The only place for a coil spring is up Zebedee's arse.
856 posts
Nov 16 2016
06 November 2017 - 16:46

Forgot to mention..

Got back from holiday in Malta the other day. 'Miss European' contenders were staying at the same hotel as us. several from each country. We saw them mostly on an evening all dolled up and posing for country group shots and single shots outside the front door. All week my girlfriend was suggesting we relax around the pool rather than go sightseeing but the one day I agreed to sit beside the pool she suggested we go out and do something else. When we got back that evening we'd missed all the poolside bikini shots...

07 November 2017 - 10:41

Enrichment in acceleration works in different ways depending on age of ECU.

It makes sense to explain how the newer ECUs work first, then it's easier to see why the enrichment in acceleration facility is there at all and why it is more important on older ECUs... Most of you will have the older type ECUs.

On newer ECU's the slider doesn't allow for enrichment at all, full right on the slider gives just the mixture that the map/pressure compensation/temp compensation provides, left of full right leans the mixture during acceleration. On the newer ECUs the only real correct position is full right, anything left of full right points to calibration/setup issues. That's because the newer systems are truly sequential - they take Pinj readings from every petrol injector and (supposedly) each cylinder's gas injector pulse length (Gnj) is calculated individually based on each individual cylinder Pinj's, furthermore the gas pulse should start at almost the same moment that the petrol injector pulse starts (where almost means at the same time or within about 2ms based on other settings such as 'extra injection filtering' where extra injector filtering in theory allows very short Pinj's to be ignored altogether).

The older type AEB based ECU's are not really truly sequential, they take the Pinj reading only from the front cylinder on each bank (blue wires), then each cylinder on the same bank gets the same Ginj as the front cylinder Ginj. Now suppose that between the front cylinder injection pulse and another cylinder's injection pulse on the same bank the driver stamps his foot down... At high rpm the manifold pressure won't have time to increase much before the other cylinders on the same bank inject fuel, at low rpm the manifold pressure will have more time to increase between injection pulses on that bank.. In cases of both high rpm and low rpm the mixture for the rear 3 cylinders (particularly the last cylinder in the firing order) will be leaner than the front cylinder mixture because it didn't read the rear 3 petrol injectors pulse times it just assumed they would be the same as the front cylinder's pulse time. To address this the system has the enrichment in acceleration slider.. The default setting of the slider (usually somewhere near the middle) gives a bit of enrichment to the rear 3 cylinders when the ECU notices manifold pressure and/or Pinj on the front cylinder rising quickly... The enrichment is a fudge, but no more of a fudge than the acceleration enrichment that a petrol ECU provides. Since the newer type ECUs read individual petrol injector pulses to calculate individual gas injector pulses the newer ECUs don't need to add in the fudge themselves because they are reading Pinjs that have already had any necessary acceleration enrichment fudge added by the petrol ECU.

The gas ECU applying an acceleration fudge (instead of the petrol ECU's fudge) isn't really a drawback. The only real drawback of the old type ECU over the new type is that it doesn't necessarily pulse gas injectors at the same time as petrol injectors are pulsed - the new type uses start of petrol injector pulse as trigger for start of gas injector pulse whereas new old type does this for the front cylinder but then spaces the rear 3 cylinder gas injector pulses according to only rpm. Not a problem on older engines but can be a problem on newer engines with features such as VVT/Atkinson cycle.

The acceleration slider won't make any difference to mixture with your foot in a constant position on the throttle, even if you're holding foot flat out, because with constant throttle manifold pressure and Pinj's stay about the same. The slider is used on older ECUs to dial out drive-ability problems when you're changing throttle position (hesitation from lean running with too lean mixture / misfires from too rich), can even be used to compensate a bit for long pipe lengths (needs to be richer during acceleration so more gas reaches the cylinder's intake port in time to make mixture correct with rising manifold pressure). Usually set while the engine is idling then stamping on the throttle (idle to flat out /idle to near flat out / idle to partial throttle) looking for crisp throttle response, and adjusted again while driving.

If you want to change top end mixture while throttle is held constant,you use the other mapping tools (map itself etc). Going too rich on LPG will result in less power than a stoch mixture on LPG because the greater amount of gas displaces what could otherwise be airflow into the engine (hence negatively effecting volumetric efficiency) to a greater extent that going too rich on petrol... You still want a rich mixture at high loads but not always as rich as would make more power on petrol. If you have a 0-1v lambda probe, where on petrol max power might arrive at richer than the narrow band lambda is capable of reading, on LPG max power might arrive at as low as 0,7v but we might still go a bit richer than 0.7v to protect the valves. Set the map first, then adjust the acceleration slider.

