LPG Discussion Forum

so the tank runs from front to back and the multivalve is at the front. Under acceleration all the gas goes to the back of the tank and possibly uncovering the pick up tube.

Also you say when you start the car from cold it misses for a bit, is that while on petrol? If it is you will need to get that sorted before the LPG problem.

I had a 3.2 running on gas, that had 6mm copper front to back. Emer MTV and never had a problem with lack of gas.
As rossko says, could be a damaged pipe.

The miss fire comes when it switches over to gas, no miss at all on petrol.

My old 3.2 had the tank under the boot running side to side, and it has 6mm pipe front to back and I never had any problems with it with loss of power etc and run that for 5 years. wanted this one's tank under the car the same and even provided detailed pics of how it was mounted etc but was told that the new 70ltr tank was to big to fit though looking at the old one it looks like the physical size of the tank is the same.

Many thanks

Dai

Do you know what make of vapouriser is fitted.

Just another thought, what does the vap temp do when the vehicle is pushed

according to the paperwork I have it's a zavoli

Hi Tommo sorry I missed you question.

The vap temp dropped from 54deg to 46deg it could have been lower but video was to blurry to be exact

Dai

vap temp should be higher than that. the temp you have should'nt cause you problems, but when under a high demand it would be better if it was higher. try and see what it drops to when pushed

Dai Fish wrote:when the seal popped on the back of the one injector rail

eh ??
What sort of rails are these?

Dai Fish wrote:just checked and the gas pressure dropped from at idle 1.7bar to 1.26bar when problem hits.

That's pants. Zavolis are much more stable than some other types.
You do mean 1.7 when idling on gas?
Zavoli S (you really should have an S and not the identical looking N) are run at nominal 1.4 bar and stressing out if tweaked to 1.7
There should be no reason your car can't be set up with it at 1.4bar

That amount of pressure drop could indicate an underspec vap - check the type. (I don't think it could be an N as you can't tweak to 1.7 I'm sure)
I doubt its a liquid supply issue as you normally get a more severe effect, and you seem to have another reason for the step power loss.
Another cause of excessive drop is that its overfuelling like crazy. So far we've only been guessing your problem is leanness. Need those lamda readings (not trim values) under load.

But do bear in mind what you see at the laptop is usually a delayed/slugged version, sudden transients turn into gentle droops. You may have to persist to see where the reading bottoms out.

Dai Fish wrote:The vap temp dropped from 54deg to 46deg

That's not an unreasonable drop during/after sustained heavy load.
The worrying part is that its not very hot to begin with. Wrong sensor selected in software, bust engine thermostat etc? Not the root cause of your high load issue.

OK first one first I have two rails of 3 valtec injectors which have red tops, at one end of the rail has the gas intake the plastic piece that the gas pipe is fitted to is held in the rail with a y shaped bracket which screws into the rail at the other end of the rail is a plastic end cap that has a rubber seal in it this end cap is held in the rail by the same y shaped bracket secured in the same way as the other end, It is the plastic end cap that had been pushed part way off the rail leaving it open for the gas to escape.

I had not noticed before the vap temp is way lower than the engine temp, the engine temp is around 90deg this I know from the temp guage and from my code reader and the engine temp goes up under load esp up the sort of hills I was driving.

I will have to wait until tomorrow (Fri) to check on the vap model. the vap was originally set up at 1.4 with the injector size of 2.5 this was changed last week when I went back with the original problem the injectors were drilled out to 3mm and vap pressure turned up to 1.7 at idle on gas.

Many Thanks

Dai

Exactly rossko, it could be going very rich and not lean. which would bog the engine down.
I think we need to know what the vap temp actually goes down to when the engine is under severe load. It could be that the gas going in is cold enough to create a much more dense mixture and create a much richer mixture.
The 3.2 do suffer with coolant circulation issue. I have had a few that would sit and idle all day, and in light driving would be ok, under any kind of load the temp would go up.
It was found to be a circuation problem (radiator efficiency usually)

If this was the case although the engine would get hotter the Vap would get colder due to lack of circulation.

does the problem occur as soon as you floor it and is it there all the time?
If it is there all the time, and is there as soon as you floor it, it probably isn't a temperature issue.(although you can't rule this out completely)

1.7Bar and 3mm nozzles seems really over the top for this engine TBH and I think they have exagerated the problem.

Right I think the temp's I gave you last night might have been gas temp not vap temp I was looking at a very fuzzy video that was taken by my wife while I was driving but I wont be able to try it until later this aft as I am out of gas until I can go fill it up.

The feeling that what has been done has made it worse goes along with what I am feeling when driving the car, only once before have I had this problem when solo and that was a time I really had to gun it, the hills that it is happening on now we drive them all the time and not had the problem until now.

It does not happen as soon as I gun the throttle it is ok until the engine approaches 4000rpm then wont go any higher but you can feel it surging, and eml stats flashing.

Now when I had the big problem when towing the horsebox and popped the seal I had the feeling that it was trying to put more gas into the pipes than the injectors could cope with hence the seal popping part way off, this was on the short run of pipe to the nearest injector rail to the vap.

Looking at the vap this morning it looks like it reads zeta/S so I think by that it is the s not the n vap, one thing I did notice when I looked at my old 3.2 and this one the old one the heater hose had been cut and ran through the vap the out side of the vap then went to the other end of the heater hose, this one both heater hoses have been cut and T pieces put in with hoses to the vap off the T.

