LPG Discussion Forum

I am keeping an open mind, but 1A sounds a logical starting point.

Replaced the bung (wine cork) and the top radiator hose. Took the car for a spin and no hot mis-fire issues?!?!?!

Problem is the previous owner did less than 100 miles in the car over the last 3 years.

Will drive it for a few more days and give the car a shake down. Already the traction control light has come on and the electric aerial spat the mast out and it will not go back in.....joy!

Brief update. This morning I had the following error codes:

P0106 - Manifold Absolute Pressure System Performance
P0311 - Cylinder #11 Misfire Detected
P1314 - Misfire Rate Catalyst Damage Fault - Bank 2

Not surprising the engine is not running right with those codes. At least bow I know (roughly) where to look.

Wish I knew which cylinder #11 is, as the Jaguar V12 only goes 1-6 and either A or B bank.....

First stop is to swap the plug in cylinder #11, then the leads, coil packs, etc, etc...

cyl 5B
http://jaguarclub.sk/service/x300_electrical.pdf

Thanks to Rossko I replaced the HT leads and the misfire has gone. Pulled all the electrical and plumbing leads out of the MAP sensors and those error codes have gone as well. Also replaced the traction control actuator, front indicators, headunit, electric aerial etc...

Looks like I can finally look at the LPG installation. It includes 2 Bigas reducers:

https://www.flickr.com/photos/95537991@N05/14374792457/

There is a small nut and a larger knurled screw. What do they do?

I appreciate tuning a V12 with 1 Leo is not recommended, but I would like to give it a go. Recommendations where I start?

Firstr challenge is establishing a diagnostic connection to Leo, and making sure both it and you have a working view of a lambda sensor.
It could pay to run two wires and a plugin connection so you can look at either bank.

I have the AEB software and a lead from Tinley that reads the Leo.

I have another lead that plugs into the OBDII port in the car - where I can read the fuel trims and O2 sensors, per bank.

Whats next?

Confirm that the Leo can see and understand the lambda readings correctly for rich/lean. Not all sensors are alike; 6 pot X300 have odd types, dunno if yours does.

Then try a changeover - and watch eveything to see what happens, goes rich or lean etc. Holding at 2-3000rpm for this allows more time to see.

I think the Leo can read the lambda, I can see the green, amber and red.

Turned the bias screw out 4 turns on both reducers and turned the idle all the way in. Set the idle actuator at 10, 10, 50, 50. Car ran nicely, smoother than on petrol. Idle was a bit low, so gave the idle screw a quarter of turn. Idle now perfect.

Spent about an hour twiddling with the Leo and the reducers and impressed with the performance.

Happy to receive any further advice to fine tune.

Will also raise a post on "Find an LPG Professional". The LPG install needs a service, checking over generally and the filler needs to move from the boot slam panel to a vertical exterior surface.

Had no response from my "Find a professional" post.

In the meantime had more twiddling with the Leo and reducers. Idle seems ok at nil turns. The earlier posts suggesting the restrictors in the airfilter were there to enrichen the mixture seems correct. I can increase the mixture on the reducers to the point where the car will not even idle and the actuator is still max'ing out. I presume that means the reducers are not up to supplying the right amount of gas across the rev range.

At 2.5k (under load) the lambda readings on petrol are green, occasionally flickering amber. At the same load, on LPG, the lambda is permanently green, which I presume is too lean?

Today found the filter for the LPG system but no time to pull it. I doubt it is causing the problem....

Advice welcome, although the slight mis-fire on the petrol injectors and the autobox error (P0751) are keeping me busy

Pulled the filter - no one mentioned depressurising the system before pulling it - ask me how I know.....a loud bang, a smell of LPG

The filter had a slight dusting on it, thats it. Put it back together.

It has been a while since my last confession.....

Since then I have managed to sort out the auto gearbox limp mode. I dropped the pan, filter, soloenoid A and treated the gearbox to a fresh oil, and gasket. It made no difference. I put it in Sport mode - problem solved. I ran it round for a month, put it back in Normal mode - problem solved.