Wouldn't bother with a rolling road, they never give same under bonnet temps as driving on a real road. Under bonnet temps effect the LPG vapour temp (and reducer temp) readings which effect the mixture. If you've been sat idling in an LPG car for a while and under bonnet temps get high, if you suddenly set off and boot it the vapour temp reading will for a while be high, causing the mixture to be richer than it will be after a while of driving on the road when vapour temp readings have settled down to normal. Greater volume / faster throughput of gas through the reducer mean that gas temp readings fall when booting it but there is lag between booting it and the temp sensor reflecting the correct temp of gas reaching the injectors - If you have hot under bonnet temps to start with and then set off booting it for a while the mix will start rich and get leaner until temp correction has fully caught up, should be setting mixture when compensation has at least nearly caught up. A rolling road won't keep the rad/engine as cool as real road speeds, AEB systems also compensate mixture for reducer temp. Seat of the pants while reading trims/mixture is probably better than a rolling road.

07 November 2017 - 12:00

In the case of Orangebean's install (where adjusting the top end mixture throws off calibration at other points) I'm not sure what ECU he's got. Some ECU's have map screens with only a few denominations for engine load, so the top end fuelling box also effects near top end calibration / some have a lot more denominations (up to about 12 as memory serves) for Pinj's between 2.5 and 18ms as standard, and furthermore the denominations can be adjustable (i.e. the 18ms column could be made a 25ms column). If you don't have enough denominations the only way to get things absolutely correct is by playing with injector spec, pressure and nozzle size... but the get around is to set top end fuelling correctly at the expense of correct trims at near top end fuelling.

Also worth bearing in mind that depending on ECU type, year of ECU and firmware the system may or may not automatically switch back to petrol temporarily (accompanied by flashing yellow light on the switch but without beeping) when it senses Ginj exceeding available Ginj window (rpm versus gas injector pulse time). If rpm's are 6000 there is only a 20ms window for Ginj, if Ginj is above 20ms the injector won't have time to close before opening again to meter fuel and the engine will run lean regardless of Ginj being 20ms or even 50ms because the gas injector has already reached the point where it is open constantly... In which case you'd need to increase pressure, and/or or fit bigger nozzles, and/or fit faster opening or bigger flow capable injectors.

09 November 2017 - 10:27

Jeez, if the damage was caused by the original fitter wonder how well he slept at night...

09 November 2017 - 10:40

Same issue only maybe worse on the Jag engine'd L322s.

09 November 2017 - 12:22

Well, there's the obvious answer of his negligence possibly leading to somebody else's accident but I expect you're right. If I did tyres and was aware of something like that I'd have held hand up and fitted a different tyre, maybe offered that tyre to someone cheap for 'off road use only' on the back axle... not that off-roaders who trailer their cars to tracks etc would likely want to buy a damaged road tyre. Wouldn't want to be doing a ton on the road with that, especially if it were on the front... Reminds me of a mate who back in the day had a Cosworth with big wheels and really low profile tyres, pulled up after doing over 140 to find one of his back tyres was completely flat and breaking up, reckoned he could hardly tell while driving it but after stopping was sickened to see it imagining what could have happened.

09 November 2017 - 17:57

Yeh Marty, yours will be truly sequential so your slider should be set fully right. The only real exception for modern AEB ECU's is on a tiny minority of vehicles that do a hell of a lot of petrol enrichment during acceleration (where acceleration is defined the same as in the slider context, i.e. increasing throttle position)... usually dodgily remapped turbo stuff that shouldn't have so much acceleration enrichment if the petrol remap was good. Too lean usually decreases power more than too rich, for much decreased power from too rich you'd probably have to be so rich that if you wound the window down a bit you'd pick up on that eggy smell.

I calibrate and drive at the same time but I'm well used to it and can just glance across... Still I prefer calibrating slow stuff rather than really fast stuff. If someone else drives you need to drill it into them that constant throttle position doesn't mean constant speed / a touch more or touch less throttle means maybe a 1% shift in throttle position not a 30% shift in throttle position / stamping down and then holding full throttle means just that / etc. You'll probably see what I mean if someone else drives! If the driver is uncomfortable holding full throttle etc it's probably safer if you drive. Full throttle doesn't mean full speed, you can slow to a stop and accelerate hard at full throttle without hitting unsafe speed at least for a short while and on some cars you can extend that time by riding the brakes at the same time as acclerating though not to the extent of cooking the brakes..

