Another thread about a misfire on cylinder 2 (1.4 AUA engine)

Before removing the head itself, the "cam box" has to come off. If, at that point, a compression test is made, that would rule in/rule out valves or cams/lifters wouldn't it? Cam/lifter problems could then be sorted, and avoid removing the head itself.
Mac.
 
Hi all,

Thought I should probably do another update on this, as things have improved.

About a week ago I decided I would do an oil flush, as there was a lot of black gunk visible through the oil filler.

I used a can of oil system cleaner and ran the engine as per the instructions. I then drained it (no filter change), and refilled with a menage of random engine oils - ends of cans from other oil changes - and ran the engine for just a minute or so as a sort of rinse, to minimise the amount of the cleaning product left in the engine. I then let that drain, with the car raised up at the front, for about 6 hours. I also removed the old filter at this point. I then refilled with some nice fresh oil of the correct spec.

Getting back to the misfire, next I cleared all fault codes and tried swapping the leads between cylinders 1 & 2 again, and immediately noticed a spark jumping from lead 1 (previously lead 2) to the cam cover.

Was delighted to have found the issue, and so let the engine tick over again until the misfire started. Stopped the engine and read the fault code only to discover that the misfire was STILL on cylinder 2. Not sure how that could be, given that lead 1 was definitely arcing out, but still, it was an excuse to go back to Euro Car Parts and get the leads replaced.

In the meantime the can of 'Wynn's Hydraulic Lifter Treatment' I'd ordered arrived (on another thread a someone reported curing a similar issue with that), so I swapped out the leads and poured that into the engine too. And I haven't managed to trigger the misfire since.

I'm not sure I trust that it's totally sorted yet, and I don't know if it was the leads or something gunged up in the head that was the problem, but it's certainly better. I do also have a new coil pack in the post, so I will swap that out too just to see if it makes any difference. Can always keep the old one in the car as a spare.

And after adding that stuff it's a bit quieter, too. It now only sounds like one 1980s Ford diesel with some loose nuts in the crankcase, as supposed to sounding like two of them. Progress, of a sort! ?

I do worry a bit that it seems so damn noisy - it makes the 2 litre SR20 in my other car sound like a well-oiled sewing machine. But I suspect until I can make it to one of the Bristol get-togethers and hear another 1.4 petrol for comparison, I can't really judge if it's an issue. Anyway, thanks to everyone for the help and advice.

Hi all,

Thought I should probably do another update on this, as things have improved.

About a week ago I decided I would do an oil flush, as there was a lot of black gunk visible through the oil filler.

I used a can of oil system cleaner and ran the engine as per the instructions. I then drained it (no filter change), and refilled with a menage of random engine oils - ends of cans from other oil changes - and ran the engine for just a minute or so as a sort of rinse, to minimise the amount of the cleaning product left in the engine. I then let that drain, with the car raised up at the front, for about 6 hours. I also removed the old filter at this point. I then refilled with some nice fresh oil of the correct spec.

Getting back to the misfire, next I cleared all fault codes and tried swapping the leads between cylinders 1 & 2 again, and immediately noticed a spark jumping from lead 1 (previously lead 2) to the cam cover.

Was delighted to have found the issue, and so let the engine tick over again until the misfire started. Stopped the engine and read the fault code only to discover that the misfire was STILL on cylinder 2. Not sure how that could be, given that lead 1 was definitely arcing out, but still, it was an excuse to go back to Euro Car Parts and get the leads replaced.

In the meantime the can of 'Wynn's Hydraulic Lifter Treatment' I'd ordered arrived (on another thread a someone reported curing a similar issue with that), so I swapped out the leads and poured that into the engine too. And I haven't managed to trigger the misfire since.

I'm not sure I trust that it's totally sorted yet, and I don't know if it was the leads or something gunged up in the head that was the problem, but it's certainly better. I do also have a new coil pack in the post, so I will swap that out too just to see if it makes any difference. Can always keep the old one in the car as a spare.

And after adding that stuff it's a bit quieter, too. It now only sounds like one 1980s Ford diesel with some loose nuts in the crankcase, as supposed to sounding like two of them. Progress, of a sort! ?

