V8 D2 mississing badly today

Well update and no closer to solving this miss fire.
I took number 5 cyl plug out and swapped it to cyl3 and vise versa, the miss still remained at number 5.
I replaced lead number 5 with a brand new one and the miss remains on cyl5 ( this is running on injected LPG.)

On petrol running with nanocom plugged in monitoring miss fire on ALL cyls,

on LPG 2,4,6,8 no miss fires, 1&3 no miss fires, Cyl 5 constant, cyl 7 the occasional miss fire. So it seems the right bank is ok on LPG .

I can't understand how on LPG the right bank is problem free and on petrol it plays up. the lpg gas injectors are wired into the petrol injector wiring. I recently checked by pulling everything off to check soldered connections where the lpg wires were connected.

Searching the net there are quite a few posts on miss firing on 1 bank only, and some mention of a bad MAF, can affect just one bank.
What is the correct airflow volume reading on a MAf at idle?

mine still not solved either, am going to grab a second hand maf just to test before coughing up full fare on the off chance that IS the problem
Can you read something on the computer for coils or are they just done to rule them out?

It's often spark. LPG needs a better spark than petrol, that's why it'll be missing in gas and not on petrol.

Have you checked and/or replaced the coil pack on that bank?

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Originally Posted by brougham

It's often spark. LPG needs a better spark than petrol, that's why it'll be missing in gas and not on petrol.

Have you checked and/or replaced the coil pack on that bank?

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Hi thanks for your input, if you read my post it only misses on cyl 5 and the odd miss on Cyl 7 ON GAS.
But on PETROL It Misses on all cylinders.
The Coil packs are Brand New, unless it is a NEW and Faulty one.
I tried a New MAF today and it has improved performance and drivability but hasn't fixed any miss.
By the way Genuine Land Rover Boxed MAFS are BOSCH and no mention of Land Rover on the MAF, so save you money guys and just by a Bosch replacement and save some dollars on the box you are going to throw out.

You really have a curly 1 there :( Given what you have replaced ( dang near everything except the steering wheel :o ) it nearly has to be somewhere in the harness wiring! or a connector? cracked insulation in the harness somewhere maybe? Sorry cannot think of anything else. I know low compression can do it but yours all check good.

Cheers Scott

I had a Magna come in last month that had one gas injector sticking open. It of course misfired mainly on one cylinder but made it run rich enough that the petrol system would self learn and lean out. The way I found the dodgy injector was to crimp the injector hoses one by one until I found one that ran better with the hose nearly crimped flat. I actually replaced just the one injector as it was worn inside from a bent return spring and had been cleaned before.

Before you do anything else, leave the engine for 10 minutes then unclamp the main gas feed hose to the injectors. A loss of gas pressure indicates a leaking injector.

If you have the manifold top off you can feed compressed air down the main gas feed hose and check which injector leaks. To clean stuck injectors you can fit a hose to each injector outlet, fill it with throttle body cleaner and back flush the injector with compressed air.

Quote:

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Originally Posted by bee utey

I had a Magna come in last month that had one gas injector sticking open. It of course misfired mainly on one cylinder but made it run rich enough that the petrol system would self learn and lean out. The way I found the dodgy injector was to crimp the injector hoses one by one until I found one that ran better with the hose nearly crimped flat. I actually replaced just the one injector as it was worn inside from a bent return spring and had been cleaned before.

Before you do anything else, leave the engine for 10 minutes then unclamp the main gas feed hose to the injectors. A loss of gas pressure indicates a leaking injector.

If you have the manifold top off you can feed compressed air down the main gas feed hose and check which injector leaks. To clean stuck injectors you can fit a hose to each injector outlet, fill it with throttle body cleaner and back flush the injector with compressed air.

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Bee utey,
That could be it , a faulty gas injector,very plausible and you may have hit it. I had a feeling it could be and when on petrol running a open gas injector was allow something into the system.

I posted recently on the LPG forum about repairing the wiring on a gas injector as it entered the injector case, after the repair I could feel the clicking of the injector,.
Unfortunately my system has the injectors hidden under the intake housing, so it's a 20 min job every time to pull the top off, waste another intake upper gasket. That's some how disappears from my stock:angel:
I was considering moving the injectors to the out side by making up an alloy spacer to raise the intake to allow the injector houses to come out the sides. The injector nozzles are currently drilled just above the petrol injectors.
Having the system out from under the intake, gives quick inspection of hose's conditions and probably wouldn't get all the heat from the engine

The wiring loom was inspected last time I pulled the intake off and undid all the insulation and repaired some heat effected wiring insulation.Where it had split.

(Just Digressing for a moment ,One thing I noticed I have a Y piece that separated the Gas hoses going to each bank, after the Y there is a filter on each line, I've seen other setups with just 1 filter before the Y piece and the other ends run direct to each bank. Is that just each fitter doing it differently, like some use 1 filter and others use 2.)
Regards, Mario

I've never replaced the gasket. Good ones go in as they were, slightly dodgy ones get a lick of gasket goo. I've also never used a spacer, just brought the hoses out the top. A spacer would mean you have to space up the lower coil pack mount by the same amount. I've seen other people's installs with spacers though, not sure I like the injectors hanging over the exhaust heat.

https://www.aulro.com/afvb/

My bad, I read it wrong way around.

Quote:

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Originally Posted by bee utey

I had a Magna come in last month that had one gas injector sticking open. It of course misfired mainly on one cylinder but made it run rich enough that the petrol system would self learn and lean out. The way I found the dodgy injector was to crimp the injector hoses one by one until I found one that ran better with the hose nearly crimped flat. I actually replaced just the one injector as it was worn inside from a bent return spring and had been cleaned before.

Before you do anything else, leave the engine for 10 minutes then unclamp the main gas feed hose to the injectors. A loss of gas pressure indicates a leaking injector.

If you have the manifold top off you can feed compressed air down the main gas feed hose and check which injector leaks. To clean stuck injectors you can fit a hose to each injector outlet, fill it with throttle body cleaner and back flush the injector with compressed air.

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Hi Bee utey
Finally got a few minutes today to start having a look. I haven't pulled the intake off as yet. Update, I mwarmed the Disco up until the temp was correct for it to self switch to LPG. I ran it for aabout 10 mins and could hear the exhaust noise was indicating it was missing.

I shut it down as you suggested and waited 10 mins and unclamped the main injector supply line, THERE WAS NO GAS PESSURE or SMELL

I then by mouth,I sucked on the main injector suypply hose and it held vaccum, my tongue was starting to get sucked into the hose and it held vaccum, but this probably wouldn't indicate an open gas injector, as I might have also sucked out the air in the air intake of a faulty injector also, it it was stuck open,
I also blew into the hose and it also stopped me blowing any further as I might have filled the intake under the gas injector with air also.

So it is going to be a job or pulling the upper air intake and check the injector wiring on number 5 , and check the operation of the injectors.

Since one petrol injector wire is cut on each injector and is then looped through each gas injector wiring am I right in assuming that if there was a fault on the wiring to gas injector it would also appear as a fault on the petrol injector on that loop?

In the mean time I have blanked and clamped the main gas supply line, with the idea of stopping any air leakage to the petrol system on number 5 cylinder from the gas supply line.