Misfiring - Loss Of Power

[maghouse]

Hi guys, having a few problems with my trusty old motor. Never had this problem before in all the years of owning.

As above a 1997 VR6 engine regulary serviced etc.

What is happening - on power the engine splutters, like it is misfiring or not firing on all 6 cylinders. This is very apparent when the engine is under load, like driving up a hill in fith, starts to labour and misfire, pulling away in first gear and when the car is laden and driving up inclines - getting quite bad.

BUT - it will cruise lovely at 70 - 80 no problems at all, general driving is also fine, the odd hiccup but generally fine - only when you 'load the engine does it not like it.

Searching the forum, it seems the following could be at fault :

1. Spark plugs - recently checked on service and appear fine (probably 5 years & 50k miles old)

2. HT leads - never changed since acquiring the vehicle - garage did comment a few years back there was a bit of arching across the leads but never seen since

3. Coil pack - never changed to my knowledge - no noticable changes in the wet ie. cracked.

4. MAFF sensor (or is that MASS sensor - sorry - bit thick)

 

Anyone had this similar problem and solved it ?

 

Thanks for you help ...

[Guest MATT jr]

the 1st 3 are the most common problems, maybe worth changing them.

 

MAF sensor just causes low power output, does not cause spluttering.

 

MJR

[dipsomaniac]

could be a blocked or partially blocked injector.

[Guest Cepheus]

I'd say it seemed more like some kind of combustion problem ..... possible spark plugs, but more likely to be related to the fuel feed. As above I'd start with a blocked/dirty injector or 2. Like you say it only happens on load and maybe not enough fuel is able to reach the chamber in time for the spark? Have you tried a good old dose of RedX? I've used it religiously since I had a similar problem on a Volvo 850 and not had the same trouble since on any car (Also getting around 4-5 mpg more on average around town)

 

If this makes no difference then I'd definately reccomment changing the HT leads if they haven't been changed in nearly 10 years of use.

[MrT]

I have recently had such a problem in that the engine would start and idle, although it seemed a bit lumpy. Under heavy load (full car + bikes on back and roof) the car seemed harsh and used more petrol. Under driving on the flat at 70mph, it seemed that nothing was wrong. The car was drivable with one cylinder not working properly.

 

Basically the problems seemed the same as yours except my engine management was detecting a misfire. The warning light would come on, go off and flash.

 

This turned out to be a faulty coil, my model which appears to be later than yours, has one coil per cylinder mounted directly on the spark plugs. However as the symptoms are so similar, I would suggest that you have a problem somewhere in your coil or plug leads. Mine was not related to being wet, the coil was breaking down inside.

 

You could remove each HT lead in turn (obviously have the engine/ignition off when you unclip it) and see if one cylinder is misfiring as when you remove the lead from the faulty cylinder, the problem will not get worse. If you have lost a cylinder, don't drive to far as the unburnt petrol could damage your catalytic converter.

[johnb80]

3. Coil pack - never changed to my knowledge - no noticable changes in the wet ie. cracked.

Most likely a coil pack. V6's are notorious for it, see many other threads on this subject.

 

They can be fine but breakdown as the HT voltage rises i.e. when the engine is under load.

 

Regards - JB

[dipsomaniac]

if the leads are 10yrs old and were arcing a couple of years ago, i would start there and replace the leads. while replacing the leads i would also replace the plugs as they will need changing shortly - you are half way there while you have the leads off.

 

if that doesn't solve the problem i would then look at the coil packs before reading any fault codes and a possible blocked injector.

[sepulchrave]

Well my mine has similar problems which VAG-COM says is down to the MAF breaking down, I've disconnected the MAF and the misfire has cleared, I think that it's safe to say that the 10 year old MAF has about had it.

I'm gonna fit a new one anyway, let you know the results.

 

BTW can anyone knowledgeable confirm the rumour that the MAF element from a Mark IV 2.0 Golf is the same as fitted to my VR6 (I know that the housings are different)?

 

Apparently all OBDII VR6's (12V and 24V) use the same Bosch MAF element.

[maghouse]

Hi guys, many many thanks for the replies,

 

Will try the Redex to start with, then replace HT leads and plugs ..... then (hopefully not) the coil pack.

 

Will let you now how it goes :lol:

[johnb80]

If it's misfiring Redex ain't going to sort it for sure, don't waste your time or money.

 

Regards - JB

[Guest Cepheus]

If it's misfiring Redex ain't going to sort it for sure, don't waste your time or money.

 

Regards - JB

JB -

 

With the greatest of respect,

 

1) you dont know for sure! Have you inspected the car? No! so you can't know for sure!

2) it isn't a waste of time or money, because a possible cause of the fault could be a blocked or dirty injector preventing the correct amount of fuel entering the chamber. As for money -

Edited May 9, 2006 by Masked Marauder

[maghouse]

Hi guys, finally got around to sorting out the trusty old motor.

 

Tried Redex for a month or so - definate improvement but still not right - very lumpy & misfiring under load.

 

Bought a new set of HT leads today - fitted & WOW ..... the proverbial off a shiny shovel !!!!!

Drives an absolute treat - no hesitation, no lumps, no misfires and acceleration - did not realise it was so quick - clearly the old leads were never 100% from the day I got the car - but now ...... sweet as a nut and accelerates so smoothly and quick !

 

So guys - if yours is misfiring - gotta be worth changing the leads - BUT - a real bugger to do - need the correct tool and a bit of dismantling needed to get into the holes ... worth it though IMHO

 

Leads (all 6) OEM silicon leads cost

[mumof4]

Glad you got it sorted in the end..one question though.....what are HT leads?..

[maghouse]

Glad you got it sorted in the end..one question though.....what are HT leads?..

 

Spark plug leads !

[chazhead]

(H)igh (T)ension Leads

 

As Maghouse said, they connect to your spark plugs, if you have a petrol engine that is. They carry the high tension pulse to the spark plug.

[MrT]

The newer V6 galaxies don't have HT leads as the coils sit on each of the spark plugs. One less thing to go wrong or several more coils to go wrong depending on which way you look at it.

[azzbamf]

hi all.

 

I had problems with my galaxy v6 were it was sputtering or misfiring and had loss of power i searched on internet

for simular problems and took the advice of one of the comments adviced if the leads look older than two years old get them replaced so i did but that didn,t solve the problem i had the plugs done at the same time which came to

[mumble_bee]

I feel your pain !

some ppl are just t*ssers, judging a book by its cover.

[maghouse]

PMSL - what a thick twat :16:

 

Reading through old posts about misfires on a VR6 .... came across this post and thought .... 'bugger me that is exactly the problems I used to have' .... it was my old post from a few years ago - didnt even realise :lol:

 

Anyway, while I'm here - the trusty motor is playing up again ... bad misfire like it it is running on 5 so checked the HT leads straight off - multimetered them and all read about 5.8 - 6.0 so knew it was not them ... checked the plugs - what a mess one had no electrode and the gap I could measure with a tape rule .... so new NGK plugs all round - much better but still has a misfire I reckon - just not right ....

 

Gotta be the coil pack I think - so fix or replace ?

[seatkid]

Gotta be the coil pack I think - so fix or replace ?

Replace.....with a TDI... :16: