Cautionary note - air filter V6

[Ron Miel]

Our V6 has been rough running for the past two or three months - surging/stalling when LPG idling at warm up temperatures but smooth and power good in the normal LPG operating temperature range. Power down, and lumpy at all temperatures and engine load states on petrol. Both getting progressively worse. Seemed to be fairly clearly an EMS control struggle going on, so hoped I didn't have anything major to sort out, e.g., clapped out camshaft or cam followers.

I had changed dizzy cap, rotor arm, and spark plugs to remedy poor starting at the end of last winter, so it was not down to any of them. Coil seemed fine, and there was no sign of ignition harness insulation problems.

The air filter was last changed in 2009 at 79,000 km, and the van had done about 101,000 km when all this started. The air filter service interval is 50,000 km (5.,000 km in handbook is a typo), so it couldn't be that could it?

Well, yes it could! After running some injector cleaner through, which only marginally improved petrol operation, I eventually pulled the air filter element, and found the underside 70%+ choked by internal combustion particulates - smell them, and there's no doubt that's where they came from.

Changed the air filter element, and she now runs silky smooth, loadsa power, no surging, no stalling, on either petrol or LPG - but there is a bit more power on LPG (yes!), due to having slightly increased the plug gaps earlier, as recommended to give a bigger spark for better LPG combustion.

Conclusion - there's probably a lot more particulates around in the air here now, than there were in Japan, when the air filter service interval was specified - so 50,000 km is too optimistic by a factor of 2. Anybody else found the same?

MOT pass today at 104,492 km BTW, no advisories and the usual (lack of) emissions, tested on LPG

[JDS]

Welcome back Ron (David) not heard from you for a while.

[apole]

Hi Ron,

Glad you are doing okay.

I change my filter every year as they are pretty cheap and do get mucked up. I pay around £6 each for them.

I have also cleaned the air inlet pipework and the MAF sensor too, all fairly easy to do and although I can't say it made a massive difference, at least I know they are clean.

If the inlet pipework is oily, it maybe worth checking the operation on the PCV valve. I changed mine last year, it was easy and cheap (same as on an MX5) from info on another post on here.

Regarding the spark plug gap, my understanding was the gap should be reduced by 10% as the gas is a little harder to ignite.

I know discount have dismantled the inlet system on another V6 LPG bongo, they found it made a good difference to the running and especially idle when warming up as the idle control valve can get crudded up over time.

Good news now on the running and MOT pass, glad it's all going well.

All the best.

Andy

[dandemann8]

Nice to have you back, I've just installed a K&N in my V6 at a cost of £35 not cheap but seems to like it and you never have to buy another

[ThisIsTheSea]

Where did you get your K&N from? I have tried searching for a K&N for the V6 Bongo, but the only ones I can find are for the diesel. Does the V6 use the same one?

[missfixit70]

This one should help - http://www.igmaynard.co.uk/bongo/forum/ ... er#p493728

[dandemann8]

Where did you get your K&N from? I have tried searching for a K&N for the V6 Bongo, but the only ones I can find are for the diesel. Does the V6 use the same one?

If you quote the ref number from the above topic to most motor facors they should be able to get you one, it was £38 delivered (told them it was TRADE)

[Velocette]

Where did you get your K&N from? I have tried searching for a K&N for the V6 Bongo, but the only ones I can find are for the diesel. Does the V6 use the same one?

If you quote the ref number from the above topic to most motor facors they should be able to get you one, it was £38 delivered (told them it was TRADE)

worth seeing if Unifilter do an equivalent, would probably be cheaper and just as good, I've had one on the bike for the last few years.

Edit, second thoughts their car stuff is all sold by size etc and looks a bit specialised.

[ThisIsTheSea]

Cheers all - thanks for the info.

[Ron Miel]

Hi Ron,

Glad you are doing okay.

I change my filter every year as they are pretty cheap and do get mucked up. I pay around £6 each for them.

I have also cleaned the air inlet pipework and the MAF sensor too, all fairly easy to do and although I can't say it made a massive difference, at least I know they are clean.