I do worry a bit that it seems so damn noisy - it makes the 2 litre SR20 in my other car sound like a well-oiled sewing machine. But I suspect until I can make it to one of the Bristol get-togethers and hear another 1.4 petrol for comparison, I can't really judge if it's an issue. Anyway, thanks to everyone for the help and advice.
Today bank holiday. Mon day and B4 I read your update I did a compression test on my engine this morning the two outer cylinders are showing 90 on tickover, the two inner pots are showing 60 and 80 the misfiring pot is the one showing 60, as soon as you increase the revs they both reach ignitable compression, so I have also gone out and purchased some Wynns, and put 40.00 pounds worth of the good stuff in the tank, unlike yours mine does not kick out any eml lights on the dash, but I will get it checked to see if I can clear any codes present, I'm sort of in the last chance saloon regarding the Wynn, s treatment, I'm hoping the valves are sticking rather them being damaged because of a past belt failure, we will see after a few hundred miles, I'm not holding my breath, looks like your prediction maybe correct Paul
(depronman).
 
I did a compression test a few weeks ago on my 1.4 petrol AUA engine. This was just a verification that the engine is ''healthy'', before I put major amount of money into the parts. All cylinders were around 9,5 with cold engine.
According to specs they should be between 10 and 15 with MIN 7 and with max difference between cylinders 3. Looks like you have a serious problem with cylinder 2 :(. I hope you will be able to sort this out with minimal costs...
 
I did a compression test a few weeks ago on my 1.4 petrol AUA engine. This was just a verification that the engine is ''healthy'', before I put major amount of money into the parts. All cylinders were around 9,5 with cold engine.
According to specs they should be between 10 and 15 with MIN 7 and with max difference between cylinders 3. Looks like you have a serious problem with cylinder 2 :(. I hope you will be able to sort this out with minimal costs...
So many do this compression test lately, I wonder of I should get it done as well.
Is there a how-to or without proper test tools it's a mechanic job? Cheers
 
Hi all,

Thought I should probably do another update on this, as things have improved.

About a week ago I decided I would do an oil flush, as there was a lot of black gunk visible through the oil filler.

I used a can of oil system cleaner and ran the engine as per the instructions. I then drained it (no filter change), and refilled with a menage of random engine oils - ends of cans from other oil changes - and ran the engine for just a minute or so as a sort of rinse, to minimise the amount of the cleaning product left in the engine. I then let that drain, with the car raised up at the front, for about 6 hours. I also removed the old filter at this point. I then refilled with some nice fresh oil of the correct spec.

Getting back to the misfire, next I cleared all fault codes and tried swapping the leads between cylinders 1 & 2 again, and immediately noticed a spark jumping from lead 1 (previously lead 2) to the cam cover.

Was delighted to have found the issue, and so let the engine tick over again until the misfire started. Stopped the engine and read the fault code only to discover that the misfire was STILL on cylinder 2. Not sure how that could be, given that lead 1 was definitely arcing out, but still, it was an excuse to go back to Euro Car Parts and get the leads replaced.

In the meantime the can of 'Wynn's Hydraulic Lifter Treatment' I'd ordered arrived (on another thread a someone reported curing a similar issue with that), so I swapped out the leads and poured that into the engine too. And I haven't managed to trigger the misfire since.

I'm not sure I trust that it's totally sorted yet, and I don't know if it was the leads or something gunged up in the head that was the problem, but it's certainly better. I do also have a new coil pack in the post, so I will swap that out too just to see if it makes any difference. Can always keep the old one in the car as a spare.

And after adding that stuff it's a bit quieter, too. It now only sounds like one 1980s Ford diesel with some loose nuts in the crankcase, as supposed to sounding like two of them. Progress, of a sort! ?

I do worry a bit that it seems so damn noisy - it makes the 2 litre SR20 in my other car sound like a well-oiled sewing machine. But I suspect until I can make it to one of the Bristol get-togethers and hear another 1.4 petrol for comparison, I can't really judge if it's an issue. Anyway, thanks to everyone for the help and advice.
Mowog, its almost a year since you sorted out your misfire I was just wondering the state of play with your car now is it still behaving re the misfire.
 
