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Author Topic: Misfire  (Read 937 times)

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JohnM

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Misfire
« on: 09 November 2019, 15:13:27 »

Hi all.
Can anyone help me out with this one please.
2.5 pre-facelift (est).

Short version.
Misfire, feels to be sometimes running on 5, or maybe 4 and two halves.
This did clear (itself) but has returned, higher revs definately helps. Last trip (back from Cornwall) it was moderately uneven.
How to prove/what should do next.

Full version.
This reared its head just before a long trip at the end of October. Quite a bad and consistant misfire, intermittantly clearing and clearing with higher revs.  No EML.
The car doesn't get used much and the outing prior was for MOT and a change of track rod end, whilst there I asked them to change the oil & filter which I provided (saves my armpit).  Seemed okay on collection. No other work recently.
Wanting to check for possible 'oil wells' (N/S gasket has always had a slight weep) I set to do this the weeks prior to our jollies. The car actually went to a local diagnostic place for these check but at that time no misfire.  Clean bill of health later and with no misfire present nothing replaced (cam gasket given a 'its weeping a bit').
Trip to Cornwall, slight misfire present hundreds of miles later. Around Cornwall, pretty much 50/50 misfire present some of the time. Return trip about the same. The journey there, most of time there and the journey back was near full-on rain.
I've set about checking the HBV for leaks (although plenty of cool/warmth as required) and whilst I can't really say for sure (can't get right around it) it seems dry. Nothing noted from the car running stone cold to just warm frm the vents.  The dis pack (top) seems dry (there are one or two shiny parts to the body but I think that is just the pack shell - paper towel didn't shoe any wetness).
But (and there's always one) the sound deadening foam pack underneath the scuttle was wet and just about the whole of the metal body under the windscreen is wet/damp and rusty.  I've had to remove the foam pack to dry it (I doubt it'll go back unless an absolute) and dried up the plastics.  This, I think, is from the failing windscreen, some delaminations and cracks to boot.

How can I prove the actually cause of the intermittant misfire, what are the odds on a dead damp dis-pack and can these be replaced still ?  Given time/help will it dry further if wet underneath (where I can't feel).
Other thoughts ?

I appreciate this is going to take some time.
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Diamond Black Geezer

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Re: Misfire
« Reply #1 on: 09 November 2019, 17:26:23 »

Right, you've got the same as I have / have had before. If that foam's wet, it needs sorting, end of even if it's not the cause of your missing (though I'm 75% sure it is)
You need to get it when it's dry, get the scuttle trim off, and reseal the join between the 'left-hand 2/3rds' and the 'right-hand 1/3rd' which contains the pollen filter. Also, try and work out what kind of sealing you have around the base of each wiper arm, as these have a foam washer, but these can let water in too.

I think that's it. Sadly the DIS may be stuffed if it's been heavily abused )that's my issue, too  :'()

Also would like to know the state/age of
plugs
leads
DIS pack
rocker/cam covers
breathers
breather box

you say the rocker covers are leaking a bit, but what's 'a bit' so try and check each well for oil

If unsure the location of any of the above, just search, if no joy ask  :y
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Enceladus

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Re: Misfire
« Reply #2 on: 09 November 2019, 22:30:48 »

".... or maybe 4 and two halves" is a good description. The coil pack is a wasted spark configuration. So a problem can affect a related pair of cylinders, one from each bank.

The EML won't come on. Misfire detection is a feature of later OBDii cars.

The official Vauxhall diagnostic procedure is to replace the plugs, if no improvement replace the plug leads, if no improvement replace the coil pack.

From your description I'd say there is a good probability that your coil pack is toast. Best thing to do is to remove it, find the Bosch part number that should be on it and then buy and fit a new genuine Bosch part. Google the Bosch number. I doubt you'll find one from a dealer any more, but if you can it will certainly cost more than your car is worth.

There are three different patterns of coil pack on these cars. They are functionally the same but they are physically different as to the position of the connector, the shape of the connector etc.

Don't be tempted to drive the car with a failed coil pack. The misfire will allow unburnt fuel into one or other of your two cats and potentially destroy it. This cat(s) will cost a lot more to fix.
« Last Edit: 09 November 2019, 22:34:28 by Enceladus »
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JohnM

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Re: Misfire
« Reply #3 on: 11 November 2019, 00:14:07 »

I wasn't using the car (failed) other than to get home last.
The scuttle was off, how I found the wet top and foam pack.  That pack is now seperated and in a fairly poor state, I don't think it'll be going back on.  Yes, washers under the wiper splines - old but dry, any water was from the screen, many of the scuttle clips were wet.
I can seal the screen (of sorts) but I need to know everything else is running okay beforehand.
No work today, but tomorrow I'll see about re-plastic sheeting my makeshift weather protection (scuttle remains off) to test run the car properly (not just ticking over on the drive).  If dry and my sheeting redone clear of the engine the car should drive (plenum is still on).
Is there any other way to prove a dis-pack in-situ?
I like the 'just remove for the p/n', I can hardly see it let alone remove it (I'd like to think removing all the rubbish and plenum beforehand would be the answer but I read it is still a task).
How does the low voltage connector come off (which bits to pull/push/twist/yank) if my type has that connector coming in from above down to the o/s of the dis-pack (to check water isn't sitting in that socket) ?
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Enceladus

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Re: Misfire
« Reply #4 on: 11 November 2019, 03:07:39 »

Here is a link to the coil unit that might be on your car. Or another here. It's the most recent version. The Bosch part number is 0221503017 (GM# 90541062).

