Wobble when idling (faulty injectors) Now Sorted!

[jasper5]

Hmmm, reminds me a little of my 407 DMF problem.

[martint]

Its a diesel. Thought they all had a bit of wobble as they get older

[Doggy]

Thing is it didn't until fairly recently and even now it doesn't do it all the time.

When it's bad, it reminds me of one of those daft american jobs with the r/c hydraulic suspension.

[steve_earwig]

Worth getting the injection checked out with one of them leak off test fings? Or perhaps have the injectors cleaned...

[Doggy]

Worth getting the injection checked out with one of them leak off test fings?

What's that then?

Or perhaps have them cleaned...

I've got the impression taking them out can be difficult, (siezed threads & the like), so it's lower down my list of options.

[steve_earwig]

You connect 4 little bottles to the injector leak of ports, crank/run the engine and measure the amount of fuel the injectors don't use - apparently it's the standard test on common rails to identify any injectors that have "issues".

[plod]

I've got the impression taking them out can be difficult, (siezed threads & the like), so it's lower down my list of options.

I've heard it's damn near impossible in many instances

I hear there is a garage in Wales that specialises in a drive in/drive out with a replacement engine service - something like £1500, which on the age of the 406's is probably prohibitively expensive

[Doggy]

Thanks for the info guys.
Been trying to get a closer handle on it's behaviour and the more I think I see a pattern, the more I am forced to conclude it's completely random.
Started & idled perfectly 1st thing this morning.
While driving gently round town warming up, (water temp 60-ish, oil temp cold), noticed 'running on 3 cylinders' type beahviour at 1000 - 1200RPM in 2nd or 3rd gear.
2 minutes later, pulls cleanly from 1100 in 4th, on full throttle!
Once warmed up, it's mostly been perfect today, just a hint of uneveness on a closed throttle.

If I get some time this evening, I'll hook up PP2000 & see if it tells me anything....

Gonna put the go-faster map back in too, mpg seems worse if anything on the 'standard' output & anyway, I've concluded I don't do patience too well.

[Doggy]

Well, I found 5 engine ecu fault codes logged.... but it turned out all were additive ecu related.

(A certain plonker wanted to try a 136bhp map and downloaded the original file last week - so it went into limp mode next morning, half way to work).

Cleared that lot & nothing returned.

Had a look at the live data - you can see the idling speed's unstable, but not much else of note. Fuel pressure, injection timing, turbo pressure, calculated injection volume all look OK, but TBH, I don't know I'd recognise incorrect value(s) if I saw them. Was hoping I might notice something different from before.

The one thing I did notice was the air flow, didn't notice the units, but at (uneven) idle the value was about 350, when I increased the revs to about 1000, the engine steadied up, but the airflow dropped to about 240. When you rev it up the value rises to over 1000. It may be that because the engine's 'hunting' at idle, you're getting a big variation in air flow, which appears higher than it really is....

Oh well, nothing ventured etc.

Nice to have a full set of horses back tho.

[Doggy]

You connect 4 little bottles to the injector leak of ports, crank/run the engine and measure the amount of fuel the injectors don't use - apparently it's the standard test on common rails to identify any injectors that have "issues".

Read up a bit on this & it does seem the way to go, (Thanks, Steve).

Anybody know what size pipe's needed, or where to get some?

Oh - & for anyone else wanting to 'try this at home' remember to plug the return line the leak-off pipes normally connect to.

[Doggy]

Was going to start a new thread, entitled, "Doggy's been for a leak", but in the interests of continuity.......



Did the leak-off test today, as you can see, there's a big variation. Weighed the bottles, (& and emtpy one to get some accuracy).

Injector No. 1 - 179 g.
Injector No. 2 - 207 g.
Injector No. 3 - 124 g.
Injector No. 4 - 153 g.

(Collected a total of about 800 ml during the test - ignore the middle bottle, it's still got water in it to help the rig stay upright).

The figures don't exactly bear this out, but the general impression was that cylinders 1 + 2 were about the same as each other, likewise 3 + 4, but the two pairs are very different. (I understand a healthy set should all be within about 10% of each other).

So, what conclusions can we draw?

Do I have TWO faulty injectors, (1 & 2)? Or something else?

Bear in mind this fault is intermittent, (and gradually worsening). Now, I think two intermittently dodgy injectors exhibiting the same behaviour simultaneously is vanishingly unlikely, so what else do they have in common?

The ecu generates two 80 Volt power supplies, serving injectors 1+ 2 and 3 + 4 respectively, but according to PP2000, both are reading about 79.5 V, under fault conditions. I know from experience that failing switch-mode power supplies can give the right voltage, but with a huge ripple content making the kit they power unreliable. Maybe that's what's happening here?

Anybody got any thoughts / suggestions regarding any of this?

[Doggy]

Oh & forgot to mention - carefully examined all electrical connections at injectors and ecu - everything looks perfect / identical resistances.

Started it with one injector disconnected - it's noticeably worse and you get the good old 'ANTIPOLLUTION FAULT in seconds, therefore I reckon that rules out any dodgy connection problems whiles it's running, as Auntie would let you know PDQ.

Then I went to the pub.

[Doggy]

* Bump *

Looking like it has to be injector(s).

I've read some horror stories, saying you can't get them out and seen other information that suggests it might not be too bad.

Anybody got any relevent experience / knowledge?

Any suggestions on where to get replacement injector(s)?

[Doggy]

Update.
New injectors £ 350+ EACH
Recon £ 180 + £60 deposit refunded on your old unit IF it comes out in one piece and can be reconditioned.
Also two rumours:
1) Recon = only the swappable bits changed, the innards can't be entirely replaced, therefore may not perform too well.
2) New = Recon, but in a Bosch box, cos they don't make new ones any more.

So I bought a 2nd hand set from Ade on the coupe forum. Came from a lowish mileage coupe that shed its cambelt, he was surprised to find these came out easily & reckons they couldn't have been in there long.



Started soaking mine in WD40 on Sunday, 2nd dose tonight, plan to do this daily until I try to shift them.
Off work next week, so wish me luck folks.....

[puggy]

Good luck getting them out doggy hope they turn out easier to remove than
you thought they would be , watching this thread with interest . Piccies
please when you do them .