2nd problem was running on LPG car as smooth as silk, running on petrol, bag of spanners. Tracked it down to a connector missing off injector 3A - smooth as silk.

Been advised that the car will run on LPG with the current setup, but with the mixers bolted directly to the throttle body, instead of being stuffed in the inlet tubing.

Cool thing is the car is running well and if I can get the LPG system working bonus!

Thought you had it running smoothly on LPG mate?

MackV12 wrote:Cool thing is the car is running well and if I can get the LPG system working bonus!

What's the issue with running on LPG now then?

Simon

Car runs quietly on petrol, just the sound of ticking injectors. On LPG the car is almost silent.

Problem is the car seems to run lean, with the stepper trying to compensate. Idle is spot on, but the car lacks power when accelerating.

When I first got the car it had a pair of K&N's with home made ally restrictors in them, I am guessing because it was running too lean. I chucked the K&N's cos they were knackered and the restrictors cos throttling an engine did not make sense (to me).

I have the Bigas reducers set at about 1 turn on idle and 3-4 turns on the knurled nut.

I was advised that the mixers should be attached to the throttle bodies instead of being stuffed in the air inlet, downstream from the engine breathers. Problem is the new plate mixers would mean having to fabricate new inlet elbows as the current plastic ones might hit the bulkhead, due to the thickness of the new mixer plates. I want to make sure I am doing the right thing before I shell out for new mixers, fab'd inlet elbows etc

Should I just give in an fab some restrictors in the new K&N's?

Either way, I am not leaving the current mixers botched into the inlet manifold trunking, with a wodge of silicone sealant.

Advice appreciated.

Apologies folks, especially to Gilbertd. I have re-read the thread and bolting the mixer plates on the throttle bodies is recommended by this forum.

Anyone any suggestions (nice ones!) as to which mixer plates are the right size/capacity for the Jaguar 6.0 litre engine and preferably just bolt up?

MackV12 wrote:Problem is the car seems to run lean, with the stepper trying to compensate. Idle is spot on, but the car lacks power when accelerating.

I have the Bigas reducers set at about 1 turn on idle and 3-4 turns on the knurled nut.

Can you not adjust the knurled nut to get the mixture correct under load, then adjust the idle bypass to get mixture correct at idle?

Personally, if the car were a keeper, I would remove the mixer system and fit 2 x 6 cylinder sequential systems.... You could then run whatever air filters you wished, no need to fabricate restrictors etc, you'd only need one reducer, performance, smoothness, drive-ability would all be better.

Only incidentally - I've had a few BMW750 V12's, I bought one that came with a Tartarini Etagas setup (Etagas is a continuous injection system so uses stepper motor controlled metering blocks, the output of which is distributed equally to each cylinder. The advantages of this over a mixer are no restrictive mixer and no chance of backfires, but it is still a separate fuel system which doesn't work as a slave to the petrol system). The system had 1 x ECU and 2 x stepper motor blocks, one for each bank of cylinders. I didn't realise initially but when running on petrol, the drive by wire standard BMW electronics (which uses a separate throttle body for each cylinder bank) doesn't close the throttles when you suddenly lift off the accelerator... Instead it cuts off petrol injection, waits for rpm to drop, then adjusts the fly by wire throttle actuators to control the idle rpm.. Guess what happens if you fit a mixer or continuous injection gas system to an engine that is controlled by petrol ECUs that work with this type of methodology - Yes, the engine runs on if you lift completely off the throttle! Not what you want when you have a 5L V12 under the bonnet! Further (but not quite so bad) complications were due to how the installer had connected to TPS, they had connected to fly by wire TPS, so when cruise control was on and pedal throttle wasn't used the Etagas system would cut off fueling, so cruise control wouldn't work. In the end with Etagas installed I could either prevent the run on situation and loose cruise control or keep cruise control and fix the run on situation... But this was only after I had replaced the (failed) single but 'dual stepper motor channel (2 cylinder bank)' ECU with 2 x single cylinder bank ECU's and done a bit of rewiring. I eventually removed the Etagas system(s) and fitted 2x 6 cylinder sequential systems but I suppose in hindsight I could have come up with an electronic fix for both problems for the Etagas setup.

