Fuel Injector Plug/Wiring Issue

[Brewy]

Hi, I have a 2003 BA XR6 Turbo 5 speed Manual Sedan with 102,000km I’ve owned since brand new, last time I drove it for about an hour with no problems and then it sat for about 6 hours and started it up and ran rough straight away, seem to run on 4 cylinders and had to drive it home like this.

It runs well when started up and after about 5 seconds starts running rough, so found out after checking/swapping around Ignition coils, Spark plugs and Fuel Injectors that it seems to be dropping power out of cylinders 2 and 4 on the Injector plug that then stops those injectors from working..

So, has anyone come across this Electrical issue before that’s dropping power to some Injector plugs about 5 seconds after running and is there some checks and how to see if a Short/Ground/Relay etc Fault is somewhere and why would it be just the 2 cylinders affected and only number 2 and 4, these No. 2 and 4 injector wiring must join up somewhere along the line for them to fail at the same time? Thanks.

Edited 27/04/24 10:12 AM by Brewy

[TurboBurbo]

Nope, I've never heard of it. Who doesn't love some good old mysterious electrical issues on a weekend? After swapping the injectors around, how are you determining it's still cylinders 2 and 4 giving you grief? Have you got some specific error codes coming up? just listening to them?

 

I HAVE NEVER DONE THE FOLLOWING. So I've done some quick googling to confirm some stuff (*=googled it) but this is how I would proceed to diagnose where an electrical issue was.

Check the battery voltage and all the grounding leads you can find. Disconnect the battery for *30 min to reset the ecu, just incase that fixes it.

Have you got a multimeter? *99% of injectors are ground switched (ie: with key on, one wire has 12V all the time, the ecu connects the other to ground, connecting the circuit when it wants to fire the injector). With the key off, none of the injector wires should have continuity to ground. If you find continuity to ground on a bad injector plug pin, check the rest of the injector plugs aren't the same to make sure I'm not telling fibs. If not all the same >> You have chafed wires somewhere.

Else, Turn the key on, and check that you are getting 12V supply to each of the injectors. If not >> chafed/broken wires.

Else, turn car off and check there's no continuity between the pins in plug2 and the pins in plug 4. Just remember which ones were the 12V supply pins because they might have continuity between each other so don't worry if that test is positive. If yes >> chafed wires. With 2 injectors going out at the same time my 2 cents would be on this one 🤞

 

Last I'd grab an oscilloscope. Or even better, a rellie who knows how to use one. Plug it all back together, fire it up and use the oscilloscope to compare the signal a bad injector is getting to what a good injector is getting. If someones watching when you turn it on you might be able to see the signal go bad after the 5 seconds of idling. Or it's flat lining to start with / intermittent / half the voltage of the others. Depending on what you see hopefully points you towards broken wiring and not broken pcm. (*our injectors contain solenoids, others are piezoelectric. The internet tells me you don't want to piggyback an oscilloscope on piezo injectors cause they generate dirty great big voltage spikes that will leave you minus 1 oscilloscope.)

Edited 28/04/24 03:15 PM by TurboBurbo

[TurboBurbo]

I know you have said you have narrowed it down to injector electrics, and this guy didn't come back to confirm, but is it work triple checking your coils? https://www.fordxr6turbo.com/forum/topic/87107-po355-fault-code/

[Brewy]

Hi TB, Thanks for your reply, Ive swapped Igniton coils and Fuel Injectors around and still 2 and 4 still drop power after about 5 seconds after startup and I put a long screwdriver on these 2/4 injectors as a  stethoscope and when engine started they tick and after 5 seconds they stop ticking and engine runs rough from them 2 dropping power.

And Ive had the battery disconnected for a day and it didnt do anything.

Ill do those injector multimeter procedure checks that you mentioned, Thanks.

 

And Ill also check the plug from these injector wires that goes to the ECU and see if any corrosion/bad contact, as someone said to check that as well on other Ford sites.

I thought it was the ignition coils that casue the problem at first, as that's the main codes that came up, but wasnt, so then checked injectors and that's when I didnt hear 2/4 not ticking, so thought they was blocked etc, so removed and resistance was with others at 15.3, so powered them up with 9v battering with clips wire to open them up and flushed them all 6 out and all clean, so when putting them back in, I swappped 2/4 with 1/3 and still had problem with 2 and 4, so that elimated coils and injectors and then left the power supply to them that I thought was never possible, as Ive EFI Cars for about 35 yrs and never had a injector power issue before, so new to me. Thanks

 

It through some weird codes that I just got out of my Autel Diagnostic scan tool today- Gave 5 x Fault codes-
P1708:00/ ODDTCs - Clutch switch input circuit malfunction.(Why would this come up)?
PO352:63 / CMDTCs - Ignition Coil B primary circuit malfunction.
PO354:63 / CMDTCs - Ignition Coil D Primary/Secondary Circuit.
PO356:63 / CMDTCs - Ignition Coil F Primary/Secondary Circuit.
P1507:63 / CMDTCs – IAC(idle Control) valve duty cycle lower than expected. (Dont know if this IAC came up because it was running rough and on 4 cylinders)?