Sometimes on repair jobs the customer drives but mostly a re-calibration gets done quicker if I drive while the customer sits with the laptop sideways on his knee so I can glance at the screen. I often regret letting someone else drive, many struggle with the concept of constant throttle (not unsafe but makes calibration more of a pain), some seem incapable of steering smoothly round a bend while holding throttle steady.

12 November 2017 - 14:32

The reducer in your pic (Zavoli Zeta S or Zeta N) is a decent unit but a bad point about these models is that they do come with pressure preset and are not very adjustable away from preset pressure which is 1.4 bar on the S and 1.2 bar on the N. You'd want the 1.4 bar Zeta S for the flow requirement of a P38 but if your injector nozzles are 3mm you'd really want less than 1.4 bar pressure maybe around 1.1 bar..If you do manage to adjust this model reducer from 1.4 to 1.1 bar it's flow ability may go down dramatically (much more than the difference between 1.4 and 1.1 bar would suggest). Lack of pressure adjustment is less of an issue for an installer fitting a new install than it is when replacing an existing reducer because the installer can choose injectors and injector nozzle size to work with the engine for the given pressure. We might assume that the original installer did that, so replacing a reducer that comes with preset pressure like for like should make for good results but the thing is a lot of installers who fitted a reducer with preset pressure won't have fully addressed nozzles / pressure so better results might be had fitting a reducer that isn't so limited in pressure adjustment.Before I could advise fitting a reducer with very limited pressure adjustment I'd need to know spec of your injectors and nozzle size, or at least know how ginj compared to pinj when the old reducer was good and calibration was correct.

14 November 2017 - 17:53

I'll have a look George thanks.

15 November 2017 - 11:05

As Tinley implied, lots of long established LPG bits / brands seem to have recently been rebranded as Tomasetto, I wasn't aware of this with the Zavoli reducers though, last time I bought one was probably early this year and was branded Zavoli.

For the temp sensor you might as well follow TT' and Gilbert's advice. I expect the brass bit is just a thread adaptor, if it's just in the location of a water temp sensor it won't cause any harm to the reducer to remove it anyway.

If your previous reducer solenoid was attached directly can you use that one's male/male adaptor?

The solenoid in your pic looks like the type that has 8mm inlet and outlet? Shiny chrome outlet and shiny nut at the opposite side of the solenoid? If so you can slacken the nut from the outlet and the solenoid will rotate around the shiny bits to allow orientation of the solenoid and it's inlet. 8mm Pipe fittings use 12mm thread.
Your reducer is listed as having 6mm pipe inlet, 6mm pipe fittings use 10mm thread.

Obviously if the solenoid has 12mm thread and reducer 10mm thread, to connect your solenoid directly to the reducer you'd need an M12/M10 male/male fitting. Male/male fittings come in a couple of lengths, you should really use the longer length with the shiny bits type solenoid because that type of solenoid valve has deep threads. I generally use a bit of gas paste when using a male male adaptor with this type of solenoid too.

Of course, if you have to go from 8mm pipe fitting on the solenoid to 6mm pipe fitting on the reducer, some type of adaptor would be necessary anyway even if you mounted the solenoid remote of the reducer. Easy enough if you had a few bits around, e.g. could just use a short length of 8mm equivalent Faro pipe with 6mm copper equivalent fitting on one end and 8mm copper equivalent fitting on the other but this probably won't help you! However, won't your existing solenoid and male/male adaptor work with the new reducer, or if you want to use the new solenoid won't the existing male/male adaptor work with the new solenoid?

16 November 2017 - 16:48


Its also worth being aware that some of Admiral's call centre staff do not know what they are talking about with LPG - they will ask for any assortment of random bits of paperwork to be sent in or just say we don't cover lpg cars. I'd recommend hanging up in this case and calling back, hopefully to speak to someone with more of a clue!

That's good advice that would be equally applicable with a lot of insurance companies regards LPG converted vehicles. Customers regularly tell me that someone at their insurers told them they didn't cover LPG vehicles / their car needs to be on UKLPG's database / they need to provide a copy of 'The green safety cert' (LPGA cert which LPGA now UKLPG stopped issuing years ago). Quite often in these cases the same or a different member of staff at the same insurers will eventually settle for a receipt from whomever converted the vehicle / the vehicle has passed an MOT since it was converted / the V5 shows LPG as a fuel type. But some such as Saga, Admiral, Hastings do very specifically want the vehicle to be on UKLPG's database. Never heard of Adrian Flux asking for anything.