Observe the connector in the photo. It has oval ends.

Bosch 0221503010 (GM# 90511450) has the connector in the same place as the one linked above, however the connector has flat ends.
Bosch 0221503002 (GM# 90444184) also has a flat ended connector however positioned on the wall of the unit at 90 to the plug lead pillars.

Using that information you might be able to tell which one is fitted to your car, without removing it. Feel for the plug with your fingers. Should be a tab on the loom mating plug that you depress with your finger and the plug pulls off. Four awkward to reach bolts secure it to the back of the nearside head. Might be easiest if you use a 1/4" ratchet to loosen the bolts and then remove them by hand, or you'll likely drop the bolts somewhere you can't see.

There doesn't seem to be any real way to test the coil pack. Sometimes they are obviously damaged.
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Re: Misfire
« Reply #5 on: 11 November 2019, 08:47:56 »

Your dis pack is clearly toast ;)

Yet another case for removing the foam. No foam means no water collecting at the Dis or coil packs, which means no problem.

The screen weather strip isn't stuck on, it merely clips into the screen frame. The best you can do is scuttle off and make sure both screen frame and weather strip are correctly fitted. Oh, and remove the foam ;)
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Diamond Black Geezer

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Re: Misfire
« Reply #6 on: 11 November 2019, 08:50:54 »

Yup, very stuffed ones through age look 'burst' and rusty, however shorting for any real length of time will leave a cosmetically nice exterior but stuffed internals.

I found one for about 40 brand new Bosch, so just get looking out there and you'll find one at the 'right' price for you. I'd guess yours is the oval plug.
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Nick W

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Re: Misfire
« Reply #7 on: 11 November 2019, 13:45:51 »

Your DIS pack is almost certainly the problem. The scuttle needs to come off to change it(which isn't a nice job), so you can remove the foam and seal the wiper holes while you're at it.


I'd budget for new plug leads as well, you only want to be in this area once.


Any motor factor will get the parts for you, although a Bosch DIS is worth the extra money.
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Diamond Black Geezer

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Re: Misfire
« Reply #8 on: 11 November 2019, 23:36:04 »

and if thats what you do (and I know it sounds obvious but...) make sure you know what lead went to what plug, you dont want to fire the car up and she's missing horribly...because you got a couple of leads the wrong way round...not that I ever did such a thing, ever....ever  :y

( i think i got the whole thing 180 degrees wrong, so no single wire was in the right place  8))
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JohnM

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Re: Misfire
« Reply #9 on: 13 November 2019, 18:32:33 »

Well the plenum is off.  But I'm unsure how much space I've really made for myself.

I'm considering removing a lot of the (air) pipework and maybe some water feeds too for some access.  Is this a good plan? (I might be asking more daft questions later, like where did this come from!)

I still can't see all 6 HT lead tops nor the dc connector - too much stuff about.  I've split the inject connector which is one less thing.  Servo air pipe next largest thing in the way.

Unlikely any work being done now for a few days (I might split the plenum for a cleanup, although the breather pipework so far looks dry and clear).
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Re: Misfire
« Reply #10 on: 14 November 2019, 13:44:31 »

Disconnecting coolant hoses doesn't help with the DIS.
The main vacuum pipe is flexible enough to bend towards the other side of the car and tie out of the way.


Removing the DIS bolts requires 1/4"drive torx sockets, and wobble drive extensions. One of the four bolts has extremely poor access for removal, and is even worse to refit - I leave it off.


It's possible to swap the plug leads around on the DIS with everything assembled, although I wouldn't recommend it. I did it in a carpark with a hot engine when I realised the misfire was incorrectly fitted leads. That's the second most uncomfortable job I've done; the worst was balancing and adjusting the carbs on a Rotax, which is done with the engine running and the prop next to your elbow.
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JohnM

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Re: Misfire
« Reply #11 on: 15 November 2019, 16:32:07 »

Cheers Nick.
Coolant pipework left as is.
I've released one more air pipe (I wonder if I'll remember where all these go!) to the metal gizmo near the FI rails (what does that do?) and also removed the cable tray.
I now have as good a access as I can.  HT lead tops marked up, OVAL connector off and now 6x HT leads disconnected (nos 4 & 6 removed, 2 out of the way). I can't read dis the p/n yet. I can only imagine where the two back bolts live.

