Engine misfire V6

[Eratosthenes]

We have a V6 that has run smoothly since we've had it.
A couple of weeks back I felt that I could sense a slight mis fire/uneven running whilst accelerating through say 1200 to 1800 rpm. However this morning it is pretty bad, at lower revs.
Later I will remove petrol filler cap to see if I am getting an air lock and will look for any obvious problems, especially around distributor and ht leads. I will run it tonight to see if I can see any arching.
It is a 2000 model with about 70k miles.
If there is nothing loose/falling off, I thought my first actions would be to change the plugs leads distributor cap and rotor arm.
There is just under half a tank of fuel, did think about filling it in case the existing fuel is suspect.
However I would really appreciate any advice or suggestions.

Thanks in anticipation,

Rich

[g8dhe]

Check the distributor and leads, especially where they go down inside the engine to connect on to the plugs;

[Eratosthenes]

Geoff,

Thanks for your reply.
I started off replacing the plugs, and I don't think they have been looked at for a while,
some were dirtier than others but the gaps were almost twice what they should be.
I noticed on one of the lead component that sits inside the head what looked like the
insulation had broken down but wasn't sure as I have never seen this before. I put some insulation tape over it, not
to insulate it but when I remove it again thought maybe I could see where it had arced through.

Just looked at your post and excellent example photo's and now realise that the ht leads need replacing.
Thanks for taking the time to reply.

Regards,
Rich GW0HDY

PS any recommendations for the ht leads.

[Simon Jones]

The best ones to get are the genuine Mazda leads but you're looking a the best part of £200 for the set. Some people have used Magnecor brand and have been satisfied with the results so it all comes down to budget. If you are running LPG you need the ignition system to be 100% which was why I went for the Mazda leads. The original ones lasted 10+ years so hopefully a new set will be good for another 10.

[Eratosthenes]

The best ones to get are the genuine Mazda leads but you're looking a the best part of £200 for the set. Some people have used Magnecor brand and have been satisfied with the results so it all comes down to budget. If you are running LPG you need the ignition system to be 100% which was why I went for the Mazda leads. The original ones lasted 10+ years so hopefully a new set will be good for another 10.

OK comments noted - appreciated, the main thing is I know what the problem is now (hopefully). Did you change the distributor cap and and rotor arm at this stage?

[Bvan]

Can I ask if there's any research into price/quality on plug leads? We're not talking about a high spec race tuned engine here. I'm intrigued into how £200 for a set of leads is good value, it's old technology with very low manufacturing costs. I don't imagine anyone's run their Bongo on a dyno to make a comparison on performance.

[Simon Jones]

There have been a number of posts on here in the past where people have bought aftermarket leads and have problems with the plugs not having the correct combination of straight connections (drivers side), right angle connections (passenger side), or being too short or in at least one instance, they were numbered incorrectly which resulted in a misfire. I don't think it's a question of the Mazda ones being high performance but they fit perfectly and just work for a very long time.

The next best set seems to be made by Magnecor which will still set you back £130 so it's not exactly a cheap alternative.

I think it's a case of you get what you pay for. Plenty of people on here have bought 'good value' suspension parts like ball joints and droplinks only to find they fail the MOT within a year or two due to the rubber boots deteriorating.

[g8dhe]

The other aspect is that yes the technology is old but some of the modern insulation products are not up to quality especially when subjected to high temperatures and covered in oil for may hours of continuous use!

[rita]

This should help you.


http://www.ignitioncarparts.co.uk/PartL ... 2728496%27

[Eratosthenes]

This should help you.


http://www.ignitioncarparts.co.uk/PartL ... 2728496%27

Hi Rita thanks for that - some difference in price!

[Simon Jones]

If you go for the cheap leads, do report back in few years to let us know how they're holding up .

[Eratosthenes]

If you go for the cheap leads, do report back in few years to let us know how they're holding up .

I certainly will.
When I remove the existing leads I will photograph them.
I have found it very helpful on this forum when folk have added pictures to their replies.
So in future I am going to keep a photographic record of any work I do - others may find it helpful.

[rita]

This should help you.


http://www.ignitioncarparts.co.uk/PartL ... 2728496%27

Hi Rita thanks for that - some difference in price!

No problem, have also found them very handy for the Rolls bit and pieces.

http://www.ignitioncarparts.co.uk/PartL ... 8100113%27

[Eratosthenes]

I have changed the plug leads, plugs and distributor cap, but failed with the rotor. I could not seem to be able to budge it at all. Does it just pull off?
However I re assembled ( with old rotor arm ) and took it for a drive. The "missing" seems to have gone but most worrying of all there just does not seem to be the power when going up hill, especially if I start driving from stop. I'm not really sure of where to go now, coil pack?. Any advice greatly appreciated.

[mikeWalsall]

The rotor is held on with two Phillips screws .. a strong magnetic screwdriver 'bit' is recommended ..





Oh ... I also used those blue "Made In England" guaranteed for life plug leads .