V6 Chugging, rev fluctuation and smoke

[tom_w21]

Hello There,

First of all, I'm relatively new to the world of Bongo's but enjoying it so far!

I've had a V6 Bongo (2000 circa 60K miles) for 9 months now and it has been running sweet as a nut until now.

Took it in to my local garage yesterday for MOT and service, they are not Bongo specialists but have serviced them in the past.

They MOT'd prior to service and found that it failed it's emissions (CO2), this was resolved after the service and it passed second time round.

Problem I noticed when I picked it up this afternoon was that:
There is (Black) Smoke coming from the exhaust
It is chugging a bit at low revs (needle fluctuates slightly
When I put my foot down, the gear change seems to be "hesitant"

Runs fine under normal driving really, but just the chugging at low revs and hesitance when you give it the boot.

As far as I can gauge from the garage, they have used a fuel treatment, changed plugs, filters etc... On the service record is something named as "Cat Cleaner Emissions".

I've searched the forums and looked at as much as I can, but generally more confused than when I started looking.

My first thought is to take it back, however I'm not sure I trust them with it now! I'm supposed to be running up to Mid Wales this weekend and was thinking a good run out and some injector cleaner might clear it up (wishfull thinking I suspect).

Any advice on what to do next would be welcome.

I'm based in Wimbledon and know of AVA Leisure & 321Away, I guess these are the best "local" specialists.

All the best

[New S Wales 2010]

Hi Tom

"Chugging" and hesitancy at low revs sounds very like the mis-firing I had due to my HT ignition. Smoke and emissions fit this too, as the mis-fires result in unburnt fuel going into the exhaust. See :

http://www.igmaynard.co.uk/bongo/forum/ ... c9#p549134

A good diagnostics guy should be able to confirm if you are getting mis-fires, (and measure the coil voltage to check this is OK). Trouble then is its very hard to tell whether it might be the distributor cap, rotor arm, or HT leads. If you can afford it you can order them all at once from www.mazdabongoshop.co.uk. Money won't be wasted as you should rule out any problems from these components in future if you are planning to keep the van for a while.

If money is tight try the HT leads first as this seemed to make the biggest difference to mine. You can fit them yourself, but only change one lead at a time as you can't get them mixed up !!!! Along with oil seals, this seems to be one of the few common problems on the V6.

[tom_w21]

Thanks for the reply, yes these were the things that I had in mind it could be from looking through previous posts.

I'm guessing here, but it seems logical, that the system was working fine until it was altered during servicing (changed performance overnight) so I guess the HT leads would be a good place to start looking.

Could the removal and attaching of the HT leads to new plugs during the service have upset the balance?

Looking on the BongoFury shop it seems that the HT leads are out of stock, anyone know where I can get them from?

Also, I would be greatful if anyone can suggest a good garage for diagnostics in the SW of London region?

Cheers
Tom

[Simon Jones]

Personally, I would return it to the garage, say that you are not happy since they have worked on it and ask for a detailed list of what work they did. If they have unintentionally caused a problem while in their care, then you should expect them to put it right (or pay for someone else to put it right). Explain the symptoms and take them on a test drive to show them what it's doing. If its mis-firing so it's not burning the fuel properly, their emissions tester machine should pick this up.

[tom_w21]

Thanks Simon

I've just taken it back into the Garage that serviced and MOT'd it, I can't help but feel like they were trying to fob me off...

Owner tried to tell me that it had almost no oil left in it when they MOT'd prior to service and had to top it up... I know this was a lie because I checked it myself (as i always do) and it was comfortably within the range.

He then tried to tell me that the black smoke that wasn't being chugged out prior to the service was because it now had some oil to burn rather than the fact it is now misfiring.

I demonstrated the chugging and rev fluctuation and I've asked them to look at it.

I told them what the common issues are i.e. HT leads, Distributor Cap & Rotor Arm (not sure if this was a wise idea). Said they are going to look at it, but i'm not filled with confidence to be honest.

This, on-top of the fact it was broken into last week (damaged lock)! It looks like it is going to be an expensive month!

Cheers
Tom

[rita]

Hi Tom,

Is there any chance that the garage might have overfilled with oil.

PS how much engine oil did they charge on the Invoice.

Cheers.

[tom_w21]

Hi

They did mention that could be the problem, but the problem does sound remarkably like that described by New S Wales above. Although it would seem strange that it just appeared after the service.

Cheers
Tom

[tom_w21]

Not got the invoice to hand, would over filling oil cause the smoking and misfires?

[tom_w21]

Just spoken to the Garage, they have said that they redrained and filled the oil <4.5ltrs.

They did some tests and found that when they disconnected cylinder 3 the engine behaved, albeit on 5 cyliners.

I guess this points to it being HT leads, Distributor Cap etc...? How easy are the HT leads to replace yourself?

[tom_w21]

Another question sorry: - Will driving it with the misfire cause any damage? Should it be gargaed until fixed?

[haydn callow]

A set of Mazda HT leads will set you back £190 and I think getting aftermarket cheaper ones is a waste of money. Dizzy cap about £50 and Rota arm about £20 if I remember right..

My V6 ran quite well on 5 cylinders for about 6 months so I doubt you will harm it.

One of my HT leads had burnt a hole right through the thick plug shroude......but it took me ages to find that fault.

Changing the leads is easy but do just one at a time....also get the Coil to Dizzy King lead included in your set.

Don't see how disconnecting a single lead can improve the running unless the leads have been mixed up and are not connected to the correct plugs.....See the Lush Projects diagram to see how they should be.

Are you on Petrol only or Petrol/LPG

[tom_w21]

Thanks Haydn, £120 for a set of leads from Mazdabongo shop.

How easy would it be to determing if the leads have been re-attach in the worng order? Are the reference # from the lush diagram on the actual leads?

Think I'll just get it to a specialist garage and get them to change the lot (Leads, Dizzy Cap , Rota Arm and coil) and just put up with a broken bank rather than a broken bongo.

[tom_w21]

Forgot to mention - Petrol only

[teenmal]

Hi,

If your vehicle V6 is only firing(running on 5 cylinders)I would definitely not use it.The unburnt fuel will be entering the catalytic converter,this will cause serious damage to the cat and the possibly of a fire.

Cheers.

[haydn callow]

Hi,

If your vehicle V6 is only firing(running on 5 cylinders)I would definitely not use it.The unburnt fuel will be entering the catalytic converter,this will cause serious damage to the cat and the possibly of a fire.

Cheers.

Yep !!! good point......are those leads Gen Mazda ones.......???

If your Bongo was running well when you took it for MOT and now it isn't.....I would look at the things they have done....Were the new plugs the correct ones ???? have they mixed the HT leads up......are all the vacuum pipes still where they should be......

I would be surprised if some part of the Ignition HT circuit just happened to fail at that moment........