Misfire and Lumpy Idle

I have checked under the bonnet at night, cant see any sparks but get this is no guarantee that they are OK.
 


Yeah I dont think that test is conclusive. I've never seen any!

I found a misfire on a Polo this way, actually the spark earthed into my finger so I would have probably noticed it in daytime too.

Peter.

OK - Quick Update.

New HT Leads arrived and have been fitted and the news is…….. Not good!

Misfire is still there, I'm thinking possible WUR now, can anyone tell me what symptoms I would have if this was playing up????

Cheers

What are the exact symptoms again? Is it that your car is running rough when cold, ie the first 5 minutes or so of running, but then once its warm runs faultlessly? Or just rough running in general? Does it intermittently drop in power at high speed/load (eg cannot accelerate as fast as it ought to) or is it a blanket loss of performance over the entire range?

If it helps, you could bring it over and I could take a look at it. There's lots of things I'd be tempted to check:

* Compression check on all 4 cylinders
* Ignition timing, including mech and vac advance achieved
* CO during warm up and once up to temperature
* Fuel pump delivery rate
* Good look at the microfilter (the tiny one inside the fuel line just before the pump)
* A good look into the fuel tank, to look for dirt in the system, or rusty inside tank
* Electrical continuity at AAV and WUR
* Operation of the 5th injector

Check for simple stuff first like an air leak on the inlet manifold and associated pipes,this will cause a missfire too  :wink:
bert

To add to the list, swap test dizzy too.....

Burt,

I have checked all arounf the manifold and cant seem to find any leaks, will check again though tomorrow.

Paul the symptoms are:

Lump from cold, idling at about 500rpm until it starts to warm, the was a strong smell of fuel too but not noticed that recently.

They engine finally settles down to a slightly lumpy idle once warm (about 900 - 950 rpm), then once warm and the engine is under load and below 2000rpm it has a misfire, as soon as the revs build the misfire clears.

I cant decide if the car feels a bit slower too, but maybe that is my imagination.  Also not getting great economy from it (about 27mpg on a run)…

Any ideas????

Where are you based Paul???  Cheers for the offer of looking over the car.

Well, you need the idle and mixture setting up properly. Low idle when cold, could be dodgy AAV or its electrics. Misfire at certain rpm could be due to incorrect mixture, but more likely ignition timing out. I'm in Wirral, Cheshire if it helps.

Cheers Paul,

Might well pop over if I dont get things sorted this week.

When I last went to  the garage the messed with my emissions and idle speed, they would them down to as low as they could get them but not convinced the car has run right since!

The electrics to the WUR look a bit dodgy although they are all intact, sorry to sound thick but whats the AAV????

What condition were the sparkplug ends in?

They were fine, thought it may have been running rough but all a nice tan colour!

The plug leads do seem to have made a difference, the misfire below 2000rpm has actully disappeared, however, the misfire when it is parked for 20mins so still warm??????

I'm really    at the moment!  Think i'm gonna have to take Paul C up on his offer of having a look.

I'm wondering if it could be the WUR, i've tested the AAv and all appears to be fine, not sure where to go next!!!

The Campaigner said

They were fine, thought it may have been running rough but all a nice tan colour!

The plug leads do seem to have made a difference, the misfire below 2000rpm has actully disappeared, however, the misfire when it is parked for 20mins so still warm??????

still points to leaking injectors to me mate.

Cheers!

I've just not got the money at the moment! Where is the cheapest place to get the??  I'm thinking GSF unless any of you guys n girls have a better idea!!!!

would appear crazyquif is cheapest.
http://www.golfmk1.co.uk/

Volkswarren,

Thanks for the tip, a set of 4 injectors purchased this evening. Was gonna try the cheap option and buy 1 but not sure which one, if not more than 1, is causing the issue!!!

Fingers crossed now for a misfire free car!

Thansk Again, I'll update you as soon as I've got them fitted!!!

Hi, did you ever fix this? I've got similar problems (poor starting from cold, misfire at low revs particularly on overrun).

Thanks,
Duncan

Im interested too- my 2.0 8v has just been diagnosed today with an injector issue- the garage checked the plugs, leads and compression and so it could only be the injector being blocked or buggered?
It misfires and idles badly as above but still runs and revs fine and is ok through the gears.
If i take the injector out this weekend will an airline blast fix it or am i soon to be off to crazyquiff with my readies?!
Ive got the injector test downloaded but i think mines already been diagnosed as number 2 cylinder  :?

I'd also like to know if this sorted it as I've got horrible idling and cold starting.

I replaced all igintion parts today and noticed one plug was wet…I'm guessing the injector is leaking?

having read this thread during my luchbreak i thought id do some checks myself this evening as ive been having similar running problems…

checked the spark plugs, starting from the crankshaft end working left to right:

1st is fine
2nd is physically damaged AND covered in OIL
3rd is in a similar condition to the 2nd but no oil
4th is fine

any ideas anyone? seals? fuel/air mixture?…it does tend to sup an excessive amount of oil.

plugs have been in the engine for around 8,000 miles and engine was reconditioned in january, which is still under warranty…do i have a case for presenting them with the solution…?

cheers for any help / advice!