16 November 2017 - 16:57

OldShep56 wrote:

I might see if the nice boys at our local car wash will do underneath mine. They're always admiring the car so let's see how much they like it. They're Iraqis and Afghans so they will do anything for a few bob. lol
Bet they get on like a bomb hehe.

Some great shiny engine bays on here, just be careful if pressure washing or steam cleaning around LPG ECUs, I've known a few get full of water that way. Best advice would be to remove the LPG ECU and gas pressure sensor.

26 November 2017 - 16:35

Yes, pros sometimes use the same approach you were thinking along the lines of! But since you can use the gas (just that you can only get 35L in the tank) why would you need to vent it's contents? Run the tank to empty, then look into changing the valve.

Does the stamp in the brass (for tank height) read 220 or 270? Should be 270, I can't see it properly in the pic but looks like could be 220, if it is 220 that would affect how much gas you can get in.

18 November 2017 - 17:44

Minimum bend radius is pretty tight, obviously better for the 6mm equivalent than for the 8mm equivalent. Based on memory I'd say a bend of 90degrees in about 6 inches for the 8mm pipe is OK. Not as tight as is possible with copper but is a lot more forgiving than copper, a kink will unkink.

4 Hole tanks usually have flange fitting outlet valves that would need an adaptor to use Faro (flange fitting Faro adaptor or flange fitting to olive fitting adaptor to normal faro end).

Can buy all sorts of fittings for 8mm Faro pipe, such as ends to fit in 8mm or 6mm olive joins, M10/M12 thread, straight, 30deg, 90degree, etc.

If I were changing 6mm copper pipe on a P38 to Faro I'd go with 8mm equivalent, especially if the reducer solenoid had 8mm inlet. I very seldom use 6mm equivalent on anything at all... Just converted a Ford 1.6 which got 8mm.

If there's any downside to polypipe at all it's that it won't stand as much heat as copper. Of course we shouldn't be fitting any pipe close to anything hot enough to be a concern anyway but question marks can arise when you have a vehicle with, say, a big back box under the width of a spare wheel well, a heat shield will then usually sit between the well and the back box, best type of tank to fit might be 30deg but even for pipe running above the shield there might be concern if using polypipe. On balance Polypipe is better in most respects, it won't break if fitted between components where there is bit of movement either.

Some of the Cop11 rules for pipe runs seem to make less sense for polypipe.

Usually when we talk about Polypipe we refer to Faro pipe but other brands are also common. Although the main brass part of end fittings will work across brands the end caps and olives are brand specific due to differences in internal diameter vs external diameter.

18 November 2017 - 20:04

If it's a single hole tank the outlet is likely to be M10 unless it has a rather old design multivalve in which case it could have flange fittings.

As said on the other thread make sure your solenoid inlet is M10, the one you pictured could be M10 or M12.

Easy to avoid running pipe close to hot parts on a P38.

26 November 2017 - 19:55

Agreed with lines of thinking above, on this design tank and valve it is the pickup pipe length that will make most difference. If the pickup pipe is 40mm too short we would expect 40mm depth of gas to be unusable (at least for purpose of fuelling the engine with a sequential LPG system)... 40mm depth of gas remaining in the tank even when the gauge shows empty and the LPG system seems to have run out of gas.

Yours is a 30degree / internal tank, if this were a zero degree / external tank we'd expect the tank to run dry but fill to be limited to 40mm below the level that it should fill to.

Wouldn't expect the 80% fill to be much affected if yours is 270 tank with 220 valve, just that the bottom bit of tank contents would be unusable... unless someone had extended the pickup tube. On most L322's I've converted I've fitted a 270 height zero degree tank upside down with special upside down Emer valve designed for purpose (and which fits inside a flexible gas tight housing). Emer valves are no longer made so on the last few I've converted I've had to fit an upside down Emer valve made for a 250 height tank, extend the pickup tube and adjust the float a bit.

