V6 issue with revs jumping up and down / stalling

[fargo]

I am having an issue with my V6 LPG conversion bongo, although the issue is the same whether on LPG or petrol.

All was running fine until a trip to France in September, you would be able to drive for 45mins to 1 hour no problem, then the rev counter starts to jump up and down (especially going up hills or under strain), if you get into a traffic queue it will then stall. I get out, leave it for 15-20 mins and it is OK again for another 45mins or so before it happens again. It is not overheating, all is fine on that front.

My garage has changed the spark amplifier (did'nt even know such a thing existed!), the HT leads, distributor cap and arm, but so far to no avail - infact it is stalling more often now, and also suffers from a sudden drop in revs when running from cold (it seems to suddenly pull back as you are driving then is fine again - all on petrol not LPG). The garage have run out of ideas despite experiencing the issue themselves, but I hold out hope that this can be fixed.

A friend suggested that it might be a sticky tappett issue (the LPG conversion does have a flash lube unit), but I was wondering if anyone else out there has any thoughts on where I can look next?

Thank-you very much!

[Northern Bongolow]

do a search on here (top right search tab).put in key words like stalling/missing/v6.
the v6 seems to be very touchy on the spark side of things, and requires a really good system to run well.
many peeps have swapped things around only to find they need to get original ignition parts not copy parts.
not having a v6 myself i would look at things like the speedo correction chip if it has one fitted.these can give nightmares. whats your alternator doing?. is it ok. next i would test the throttle position sensor.
maybe check the breather on the fuel cap, but you say it does it from cold so!!!.

there are some good v6 guys that will help shortly im sure.

[Northern Bongolow]

do a search on here (top right search tab).put in key words like stalling/missing/v6.
the v6 seems to be very touchy on the spark side of things, and requires a really good system to run well.
many peeps have swapped things around only to find they need to get original ignition parts not copy parts.
not having a v6 myself i would look at things like the speedo correction chip if it has one fitted.these can give nightmares. whats your alternator doing?. is it ok. next i would test the throttle position sensor.
maybe check the breather on the fuel cap, but you say it does it from cold so!!!.

there are some good v6 guys that will help shortly im sure.

[Northern Bongolow]

do a search on here (top right search tab).put in key words like stalling/missing/v6.
the v6 seems to be very touchy on the spark side of things, and requires a really good system to run well.
many peeps have swapped things around only to find they need to get original ignition parts not copy parts.
not having a v6 myself i would look at things like the speedo correction chip if it has one fitted.these can give nightmares. whats your alternator doing?. is it ok. next i would test the throttle position sensor.
maybe check the breather on the fuel cap, but you say it does it from cold so!!!.

there are some good v6 guys that will help shortly im sure.

[Ron Miel]

You've done most of the things I did to try to cure similar conditions - but in the end I simply found that a very prematurely blocked air filter was the main problem. Lots of motorway driving, collecting excessive HGV diesel particulates in the process, was probably the root cause. Anyway, changed the filter and she ran like a bird! Since discovered that many peeps ignore the air filter's prescribed service replacement interval, and change them at least annually, in response to modern UK pollution levels - makes you think! The air filter service replacement interval was written for Japan in 1995 and, although the place is very crowded, road speeds are much lower and emission controls are tighter.

O2 sensor (adjusts fuel mix by signalling the ECU, in response to detected oxygen content in exhaust flows) is a possibility but it doesn't sound quite right for that, to me - the variable onset is odd (and would be for a choked air filter, I suspect).

Spark amplifier - never heard of the need for one of those. Are you sure that isn't the cause, rather than the solution? ECU not coping with whatever its effects are, for example?

[rita]

You've done most of the things I did to try to cure similar conditions - but in the end I simply found that a very prematurely blocked air filter was the main problem. Lots of motorway driving, collecting excessive HGV diesel particulates in the process, was probably the root cause. Anyway, changed the filter and she ran like a bird! Since discovered that many peeps ignore the air filter's prescribed service replacement interval, and change them at least annually, in response to modern UK pollution levels - makes you think! The air filter service replacement interval was written for Japan in 1995 and, although the place is very crowded, road speeds are much lower and emission controls are tighter.

O2 sensor (adjusts fuel mix by signalling the ECU, in response to detected oxygen content in exhaust flows) is a possibility but it doesn't sound quite right for that, to me - the variable onset is odd (and would be for a choked air filter, I suspect).

Spark amplifier - never heard of the need for one of those. Are you sure that isn't the cause, rather than the solution? ECU not coping with whatever its effects are, for example?

Mazda call it an Igniter, its item 18-251b on the drawing..

http://lushprojects.com/bongopartsmk2/c ... o=.html#21

[g8dhe]

Mazda call it an Igniter, its item 18-251b on the drawing..

http://lushprojects.com/bongopartsmk2/c ... o=.html#21

Its also just a transistor that is used instead of a contact breaker B4-05 below;


It appears that there are other things called "Spark Amplifiers" according to a Google search, but the explanations are nonsense (at least the one I tried to read!) and the pictures look suspiciously like bits of well insulated wire! Seem to be marketed in the biking world a lot, where there is also much suspicion about them!

[mikeWalsall]

I remember the 'Norton' (load of rubbish) ignition amplifier for motor bikes ..

I had a Ford V6 where the revs 'pulsed' ie; raised / lowered on tick over but the engine ran OK on higher revs .. this phenomenon was also coupled to 'iiffy' gear changes ... like the box occasionally 'hanging' onto gears longer ...

Tracked both problems down to a (small) split in the rubber vacuum pipe from the inlet manifold to gear box ..

