1.4 petrol, running problems

A

Axit

A2OC Donor
United-Kingdom
2003 1.4i petrol, 57000 miles,
Car was working perfectly then become hesitant and EML starting flashing, I picked up a new coil pack and tried replacing that which made no difference.
I took it to an Audi specialist, his diagnostics stated a misfire on cylinder 3, we checked the spark plug and tried a new coil pack and no difference.
There was a build up of oil in the cylinder, so we flushed it out with brake cleaner, put it all back and still no difference.
Finally with engine running we disconnected the injector on cylinder 3 and there was no difference, so we thought we had found the culprit.
Injector ordered £234 lighter, and we tried that, the engine idles perfectly, but when put under load it chugs to higher revs, its not nice and smooth.
EML after being deleted, came back on, so the car is indicating a mis fire on cylinder 3,

Any ideas would be gratefully appreciated.

Thanks, John
 
The car is 20 years old. I have a 52-reg AUA which needed all of the fueling and sparking bits replaced to get rid of a misfire and running issue. First question I'm going to ask. You have encountered this problem apparently just as we've entered a cold-snap, where low voltage can be an issue.

Is the battery in good condition - and if the answer to that is yes - are the alternator and starter-motor earth in good condition. About 4 years back I thought I needed new batteries when the cars stopped starting in a cold snap, whereas after new batteries couldn't start the car the starter earth became obvious as the problem. Cleaning this makes a huge difference. Remove passenger side headlight, and find the earth below the a/c and ABS pipes - the wire in black insulation from the starter motor leads to the front chassis leg where this earth is bolted in, and it needs to be unscrewed, cleaned up and refitted.

Thereafter - plugs and leads, coils/coil pack depending on AUA/BBY status, lambda sensor. Throttle body and EGR also needed to be cleaned / replaced.
 
Hi

So you could try moving spark plugs to see it moves cylinder ( I see you checked the spark plug but doesn’t hurt/cost to try). If you eliminate electrics, that leaves fueling in which case you could try moving injectors. Will need acces to VCDS to scan

J
 
Have you thought of looking for an air leak around the misbehaving cylinder?
It might just be a lean burn misfire ?
 
I`ve read all the above comments, and they are much appreciated.
I also think the problem is electrical. The battery is fairly new with no problems starting etc, alternator replaced last year.
I know a good mechanic who loves solving problems, very good at diagnostics, he cant fit me in till 14th Dec,
So that is my next plan.
I will update what we find for future reference.

Thanks, John.
 
Just to conclude this post, I got an experienced mechanic to look over the car, he found cylinder 3 was not holding enough pressure, his verdict is a head rebuild and skim, and new valves.
His guesstimate £1000-£1500, which I`m going to go ahead with, as I`ve become attached to the vehicle and a replacement car would cost me a lot more.
It`s too good to be scrapped.
 
I watched the first mechanic do the compression test and I thought it was OK too. The second mechanic said the VAG 1.4 platform is renowned for valve problems, so he knew what to look for.
 
Axit said:
I watched the first mechanic do the compression test and I thought it was OK too. The second mechanic said the VAG 1.4 platform is renowned for valve problems, so he knew what to look for.
Click to expand...

Only just seen this thread. I’ve chased random misfires on the AUA engine changing all the usual culprits to no avail. The problem turned out to be a sticking valve
Head off cleaned and polished all valve stems and cleaned guides. And clean and replaced a few valve lifters
Ran perfect after that

The ecu shuts the injector down after 400 misfires on any cylinder to protect the cat
I also fell for the injector faulty but used a second hand one so no big expense. It made no difference as the injector was not the root cause of the misfire

Paul


Sent from my iPhone using Tapatalk
 
Get a second opinion. Head gasket would likely show as a leak that could be traced. 57K engine would have had to be run hot, hot damn hot to damage the gasket.
Robin Cox has given a great response. Deproman also,.... there both right in what they say.

Oil in the cylinder you say, did you mean oil in the spark plug well?
You flushed it with brake cleaner so I suspect you mean the spark plug well.


If there is oil in there the rocker cover needs to get removed, cleaned and new bead of sealant. There is no gasket between the head and the rocker.
These engines dislike vacuum leaks.

Petrol Rocker Cover

I'm no expert, just wanted to pitch in a medium cost option.
 
Last edited by a moderator:
So I finally picked up the car today after the work.

The head was skimmed, 8 exhaust valves were replaced along with followers and guides, oil change and filter, fresh coolant, costing £1125.00.
The inlet valves were also checked and passed the inspection.

I`m very happy, although it`s a big bill, a replacement car would have cost me a lot more and it`s good to keep one of these vehicles on the road.

I`ve owned the car for over 10 years covering 30,000 miles and the highest I`ve ever seen the mpg on the DIS is, 44.7 mpg, I`ve just drove the car home covering 50 miles at a steady pace and the car is now showing 47.2 mpg, so happy with that figure.

John.
 
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