but since then, after several more visits to his mechanic, the miss persists. I've exhausted all other possibilities, so it appears the cam sensor could be causing the ECU to be confused as to where #1 is. Anyone got any ideas?

[SPArKy_Dave 8,875]

4 hours ago, Bob Valdez said:

found the ECU to be red hot, but since then, after several more visits to his mechanic, the miss persists.

 

From your description, my guess would be the original coil pack shorted to ground, creating a massive increase in current.

This high current, has likely damaged the 1/6 coil driver transistor, inside the ECU.

 

From memory, the CMP sensor only signals the ECU to switch off a faulty coil, if the current is too low

(ie open circuit no spark), to prevent excess emissions from unburnt fuel.

 

I would remove the ECU, and have it tested/repaired by Logicar, Injectronics or similar vehicle ECU repairer.

Someone handy with electronics, could also likely diagnose and replace the damaged coil driver transistor.

 

https://fordforums.com.au/wsmpub/augx/Part 9-1.html

 

 

 

[Bob Valdez 136]

Forgot to mention, it has a replacement ECU of the same part number. (Been tested with 2 other different ECU's of the same number from running vehicles)

New:

Coil pack(s).

Leads. Plugs are platinum, and are all fine.

Injectors

O2 sensor

Fuel filter (recent)

 

 

Been tested:

TPS

Crank sensor

MAP sensor

wiring continuity. Mobile sparky reckons the wiring in the coil triggers has a possible interference from the dash (!) as the scantool reports an external interference in one of the coil trigger wires (didnt say which one) and no-one bothered to isolate the cause.

 

Yesterday, I found the cheap replacement coil pack has blistered the potting underneath the 1-6 coil, so if the wiring was faulty, that could have fried both the replacement coil pack AND the replacement ECU. The coil trigger wiring is now external to the entire harness BEFORE fitting the new coil pack, so a short there is impossible. Now it might need another ECU due to a possible wiring short cooking the coil driver again.

 

I've picked this up from yesterday after two weeks of others fucking with this thing, and my Dad is going crazy (he is 82 and needs the car).

 

 

 

 

[SPArKy_Dave 8,875]

Sounds like you'll need to go back to square one,

and check all the obvious things.

 

Not sure if the AU's are sequential injected - I think they are, having EDIS and the 104 pin ECU?

Unlikely two injectors have failed at once.

I know EL's are batch injection (fired in two groups of 3 injectors)

 

Check the cheap coil isn't fried.

Check for an open circuit spark plug - even just one, will cause a two cylinder misfire, due batch fire ign.

 

Personally, I always keep in the back of my mind - even new parts can be faulty these days - especially cheaper non-oem.

 

 

What may have happened, is the following -

 

Original 1-6 coil has shorted (possibly due to high resistance spark plug/s and/or plug lead/s)

Shorted coil kills ECU coil driver - transistor fails ON (points closed).

Cheap replacement coil is fitted

Replacement coil is then damaged by being held in constant dwell - due to above failed ECU driver

Replacement ECU is then fitted

Above replacement coil (now damaged from original failed ECU), damages replacement ECU.

 

If it were me, I'd start fresh -

fit oem bosch (new or used) coil-pack, verify spark plug and lead resistances, test coil ECU trigger wires for short (unlikely IMO)

reinstate original coil trigger wire and retest,

have original ECU repaired and refit.

 

 

 

 

 

[Bob Valdez 136]

Had a chance to have an in-depth chat with Dad's 'mechanic' and have a clearer picture of what he thinks has happened:

 

Paul believes that there has been a 'short' in the engine to ECU harness which shorted out the 1-6 coil and took out the ECU. He says when the car arrived at his shop on a truck, the ECU was 'very hot, and couldn't hold his hand on it for long. Because he was just out of a hernia op, he got the guys across the road to look at it. They replaced the coil pack, leads, cleaned and tested the plugs and checked some other stuff and after some fiddling around, got it running. It was still playing up, so Dad's mech replaced the ECU and it ran on all 6. After a few days, though, it started missing again. Paul has tried another ECU but it still misses. A mobile auto sparky spent a couple of hours on it, but says he can't find anything wrong, other than an 'external interference' in the 1-6 trigger circuit.