If the inlet pipework is oily, it maybe worth checking the operation on the PCV valve. I changed mine last year, it was easy and cheap (same as on an MX5) from info on another post on here.

Regarding the spark plug gap, my understanding was the gap should be reduced by 10% as the gas is a little harder to ignite.

I know discount have dismantled the inlet system on another V6 LPG bongo, they found it made a good difference to the running and especially idle when warming up as the idle control valve can get crudded up over time.

Good news now on the running and MOT pass, glad it's all going well.

All the best.

Andy

Hi Andy,

Yes, you're right, of course - smaller plug gaps. Senior moment! As for all the other points on general crud and the PCV, it really is running so nicely at the moment, I'll put them on the list of things to do when I have time to check them out. Lot's of non-Bongo preoccupations hit us this year, gobbling up huge amounts of time - you know, family stuff - main reasons I've been AWOL here. Thanks for the greetings and hi all, though!

Interesting, there's apparently a K & M to fit a V6 now. Didn't bother to re-check as I already had my cheapo filter element on the shelf. Like you, I had also intended to change it annually. However, it was still there because it was in a whole set of service "consumables" bought from Ian for last year's service but which the cowboy who serviced my van then didn't bother to fit "because he didn't think they needed changing" - ignoring whatever mileage I might have planned for the period ahead.

Come to think of it, that's why I found myself changing the plugs back at the end of winter - he didn't consider they should be changed until the engine actually ran badly. Now I'm on this rant, I'll also add that his failure to properly bleed (because he decided to leave the degassing header tank to finish the job) after the coolant change he did, is still occasionally raising my blood pressure when I find that another trapped air bubble has finally found its way to the header tank. The coolant level suddenly dropped about another 100ml about a month ago - definitely no leaks, weeps or overheats, just insufficient bleed, not enough fresh coolant in, and small amounts of trapped air still working their way out. At least it has shown that the V6 apparently can take a bit of abuse in that department. I thought it had stopped months ago though, so hadn't done a Mazda-bleed myself, but seemingly it hadn't quite.

We live and we learn - shan't go there again.

Regards

David

[Ron Miel]

Our V6 has been rough running for the past two or three months - surging/stalling when LPG idling at warm up temperatures but smooth and power good in the normal LPG operating temperature range. Power down, and lumpy at all temperatures and engine load states on petrol.......
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Changed the air filter element, and she now runs silky smooth, loadsa power, no surging, no stalling, on either petrol or LPG - but there is a bit more power on LPG (yes!).........
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Well, there (of course) was an underlying reason for the power differential between LPG and petrol being the wrong way round but as I said, with all else being equal the good old J5-DE V6 nonetheless manages to maintain a high degree of smoothness on petrol, even when one of its six petrol injectors is, as I now know, completely blocked - more recently discovered, by Ian Taylor, during a cambelt and tensioner job!!! At least it's not filling a cylinder, the sump and exhaust with unburnt fuel.

There is just an almost imperceptible hesitation when accelerating away from a standstill on petrol but once the flywheel gets going, and there's some forward momentum, it feels pretty much as smooth on petrol as it does on LPG, five cylinders or not. The only difference then, as above, is a small reduction in pulling power when switching from LPG to petrol on the roll - plus the LPG consumption worsened recently, perhaps due to a resulting change in main ECU mapping, and the LPG ECU being piggy-backed on the main (petrol) one.

Ian Taylor doesn't like recon/cleaned injectors, so I've been looking for a breaker or similar replacement injector, without success. I then asked Mazda for a price - it would have to come from Japan, and costs an outrageous £360, including two O-rings, per injector (£340 without the O-ring), and I'm not even sure that includes VAT!!!!!!!!! Anybody know of another source, or a good place to get a blocked petrol injector sorted out?

Meanwhile, having used Wynns Injector Cleaner early on (twice) with little effect, I'm now half way through a tank of petrol with BG44K added. No real difference yet. Anybody had any real success with BG44K?