Auto Gearbox - under 2000rpm jerkiness

[Bongo Virgin 2]

Hello all

Just interested to hear people opinions about the problem I've just started to get on my Year 2000 V6 Bongo.

I went to Wales for the weekend and decided to run STP injector cleaner through it to check that all was clean with the injectors. (This may be irrelevant!)

The next day I was running down some longer hills at slower speed and the van started to jerk about a little like a misfire, but not as violent. I got the impression it was having trouble selecting or completing a gear change. It hadn't done it from stand still so I presume the problem was partly temperature related. As soon as I took the engine revs over 2000 rpm it performed fine, apart from increased jerkiness up at very high revs once. I don't know anything about Auto boxes but the problem felt a little like a slipping/bouncing Clutch.

Ironically I was due to get the Gearbox serviced by a specialist in Weymouth (The name escapes me) but I wondered what experience people had of this sort of thing so I can investigate part replacement (Possibly for the engine?) as well as the service. I live in the New Forest so I think the People in Weymouth are the most local.

Anyway, any thoughts people have would prove interesting.

Many thanks.

[Bongo Virgin 2]

Ok, a bit of an update.
The V6 Bongo went in to get the Auto box serviced last week. My wife was driving it and it performed true to form after about 20 mins. Anything under 2000RPM and it misfires a plenty. The gearbox guy new straight away it was engine related, got another guy to take a look and found the plugs to be dirty. He thought that was it but obviously that was just a symptom. I took it out again today and it is doing it quite consistently. if it's misfiring the accelerator won't really get you any power as it can't get the engibe revving. I have to use road speed and the gearbox to force the engive revs higher than 2000 and then it's driveable and exhibits no discernable problem. I have checked the distributor cap and all seems well enough, though there was a reasonable amount of scale on the contacts as there was on the Rotor arm.
I am now looking at taking it to SVS in Three Legged Cross, HDM in Ringwood or Hurn Autos in Hurn. The latter is the nearest. Their website says they're very experienced with Bongo's...anyone had any good experiences there?
I could change the cap, HT leads etc but am imagining it to be a sensor due to the sub 2000RPM bit.
If anyone has any thoughts after this update then I'm sure I'd welcome them.

[M 80NGO]

Hi, from what you've described i'd say its a dodgy plug lead but before you spend any more £££££££££ take off the dizzy cap and clean all the terminals and rotor arm next check that all the plug leads are connected nice and tight, its also worth checking the plugs individually as it only takes a hairline crack in the ceramic element or the little screw on plug top conneter to be loose to cause a misfire, if this solves the issue then i'd renew the whole HT components that i've just described, also if the van is mainly driven slowly, get her nice and warm then give it a good clearout down the motorway.

Hope this helps

[mister munkey]

I have a V6 MX6, similar engine, which had almost identical symptoms.
A £40 set of HT leads sorted it.

If they are original, try & get them checked. They can break down with age.

[Bongo Virgin 2]

Thanks very much for your thoughts. I'll take a look at replacing the leads, distibutor cap and possibly plugs too. The Distributor cap is original as are the leads I think. The Plugs are a couple of years old but it won't do any harm.
I'll let you know if it works.

[Bongo Virgin 2]

Ok, a little update.
I changed the HT leads, changed them one by one to avoid any muddling, and drove to work in it this morning. Now it misfires a little from cold but is still better at higher revs, though you can still feel a misfire. Lifted the passenger seat tonight and started it when it was nice and dark. I can see a little sparking around the coil, or the blue glow from where one is, so I'm presuming the coil is at fault, cracked maybe. Because it's dark it's difficult to see where the spark is coming from exactly. I'm assuming that I shouldn't be able to see any evidence of a spark around there whatsoever.
Does anyone know for certain that I shouldn't be able to see any evidence of a spark around the coil?
Thanks.

[g8dhe]

You shouldn't see any evidence of a spark around anything! Otherwise all that energy is being lost and not put into a nice fat spark inside the cylinder!