Yesterday, the first thing I checked was coil trigger wiring, leads, plugs (resistance, etc) and whatever I could test without disassembling too much. One of the injectors was suspect anyway, so I've replaced them as a matter of course, as much to eliminate them as a culprit, also to change them for fresh ones (it has 340K on the odo). I removed the replacement coil and found the blistering. It seems to test fine, but as a precaution, I bought a VDO replacement, which is a much better looking replacement. No-one has a Bosch unit anywhere that I could find. BEFORE I fitted the coil and ran it, I did the coil trigger wire bypass with Deutsch plugs and made sure there is no shorts, good continuity and all tested good. However, the miss continues. I can only assume that the coil driver in the ECU has failed due to the short in the engine harness (if it exists). Bypassing the harness removes this as a culprit. It is easily reinstated. I am concerned that doing that will start the whole sequence off again.

Looking at the repair history, they never removed the possibility of the wiring harness being at fault, and just threw parts at it. All the while, each time has just wrecked the new stuff one by one in a continuing trail. The short burned the coil, which burned the ECU, which burned the new coil, which burned the replacement ECU, etc etc. Now, I have precluded the short as being the issue and hope that now, it's only the ECU that needs to be replaced AGAIN. I've tested everything the workshop manual says to check, it all tests up as specced and I can't find anything else to blame.

This bloody thing was the model of reliability previously and now, Dad is ready to consign it to the scrap heap and get another car. No-one else wants to touch this thing. I'm stuck with trying to solve the conundrum. Dad is 82, he depends on this car for his mobility and security. The thing not running is doing the poor bugger's head in. I just want to fix it and get him mobile again. I'm two hours away from Dad. I have to take time off work to go look at it or fix it now. I'm happy to do it for him, he is my Dad, so I try and help where ever and when ever I can. Any ideas are gratefully appreciated.

[SPArKy_Dave 8,875]

A random wiring short seems unlikely, but is easy to test for.

 

Assuming EDIS coil 'primary windings' are ground-side switched (as per any normal coil),

only a continual short to ground (dwell), would boil the coil.

 

A continual ground short would not damage the ECU - as the coil driver output is already at ground potential

(ground side switched to fire coil)

 

A trigger wire shorted to 12v would likely fry the ECU driver, but would not harm the coil.

(a triggered/discharged coil has 12v potential on both primary winding terminals)

 

The fact you say the car arrived with a very hot ECU, tells me a likely 12v short/high current through the coil driver transistor -

Most likely shorted coil winding, as a 12v short in the trigger wire between coil and ECU, would not harm the coil.

 

Questions -

what caused it to arrive on a tow truck (ie, total breakdown)?

have you verified the 1 and 6 plug leads are still not generating spark?

 

[Bob Valdez 136]

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Posted 11 hours ago

'Questions -

what caused it to arrive on a tow truck (ie, total breakdown)?    Apparently, Dad started the car as usual, it ran for a moment, then started farting and carrying on and stopped. It would not restart. When it arrived at the repair shop, it would not start there either. As I have said, I haven't been involved in this until no-one could fix the miss. Now, I'm stuck with it.

 

have you verified the 1 and 6 plug leads are still not generating spark?   Put spark plugs into the leads and cranked the engine. With wasted spark, it should spark at every revolution. No spark at either plug. If it were the lead, I would have at least one plug firing, the chances of both new leads being faulty are unlikely in the extreme.

[SPArKy_Dave 8,875]

15 hours ago, Bob Valdez said:

 If it were the lead, I would have at least one plug firing, the chances of both new leads being faulty are unlikely in the extreme.

