Misfires On Petrol Engines

[marcr]

It seems misfires aren't uncommon but identifying the culprit is tricky. Even if a logical approach is taken to pin it down to just one part you end up checking all the components.

This poll is just an attempt to see which part people feel finally nailed it. :D

[sepulchrave]

marcr, your poll is fatally flawed.

 

I would need to tick FOUR of those boxes, I have needed all those components by now.

[marcr]

Ah, but that's the point. I'm trying to identify if it's a waste of time looking for one thing.

I appreciate that renewing each compenent will restore some efficiency but might not cure it on it's own but people will know what finally got it sorted for them. I'm still interested in people's replies. :D

Or should we bite the bullet and renew the whole ignition system when a misfire starts?

[seatkid]

Silly poll.

 

Everyone knows that when you get a misfire on a petrol engine, the recommended thing is to throw the car away and buy a brand new one.....

[mikej]

A good idea for us petrol heads but could we include lpg'd galaxy's as well or am i the only one ?

I have to admit the thought of fault finding on a diesel scares me and my pocket even more , one of the reasons i side with petrol , simple to fault find and a dam sight cheaper to repair i would have thought ! :D

[Stevoo]

whenever u get a missfire, i always replace plugs first as they are cheapest, also along with ht leads.

Coil packs arent cheap and id rather get a garage to confirm if they are naff before forking out.

 

But as i always say get your ecu read for any faults and go from their.

[sepulchrave]

Ah, but that's the point. I'm trying to identify if it's a waste of time looking for one thing.

I appreciate that renewing each compenent will restore some efficiency but might not cure it on it's own but people will know what finally got it sorted for them. I'm still interested in people's replies. :rolleyes:

Or should we bite the bullet and renew the whole ignition system when a misfire starts?

 

That's the point marcr, if you haven't replaced the plugs and leads you should do that first, if the misfire persists you should replace the coilpack (if you haven't already), and finally the Lambda probe if that's still original since it's easy to check by looking to see if it's the original VAG part.

The leads ALWAYS fail and are as such a consumable item which you should replace as a matter of course when you change the plugs.

Dodgy plugs and leads as well as age inevitably lead to coilpack failure.

Age leads to Lambda probe degradation.

I have recently changed my EMS temperature sensor as well because it was so cheap and was also bound to have degraded with age.

MAF will have gone by 100k and should be also be replaced if original.

If the car won't start at all or cuts out and won't restart for 15 minutes when hot you need a new CPS.

Batteries don't last long, and can give problems with the EMS when tired, so replace the battery if needed.

That summarises the consumable components which Motronic needs to do it's job properly, since I believe the TPS and stepper alone to be highly reliable (so far).

 

Anything else is denial, struggle at leisure with it or face it and act accordingly.

[MrT]

Just for those who did not know, the early MkII V6s (and other VW cars) were fitted with poorly manufactured Bosch coil packs (one per cylinder) which were recalled by VW but Ford failed to recall and refused to replace them. The exact details of the faulty parts were posted by myself and others somewhere on this forum in the past.

[marcr]

Thank you, you're right. Because i was on a tight budget i was looking for a quick fix with one component but truth is eveything is original and in need of replacing. Am looking forward to getting it all done soon and running super smoothly again.

[mk2vr6]

Because i was on a tight budget i was looking for a quick fix with one component

 

well theres one of your problems for a starter! you dont run a VR6 on a tight budget! :blink:

[POMPEYFAITH]

CPS ????? Anyone what is it

[mk2vr6]

CPS ????? Anyone what is it

 

crank position sensor

[ezetobebad]

I run a 2.3 LPG,

The plugs cost me

[ezetobebad]

I forgot to say, that on one occassion I replaced the coil & it still misfired. I then replaced the leads (one at a time) & that cured the problem. I then back tracked & swapped out the new coil with old coil pack & the problem reoccured. So out of the 8-9 coil pack I have changed, only once has the ht leads been PART of the problem.

 

happy new years all you gals.

 

eze

[CM2007]

A good way to start with a misfire is to firstly disconnect the coil pack (CAREFULLY, they are high voltage!) and turn the engine over a couple of times. If you find one or more of your spark plugs are dry, there is no or little fuel getting to those plugs and so may be looking at injectors, fuel lines etc. If all the plugs are wet, then you know the fuel side is fine and it's lacking the spark. When the HT leads failed on my V6, in the dark, when you had the engine running with the bonnet up, you could see tiny little sparks jumping from the leads to the engine cover, therefore earthing out at the easiest point so the spark wasn't making it to the plugs. (Don't touch the leads with the engine running when this occurs because you can get a little jolt off them, nothing too serious but if you are accident prone like me, it made my arm jump and I smacked my funny bone on the airbox lol!) This told me straight away it was the leads so it's a good indicator and quite easy to see in the dark.

 

Obvioulsy if the fault doesn't show as easily as mine did, then plugs are cheap enough to warrant trying (ensure if they are not pre-gapped that you do the gaps properly) I'm not sure what tests there are (if any) for coil packs but I'm guessing this would be the next port of call but a decent garage will probably assist with this.

As for the MAF, there is a default setting within the ECU which the car will revert too if the MAF is disconnected. If you disconnect the MAF and suddenly the car runs smoother, then it's verylikely that is your cause. Get it fixed soon though because the default in the ECU tends to make the car run quite rich and you'll see the fuel disappear!

 

Just my 2 pennorth!

 

Cars are often the cause of our woes but also our pleasures, most of the pleasure comes when you have cured the woes lol!

 

Mike

[marcostig]

[davie]

It seems misfires aren't uncommon but identifying the culprit is tricky. Even if a logical approach is taken to pin it down to just one part you end up checking all the components.

This poll is just an attempt to see which part people feel finally nailed it. :lol:

 

I finally found out why my gal was misfiring when i bought it around a month ago it came fitted with a gas conversion and ran great but i started to grow a misfire so i changed the plugs then the 2 plug leads the 2 coil packs and even the O2 sensor, no change i was going round checking every sensor conection whilst doing this i noticed that the manifold for the gas was loose so removed it and the car has run great since. It must have been drawing air between the two manifolds so causing the fuel mix to be weak.

[maghouse]