[teenmal]

Hi Bongo Virgin 2,

A wee tip that might help you,If you wait till its dark, get a spray bottle with water in it,spray a fine MIST of water on the leads/dis/and coil,any leaks will soon show up.

Mal..

[wishmaster]

Hi Virgin, while your at changing things i'd recomend replacing the plugs to 'bosch super 4's' got em in my V6 and i find them much better than the standard plug, a few other V6er's have got em in too £3.49 each on Ebay.

Izzy

[Bongo Virgin 2]

Thanks for all the comments. I'll try the water misting as I'd like to confirm things for sure. I couldn't be sure if there was a spark where 3 leads are clipped to the block last night when I had a look, as well as obvious sparking at the coil. Glad to know my suspicions that any sparking anywhere is bad.

Will probably go for those spark plugs too. Sound like a bargain.

[Bongo Virgin 2]

Well, well. Keeps getting more interesting. HT Leads changed...still misfiring, only differently than before....now sub 2000rpm too. JUst tried a new coil, all be it not quite the same as the old one. It's still arcing left right and centre...around the coil and even small ones across the HT leads to the head where they clip in. Could be down to the wrong coil I guess but now wondering if it might be some sort of earthing problem.

I have bought the Super 4 plugs to go in but am going to get rid of the arcing first.

Any thoughts anyone?

[teenmal]

Well, well. Keeps getting more interesting. HT Leads changed...still misfiring, only differently than before....now sub 2000rpm too. JUst tried a new coil, all be it not quite the same as the old one. It's still arcing left right and centre...around the coil and even small ones across the HT leads to the head where they clip in. Could be down to the wrong coil I guess but now wondering if it might be some sort of earthing problem.

I have bought the Super 4 plugs to go in but am going to get rid of the arcing first.

Any thoughts anyone?

Hi Bongo Virgin 2,

I would imagine that you will have to cure the leakage problem,but I keep thinking about the injector cleaner.Did you have the miss-firing problems Before you used the cleaner.

Cheers Mal..

[teenmal]

Well, well. Keeps getting more interesting. HT Leads changed...still misfiring, only differently than before....now sub 2000rpm too. JUst tried a new coil, all be it not quite the same as the old one. It's still arcing left right and centre...around the coil and even small ones across the HT leads to the head where they clip in. Could be down to the wrong coil I guess but now wondering if it might be some sort of earthing problem.

I have bought the Super 4 plugs to go in but am going to get rid of the arcing first.

Any thoughts anyone?

Hi Bongo Virgin 2,

I would imagine that you will have to cure the leakage problem,but I keep thinking about the injector cleaner.Did you have the miss-firing problems Before you used the cleaner.

Cheers Mal..

I would also fit your new plugs,the old plugs could be breaking down under pressure..

[g8dhe]

If the gaps on the existing plug are really, really way out you maybe getting the arcing because of that ie. no load so the voltage keeps going up until it finds a path, in which case you won't get rid of the problem until you replace the plugs.

[Bongo Virgin 2]

Thanks for the further comments. I have just fitted the new plugs and the misfire still seems to be there as before though I can't see arcing as it's still light. All the plugs that came out seemed fine, just with the fuel smell as you'd expect from incomplete combustion. Tomorrow see's the arrival of the new Distrubutor cap and Rotor Arm courtesy of Bongo Towers.

I'll fit those with crossed fingers. If they don't work then the fault must lie outside of the ignition and I'll be back to where we came in, wondering if that injector cleaner did something. I can't imagine how that could be causing the spark leakage though.

Mal: No I hadn't experienced the problem before the Injector Cleaner went through. My first thought when I got the original misfire was that the cleaner must have dislodged something but since I knew I was losing the spark I've assumed the two issues were unrelated and just coincidental. I guess the spark being the issue was compunded when I changed the HT leads as the problem stopped being under 2000rpm and when warm and instead became constant, from cold and even at idle. Obviously the new HT leads are conducting in a different way, or when I fitted them to the Dizzy cap they made a crack or something worse.

All good fun and not too costly yet....the emphasis on the YET as if the cap and arm don't fix it then I must need to be looking elsewhere.

Thanks for all the comments as ever.