 

To my knowledge, with EDIS waste spark ignition, either of the two leads going bad will affect both cylinders, on that coil.

Same with spark plugs.

 

[Bob Valdez 136]

What I have to do now, is figure out how to permanently shut down the traction control. It is stuck on and trying to pull down the engine ALL the time by killing spark and injection in # 1 and #4 cylinders. Live data shows this, as all the sensors are functioning, the coil wiring is intact and the coil and ECU are working, but the traction control is trying to pull down the engine, thinking there is a loss of traction. I have been told that function is in the BCM, so perhaps a replacement is in order. That might explain all these shenanigens.

[Thom 6,651]

What I have to do now, is figure out how to permanently shut down the traction control. It is stuck on and trying to pull down the engine ALL the time by killing spark and injection in # 1 and #4 cylinders. Live data shows this, as all the sensors are functioning, the coil wiring is intact and the coil and ECU are working, but the traction control is trying to pull down the engine, thinking there is a loss of traction. I have been told that function is in the BCM, so perhaps a replacement is in order. That might explain all these shenanigens.

If that's the case then I would go looking for a faulty wheel speed sensor or vehicle speed sensor, could even (but very unlikely) be something dicky with the abs module, with each of these items they will be producing a signal but at the wrong value cause the ecu to think the car is experiencing wheel spin

[Bob Valdez 136]

18 hours ago, Thom said:

On 4/5/2023 at 6:07 PM, Bob Valdez said:

What I have to do now, is figure out how to permanently shut down the traction control. It is stuck on and trying to pull down the engine ALL the time by killing spark and injection in # 1 and #4 cylinders. Live data shows this, as all the sensors are functioning, the coil wiring is intact and the coil and ECU are working, but the traction control is trying to pull down the engine, thinking there is a loss of traction. I have been told that function is in the BCM, so perhaps a replacement is in order. That might explain all these shenanigens.

If that's the case then I would go looking for a faulty wheel speed sensor or vehicle speed sensor, could even (but very unlikely) be something dicky with the abs module, with each of these items they will be producing a signal but at the wrong value cause the ecu to think the car is experiencing wheel spin

I've found the #62 wire at the ECU is the traction control torque control request from the ABS module. We suspect that the ABS module has had a meltdown, burned some wires inside the body harness and is somehow causing the ECU to think that the car is losing traction and is cutting cylinder(s) to reduce 'wheelspin'. That might explain the random ABS and TC lights and codes. If I cut the #62 wire close to the ECU plug, allowing me to reconnect it if needed and removing any possible signal leakage into the ECU, that MIGHT stop all this bullshit. I'll also do a full comp test and leakdown, plus check a few other mechanical things to make sure it's not a mechanical issue. Being this car has been faultless prior to this issue, I doubt that is the problem, but hey, anything can happen, even to perfectly good engines.

[SPArKy_Dave 8,875]

3 hours ago, Bob Valdez said:

If I cut the #62 wire close to the ECU plug, allowing me to reconnect it if needed

Being this car has been faultless prior to this issue, I doubt that is the problem,

 

Was it cylinder's 1 and 4 missing all along, rather than 1 and 6?

 

Rather than cut any wires, just withdraw that pin from the ECU plug, (de-pin)

then put some heatshrink over the bare pin, and tape it out of the way.

 

If u need to reinstate it later, then just click the pin back into it's spot.

 

I'd verify wheel speed sensor outputs.

Something has changed all of a sudden - maybe ran over something and damaged an ABS sensor wire, or metal debri on the sensor face/magnet?

Were new front wheel bearings/tone ring assemblies recently installed?

[Bob Valdez 136]

13 hours ago, SPArKy_Dave said:

 

Was it cylinder's 1 and 4 missing all along, rather than 1 and 6?

 

Rather than cut any wires, just withdraw that pin from the ECU plug, (de-pin)

then put some heatshrink over the bare pin, and tape it out of the way.

