JAG XJ6 wont run on petrol

[xj8user]

Hi just bought a 2003 x350 XJ6 with LPG. seems install was done 2008 from old MOT's and has done 140K
Firstly the Zavoli install looks poorly done, but main problem is it struggles to start on petrol with rough idle, and will only idle after engine is warm say 1/3rd on temp gauge.
Runs reasonably on LPG but is down on power?
There is a unit attached to the petrol pressure sensor harness which has no markings but has an adjustable pot inside? wondering if this is a petrol pressure emulator? cant see any signs of return line?
I have replaced the yellow O rings on the manifold valve with new style green ones and put in new NGK standard plugs gapped to 1.0mm as advised on NGK site for LPG.

Any thoughts or help appreciated

[rossko]

Could be an emulator. Could be broke, or incorrectly set, or simply not suitable for this car. Poor/missing emulation can lead to non starter, as insufficient fuel pump drive gets learnt.

[xj8user]

Thanks Rossko,
from reading about the Jags petrol pressure issues, is it best to forget about an emulator and fit return line or buy a new emulator and fit that first?

[LPGC]

Assuming this is an X Type not an XJ6.

Pretty much agreed with Rosko (in any case).

If it is an emulator, and very likely it is, then if you change an aspect of it or fit a fuel return then the LPG system will probably need to be re-calibrated. But this course of action would still be what I would advise.

Been a long time since I tried fitting a fuel pressure emulator to a Jag, in experience they seldom work in the long term so I always fit an actual return (couple of 'J' and other type emulators tried on cars but removed and now living indefinitely in a box around here!). Come to think of it, I can't remember them wiring to LPG system active - but unless such a unit is more advanced than we might assume (i.e. can tell from it's readings which fuel the engine is running on - this is in fact possible) it would be active all the time so could mess up petrol running.

But have seen a few of these cars with broken fuel pumps too, seems to occur much more commonly where a proper return isn't fitted though.

Any info on OBD2 petrol pressure reading when running on petrol / when running on LPG?

If LPG calibration is poor then the poor running on petrol could be due to fuel trim issues. In which case given what you've said would expect LPG system to be calibrated too lean at high loads and too rich at low loads.

Simon

[xj8user]

Thanks Simon, No it is a 2003 XJ6, Ally Body, with 3.0L engine as in X and S types.

Its a while since I messed with an LPG system so tried an old RS232 interface with Zavoli software but couldnt connect, so have ordered a new USB one from internet.

Will report back when it comes and get some data.

Will also order some kit to fit fuel return, where is best place to fit on Engine and Tank side?
I assume I can TEE off fuel Delivery line and fit solenoid valve wired to open when on gas and close when not?
Does it work by using a restrictor/regulator in the return?

[rossko]

Yes, you have got it with regard to how the return works. Yes, you must insert a restrictor.
You need to calibrate restrictor size by observing OBD data, don't attempt this without some kind of OBD live data display. Last X350/6 I did worked out about 1.5mm bore from memory. Copper pipe stub filled with solder and drilled. Tee, solenoid, restrictor in engine bay, return to nearside tank under rear seat.

[xj8user]

Thanks rossko, I have ordered a return kit from Tinley Tech, looking at Pic think there is a valve of some sort or whether its the solenoid.
Will look when it turns up and if needed use your method and drill.
I have a copy of Jag software so will use live data from it.

Thanks again will report back when installed and running.

[LPGC]

Maybe it's good that a 1.5mm nozzle works, that's just about the smallest drill that comes in drill box sets without getting down to Dremel sized stuff. Usually I steer clear of buying boxed drill sets - over expensive and under par. I usually buy drill bits from the same place I buy nuts and bolts.. Recently I needed a new high tensile M8 bolt to replace the slide bolt on a brake caliper - got that bolt, also got loads of M6, M8 and M10 machine bolts + washers etc, and 2x complete drill bit sets... The lot for £10! The smallest they sold was 1.5mm though.

I've used some 'off the shelf' kits but some are a bit worrying in that the petrol hosing included won't fit over the shanks on the T itself so piping has to be crimped to the screwed in nozzle, which itself is only connected to the T by a very short length of thread, and said threads need sealant or will leak. Not always easy to drill the solder in said nozzle either without loosening the solder (the nozzle is supposed to be, and is, very smooth inside).

Last thing wanted is for petrol under pressure to leak / squirt in the engine bay. I usually fit different petrol pipe (none braided) that will fit over the flanges on the T. A 1mm semi-commercial MIG welding jet can be crimped in the pipe and restricts petrol flow enough without working the petrol pump as much.