E10 for the easiest bolt, my 3/8" just goes on okay but I need to get a 1/4" E10 and a 1/4" wobble as I don't have one.
Do I really have to go to Halfrauds?
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Re: Misfire
« Reply #12 on: 15 November 2019, 17:19:54 »

Cheers Nick.
Coolant pipework left as is.
I've released one more air pipe (I wonder if I'll remember where all these go!) to the metal gizmo near the FI rails (what does that do?) and also removed the cable tray.
I now have as good a access as I can.  HT lead tops marked up, OVAL connector off and now 6x HT leads disconnected (nos 4 & 6 removed, 2 out of the way). I can't read dis the p/n yet. I can only imagine where the two back bolts live.

E10 for the easiest bolt, my 3/8" just goes on okay but I need to get a 1/4" E10 and a 1/4" wobble as I don't have one.
Do I really have to go to Halfrauds?
You'll have to buy them somewhere, the 3/8" won't go on the front screw heads. It's a tricky job, done partly by feel. Good luck! There is good guide in the maintenance section.
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Re: Misfire
« Reply #13 on: 15 November 2019, 21:52:13 »

Ok, as I've done this job myself as recently as yesterday, I'll chuck my twopenneth in  :y This is from my own experiences of making mistakes and learning as I go.

If you're worried about what hose/wire goes where, don't feel stupid for labelling things. HT leads I label 1-6, and why not?, other stuff I'm pretty used to now I can tell by just looking at it.

The breathers, there are four, the large diameter 'Y' is easy, only one place is can go on the plenum, there is one similar-diameter one - this is the gearbox breather, and can be bent out of the way wherever you like, forget about it. The two smaller breather pipes is easy also these also go on the plenum between where the 'Y' sits - trace them back the one that goes to the breather box on the left, goes on the leftmost on the plenum, the one that goes deep elsewhere to the right, goes on the rightmost one. easy  :y

Pitfalls, forwarned is forearmed... try and get the plenum on square when refitting, don't squirm it round too much(there are locating pins) the reason is the large o-rings can be dislodged, you won't realise and an air leak will result, causing poor/lumpy runnning, and the nearest object to be hurled across the driveway.
-The HBV (google it) has a fairly delicate spigot and vac lone on the top it's not impossible to snap this whilst diving you hand in behind the engine. Be careful. Again, vac leak and hot cabin will result!
-Torque settings - DON'T attempt to guess when doing up studs in the plenum, it is alloy, soft and easily stripped. Halfords torque wrenches are top quality, made in England (probably by Norbar), last a lifetime, and will save you many headaches over the years. I use mine as often as I can.
-You need more silicone when sealing the scuttle than you think. I have had about 10mm thick splodge and it's still not enough.
-Photos. Similar to labelling, don't be afraid to take pics as you go, it can be a real aid, also some bright yellow insulating tape on the plugs, especially the one that goes back right of the plenum (part of the multiram setup) doesn't go amiss when it's 10pm and you can't find it because it's dropped behind everything you've just assembled.
-you don't mention removing the scuttle for the job - I'd assume you have/will, depending how far down you have gone, it may be worth it. If you go right down to the 'cylinder heads' then no need, however removal and re-sealing 'futureproofs' it. You don't want to fry your lovely new DISpack when it rains!

Halfords Advanced tools. many on here, and many pro mechanics use them. It may be annoying if you already have a decent set of sockets in your possession, but the t-torx, e-torx, deep drive and impact drive sockets are very useful, and any modern car will have a plethora of torx, whether you buy just 'a set' of Torx, or an entire 170/200 piece socket set, just get them, rather than one socket here... one extension there, it soon gets annoying having to drive out for a slightly larger hex bit when the light's failing and the car's still in bits. Its near xmas there's always a sale on, never pay full price.  :y

Just some thoughts for you, take or ignore what you wish  ;D
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JohnM

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Re: Misfire
« Reply #14 on: 15 November 2019, 23:01:56 »

Post #3 I had the scuttle off.
It is all dry and shiney now on the garage floor - less the foam pack that is sitting in a bucket not dripping on the carpet.

Oh I'll take any advice/help/thoughts available, if I knew it fine, if its new to me then good.
I have a half-decent tool setup, but I don't have everything by any stretch, and I'll buy in what I need. My torx sockets happen to be 3/8" and my 1/4" setup is missing any wibblies.
Breathers won't be an issue, obvious stuff shouldn't be but I've got what feels like half a garage floor of stuff that belongs in that engine bay and I'd like to get it back in the right order.

I'll test out Halfrauds tomorrow - but the local branch has a pretty bad rep from my last few visits,
- like, "no sir we don't seem to have that in xx mm, but here's the next one up that'll do" (it was yy mm)
- and, "if we have them they'll be around here somewhere, oh I'm surprised I thought we would stock those."
I have grave doubts about asking for a 1/4" E10, probably be offered a 1/2" E8 !  They might have some 1/4" wobble extensions.   

What silicone did you use and did you squeeze it up the seal or over the scuttle top (over the clips) ?
Maybe I should get the windscreen changed - I should check how much the ins. are going to charge me (I wasn't going to keep the car!) - perhaps Mark knows someone to use  :'(
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