M

Murtle

Active Member
It's been running a bit rough at idle recently, but seems fine accelerating and cursing. I have two Lambda sensors in the exhaust one for left and one for right, there is no injection system (though I am using the 3.5L injection manifold etc) or ECU, this is an pure LPG machine. Left bank constantly reads Lean mixture. I added the Lambda sensors as a tuning guide, but no matter how much I increase the fueling the left back stays lean.

I've also done a compression test and all cylinders come out with in 5psi of 150psi

These plugs have probably done 10K max, they are Bosch Super 4's
plugs01.jpg


Any thoughts?

Cheers Nath
 
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Are all the gaps in the plugs set the same? I haven't seen plugs growing warts like that sorry
 
so single point lpg??pics of lpg setup...

first try ngk plugs..nothing flash, single earth not 4.. not bosch..!
 
No injection at all, only an injection manifold, and BLOS carb, prior to this it was a pair of SU's and horrid LPG sandwich plates. The misfire was there before the lateset BLOS addition but I was busy with everything else, also as the lambda sensors were showing lean I hoped it would resolve the problem. I've since found out the a miss fire will cause a lambda sensor to read lean as it detects the extra oxygen in the exhaust.

I tried getting some NJK BPR6ES plugs today but my local Halfords only sells them singular labled a mower plugs, and to top it off the only hold THREE in stock at any one time!!!
 
since it ashed plugs doesnt fit with one carb running wrong id think you were burning some oil in those cylinders
 
I'm thinking it's oil contamination as well, would worn out valve oil steam seals cause this and lead to a miss fire?
 
is there any smoke??i would av thought there would be some blue out the exhaust with them plugs??
 
Definitely oil debris on some of those plugs, probably valve stem seals.

Here are 8 of ours:

HeadGasket1.jpg


HeadGasket2.jpg


Peter
 
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I'm trying to devise a way in my head that I can change the valve stem seals without removing the heads. Anyone tried this?

I'll also order up a set of normal NGK's, rotor arm and cap and see how we go, I'm reluctant to change the HT leads as they are Magnecore and look to be in good condition.

As a temporary measure I gave the plugs a dam good wire brush off and general clean, re-fitted them and still it feels just as rough at idle. This rough idle that I have is not like the normal misfire I'm used to if for example when there is condensation in the dizzy cap, usually it's ok at idle and misses like buggery when you pick up the revs. This just feels rough almost as though it's unbalanced, but seems fine when the revs a re picked up and during acceleration?
 
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Rolls-Royce and others had a tool that screwed into the spark plug hole and had a tip that could be swung round under the valves to hold them while a spring was compressed by a separate tool above.

I might be wrong but I think the Merlin was one of the engines that it was used on.

Peter
 
zen said:
show off!!..he he
Click to expand...

Yeah :)

That was the time after I hauled Robert's 110 CSW back from Barnstaple and one of the head gaskets came loose and started leaking into one of the front cylinders.

Didn't do any damage, changed gaskets on both heads straight away and used Victor Reintz rather than ebay rubbish, AND the valve stem seals fitted properly!

Peter
 
listerdiesel said:
Rolls-Royce and others had a tool that screwed into the spark plug hole and had a tip that could be swung round under the valves to hold them while a spring was compressed by a separate tool above.

I might be wrong but I think the Merlin was one of the engines that it was used on.

Peter
Click to expand...

i once changed some broken collets on a petrol 4 pot vw when i was super skint student by stuffing old 4mm climbing accessory cord into the sparkplug hole until the cylinder was full of it then turning the crank to push the piston up to hold the valve shut so i could compress the spring.

it was semi semi successful but fecking hard work had to get my brother to help, valve springs are STRONG. it also fluffed up the timing totally which took some fiddling to do as i had again, and i damaged the top of a valve stem.

it would have been easier to whip the head off but i didnt have the money for a new headgasket or coolant etc

wouldnt recommend it to be honest
 
I know this might be a silly question, but you have your leads on it the right order???

Looking at those plugs its either burning oil/coolant or firing inefficiently.
Run it up and using thick gloves and insulated pliers remove each lead in turn to see if it makes any audiable difference to how its running.
 
Murtle said:
I'm trying to devise a way in my head that I can change the valve stem seals without removing the heads. Anyone tried this?

I'll also order up a set of normal NGK's, rotor arm and cap and see how we go, I'm reluctant to change the HT leads as they are Magnecore and look to be in good condition.

As a temporary measure I gave the plugs a dam good wire brush off and general clean, re-fitted them and still it feels just as rough at idle. This rough idle that I have is not like the normal misfire I'm used to if for example when there is condensation in the dizzy cap, usually it's ok at idle and misses like buggery when you pick up the revs. This just feels rough almost as though it's unbalanced, but seems fine when the revs a re picked up and during acceleration?
Click to expand...

have you done a search, if you look you will find. There are a couple ways
 
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