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PostPosted: Tue Sep 03, 2013 7:54 am 
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Good morning, First post, read many but can seem to find answer I need....

Car-
Range Rover P38 4.6 V8
Brought with gas already fitted and was running perfect for 3 months after purchase.

Symptoms-
As soon as the car engine temp raises off of the blue ie gets warm, starts to pop and bang in the exhaust when accelerating. Runs perfect for the first few minutes when cold. Runs perfect on petrol ruling out electrical problem. Change over from petrol to gas is same as always been and never played up or been a problem.

The gas system-
Zavoli system, Reducer has S 05.05, 002227 stamped on the top.
Zavoli matrix XJ544 injectors.

Whats been done so far-
As I knew nothing whatsoever about LPG I took to local LPG "specialist" who in turn put it on his laptop and done some updates and said everything was showing up as working as should be...
Took it home and it was no different at all, still popping and banging and missing... After some reading on here I decided I would try taking the injectors apart and clean them up... They were very dirty and sticky so gave a good clean with WD40 and a cloth.. back together no change :twisted:
Vapour filters were then replaced and took back to LPG garage yesterday... Hooked back up to Laptop and still he couldn't see any problem. On collection of the car he told me he had changed the firmware and replaced the "mapping"? and to give it a try... which I did last night and its still miss firing when warm/hot!! :( :?: :cry:

To my limited engine brain it sounds and feels like it is under fueling??

What next?-
I was going to try a repair/service kit for the reducer?
Do the markings from the top of the reducer (S 05.05, 002227) tell me the model as I have seen so many for different BHP engines?


Many thanks for all advice and help


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PostPosted: Tue Sep 03, 2013 8:11 am 
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Is the misfire there all the tie once warm or just under load.

Have you done a compression test. I've had a few RR's in this year with very low compression on most cylinders.

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PostPosted: Tue Sep 03, 2013 8:17 am 
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classicswede wrote:
Is the misfire there all the tie once warm or just under load.

Have you done a compression test. I've had a few RR's in this year with very low compression on most cylinders.



Morning,

Sorry yes its when under load.
I did a compression test when it first started to miss yes... cant remember now the exact figure other than all 8 cylinders were around the same compression which IIRC was 10 on the gauge... would that be 10 bar??

Thank you


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PostPosted: Tue Sep 03, 2013 9:27 am 
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That engraved "S" tells you it's a Zeta-S type regulator. They're usually reliable, if your man with the laptop is worth his salt he should have spotted any problems with pressure variation.
I'm sure he would also have noticed if one of the lambda sensors was busted.

I would guess this is a fairly elderly system, as you have Matrix rather than the Zavoli own-brand injectors. Those injectors do eventually wear out, did you examine the thin mylar shims under the metal fingers carefully when you had it apart? Performance is ruined when they're worn through.

Basics first though; with any petrol engine, spark ignition is the first suspect. This still applies if only misses on gas and OK on petrol. Be really sure the plugs and leads are in good condition. These engines benefit from lead renewal every five years or so.

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PostPosted: Tue Sep 03, 2013 9:48 am 
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rossko wrote:
That engraved "S" tells you it's a Zeta-S type regulator. They're usually reliable, if your man with the laptop is worth his salt he should have spotted any problems with pressure variation.
I'm sure he would also have noticed if one of the lambda sensors was busted.

I would guess this is a fairly elderly system, as you have Matrix rather than the Zavoli own-brand injectors. Those injectors do eventually wear out, did you examine the thin mylar shims under the metal fingers carefully when you had it apart? Performance is ruined when they're worn through.

Basics first though; with any petrol engine, spark ignition is the first suspect. This still applies if only misses on gas and OK on petrol. Be really sure the plugs and leads are in good condition. These engines benefit from lead renewal every five years or so.


The shim was in perfect condition yes, no sign of any wear or damage once cleaned up.
My first thought when miss fire started was ignition, so new plugs, leads and coil pack fitted.

Dan


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PostPosted: Tue Sep 03, 2013 6:56 pm 
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dangerousdan8 wrote:
As soon as the car engine temp raises off of the blue ie gets warm, starts to pop and bang in the exhaust when accelerating. Runs perfect for the first few minutes when cold.
Am I reading this right? As soon as the temp gauge starts to move the problem occurs but is this as soon as it changes over to gas or while it is still running on petrol while waiting for the temperature to get high enough to change over? As Ross says, my first thought was plugs and leads too but you seem to have been there already. Popping in the exhaust is due to unburnt fuel being spat out into the exhaust manifold and then igniting in there. For that to happen you would need either a misfire, so the fuel just passes through the cylinder and out of the exhaust port, or too much fuel going in so only some of it is being burnt, the rest ending up in the manifold.