 

If u need to reinstate it later, then just click the pin back into it's spot.

 

I'd verify wheel speed sensor outputs.

Something has changed all of a sudden - maybe ran over something and damaged an ABS sensor wire, or metal debri on the sensor face/magnet?

Were new front wheel bearings/tone ring assemblies recently installed?

Sorry, a mis-print, I meant to type #1 & #6, not 4.

 

The plan is to remove that pin from the ECU plug. By "Cutting", I was alluding to disconnection of that particular circuit. I'm just trying to eliminate every possible interference.

 

None of the wheels/brakes have been touched, so unless he ran over something and didn't tell me, until I can get it onto a hoist and check wheel sensor wiring and trigger wheels, I'll just disconnect the ABS/TC and see what happens. The ABS and TC lights have been coming on randomly, so it's possible something happened and it's done some damage somewhere. Short of removing the harness from the car and testing/replacing it, it's more than I'm prepared to do right now.

 

I did an hour and a half session with a decent Scantool and came up with #1 coil A circuit failure and #1 injector circuit failure. Checked everything, did continuity tests and everything came up fine. Coil is fine, ECU is showing up correctly from workshop manual requirements. The ABS came up with a no engine speed code. I cleared everything and kept running both key on engine off and engine running dynamic scans and kept coming up with random faults. Nothing came up that would not go away. So, to throw a proverbial spanner in the works, I disconnected #2 injector plug. After running both tests twice, and clearing between each, only the #2 injector circuit fault came up. After that, I disconnected the battery and replaced the ECU ECT sensor (because I had one and I had to break the old one to remove the connector plug without fucking it) and after reconnecting the battery, ALL the tests came up with ZERO faults or codes. I ran it all 3 times, with Dad and my brother looking on. However, in the last test sequence, the ABS came up with a no engine speed fault and the ABS/TC lights started going mental. The miss persists. I've pulled the 60A fuse for the ABS to disable it until we sort this out. Now, the ABS and TC lights are always on. It is remotely possible that there is a fault in the harness behind the dash and that the TC request wire is sending random pulses to the ECU. Until I try that, we are still hunting for the mystery miss, ONLY on #1 plug. #6 is now firing normally now, so unless the TC is causing it, the only other thing it can be is a mechanical fault in the engine (burnt/leaking valve, broken lash adjuster, valve spring, or broken piston/rings.) There are no apparent engine noises or any other problems, only the miss at #1. No-one else wants to touch this car, so i have to do something to help. Rather than just throwing new expensive parts at it, I'm trying all the old fashioned methods to narrow down and hopefully eliminate the problem.

[SPArKy_Dave 8,875]

A leakdown and compression test should show any mechanical faults?

 

Check for cruise control or brake light switch issues also.

Single cyl misfire, could be an Crank angle sensor or harmonic balancer tone wheel issue?

Possibly a faulty cam sensor.

 

 

 

[Bob Valdez 136]

Crank sensor has been replaced with a good known one, balancer has been removed to check tone wheel, which was perfect.

Cam sensor tests ok, plus it would have showed up in the scan test.

 

[SPArKy_Dave 8,875]

9 hours ago, Bob Valdez said:

Crank sensor has been replaced with a good known one,

 

At this stage of the game, an oscilloscope is likely needed, to track down the culprit.

U probably need to look at ignition waveforms, sensor output waveforms, etc.

 

I'd also check the alternator, for excessive AC interference from failing diodes.

(temporarily unplugging it, should do the trick)

 

[Bob Valdez 136]

I've considered there is a failed diode in the alternator. That's where I'm looking first next visit to Dad's place.

