V6 erratic idling, cuts-out

[Mrs Feynmans Bongos]

A new Bongo season dawns, but mine is poorly so advice appreciated.

1999 2.5 V6 petrol, 69k miles, never missed a beat, including weekly local runs, until Jan cold snap
A bit of bonnet ingress, as a few inches of snow thawed at bottom of windscreen, overflowing the channels.
On its FIRST run after the snow, idled erratically, then cut out as wife gave way at first roundabout. From cold it now idles for about 5 mins, hunting between 500-2000 revs, before cutting out. During 20 mile run, ie up to temperature, it hesitates/sluggish on hills, cuts out at end of trip. I now have to drive two-footed (it's an auto).

Since Jan it has been serviced, plugs, HT leads and all filters replaced, no difference. I am now thinking a VACUUM LEAK somewhere (eg an orig. seal hardened/failed in the frost?), or issue with COLD START SOLENOID. Where could the vacuum leak be: throttle body, inlet manifold, crankcase? May need a garage to smoke test it?

Very grateful if any gurus have seen this one and can advise. Onset straight after a cold snap seems a BIG clue.

[mikeWalsall]

I could be wrong ... but to me it sounds more like ignition than fuel .. until you said it had new plugs / leads I would have said check them out and give it a spray with water dispersal fluid (WD40) as damp may have got in the HT system ..

You did not say if the dizzy cap / rotor had been replaced at the same time as the plug leads .. but I would have thought any damp in there would have been 'steamed' out with a warm engine .. still, a spray with WD fluid won't hurt ..

Have the plug leads been put back to the right firing order .. maybe a 'bad' new spark plug ..??

Cold start solenoid .. ?? never heard of one .. Petrol injection systems do not have a choke .. the temperature sensor on the engine cooling system sends information to the ECU to inject more fuel (to richen the mixture).. this is adjusted automatically as the engine warms up ..

[g8dhe]

Got to agree it sounds like Ignition, very much like the problems we had a year or more ago. I wonder if the change of leads was for a good quality set, there have been reports in the past of some leads available not being that reliable.

[mikeWalsall]

Did you clean out the gutter outlet ..??



When I had erratic tick over on my LPGd V6 ..I changed my Plugs .. dizzy cap .. rotor and used 'guaranteed for life' English made plug leads and they have been fine ..



BUT .. In the past I have also had duff spark plugs so now I always check the gaps 'just in case' ..

[Mrs Feynmans Bongos]

Thanks Mike, Geoff.

PLUGS: service replaced Iridium's (BKR5EIX-11) with NGK's (BKR5E-11). What should Spark Gap be?
I forgot to say that both the Distributor Cap +Rotor Arm were also replaced on service.

HT LEADs: these were £60 for a new set of 7. Fairly sure I got the order right, although it took me a while to find it online. Looking towards rear, is it LH/Drivers side 1,3,5, RHS 2,4,6, firing in that order?

I also found and cleared the Gutter drain hole.

Ok so no Cold Start thingy, I read that on a forum, but some folks don't seem to state their model
I will replace that idea with potential FUEL INJECTION fault. Are new replacements available, or are we talking recon/breaker? I cant find one on MazdaBongo.com, although VACUUM SEALS are there: Rocker set £90, Inlet Manifold L+R~£60. (Haynes manual generic sections gives those two as candidate faults).

I am thinking about getting garage to look at those next, am told they can use smoke to test for leaks.
Any further ideas greatly appreciated about what I can do to focus their effort, so minimise the costs.

[g8dhe]

Well the HT leads are the cheaper ones, but I wouldn't want to suggest replacing with the genuine Mazda ones at £200 without more evidence that they are the cause.

[mikeWalsall]

To the book .. the NGK BKR5E-11 sparkies are set to 1.1mm .. but as I run mine on LPG I find that it runs better closed down to 1.0 mm ..

Search (middle top) .. there have been a few posts on the V6 like ..

http://www.igmaynard.co.uk/bongo/forum/ ... er#p648223

[Northern Bongolow]

this will show you what goes where.

http://lushprojects.com/bongopartsmk2/c ... mgno=.html.

18-230 on here is the crank sensor, this tells the ecu what revs the engine is at, as its mounted at the front of the engine it is susceptible to water ingress, a remove and clean up is sometimes what is needed.

http://lushprojects.com/bongopartsmk2/c ... no=.html#2

[Simon Jones]

Photo of above item. Worth unplugging and replugging the connector a few times to ensure it's making a good connection.

[teenmal]

Before you start chucking money at this problem by guess work (no offence meant) it would be worthwhile letting an experienced Automotive diagnostics Centre have a wee look at it.

The fact that the engine is Hunting between 500~2000 rpm could be a potential danger to the catalytic converter.

[Mrs Feynmans Bongos]

Ok, I found the CRANK SENSOR connector, re-mated it many times but no difference
(With Dizzy cap off, I can reach it adequately from passenger seat, using head torch & wife's compact mirror perched on the fan cage)

Not sure what to try next, MOT due in a few weeks, garage are good but not a Bongo specialist. What should I suggest they try next (unless they have a better idea): ?smoke test? for SEAL LEAK, would fixing that be cheaper than FUEL INJECTION/PUMP fault?

Is there any point adjusting the IDLE revs, does something move the THROTTLE cable when cold/idling?
PS VERY grateful to Simon for those photos, also the exploded diagrams on Lush Projects.

[Simon Jones]

Where abouts are you based? There are a few places I would trust my V6 including Allan's in Plymouth and Discount Trucks in Newbury. If it's been laid up for a while over winter then the petrol may have gone a bit stale. Perhaps fill the tank with some premium unleaded and chuck in a bottle of Redex into the tank to give the fuel system a good clean.

[mikeWalsall]

Maybe double check the firing order ..and make sure the coil lead is in 'C' ..??

Firing order = One.. six .. two .. four .. three .. five ..



Right bank O/S (drivers side) .. Radiator = .. one .. three .. five



Left Bank N/S (Passengers side) .. Radiator = .. two .. four .. six

[Mrs Feynmans Bongos]

Firing order definitely ok: I just checked again, new HT leads all go from given numbers on Dizzy to Cylinders labelled as Mike's photo.

VALVES: do V6s have an EGR? I read on another thread these can stick ?open, could this/another cause poor idling, should I BLANK it?

I am in BEDFORD, MazdaBongo.com gives nearest specialist as "ContractMechanics" of Milton Keynes (15m), but their ad says "Full mobile servicing, general repairs". I was a bit sceptical about doing it all on jacks, has anyone used them, can you recommend or not?

Otherwise I may have 2 local options, Chris KEY of Wilden (who replaced an acquaintance's Bongo engine recently), LA Auto Services (solved stuff on my Focus). I have family in SW so could conceivably visit ALLANS: I tried to ring for advice but they never seem to answer. Sun is shining, so am getting a bit desperate now ....

[Simon Jones]

No EGR on V6 to worry about. Allan is a busy man so try his mobile as well or leave a message.