Power loss (V6)

[mr_marrakesh]

Hello, I've been having power loss issues with my V6 (it has been converted to LPG but I don't think? it's an LPG issue).

A few months ago I noticed that sometimes when I pressed the accelerator it was stuttering and not producing much power. It seemed to be when it was a damp day. This was on LPG, if I switched to petrol that seemed to cure it. Then I’d switch back to LPG after a few minutes.

But it got worse and for about the last month it seems to have permanently lost power still stuttering but also constant power loss. Getting up hills is a struggle. This is using petrol or LPG although sometimes switching to petrol seems to help a bit but sometimes not. Also it’s knocked the fuel efficiency down by about 1/3 I’d say. Also if it's been straining to get up a hill and I stop at the top there's a strange smell. The only thing I can compare it to is the wax used for waxing leg hair with! Also the last week or so it's sometimes struggled to start. I have to turn the key for 10 - 20 seconds. The gearbox seems fine but it's having to kick down the gears a lot to get enough power.

I took it to my local mechanic, he said he'd checked all the basics and everything was fine. He's put a engine cleaner in the petrol tank and told me to run it on petrol for a week and see if it gets better but I'm not hopeful. He said if not he'll have another look but the remaning things to check are the expensive things.

Has anybody got any idea what might be wrong with it so I could give my mechanic some pointers? Thanks.

[mikeWalsall]

My 1998 V6 used to be a bit hesitant when initially switching over to LPG while the engine was still 'coldish' to the point of cutting out in stop / start traffic ..

The V6 ignition system as been reported as being a problem with LPG so I changed the .. Dizzy cap / Rotor / plug leads and NGK spark plugs (which I closed from the recommended 1.1mm to 1mm) ..

The difference was remarkable .. but there again given the age of most of the old ignition bits they where due for renewal anyway ..

[g8dhe]

You hint that it seemed worse on a damp day ? Which might suggest distributor or leads being a problem, and I understand that LPG also needs the spark system to be in tip top condition to work well. Perhaps worth checking the leads and plug sockets for any damage and maybe spraying some WD40 over the distributor when its dry and seeing if it leads to any improvements before replacing ...

[Simon Jones]

When was it last serviced: air filter, spark plugs etc? I agree with Geoff that it sounds ignition related if it's not right on petrol & worse on LPG. Personally, I replaced all 7 HT leads, rotor arm, dizzy cap & plugs before I had my gas conversion as LPG is much more susceptible to a weak spark.

[Jim the Box]

Simon and Geoff, are spot on, I had the same issues a while back and got the same advice from them both, I fitted a new set of magnacor leads and upgraded the plugs, (not cheap) the mangacor leads are less expensive than a set of genuine Mazda leads but still were about £130, spark plugs were
NGK LPG 1 think they do about 60000 miles before they need replacing.
Took mike's advice about the 1mm gap on the plugs and never had any further issues

[mr_marrakesh]

Wow, thanks for the speedy advice everyone. That gives me something to talk to my mechanic about.

It was serviced in April and I assume had spark plugs and air filter replaced but I don't know for certain, I'll have to ask.

Thanks again, I'll let you know how it goes.

[mikeWalsall]

As standard NGK spark (ie not Iridium) plugs are relatively cheap at around £10 for six .. and so very easy to change .. it's worth while changing them routinely each year when you have a full service ..

[roosmith]

Hijacking the thread slightly - for those who have used the NGK LPG plugs - are they worth the extra money? Or is a good set of standard plugs just as good?

[teenmal]

As standard NGK spark (ie not Iridium) plugs are relatively cheap at around £10 for six .. and so very easy to change .. it's worth while changing them routinely each year when you have a full service ..

Its not advisable to leave the spark plug /glow plug holes exposed while working on an engine.

[mikeWalsall]

Umm .. I wonder how many change one spark plug at a time .. saying that though ..

I once rebuilt a Ford V6 RS 3100 engine and when fitting the spark plugs .. un noticed by me .. a top had un scewed from one of the new plugs .. sods law dropped down an open plug hole ..!!

[windywatson]

I've been running my LPG converted bongo now for nearly 8 years on the recommended plugs for the vehicle without any issues.
I must say however when I first had the LPG conversion done I had a number of teething issues, not really solved by the original installers. I found a local LPG installer who has been installing for many years (not just jumped on the band waggon when it became popular) & who I consider to be very good & meticulous in his work. Once he had gone through the system, made adjustments to the install & tweaked the settings the van ran great & with regular LPG serving has done so since.
Having read many threads on here I do feel it is the luck of the draw with LPG installers, so get recommendations from members as to who is good with LPG out there.

cheers

[redz79]

Hi
My v6 runs great on lpg until it gets down to the last light on the gauge the the tickover becomes lumpy and cuts out sometimes, the tickover speed is lower aswell, fill it back up and it runs fine again, on petrol it runs fine , at the next service dizzy cap leads and rotor arm will be replaced but what plugs to use, i use irridium plugs in the bikes, are special lpg plugs worth the extra
Rgds Ian

[mikeWalsall]

I use Iridium plugs in my LPG Estima as the floor as to come out to remove them and they are reputed to do 40-60,000 miles .. in fact when I last changed them (at less miles than that) they still looked brand new ..

Similar to my LPG V6 Alphard .. as the three back plugs are a bugga to get to I have had (expensive) NGK LPG plugs fitted ..(I think the old Iridium plugs may have been in since 2003!!)



BUT .. with the easy to fit .. low cost plugs I have gone for standard NGKs in my LPG Bongo and to be honest I have not noticed the slightest difference between them and Iridium ..

Thing is .. it's what you are happy with what suits you .. I only use fully synthetic oil .. have Flash Lube on all my LPG motors .. maybe no better .. just suits my personal peace of mind ..

[Simon Jones]

Hi
My v6 runs great on lpg until it gets down to the last light on the gauge the the tickover becomes lumpy and cuts out sometimes, the tickover speed is lower aswell, fill it back up and it runs fine again, on petrol it runs fine , at the next service dizzy cap leads and rotor arm will be replaced but what plugs to use, i use irridium plugs in the bikes, are special lpg plugs worth the extra
Rgds Ian

Sounds like you've got a problem with the LPG system rather the ignition as the spark won't change when the gas gets low. Perhaps ask to get the regulator pressure checked at your annual service.

I use NGK LPG1 plugs in mine, although at about £12 a piece the cost probably outweighs any benefits but as it's done now so I'll stick with them.

[redz79]

Hi
I'll get the pressure reg checked out at the next lpg service,its not lighting up on all six on start up after standing for a few days though, figure thats the plugs on there way out, i could realy tell the difference running on petrol on the big climbs in cornwall a few weeks ago i would gues 25 more horses come out to play on petrol, thats the good stuff V power.
Rgds Ian