I love the smoothness of V12s and the way they never sound like they're being worked hard, would love another to play with, but with the BMW's the V8's are nearly as powerful, handle better (less front end wieght) and are much more economical... Ask me (or rather don't!) how easy it is to change the plugs, propshaft, repair the exhaust (mig), water pump, nitrogen filled suspension and ABS components etc on the old V12 7 series

Simon

Simon - will indeed do some more twiddling with the mix/idle. Figured out the OBD2 reader will show me what the lambda is doing on each bank. Will see what readings I get for petrol/rev range (underload) and twiddle the LPG to match.

Clearly the restrictors I chucked were there for a reason, so I will fab some up out of a can of Aldi's finest baked beans.

Once I get the system running I will check it in with your goodself to make it safe/insurance compliant/reasonably efficient - this is a V12 after all.....

I look forward to our meeting / next chat!

Simon

MackV12 wrote:Problem is the car seems to run lean, with the stepper trying to compensate. Idle is spot on, but the car lacks power when accelerating.

The lack of power also suggests lean, not good for your engine.

Mixer size, I'd say 40mm max for each bank, straight sixes seem to need smaller mixers to function at idle than (smaller capacity/power) four cylinder vehicles, you may just have to find a way to make them fit. Fitting the mixers as close to the throttle body is best, but a low priority compared to your current issues.

Do you fundamentally understand what the Leo does and tries to do during operation and also what the vapourisor does and the adjusters on it, and therefore what the end result is you're trying to achieve?

Ps) I DIY'd my Leo 175 install.

Defo too lean. Good guess on the mixers, the actual internal diameters are 37mm.

Spent some quality time with a baking tray this weekend making making reducers for the existing mixers. Tried 30mm restrictors and turned the LPG reducers right down - still too rich.

Clearly the ideal diameter is between 30-37mm and I think it is possible to move the the mixers 30 cms closer to the throttle bodies. I am no LPG guru but if the engine has 2 breathers on the nearside and 1 breather on the offside feeding in to their respective induction trunking that must make the breathing unbalanced, especially as the mixers are downstream of the engine breathers. Upstream of the breathers and closer to the throttle bodies seems logical to me.

Time to call in the experts to make the LPG system safe/insurance compliant/efficient or remove it all together.

Will keep you informed of progress.

The saga for my 1995 LPG V12 Daimler is finally coming to an end. Still got the air con condenser to sort and the steering reach mechanism, but they are both known quantities. Key thing is I now have a working LPG system.

A quick recap - The LPG system fitted to the Daimler has clearly run in the past, but with the current single Leo ECU configuration it would not be efficient. Thanks to this forum I got the software, the right cable for the ECU and twiddled the reducers. The car would now run on LPG, but badly. Time to ask the professionals.

I approached LPGC (Simon) via this forum for his honest opinion and got it. The fact that there was one Leo running both banks of the V12, means that bank B will be running according to input from the lambda sensor for bank B, whilst bank A will also be running with input from lambda sensor B. Clearly less than ideal!

Simon checked the running of the system and found the following issues:

1. The reducer for bank B was faulty
2. The lambda sensor was under-reading
3. The mixers were not equal in diameter and were slightly too big
4. The fuel tank was not registering
5. The software and reducers needed tuning

Simon recommended fixing the above and adding a Leo to take care of bank A. Picked the car up a week later and what a revelation. Car reacts well throughout the rev range. I can now run the engine on either LPG or petrol and switch over occurs at 1600rpm. I can even choose which bank to run what fuel on – amazing!

I am sure Simon will respond to this post with a techy response of what he found and how he fixed it. For me, I now have a V12 engine running super smoothly on LPG at 65p litre, with a V12 - every little helps!

Big thanks to all the forum for your help.