26 November 2017 - 20:17

Lol 40mm, brains not even working out 270-220 tonight it seems ;-)

26 November 2017 - 21:32

This may not concern you much if you run the tank on it's side to use up the bottom bit of gas... One of a valve's seldom mentioned safety features is an excess flow shut off mechanism, if you do vent gas to atmosphere it can be quicker to restrict flow using the thumbwheel to adjust flow of gas coming out to the point just before the excess flow valve activates, particularly if your pickup tube is below gas level. Otherwise if you had say 30L of gas in the tank you could have gas escaping to the point of hearing a strong hiss but get up the next morning only to find it's still hissing to the same extent lol... So then you start undoing the 6 hex bolts cross pattern until you're down to only 2 opposing bolts sealing the valve, which can be a bit of a worry the first time you do it when you know there's still a fair bit of liquid gas and pressure in the tank and the next move will involve breaking the seal... but it's not so much a concern when you've done it a few times. Don't be worried if you need to undo the valve bolts with gas in the tank, if it all seems to be happening too fast etc you can always re-tighten valve bolts, don't be too worried about hissing or cold it isn't that bad. To prevent the car interior stinking you can refit or at least rest the tank valve area cover so most escaping gas goes outside the car rather than inside.

Anyway, your valve might have a pickup tube for a 270 height tank yet, anyway you could probably avoid most of the above running on LPG with tank stood on one side.

26 November 2017 - 20:42


If replacing the lines with Faro you could temporarily fit just the line to the engine making it quite a bit longer at the tank end than you need, and since you'll be shifting the tank anyway you could temporarily stand the tank on it's side valve end down... should allow driving on LPG to get more of the gas out before you take the valve off. Faro ends are all re-usable.

Bit of an aside... Many years ago I converted a limo for a company in Birmingham, I did the engine first and was completing the tank install when I broke the multivalve. The firm needed the car back for the weekend and at the time I didn't have many spares around (certainly not a tank diameter specific mulivalve) so I called around local installers to see who might be able to sell me a suitable valve... A 'done in a day' firm in Leeds who at the time fitted 'Aldesa' gear said I could buy a valve from them, so I went through and bought one from them at a price they'd inflated, and this turned out to be for a second hand valve (could smell gas on it). Still I bought it and fitted it and all seemed well, until the limo firm said they could sniff gas after parking the car up... So I bought another valve on the Monday which arrived on the Tuesday and I went to Birmingham to change the valve, which I found to be leaking from it's PRV, but their limo storage area was under arches in a kind of massive underground limo storage area so I had to take the limo out for a drive by myself around Birmingham to try to find somewhere to vent about 30L of gas. Luckily it was a summer day... so there were no clouds of gas drifting down the hill on the quiet street on a hill I eventually used.

I once vented (er more like released lol) 100L of gas from a cylinder tank in the yard, but first I made sure neighbours etc were out. There was a fair sized stream of very cold liquid LPG running down the yard for about 20 yards, all the tarmac in the area of the stream super chilled, some of the tarmac (in the yard) broke up. Once all the pressure has gone out a tank (because it's got so cold) you can literally pour the gas out, just that whatever the gas then contacts warms it up until the contact has cooled to the same extent.

26 November 2017 - 22:13

Can think about it like this.. If diameter of valve opening is only a couple of inches that's only 3.14 square inches, if temp of gas in the tank is only 10c it's at a pressure of only about 75psi, so there will only be about 235 pounds pushing the whole of the valve away from the tank... and recent temp isn't even 10c. Undo the 6 valve bolts slowly and there'll be enough slack on the bolts to provide space between the valve and tank while still fairly evenly balancing the 235 pounds over the 6 bolts... Then it seems not much of an issue.

But you could avoid the above almost completely, either by running the fuel out by sitting the tank on it's side and driving the fuel away or by slowly venting the gas even if the excess flow valve kicks in and slows venting to a very slow rate. If I ever have to do it I slacken the 6 bolts while the tank is venting, I got used to it a long time ago and it doesn't worry me, but it did the first time and I still don't like slackening the last couple of tank bolts even though I know it'll be OK.

If the pressures involved were CNG like then I'd be more concerned but with LPG we're not really talking much pressure

In most cases like the above I've been laid down under a car fitted with a zero degree tank, so liquid gas has escaped after I've removed the valve. Far less concerns on a 30 degree setup where only vapour will escape after slackening a valve, you're not going to get liquid gas squirting out,..A drop of liquid gas hitting your eyeball and cooling it's surface by about 30degC really hurts, this won't happen on a 30 deg setup if the tank is less than half full because only vapour will be expelled