[Bob Valdez 136]

Spent 4 hours on this yesterday after we found Dad a clean BA XT Mk2 sedan. Short of pulling the engine apart or replacing the entire wiring harness, I can't find what is causing this bloody miss. Every part involved is either new, fully tested, or a working example from another car. When it comes to my place where I have my full arsenal of tools and test equipment, it's getting the full monty, comp test, rocker cover off, full electrical check for EVERY ECU wire for continuity and crossover and then, I'll decide what to do next. Shiity weather meant I couldn't pull the valve cover at Dad's place and I was limited somewhat to what I could do without major dismantlement of the dash (that will come if required), so I did what I could (which wasn't a lot, unfortunately) and I will continue the search under cover at home with a vigor. This thing will not beat me. I WILL find the problem.

[dex 2,065]

Cars ,,,

 

who’d have them 

not for quids 

 

 

unless you had more quids ,,,

 

keep at it ,, 

trouble is ,, 

it’d be the 50 cent bit causing it .

 

keep at it 

[SPArKy_Dave 8,875]

On 4/22/2023 at 10:06 AM, Bob Valdez said:

This thing will not beat me. I WILL find the problem.

 

Maybe be the parts cannon, has misfired somewhere?

Starting a fresh, definitely sounds like the way to go...

[Bob Valdez 136]

6 hours ago, SPArKy_Dave said:

 

Maybe be the parts cannon, has misfired somewhere?

Starting a fresh, definitely sounds like the way to go...

Absolutely. Most of the 'new' parts were fitted by others. Mine are the injectors, coil pack and CTS in the back of the head. The others (ECU, etc) are parts from a known running engine in working order. Because much of the wiring 'testing was not done by me, I have to reassure myself that it was done correctly. I've run nodes on the injector plugs, they all fire correctly, only #1 intermittently does not flash. I have spark at #1, again intermittently, but spark none the less. All the sensors check out, according to the factory resistance values, including many of the old replaced ones. My biggest issue is I haven't have the time I needed to delve deeper into the whole problem. All the info I have on what was done is second hand, so I'm not entirely certain I'm getting the full story. When I visit Dad, I HAVE to leave by 2 pm at the latest, or it takes over an hour to get through the mad afternoon traffic clusterf*ck that is the Ring road and Calder 'highway' to get to and past Calder Park to get home. Once I have the car here, I can start my investigation of the cause without any interuptions (other than the squealing handbrake) and work.

While the electronics and wiring on AUs is very complex, I'm still not entirely convinced this is an electrical gremlin, rather a mechanical fault. Without a doubt, the ECU failure was a primary cause of the original no-start, it run fine after for a few days, then started missing. That has NOT gone away. I'm thinking that during the original repairs, those apes revved the absolute piss out of the engine and started an internal failure that continues to this day. Anyway, I will get to the bottom of it, even if it entails replacing the ENTIRE wiring harnesses and/or engine of the car itself. If it's an engine replacement, it will go V8.

[deankxf 20,288]

@Bob Valdez a mate of mine just mentioned an issue with an EL his mate has. 

The injector for number 3 cylinder on my mates EL was BENT, causing a misfire

assume damaged on install? 

[Bob Valdez 136]

8 hours ago, deankxf said:

@Bob Valdez a mate of mine just mentioned an issue with an EL his mate has. 

The injector for number 3 cylinder on my mates EL was BENT, causing a misfire

assume damaged on install? 

Probably some idiot was banging on it with a hammer/spanner to make it work and damaged it.

 

All the injectors in the AU are brand new, and I made sure to fit them spotlessly clean and correct in both orientation and alignment. The nodes indicate that they are firing from the ECU, it's just that intermittent #1 spark and injector 'fault' that comes up.

[jez 5]

Keep at it mate - nice to see someone doing something like this for family for the sake of it.  All the best and hope it gets sorted out. 

[Bob Valdez 136]

Thanks.

 

Picking up Ol' Blue tomorrow and bringing home on a trailer. Once the miss is eliminated and all the electrics sorted, I'll get a RWC and transfer it, then it might go up for sale. I need the space and money for the XF.