These 3.2's do suffer with cooling problems which I am very aware of and as such have made sure that flow is not a problem on mine the thermostat was changed a few months back when I had the inlet man off to change the gaskets, a lot of the cooling problems with them come from the viscous fan not working properly, I have fitted twin electric fans on mine to get around the normal issues with the fan.

I will get the laptop and code reader hooked up as soon as I get back and will try and get the readings again from both with the lamda readings off the code reader not the lap top.

Many thanks again

Dai

Okay, so a gas hose popped off, I think?. That should never ever happen (there is safety valve on the Zeta to prevent excess pressure in the hoses in a fault situation) but that's just a matter of securing it properly. May we assume you put it back on?

Don't worry about the plumbing yet, as it turns out no-one has any idea if you really have a temperature problem.
Info required on reducer temperature behaviour.

Info required on lambda behaviour (which you might have to get from an OBD reader unless the gas system has been wired to the sensor)

A lot of people belive it is the viscous fan, when in fact it is due to a radiator that is just about adequate for the engine. Fitting electric fans only masks the problem.
T'ing into the heater hoses should not cause you any problems although putting the vap inline with the heater hose will help if it is a circulation problem.
As Rossko says this is all speculation until you can give us the Lambda and injection times.

At last I have the figs you wanted or at least I hope I do. Hope you can make some sense out of these

Gas pressure start 1.67
at fault 1.20

map start 0.47
at fault 0.93

petrol injector at fault Gas injector
14.5 23.0

Gas temp start 47
at fault 34

Red temp 80

Lamda at fault from OBD code reader
B1 sensor 1 0.900
B1 sensor 2 0.930
B2 sensor 1 0.900
B2 sensor 2 0.935

Many thanks for your continued help

Dai

Dai Fish wrote:Lamda at fault from OBD code reader
B1 sensor 1 0.900

I think (like the rest of us) they've just assumed it was going lean under load and have now over-egged it.
Sensor says its rich under load - which is normal and desired - but not how much rich.
Something's wrong, and its not lean, so lets guess its way rich (taken with what appear to be too-big injector nozzles and high pressure)
Can you smell rotten eggs with the windows open after drag racing?

For an experiment, turn gas pressure down to 1.4 and see if it changes the failure point.

Dai Fish wrote:petrol injector at fault Gas injector
14.5 23.0

Assuming less than 5000rpm thats fine, there is time to cycle

Do we know what reducer and injectors have been used?

My experiences of the Stag kit with Red Valteks (and other similar style injectors) is that they don't like the LPG pressure any greater than 1.2 BAR. If the nozzles are correctly sized there is no need either

My 3.2 Omega (same engine) is running a KME Gold Reducer and AC/Motogas injectors drilled to 2.3mm at a pressure of 1.1 BAR and is faultless

Hi guys just to update you all on what has happened, I took car back to installer and first off they were going to change the red that was until I showed them the figures I showed you on here, they then did another calibration on the laptop and we took the car out on the road, it was much better than before they upped the pressure and drilled the nozzles out to 3mm etc but there was still a problem at high rev's but they felt it was a problem with the car and not the LPG as the MIL code had changed from random multi cyl miss fire which I was getting to cyl 6 miss fire they checked the plugs changed coil packs around but no matter what they did the same code kept coming up, I was there all afternoon going through it with them and with no solution by the end of play was asked to go back two days later so they could try again, I have to say they did work hard in trying to get to the bottom of it.

The following day I went through it all again and found that one of the coil packs was in the wrong pos, I was quite surprised to find that there were 5 coil packs the same and one that was different and the one that was different is for cyl no 6, to the eye they all looked the same (on my W reg one they are all the same) once I sorted that out I drove the car and could not get the MIL to flash and no codes pending, this was done at fairly high rev's.

Took the car back as arraigned on the WED told them what I had done and how the car seemed to be ok except that when I had started the car that morning (very cold) as soon as it changed over to gas it was missing like a pig which it had not done before they changed nozzle's and upped the pressure, was asked to leave it on petrol for a bit longer and to drive the car for a while and see how it went.

On the whole the car has driven well apart from the miss when cold, but there is still a miss at idle on gas and the code still comes up with cyl 6 miss fire now I have tried different plugs I know that the coil pack is ok because when it was in the wrong cyl it did not throw up any problems (the difference is not in the coil part of it, it is the stem that there is a difference, it is the same length as the others but the seal at the very top of the stem is a little smaller in diameter to the other five and sit's a little lower than the others, so it will fit in any of the other cyl's) so I am now trying to go back through the looms etc looking for a loose joint or cracked wire or anything else that might explain why it is happening.

As for the original problem that I had while towing I have not been able to get out with the horsebox to try it, I know that it is a little long winded in my trying to sort it out but i am unfortunately disabled and suffer chronic pain and can only do things like this for short periods of time, when I can.

As it stands at the min the lpg pressure is still at 1.7bar and the nozzles at 3mm.

Many thanks for all the help

Dai

Just completed a 3.5 trooper. Same engine as yours just a bigger displacement. 1.4 bar pressure, 2.5mm nozzles and runs like a dream.

I'd guess rough idle is due to injector nozzles too big, the setup will have injector times too short which leads to erratic fuelling at idle. It probably needs to go back closer to the setup they started with

I'd bet your 'odd' coil is just one that was replaced earlier with a pattern or later part.