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[Kevin Wood]

To update on work carried out:

Plugs removed and dried, compressions tested. Now all 12-14 bar.

LPG loom disconnected and original injector loom replaced.

All injector signals tested during cranking. Pulses seen as expected.

All plug leads removed, checked for spark during cranking with a timing light in series with plug. All OK.

Fuel pump run with plenum off. Checked down intakes. No leaky injectors.

Reassembled and run.

Again, it did seem to be quieter for a second or two before the noise returned.

I have one more theory. The injectors and fuel rail were removed from one manifold and put back on another with LPG nozzles fitted. Maybe some crud got into the fuel rail and has blocked the pressure regulator giving high fuel pressure and therefore overfuelling and bore wash. The plugs are still getting quite damp although it appears to idle reasonably stable.

I have a second manifold with injectors. I thought about fitting it in this instance but decided against introducing an unknown. Maybe it's time to try that?  :-/

Obviously open to any other ideas because I'm starting to run short of them.

Kevin

[Kevin Wood]

Thanks to Jimbob for the MP3 conversion BTW.

FLAC was about as close as I could get last night.

Kevin

[TheBoy]

2woody, iirc, said he would bring along plug leads, maybe worth a quick try when he comes over to see you, seeing as we did disturb leads to change plugs ? (Just really on Loo-knees suggestion)

Then again, plugs? Could the news ones be faulty? Worth popping others back in - could the new ones be faulty? (eg, an internal break in one?)


I really, really am clutching at staws, really am at a loss now.

[Jimbob]

Worth ruling anything and everything out in my book.

not that long ago mark showed me a new broken plug.  :-/

[Kevin Wood]

Maybe some crud got into the fuel rail and has blocked the pressure regulator giving high fuel pressure and therefore overfuelling and bore wash.

.. of course, a quick and dirty check might be to disconnect the return line from the fuel rail and see if the expected torrent of fuel is emerging.

I must admit, now I come to think about it, when I ran the fuel pump with engine stopped the FPR was making an unusual noise. Kind-of like a toilet cistern filling when it's almost full. Could be indicative of a small trickle of fuel trying to escape through a partially blocked hole whereas with no fuel demand from the injectors it should be flowing full bore (litres per minute). :-/

Dismissed it at the time as I'd never heard one of these fuel systems pressurised without engine noise.

Kevin

[TheBoy]

Maybe some crud got into the fuel rail and has blocked the pressure regulator giving high fuel pressure and therefore overfuelling and bore wash.

.. of course, a quick and dirty check might be to disconnect the return line from the fuel rail and see if the expected torrent of fuel is emerging.

I must admit, now I come to think about it, when I ran the fuel pump with engine stopped the FPR was making an unusual noise. Kind-of like a toilet cistern filling when it's almost full. Could be indicative of a small trickle of fuel trying to escape through a partially blocked hole whereas with no fuel demand from the injectors it should be flowing full bore (litres per minute). :-/

Dismissed it at the time as I'd never heard one of these fuel systems pressurised without engine noise.

Kevin

And I guess ECU won't trim back until it goes closed loop?

[feeutfo]

listening several times, noise doesnt appear until it actually fires, its not present while cranking. If it was damage metal to metal or failed baring would it not be present each rpm reguardless of cranking or firing, as said previouly with crank sensor unplugged...some reasurance there perhaps? Although a most unpleasent noise.

[Marks DTM Calib]

Sounds like bore wash as its a very piston slap type sound....

[Lazydocker]

Just a quick thought... Did you swap the existing injectors and FPR onto the replacement manifold?

If you've got original parts on then it could be crude in FPR.

Failing that, stick the old plugs back in... I've encountered new plugs which are FUBAR several times.

[Lazydocker]

Should add, I've not managed a decent listen as I'm at work and on a mobile but from what I heard it can't be as serious as first feared... It only shows when firing, not under cranking. Some consolation I suppose?

[Kevin Wood]

The original injectors, rail and FPR are fitted, but they were transferred to the new manifold. Injectors were removed from fuel rail in the process.

During cold start the ECU will indeed be in open loop so none the wiser to the overfuelling.

When we first fired it up, after a few starts it got reluctant to start. Plugs had got quite wet. Assumed that this was due to cold start enrichment and not leaving it running for long enough but now I'm not so sure. :-/

Then the unusual sound from the FPR.

I think I have something to follow.

Kevin

[Lazydocker]

The original injectors, rail and FPR are fitted, but they were transferred to the new manifold. Injectors were removed from fuel rail in the process.

During cold start the ECU will indeed be in open loop so none the wiser to the overfuelling.

When we first fired it up, after a few starts it got reluctant to start. Plugs had got quite wet. Assumed that this was due to cold start enrichment and not leaving it running for long enough but now I'm not so sure. :-/

Then the unusual sound from the FPR.

I think I have something to follow.

Kevin

It definitely sounds fuel related... Just out of interest, did the plugs go back in the same places they were removed from after the compression test? That would rule out a dodgy plug as I assume the same cylinder is getting borewash?

[ians]

Are the plugs back to the originals now?  Its got to be worth eliminating that change - esp on no.1 as easily accessible and most suspect :-/

No leads dislodged at the DISpack end..?

[Kevin Wood]

It definitely sounds fuel related... Just out of interest, did the plugs go back in the same places they were removed from after the compression test? That would rule out a dodgy plug as I assume the same cylinder is getting borewash?

yes, after the compression test. Not after being dried out.

If my theory is right all 6 are getting hosed down with fuel and I suspect what happened to no. 1 is that it fouled its' plug so wasn't firing at all hence it was wetter than the others.

We shall see.

Kevin

[manny]

Can injecters let to much fuel into cylinder? If it was over fueling it would make a noise like your getting. Just a stab in the dark.