Edited 29/04/24 11:15 AM by Brewy

[TurboBurbo]

🫤 Id need someone else to confirm whether the Barra pcm does this, but something that might muddy the water for you is those ignition coil errors. P0452/4/6 on some other cars disable the respective injector so they aren't pumping unburnt fuel into the exhaust and smoking your cat + fuel trims. Do all those errors return quickly after clearing them?

[Brewy]

Hi TB, Its wired situation, those 5 fault codes still come up after clearing them, I went into more description on these fault codes with the Autel diagnostic scan tool and down the bottom in the coil fault description it’s also got that the ECU could be at fault as well and after I’ve eliminated coils, spark plugs, fuel injectors and I’ve removed/inserted all injector plugs and did the last wire harness plugs that goes under the ECU/PCM today and cleaned/reinserted and still 2 and 4 are out, and checked out along the wire harness, nothing rubbed through, as it’s got that black plastic conduct all around it, so I’m thinking that since 2 and 4 fire/fuel at the same time in Engine firing order, some electrical component inside the ECU-PCM has failed that operates 2 and 4 fuel injection, as its too much of a coincidence that it’s the same 2 cylinders that work together that’s the problem is?

[Puffwagon]

The PCM can cut cylinders for reasons, there is a DMR logging parameter that shows how many cylinders are active. AFAIK it will cut half of the cylinders via injector cut for various FMEM reasons ie: overboost, etc. There is that side of things.

 

Onto losing power at the injector, they are 12V live all the time and the PCM pulls them to ground. First check for pin connection, it is common to have issues there. Either the pin will back out of the plug or it will open up inside the plug and cause issues. Pigtail connectors for aftermarket injectors are notorious for this. If there is an intermittent fault with the injector 12V, bypassing it with a direct battery feed will show results. Literally run a wire from the battery positive to the injectors in question and that will rule that out.

 

Other things I've seen, the coil cover fasteners can pick up the coil or VCT loom under the coil cover and can earth it out through the rocker cover.

 

I can see you've checked some of this, it can pay to double check things, especially if you've been rushed.

 

I haven't opened up a PCM and can't say what will fail and at what age, however I have seen a few dry solder issues with white goods that are easily fixed. This would be the last place I checked, unless of course you have access to another PCM that will run the car.

 

Hopefully there's something there for you.

[Brewy]

Hi Puff, Thanks for your input. I'll do some of those checks, thanks, as dont know anyone around south east Brisbane to try a PCM.

   As firstly had engine running and lifted each coil up to see if engine died slightly and 2 and 4 cylinders didnt die, so thought then it was No.2 and 4 Igntion coils, so thought I would double check them by swapping them with 1 and 3  and those 2 and 4 coils worked in 1 and 3, so thought then its not coils, will this procedure eliminate coils? As I also had 2 and 4 coils out seperatly out with spark plug in end and still sparked while engine running, they didnt cut power out of them like it does with fuel injectors.

Can the coils also be checked for a resistance check like the fuel injectors? Thanks.

[Brewy]

11 hours ago, Puffwagon said:

The PCM can cut cylinders for reasons, there is a DMR logging parameter that shows how many cylinders are active. AFAIK it will cut half of the cylinders via injector cut for various FMEM reasons ie: overboost, etc. There is that side of things.

 

Onto losing power at the injector, they are 12V live all the time and the PCM pulls them to ground. First check for pin connection, it is common to have issues there. Either the pin will back out of the plug or it will open up inside the plug and cause issues. Pigtail connectors for aftermarket injectors are notorious for this. If there is an intermittent fault with the injector 12V, bypassing it with a direct battery feed will show results. Literally run a wire from the battery positive to the injectors in question and that will rule that out.

 

Other things I've seen, the coil cover fasteners can pick up the coil or VCT loom under the coil cover and can earth it out through the rocker cover.

 

I can see you've checked some of this, it can pay to double check things, especially if you've been rushed.

 

I haven't opened up a PCM and can't say what will fail and at what age, however I have seen a few dry solder issues with white goods that are easily fixed. This would be the last place I checked, unless of course you have access to another PCM that will run the car.

 

Hopefully there's something there for you.

Thanks Puff, that makes sense and since it’s got mainly 3 coil faults all of a sudden that seems unusual and there’s a chance that these faulty coils could disrupt the PCM if shorting/grounding and limit some fuel injectors power to put it in some type of Limp Mode?  I’ve order a set of new coils to eliminate them and hopefully that’s causing the 2/4 fuel injector power loss issue, as at the start I was hoping it was just the ignition coils until I looked into it too deeply by also diagnosing it Old School by swapping Coils around and then checked out fuel injectors that was cutting power to No.2 and 4 out that made it all confusing.

[Puffwagon]

Let us know what happens with new coils.