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PostPosted: Wed Sep 04, 2013 7:30 am 
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Gilbertd wrote:
dangerousdan8 wrote:
As soon as the car engine temp raises off of the blue ie gets warm, starts to pop and bang in the exhaust when accelerating. Runs perfect for the first few minutes when cold.
Am I reading this right? As soon as the temp gauge starts to move the problem occurs but is this as soon as it changes over to gas or while it is still running on petrol while waiting for the temperature to get high enough to change over? As Ross says, my first thought was plugs and leads too but you seem to have been there already. Popping in the exhaust is due to unburnt fuel being spat out into the exhaust manifold and then igniting in there. For that to happen you would need either a misfire, so the fuel just passes through the cylinder and out of the exhaust port, or too much fuel going in so only some of it is being burnt, the rest ending up in the manifold.



Ok let me re write... Starts on petrol as normal all ok.. changes over to gas as normal all ok (after being left ticking over for couple of minutes on petrol first).... runs perfect on gas until the temp gauge reaches off the cold reading and into the middle (normal running temp section) then when accelerating it will miss and pop and fart. Personally I don't think its over fuelling it feels more like its under fuelling. (but that is based on gut feeling nothing else.)
Would having it linked to laptop when driving show if it getting enough/to much fuel? Pressure dropping etc?

I have replaced Plugs, Leads, Coil pack on the electrics side of things.
Done compression test on all 8 cylinders which as stated all read IIRC 10 on the gauge, without going into the shed and getting gauge I don't remember exactly if this was 10 bar or what but can check at weekend.

Have ordered myself a interface kit so I can have a look for myself what is going on (not that I will necessarily know what it means)... should be here Friday

Still stumped :evil:


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PostPosted: Wed Sep 04, 2013 6:07 pm 
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The software is the best place to start. It could be something as simple as a split hose but I'm more suspecting a duff temperature sensor.

Once you have connected with the lead and software post up some screen shots. Make sure you save your config file before making any changes.

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DIY LPG Kits

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PostPosted: Thu Sep 05, 2013 7:21 am 
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classicswede wrote:
The software is the best place to start. It could be something as simple as a split hose but I'm more suspecting a duff temperature sensor.

Once you have connected with the lead and software post up some screen shots. Make sure you save your config file before making any changes.



Morning.
I should get software tomorrow so once I get it installed I will get connected and post some shots and hopefully some of you experienced guys (or gals) might spot something suspect.... I wont be making any changes on me own not till I know what I'm doing.
Thanks all for help and advice so far.
Dan


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PostPosted: Fri Sep 06, 2013 1:41 pm 
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Ok, here are a few photos... Only thing I can see is the lambda sensors are going up and down all over the place??

Image

Image

Image

Image

Image

Thoughts please


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PostPosted: Fri Sep 06, 2013 5:54 pm 
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dangerousdan8 wrote:
Ok, here are a few photos... Only thing I can see is the lambda sensors are going up and down all over the place??
That's good, they are supposed to. You have the Titania sensors and 5V is a lean mixture with 0V being rich. The sensors will flip flop from one extreme to the other, if they stay at one end then you have a problem. The only thing I notice from that is that the Tinj petrol when idling on petrol is lower than it is when idling on gas. That shows that the mixture on gas is a bit on the weak side and the petrol ECU is increasing the pulse length to get the mixture correct.

As you don't have a problem at idle, then those screenshots don't show much. You need to get an assistant to either drive while you watch the computer or the other way round so you can see what happens when the problem occurs. Does the gas pressure drop? Do the lambdas sit at one end of the scale? Try accelerating while running on petrol and watch what the Tinj petrol shows and then see if it does the same when on gas.

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'96 Saab 900XS, AEB Leo, sold
'93 Range Rover 4.2 LSE, Lovato LovEco, sold
'98 Ex-Police Range Rover 4.0, Singlepoint AEB Leo, my daily motor
'97 Range Rover 4.0SE, eGas multipoint, a project.....

Proud to be a member of the YCHJCYA2PDTHFH club.


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PostPosted: Fri Sep 06, 2013 6:07 pm 
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Gilbertd wrote:
dangerousdan8 wrote:
Ok, here are a few photos... Only thing I can see is the lambda sensors are going up and down all over the place??
That's good, they are supposed to. You have the Titania sensors and 5V is a lean mixture with 0V being rich. The sensors will flip flop from one extreme to the other, if they stay at one end then you have a problem. The only thing I notice from that is that the Tinj petrol when idling on petrol is lower than it is when idling on gas. That shows that the mixture on gas is a bit on the weak side and the petrol ECU is increasing the pulse length to get the mixture correct.

As you don't have a problem at idle, then those screenshots don't show much. You need to get an assistant to either drive while you watch the computer or the other way round so you can see what happens when the problem occurs. Does the gas pressure drop? Do the lambdas sit at one end of the scale? Try accelerating while running on petrol and watch what the Tinj petrol shows and then see if it does the same when on gas.


