Project HaeThere! (Coupé restoration)

[jasper5]

If you think about it, it's unlikely to be injectors not working if you can smell petrol in the exhaust.

Just a guess this, but isn't it possible for an injector to fail 'open' i.e. let far too much fuel through flooding that cylinder?
Don't know how you could cut the fuel supply off to it though....

Well, another test to find a faulty injector, is to take off the electrical connector that goes to each injector in turn, so, this is the way to shut off a stuck open injector.....never heard of a stuck open injector.

When I get a 206 with a misfire, I first take off the electrical connectors from each injector in turn, as above, if there is no change in engine note when any single injector is disabled, that indicates the faulty cylinder.Vise versa, any change in engine note with an injector disabled indicates a working cylinder.

I do this because the coil pack is a complete unit of four cylinders, therefore you can't tell which cylinder is faulty.On the 206, you swap the injectors about first, as I said usually this fixes the misfire, but if the misfire is still there, it's the coil pack....saves buying a new coil pack at £60 unless you have to.

[mjb]

Well, another test to find a faulty injector, is to take off the electrical connector that goes to each injector in turn, so, this is the way to shut off a stuck open injector.....never heard of a stuck open injector.

I imagine an injector stuck open would throw petrol into the cylinder at an insane rate and my cat would have exploded by now

On the 206....saves buying a new coil pack at £60 unless you have to.

A 4-coil pack for £60 when a 3-coil pack for the V6 costs £153 (eurocarparts) Bastards!

Still I guess the V6 coils need to cope with sparking twice as quickly as the 206s...

[mjb]

6. New washer jets needed. The N/S one is rusted up and barely able to hit the windscreen. I'm going to get a set of Citroen mist type ones on there.
Ordered at the dealers, should be here Thursday

7. I'm firing on only 5 cylinders. Erk!
Bought an inlet manifold gasket and ordered another, so I can get to the rear cylinders now
Bought a set of NGK Iridium spark plugs from ebay, should be here soon
Just need some weather that doesn't suck so I can at least disable the injector on the bad cylinder - wearing glasses sucks royally when it comes to attempting to do stuff in the rain

8. Need to get my JVC head in there soon before I go mad
My line-out adapter has apparently been dispatched so I should be back on the good ol' mp3s tomorrow night

Also bought a few new screws for the engine cover. Don't like the nasty rusty ones - they ruin the looks Just need to figure out how to clean the cover now, especially the screw recesses

[Welly]

Getting there m, I really hope you can sort the iffy cylinder out - then you'll be able to relax a bit about it.

[mjb]

Aye, if I can't sort it I'm going to need to chuck the car on ebay before it blows up

[mjb]

Tried unplugging things this evening. Yanking the plugs to the rear bank had negligible effect except for the middle cylinder, but there was an effect nevertheless. I think. Damn V6. It's not like a straight 4 where you KNOW when you're missing a cylinder - seems this thing is quite happy to run with 2/3 of its pots missing without looking like it's about to leap out of the engine bay

I did however notice no discernible difference after I unplugged the front bank injector at the same end as the oil filler (n/s) other than the smell of petrol seemed to go from the exhaust. I've left it that way but I hope I've killed the right cylinder!!! Reckon I should try pulling enough pots so the difference is very noticeable?

It's a long shot, but I'm hoping it's all down to the spark plug hole being full of oil from less-than-careful filling (there's a lot of oily gunk around that end of things). My spark plugs arrived today so I'll try yanking the coil pack, cleaning everything up, and replacing the front plugs tomorrow evening.

One thing I did notice during testing is that when I revved the engine from opening the throttle by hand, I was seeing arcing between a clip or something holding the coil pack on, and the PLASTIC BASE (!!!!) of the coil pack's socket for the o/s rear ht lead . This occurred whether or not the ht lead was connected and only happened at about 3000+rpm. Coil pack in need of replacing? I hope not, it's a hideously expensive part!


I got my PC2-36-AMP today too. I'd have fitted it already if it weren't for the 2 flyaway wires marked 'earth'... Why aren't they connected to the earth line on the main plug? They're probably for what I suspect to be smoothing caps under a large shrink-wrapped section, but I dunno what to do with them. I don't know what I can solder them to and get some heat shrink around happily :/

[steve_earwig]

I did however notice no discernible difference after I unplugged the front bank injector at the same end as the oil filler (n/s) other than the smell of petrol seemed to go from the exhaust.

Doesn't that mean you found it?

...the coil pack's socket for the o/s rear ht lead

Perhaps not then

The arcing would happen at lower revs if the engine was under load, I was just thinking maybe you should run it in the dark and look for any lightening under there. I'm guessing the plastic now has a carbonised track on it, you need to try scraping/sanding this off (you never know) and getting the plug out to have a look.

Hold on a mo, what's the firing order? Are those two on the same coil??