Whenever I install a fuel return, as sure as I am that I have installed it all properly and secured all piping, despite however many checks I do before handing the car over, I always ask the customer to keep their eye on it when I hand the car over and to call me if there are any issues. On one fairly recent job (supercharged RangeRover) the fuel return DID get a drip, customer told me one day and I did a 200 mile round trip the next day (a Sunday) to sort it.

Simon

[xj8user]

Quick update, Have the petrol return kit will install tomorrow.
Also got the new interface but no matter what I try it wont communicate with zavoli ecu get C03 and C04 errors have tried every version of their software from N4.6.3 UP N6.1.2.0IC?
The ECU doesnt have its sticker but date stamp on back is June 2008.

[rossko]

Be sure to use Alesei software if it is a 2568 ECU.
Sounds like it is not a Zavoli ECU. Many other brands are pin- and mostly function-compatible, but they differ with firmware which will only chat with matching laptop software.
You can verify by seeing different error code with cable unplugged?
Try other popular brands - King, OMVL, Bigas, etc.

[xj8user]

Sorry Rossko my post is confusing!
The ECU has the big sticker on front with Zavoli Alisei N but no sticker on side with date or ver no?
It has a date stamp on back of alloy case which ties up with the first MOT showing LPG 2008.

I have a BIGAS sequential ECU 6 cyl in a box date stamp is Feb 2005 2 separate plugs on base and has a pipe nipple near top side?
Could I swap this in and try with Bigas software, are they any good?

[LPGC]

Bigas with a pipe nipple might be the older 'C type' (none slave) ECU which wouldn't be compatible.

What's this cable you're using?

Simon

[xj8user]

http://www.ebay.co.uk/itm/Zavoli-Uni-Pr ... 541c95368f
This is the item using the white connector.

Yes checked the bigas ecu and it has 2 plugs of 3 rows of pins, The Zavoli has longer plug with 2 rows of pins; so definately not interchangeable without using bigas loom?
I am running on petrol at moment to see if problem still exists once running ok on petrol for a few days and then will try again to connect but am stumped at moment.
Last resort may be to buy another ecu and change front end?

Joe

[LPGC]

Plug should work. Just to help confirm (can't see in the pic) what number is on the lead with the white plug? Are all the wires on a single row in the connector?

A Bigas SgisN ECU would be compatible with your system. The Bigas ECU you have is the earlier type as mentioned above.

Probably a bit premature to start fitting a new ECU (or especially the full front end - You shouldn't need to change the loom anyway, brand new ECUs will work properly with your loom).

Are your serial port device drivers all working OK (nothing showing wrong in Windows Device Manager)? What version Windows are you using? What version Zavoli/Alisei software have you tried to use?

Question will probably need to be asked at some point... Do you have Zavoli's own injectors or Matrix injectors (which still probably have a Zavoli sticker on them!)?

Simon

[xj8user]

Plug on lead is No1 all wires in top row below clip.

Using windows 7 device manager doesnt show any conflicts and has USB Serial port in Com2

I think injectors are Matrix its a black block with big chunky connector attached.
I have 6 new OMVL fast injectors I bought couple of years back and never used so can swap out if needed assuming Zavoli support them?

Joe

[xj8user]

Started fitting the petrol return, the kit includes a solenoid valve with integral 180 degree lever which allows it be used as normally open or closed
interestingly the Y piece has 2 nipples and a 0.8mm mig tip for branch to solenoid as restrictor, I put in a 1.2mm mig tip which was between your size and Rossko's

How do you actually terminate the line at the tank end? In through the top of fuel pump plate?

Joe

[xj8user]

Eventually made connection to zavoli ecu, it only seems to like ver 6.1.1.0IC tried about 12 others, earlier and later versions that I could find, and bingo worked with this one?

So now can see whats going on and immediately see, with engine just on, gas temp is at 110deg? have traced reducer sensor end and wires seem to have come off sensor, or have been joined together, same with sensor cables at injectors.
Could a resistor fool the ecu into thinking the temp was say 85deg

The install manual show another gas temp sensor and search on web shows one attached to an inline connector? do you need both?

The wiring in manual shows orange/black and black for one which I assume is near to injectors and orange and black to the reducer.

one of the coolant pipes to the reducer seems to be kinked due to having to double back on itself which cant be helping.
The more I see of this system cant help thinking someone has been bodging recently.

Joe

[xj8user]

Latest: have lashed in 2 temp sensors to the 2 sets of black and orange wires,
get reducer temp of 45 and gas temp of 60 plus. tried to auto calibrate and keep getting message " Can't calibrate gas temp too low"

I would have thought anywhere above 40 would be ok?
Also being an auotmatic should it be set to change to gas above 1600rpm?

Are there special considerations for automatics?

[rossko]

Swap around your temp sensors so that the reducer reads the higher.

[xj8user]

Thanks rossko will do