[cheffy34]

I am having an issue with my V6 LPG conversion bongo, although the issue is the same whether on LPG or petrol.

All was running fine until a trip to France in September, you would be able to drive for 45mins to 1 hour no problem, then the rev counter starts to jump up and down (especially going up hills or under strain), if you get into a traffic queue it will then stall. I get out, leave it for 15-20 mins and it is OK again for another 45mins or so before it happens again. It is not overheating, all is fine on that front.

My garage has changed the spark amplifier (did'nt even know such a thing existed!), the HT leads, distributor cap and arm, but so far to no avail - infact it is stalling more often now, and also suffers from a sudden drop in revs when running from cold (it seems to suddenly pull back as you are driving then is fine again - all on petrol not LPG). The garage have run out of ideas despite experiencing the issue themselves, but I hold out hope that this can be fixed.

A friend suggested that it might be a sticky tappett issue (the LPG conversion does have a flash lube unit), but I was wondering if anyone else out there has any thoughts on where I can look next?




Sounds familier


Dar

Thank-you very much!

[Ron Miel]

Mazda call it an Igniter, its item 18-251b on the drawing..

http://lushprojects.com/bongopartsmk2/c ... o=.html#21

Its also just a transistor that is used instead of a contact breaker B4-05 below;


It appears that there are other things called "Spark Amplifiers" according to a Google search, but the explanations are nonsense (at least the one I tried to read!) and the pictures look suspiciously like bits of well insulated wire! Seem to be marketed in the biking world a lot, where there is also much suspicion about them!

Thanks rita - and Geoff.

If it's what I think it is then, it's perhaps more appropriate to call it an "igniter" than a "spark amplifier". My V6 at least, has a contactless Hall effect distributor, where an integrated circuit within the dizzy cap is sequentially exposed to then screened from a magnetic field, created by a permanent magnet, by a rotating series of screens (vanes) and open gaps between the screens. Logically, that IC will only locally create a remote switching signal to trigger a solid-state on/off switch (the "igniter") wired into the coil's primary winding. If so, all the igniter is doing is to replace the switching action of the old fashioned contact breaker. That sound right to you Geoff?

Agree that there's a lot of gobbledygook in Google returns, regarding other types of "spark amplifiers" and, having read them, I would much rather think my engine had an "igniter" - that's why I queried it. Igniter makes it sound a bit like a jet engine too

[g8dhe]

My V6 at least, has a contactless Hall effect distributor, where an integrated circuit within the dizzy cap is sequentially exposed to then screened from a magnetic field, created by a permanent magnet, by a rotating series of screens (vanes) and open gaps between the screens. Logically, that IC will only locally create a remote switching signal to trigger a solid-state on/off switch (the "igniter") wired into the coil's primary winding. If so, all the igniter is doing is to replace the switching action of the old fashioned contact breaker. That sound right to you Geoff?

Has it been changed then ? The normal one in the V6 is a standard distributor as far as I 'm aware ( well not sure after 1999 it may have changed ?), although I think the 2.0 litre one perhaps has the Hall effect sensor as it has the extra connections see the Lush projects diagram and the wiring diagrams;
V6 Lush diagram http://lushprojects.com/bongopartsmk2/c ... no=.html#5 and http://lushprojects.com/bongopartsmk2/c ... mgno=.html
The wiring diagram doesn't show any connections to the distributor at all as its considered a mechanical part

Whilst on the 2.0 Litre FE-E Lush diagrams http://lushprojects.com/bongopartsmk2/c ... mgno=.html and http://lushprojects.com/bongopartsmk2/c ... mgno=.html
The wiring diagram does have the distributor with its extra sensor connections its B3-03;


But I can't say I have physically inspected either variety in detail.

Edit: Checking in a bit more detail there are two Cam shaft sensors on the V6 and one does have a sub-marking of DIS so maybe this is the sensor your referring to, but I can't see any equaivalent part on the Lush diagrams he says .... more to come maybe ....

[Ron Miel]

Yes, my "2001" (actually ex works 15/12/200 but showroomed until first reg the following April) V6 definitely has a Hall effect set up. Saw it when I changed the dizzy cap and rotor this year.

[Ron Miel]

Well I suppose the wheel was in regular use by 15/12/200 but I don't think Bongos were ex works that particular day.

15/12/2000

[apole]

Hi guys,

could also be heat related.

Another v6 lpg owner had issues after it had warmed up. It was eventually traced to the temperature sensor, this was starting off giving a good reading, then as the coolant temp rose it started going haywire and sending the ECU misleading info, causing very poor running.

The V6 has 2 coolant sensors. One is for the gauge on the dash, the other is at the top of the block drivers side under the inlet manifold, the latter is the one that feeds a signal to the ECU.

You can pick one up for around £30 so it's well worth checking this if all else fails.

Good luck and hope you sort it.

[flossie]

Hi guys,

could also be heat related.

Another v6 lpg owner had issues after it had warmed up. It was eventually traced to the temperature sensor, this was starting off giving a good reading, then as the coolant temp rose it started going haywire and sending the ECU misleading info, causing very poor running.

The V6 has 2 coolant sensors. One is for the gauge on the dash, the other is at the top of the block drivers side under the inlet manifold, the latter is the one that feeds a signal to the ECU.

You can pick one up for around £30 so it's well worth checking this if all else fails.

Good luck and hope you sort it.

Yep this was me all sorted after we changed it though Ady did do a slight adjustment for me when we were at Wellington Park back in the summer. Do let us know if this sorts it for you (hope so).