[mjb]

Code: Select all

+-------------\
|              |
+-----------+  |
| | | | | | |--+
| | | | | | | BACK
| | | | | | |
+-----------+
         |||
+--------///+
|    __///  |
|  _/ _| _\ | FRONT
| <_><_><_> |
|           |
+-----------+

  /\     /\
  ||     ||
arcing   ||
         ||
        now
      unplugged

FUNKY ASCII ART!!!! (damn scroll bar in the way, i've labelled which is which)

Thing is, the petrol smell was still missing after I temporarily plugged the injector back in... It's so hard to tell when killing a pot makes so little difference... Everything I've found seems to be on the front bank, so different coils

[steve_earwig]

I'm afraid I can't get my head around that diagram but if you reckon the coils do one front and one back then it's that idea out the window. I suppose it would be a bit odd if they're right next to each other anyway. Hopefully things'll get a bit clearer once you get the plugs out (yeah, I know it's a pain)

[mjb]

I've been thinking about the arcing...

Would it not indicate one or both of the routes to spark on that coil (either the directly attached plug or the HT+rear plug) is giving so much resistance that the voltage generated by the coil finds it easier to jump the ~10mm through to the clip to discharge?

Then again it's only an occasional arc, not the 33/sec you'd get if it were always arcing at 3000rpm, so I think it could well be a red herring in this case (albeit a good sign something else is up I guess)

Where's jasper's experience when you need it?

Hopefully I'll remember to reset the trip computer before I leave for work in the morning. If I've disabled the injector on the dead plug I should get more than the 13mpg I've averaged since filling up 25 miles ago

[mjb]

got 16mpg on the way to work, although the traffic was light. I don't know what to make of that... Can't even tell what the engine sounds like under load either because of the stupid grinding wheel bearings

I did manage to fit my JVC head this morning. Well, almost. I forgot the fascia adapter so I've left it half wedged in the slot Got a buzzing from one of the channels and I've got no door speakers

[jasper5]

I was at the football last night

I don't like the sound of the arching.Can you take out the plug lead on the suspect cylinder, then stick a new plug in it, resting it on the engine (earthing it) and check for sparking with the engine running? The arcing could be caused by a faulty lead.

Steve makes a valid point, is the firing order correct? Is it possible for someone to have mixed up leads?

One thing that I would try, if it's possible.....you have one bank running perfectly? Try changing the coils over from the good bank to the bad bank, if the problem transfers, then you know it's something to do with the coil.If the problem is still there, try swapping leads on the faulty bank (at the coil end).

[mjb]

I don't like the sound of the arching.Can you take out the plug lead on the suspect cylinder, then stick a new plug in it, resting it on the engine (earthing it) and check for sparking with the engine running? The arcing could be caused by a faulty lead.

The leads only detach at the coil pack end

Steve makes a valid point, is the firing order correct? Is it possible for someone to have mixed up leads?

I don't think it's possible - the leads are only long enough to *just about* reach the coil pack. It's possible 2 of them may be able to be switched though, I'll have a play later. Mind you I don't know what the leads look like under the inlet manifold - it may turn out there's loads of slack under there. I'll have to look (why did they have to build these things so difficult to inspect?)

One thing that I would try, if it's possible.....you have one bank running perfectly?

I think the back bank may be working, but with the V6's ability to run happily with only 4 cylinders, it's hard to tell. I might try unplugging a known good cylinder so I drop down to 3 cylinders firing when I disable a second working cylinder. Surely that'll make a difference...

Try changing the coils over from the good bank to the bad bank, if the problem transfers, then you know it's something to do with the coil.If the problem is still there, try swapping leads on the faulty bank (at the coil end).

There's only one coil pack with 3 coils, and that's on the front bank. The rear bank has a "fake" coil pack with three non-detachable HT leads which go to the front coil pack

If luck would have it and I have a suitable spark plug socket in my set, I'm going to try changing the front plugs at lunchtime. See what I can see... I'm going to have to wait until the weekend for the rear bank - don't fancy my chances beating sunset on this one

[Welly]

Maybe you'll just find one or two plug wells are full of oil where the O-ring has perished on the rocker cover....it happens

[mjb]

Should there be spark plugs under the oil?

I eventually (had to use my torque driver as I was about to snap the allen key!) got the coil pack unscrewed, lifted it a couple of mm, dropped it because it caught on a pipe, and sent oil splashing everywhere It was *completely* flooded with oil! Used a whole roll of Bounty to soak up most of it, yanked the old plugs out (no idea what state they were in before the oil enveloped them...) cleaned up as best I could and shoved the new plugs in

Put it all back together, fired it up and once it had finished choking on the oil.....

No difference



Stopped the engine, plugged in the injector I unplugged last night , fired it up and

Nothing. Idling a little high at 1000rpm but it was doing that 1000rpm without shaking everywhere! Put in in 5th with the handbrake on, no shaking.

Took it for a drive... and... HOLY F*CK!!! I have me a ~200bhp V6 again It's amazing how I managed to forget about all that lovely ES9J4 power in just a fortnight because it scared the crap out of me like when I first got the saloon! Only this is worse because of the coupe's sporty suspension. I have engine braking again! Lifting off sharply in 1st is not to be recommended unless you like whiplash!

My god I'm a happy little bunny! Still think I should attack the rear bank at the weekend though. Might get me a pair of wheel bearings too now I know I don't have to buy a coil pack.