@Kramretsimis @mtl @Sylvester

Hi all,

I actually sold the car a week or so ago, but I just wanted to chip in here in case I can share anything that might the helpful.

(1) A compression test is certainly a good way to diagnose a stuck valve (i.e. stuck in the 'out' position / not sealing back into the head) or worn piston rings. I never did one because the problem was intermittent, and because I didn't have a compression tester with a long enough reach to get to the plug holes. But for those who haven't done a compression test before, you need to take out all the spark plugs, then one at a time push the tester against each plug hole while an assistant cranks the engine on the starter while holding the throttle wide open. That last point is quite important - before I knew any better, I confidently told a friend that his engine was scrap after doing a test without opening the throttle! Anyway, crank the engine until the needle stops climbing. Some compression testers come with nifty screw-in attachments so you can fix them into the plug holes, but I can honestly say from experience with older engines that one with a squashy rubber seal that you jam against the opening will work just as fine. I don't know if it's OK to do on a modern engine, but certainly on older stuff if I had poor compression on any cylinder I would then test again, but this time after pouring a tiny amount of oil into each plug hole. If the compression remains very low on one or more cylinders then you know you have a leaking valve.

(2) Broken valves are not a particularly common fault on any mass production engine, as far as I know, whereas a valve that isn't sealing for other reasons is quite easy to achieve with poor maintenance. My belief is that VW approved so-called 'long life' servicing on these engines as a sales tactic, safe in the knowledge that they'd have passed to third or fourth owners long before the sludge became an issue. Basically, sludge builds up in the engine because the oil isn't being changed often enough, and it blocks the strainer in the sump, and the oil ways in the head. The result is sticking valves, and worn lifters and camshafts. And that's why my engine sounded rough at tickover but fine (with plenty of power) at high revs, as the oil pressure rose.

(3) In my experience flushing and Wynn's Hydraulic Lifter Treatment really helped. In the months after doing all the work detailed on this thread I think the light came on three times, and the engine dropped into three cylinders just once. In all cases it happened when the engine was left ticking over or struggling at low revs for too long (when giving my wife driving lessons, for instance), which I think bears out my explanation.

(4) All that said, I would still start with the coil, leads and plugs. As a brilliant mechanic (my Dad) once said, "99% of the time when a car won't run, it's something electrical. And the other 1% of the time it's the electric fuel pump"

(5) If you do diagnose a sticky valve, and flushing / lifter treatment doesn't help, then the most sensible next step would be to take off the cam box to replace the lifters and camshafts (or get them reground, if that's possible on one of these engines). But really, these sadly aren't valuable cars right now, so if you can get the fault down to manageable proportions (i.e. a couple of warning lights a year) and emissions and performance aren't effected, you might be better just living with it for now.

I hope some of that is helpful. This forum was absolutely amazing in helping me out when I was having issues with my A2, and I just wanted to get a few thoughts down here for others who come across this thread
 
The symptoms you describe are exactly the same as mine albeit mine is the 05 bby engine with separate coil packs, I picked up a compression tester for a tenner at the car boot on Sunday with a screw in long adapter, I tested it running, not running and plugs out, each time 3 was showing lower readings, however I didn't try it with throttle open,? what is the significance of having it open, anyway I'll try the flushing and Wynns treat ment and see it if that helps, I hope so, I haven't done valves B4 so I don't fancy it, I'll probably see if someone can do them for me, thanks for the info, Mark.
 
The reason for opening the throttle fully is that you want the engine to breathe as freely as possible if you want to get true readings of the actual compression generated by the pistons. I think that it shouldn't make any difference if all you're interested in is relative readings (i.e. to see if one cylinder is worse than the others).

One low reading obviously means that the combustion chamber isn't sealing properly. That could be a worn bore, or worn piston rings (this is why you try the oil test), or a broken valve, or a valve that is no longer sealing properly. The last is far and away the most likely reason, in my experience. And that could be due to a number of things, the cheapest and simplest to fix of which is a simple build up of crud (technical term) in the head causing the valve to not quite close properly once the cam stops pushing on it.

All of which is a really long-winded way of saying that flushing and hydraulic lifter treatment are a great idea, because there is a solid chance they'll help, and they're much less hassle than anything else!

Hope you get it sorted :)
 
Back
Top