Pinging like mad on LPG. Ok on Petrol.
Posted: Thu Sep 06, 2012 12:20 pm
Question for the collective, background as follows:
Land-Rover 90 running a Rover 3.5. 9.35:1 comp with 10 bolt heads, later cast 4-2-1 manifolds and flapper efi top end being run by megasquirt. Lpg is currently a bigas m84 vap feeding a mixer ring on the Plenum. Previously this fed mixer plates on the SU's.
Problem is that it is pinging like mad on anything but the lightest throttle when on gas! Petrol runs normally and is unaffected.
This has only started since I swapped my SU's for the flapper gear a month or two ago.
Prior to this it was running fine - Megasquirt has been running ignition only for ages, and before that megajolt was the same. I had not made any changes to spark map at all prior to this starting.
I readjusted the gas when I fitted the new intake setup and am getting around 13:1 when accelerating hard. (for sake of simplicity i will describe mixtures in Petrol AFRs)
I initially thought it was being caused by my breather system drawing too much oil vapour through as when I swapped to Efi I still had the old round rocker covers fitted. The old crankcase breather hoses (with flame traps)joined at a Y-piece and fed into the plenum. The bore of the pipe on the plenum is way bigger than the SU's so i thought that was my problem.
This was not too much of an issue as I wanted to tune my Petrol running at the time, but that is pretty much done now so I need to go back to cheap running.
I swapped over to later efi rockers and the "proper" breather setup (with the foam filter on one rocker and the breather and brillo-pad filled canister on the other) earlier this week and this has not eliminated the problem.
I have tried running things rich, and even when I am getting 12-13's it still pings under mid-speed acceleration.
Have also tried pulling timing from the entire map and although this has helped it has not solved the issue. The LPG map is probably about as advanced as the Petrol one now.
So my thoughts are:
1)
Perhaps during tuning for Petrol I may have sooted things up- It was running very rich when I began tuning. This could be giving me detonation, although I would have thought it would also do the same on petrol- which it doesnt.
2)
Weeping petrol injector causing petrol to be going in with LPG?
3)
My wideband is lying to me and I am not running as rich as I think I am.
4)
My air filter is now pulling air from above the drivers side exhaust manifold- the extra heat may not be helping, although MS indicates it is usually about 30-35 degrees C when up to temp and cruising in this weather. Thats not excessive is it?
My next plan of action was going to be recalibrating the wideband, pulling the plugs and checking them, followed by the injectors.
So does anyone else have any ideas on any other potential causes I can check?
Noise is like a rattling bunch of keys crossed with a couple of marbles being banged about in a jam jar. Dissapears as soon as I back out of the throttle.
Thanks all!
Land-Rover 90 running a Rover 3.5. 9.35:1 comp with 10 bolt heads, later cast 4-2-1 manifolds and flapper efi top end being run by megasquirt. Lpg is currently a bigas m84 vap feeding a mixer ring on the Plenum. Previously this fed mixer plates on the SU's.
Problem is that it is pinging like mad on anything but the lightest throttle when on gas! Petrol runs normally and is unaffected.
This has only started since I swapped my SU's for the flapper gear a month or two ago.
Prior to this it was running fine - Megasquirt has been running ignition only for ages, and before that megajolt was the same. I had not made any changes to spark map at all prior to this starting.
I readjusted the gas when I fitted the new intake setup and am getting around 13:1 when accelerating hard. (for sake of simplicity i will describe mixtures in Petrol AFRs)
I initially thought it was being caused by my breather system drawing too much oil vapour through as when I swapped to Efi I still had the old round rocker covers fitted. The old crankcase breather hoses (with flame traps)joined at a Y-piece and fed into the plenum. The bore of the pipe on the plenum is way bigger than the SU's so i thought that was my problem.
This was not too much of an issue as I wanted to tune my Petrol running at the time, but that is pretty much done now so I need to go back to cheap running.
I swapped over to later efi rockers and the "proper" breather setup (with the foam filter on one rocker and the breather and brillo-pad filled canister on the other) earlier this week and this has not eliminated the problem.
I have tried running things rich, and even when I am getting 12-13's it still pings under mid-speed acceleration.
Have also tried pulling timing from the entire map and although this has helped it has not solved the issue. The LPG map is probably about as advanced as the Petrol one now.
So my thoughts are:
1)
Perhaps during tuning for Petrol I may have sooted things up- It was running very rich when I began tuning. This could be giving me detonation, although I would have thought it would also do the same on petrol- which it doesnt.
2)
Weeping petrol injector causing petrol to be going in with LPG?
3)
My wideband is lying to me and I am not running as rich as I think I am.
4)
My air filter is now pulling air from above the drivers side exhaust manifold- the extra heat may not be helping, although MS indicates it is usually about 30-35 degrees C when up to temp and cruising in this weather. Thats not excessive is it?
My next plan of action was going to be recalibrating the wideband, pulling the plugs and checking them, followed by the injectors.
So does anyone else have any ideas on any other potential causes I can check?
Noise is like a rattling bunch of keys crossed with a couple of marbles being banged about in a jam jar. Dissapears as soon as I back out of the throttle.
Thanks all!
So no extra unwanted (at this time of year) warming of incoming air/gas..