Hi, thank you for your reply. Yes I was thinking I would probably try and get some one to drive it for me so I could get some screen shots of it when the "missing/popping/farting etc" is occurring. Now also know a couple of the points to look out for... photos to follow asap.
Again thanks for your help.


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PostPosted: Sat Sep 07, 2013 9:19 am 
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MAP is perhaps a little high for idle, that may indicate an air leak.

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PostPosted: Mon Sep 09, 2013 9:25 am 
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rossko wrote:
MAP is perhaps a little high for idle, that may indicate an air leak.


Hi... What does MAP stand for firstly?? Secondly, where should I be looking for air leaks, the main air intake from the air box?
Thanks


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PostPosted: Mon Sep 09, 2013 9:39 am 
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Manifold Absolute Pressure. There will be a small sensor with vacuum hoses connecting it to the inlet manifold vacuum take off and the reducer or injector rail. The vacuum hose may be Tee'd into an existing vacuum hose rather than directly off the manifold. Check these hoses for splits, particularly at the ends where they push onto the nipples.

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'93 Range Rover 4.2 LSE, Lovato LovEco, sold
'98 Ex-Police Range Rover 4.0, Singlepoint AEB Leo, my daily motor
'97 Range Rover 4.0SE, eGas multipoint, a project.....

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PostPosted: Mon Sep 09, 2013 9:43 am 
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Gilbertd wrote:
dangerousdan8 wrote:
Ok, here are a few photos... Only thing I can see is the lambda sensors are going up and down all over the place??
That's good, they are supposed to. You have the Titania sensors and 5V is a lean mixture with 0V being rich. The sensors will flip flop from one extreme to the other, if they stay at one end then you have a problem. The only thing I notice from that is that the Tinj petrol when idling on petrol is lower than it is when idling on gas. That shows that the mixture on gas is a bit on the weak side and the petrol ECU is increasing the pulse length to get the mixture correct.

As you don't have a problem at idle, then those screenshots don't show much. You need to get an assistant to either drive while you watch the computer or the other way round so you can see what happens when the problem occurs. Does the gas pressure drop? Do the lambdas sit at one end of the scale? Try accelerating while running on petrol and watch what the Tinj petrol shows and then see if it does the same when on gas.


Morning
Below are couple of screen shots of what happens when running under load... What they don't show is the "press. gas" dropped to 0.8 bar under acceleration.... is this normal?
Image

Image

Image

Image

Image

Image

Thoughts?


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PostPosted: Mon Sep 09, 2013 1:26 pm 
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Pressure shouldn't drop and your first picture is showing the lambda at very lean, but then your 4th one shows the lambda showing very rich even though the pressure has dropped but the injector times are ridiculously long.

You need someone more familiar with these systems than me but the drooping pressure suggest the reducer may be on it's way out.

_________________
'96 Saab 900XS, AEB Leo, sold
'93 Range Rover 4.2 LSE, Lovato LovEco, sold
'98 Ex-Police Range Rover 4.0, Singlepoint AEB Leo, my daily motor
'97 Range Rover 4.0SE, eGas multipoint, a project.....

Proud to be a member of the YCHJCYA2PDTHFH club.


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PostPosted: Mon Sep 09, 2013 1:41 pm 
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Gilbertd wrote:
Pressure shouldn't drop and your first picture is showing the lambda at very lean, but then your 4th one shows the lambda showing very rich even though the pressure has dropped but the injector times are ridiculously long.

You need someone more familiar with these systems than me but the drooping pressure suggest the reducer may be on it's way out.


Gilbertd, my original thought was reducer being on its way out... as I said in my posts before it feels like, for want of a better phrase its "under fuelling".
As for the lambda readings, they go up and down continuously, not sticking on a reading for any measurable time.
What does the injector time tell us??

I appreciate your input and if someone else can expand on this it would be great. Hopefully can get to the bottom of it.

Thanks


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PostPosted: Mon Sep 09, 2013 2:05 pm 
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Pressure will drop under load, its a question of what is acceptable. This one is not, really. No-one's mentioned replacing the liquid filter yet, or checking for crushed tank-to-front supply pipe. Do your testing with more than half a tank of fuel to rule out slosh contributing.

Still got my money on an ignition problem.

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PostPosted: Mon Sep 09, 2013 2:42 pm 
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rossko wrote:
Pressure will drop under load, its a question of what is acceptable. This one is not, really. No-one's mentioned replacing the liquid filter yet, or checking for crushed tank-to-front supply pipe. Do your testing with more than half a tank of fuel to rule out slosh contributing.

Still got my money on an ignition problem.


Hi. So what would be an acceptable drop?

Ok to your ignition theory..... I have replaced the plugs, leads (twice) and the coil pack... what else could you suggest?
I have had the car plugged in to diagnostics machine at a local garage and nothing shows up on that side of things, and it does run perfect on petrol all the time. I'm open to all suggestions, just want to get it sorted :(

Thanks


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