S80: Engine Problems won't go away. What else could there be?

[Laird Scooby]

Originally Posted by venomtail

Yes, I've tagged each injector so I know which one came from where. At one place I was told that swapping the injectors around changed nothing. The problem persisted. However no idea if problem persised with the same cylinder 4 or had moved to a different one, but if it did it would have shown up on my diagnostics as 2 cyliders misfiring.

Illogical Captain!

It doesn't work that way.

If the injector is faulty and it is moved to another cylinder, the fault will move with it - you won't have 2 pots misfiring.

If the fault is staying on the same pot, the fault must be in the wiring or control circuitry for that pot.

[venomtail]

Originally Posted by Laird Scooby

Illogical Captain!

It doesn't work that way.

If the injector is faulty and it is moved to another cylinder, the fault will move with it - you won't have 2 pots misfiring.

I meant "it would have shown up on my diagnostics as 2 cyliders misfiring." by the diagnostics showing me history. VIDA shows you dates and times of all errors even ones that don't appear now, so in theory if I have faulty injector it would show 'cylinder 4 misfire.' Then I'd move the injector to another cylinder, run car and diagnostics again and I'd now have a different cylinder misfire. However because I didn't delete it's history then I can go in history and see that for example cylinder 3 is now misfiring, but right before the swap 30 minutes earlier cylider 4 didn't work.

Originally Posted by Laird Scooby

Illogical Captain!
If the fault is staying on the same pot, the fault must be in the wiring or control circuitry for that pot.

The wiring was checked twice and was in the clear both times. I want to check for myself though, I'll order some noid lights to see if it's all good.

[reggit]

Just a thought, could there be a dry joint on the output stage (transistor?) on the ECU stopping the signal ever reaching the wiring that’s tested ok?

I’m not completely sure how the injectors get a signal to fire.

Also does it always misfire on number 4? If so, have you tried a little easy start in the inlet tract with the engine running? If it’s the injector/signalling I’d expect that pot to briefly pick up. Diesels knock there head off on that stuff, just to warn you!

[venomtail]

Originally Posted by reggit

Just a thought, could there be a dry joint on the output stage (transistor?) on the ECU stopping the signal ever reaching the wiring that’s tested ok?

I’m not completely sure how the injectors get a signal to fire.

Also does it always misfire on number 4? If so, have you tried a little easy start in the inlet tract with the engine running? If it’s the injector/signalling I’d expect that pot to briefly pick up. Diesels knock there head off on that stuff, just to warn you!

Yes the cylinder always misfires. To the point where I'm actually convinced that it's not running at all by the sound, smoke, lack of power and engine shake.

[seanc]

Originally Posted by venomtail

Yes the cylinder always misfires. To the point where I'm actually convinced that it's not running at all by the sound, smoke, lack of power and engine shake.

I think I have to know if swapping 4 and 5 injector makes a difference. Its injector, cylinder head damage due to timing belt snap, ecu or wiring. If the problem moves with injector I think that's the best possible outcome.

[venomtail]

Since my last update I've done a bit of testing.

Received my noid lights and went to test the signal, to see if the noid lights will light up. All of them did as well as saw that fuel was being pumped through the fuel lines. So no fault there.


Received all my parts with which I could test the injectors with. Took a while because the first signal generator didn't work with my injectors, so had to get a different one.
Tested each injector and all worked perfectly fine, even the 4th cylider one that had the fault code. Everything checks out.

Don't know what's left. Have to check the recently replaced swirl flaps? Will have to put the injectors back and maybe swap them around. Maybe something changes then but last time it didn't, so not sure.

[Laird Scooby]

Originally Posted by venomtail

Since my last update I've done a bit of testing.

Received my noid lights and went to test the signal, to see if the noid lights will light up. All of them did as well as saw that fuel was being pumped through the fuel lines. So no fault there.

[

Just to be clear, did the NOID lights pulse on the injectors with the engine running?

Might be an idea to take a video with your phone as that will highlight whether they're pulsing or not. (different frame speed on the phone camera to the frequency of injector pulses will show up as a slower pulse of light from the NOID lights)

If they all pulse evenly then the fault doesn't appear to be the injector or the control - if #4 (the suspect cylinder?) is on more or less than it should be that is likely to be the fault.

[venomtail]

Been trying to put back the injectors we took out but now the engine wont start. Checked all the fuel lines and they are working fine, bleed the fuel system and the fuel is being delivered to the injectors, however still nothing. Checked the connection of the injectors with my Noid lights and not a single cylinder is being lit up by it. Must mean no signal is being sent to the injectors and I can't figure out why. DICE doesn't mention anything about injectors.

[YOUTUBE]https://www.youtube.com/watch?v=aTNlozm0VAw[/YOUTUBE]

Also, Putting back the injectors we've found out that the threads for 3 of the injectors (2,3,4) have been stripped and the bolts just infinetly screw when tightening with your fingers. We've made new threads and the injectors now sit nicely, just now I'll know to not go to any garage... How can someone strip something so important and not tell us?


On a side note, checked the swirl flaps. They're like new. No build up or any wear in the slightest.

Kinda don't know where to go from here. Will have to look up how to diagnose no signals being sent to injectors issue.

[Laird Scooby]

Originally Posted by venomtail

Kinda don't know where to go from here. Will have to look up how to diagnose no signals being sent to injectors issue.

Check you have all the correct signals reaching the ECU, all fuses for the ECU are correct and you have a +ve feed to the injectors (they normally have a +ve feed - ignition switched of course - then the ECU switches the earth path on via [usually] MOSFETs to turn the injectors on) and if all of that is ok and there is still no signal on the injectors and a non-start scenario :

https://www.atpelectronics.co.uk/

Testing and reporting on the ECU is i believe ~£50, repair tends to be ~£300 but if you have the repair done the testing/reporting gets included in that. If it's not the ECU, it'll cost £50 ish to find that out, if it is, about £300 to have a guaranteed unit come back to you.
These prices are approximate based on fairly recent experience, they may vary as they were for an earlier Volvo than yours but gives you an idea.

[venomtail]

Just put in more fuel and tried to bleed the fuel system again

and for a minute I got the engine to run. GOOD NEWS!

I just need to bleed the system again, maybe look up again on how to properly do the process, cause I'm messing up somewhere.