p38 4.0 lpg

[shealyp38]

hi guys im new to this forum and have an issue with my range rover 4.0
when i got the car it needed to have the gas system serviced its a dream xxl-n system
so took it to get done only to be told that it was running a bit rich on petrol and maybe a possible misfire somewhere
anyways he wouldnt touch the gas until this was sorted
so i went and got a cable for my system and below is a couple of pictures of the car on tickover running on petrol and gas
if someone could help me out with this id be very grateful

[Gilbertd]

It's running very rich with petrol injector times that high at idle. I suspect you have a problem with one or both of the lambda sensors so the petrol ECU has gone into default which is richer than it needs to be. Do you have an OBD reader (although my U581 doesn't give accurate live readings on a GEMS P38 because of it using 5-0V Titania sensors, but it will give you an idea of what is happening) to see if you have any stored fault codes. If you do I would suspect they will be lambda related ones.

[shealyp38]

would i have my MIL lamp lit if there is a fault code stored?

[classicswede]

With injection times that high it must be either stinking rich. I think we can rule out low fuel pressure as the times are still very high even while on LPG

[shealyp38]

just plugged my laptop into the car and got these codes
p0102
p0130
p0135
p0150
p0155
p1319

[Gilbertd]

As you by now have discovered, stored codes don't always bring on the MIL, only serious ones. The codes you have are:

P0102 Mass Air Flow Sensor Low Out of Range Fault
P0130 Oxygen Sensor Cycle Fault Bank A
P0135 doesn't appear in the LR list?
P0150 Oxygen Sensor Cycle Fault Bank B
P0155 doesn't appear in the LR list?
P1319 doesn't appear in the list either but is connected with the ABS system.

So, it certainly appears that the lambda sensors aren't well and the MAF could probably do with a clean. Squirt the MAF with some carb cleaner to get the black crud out of it and clear the codes. Run the car for a while and see which of the codes come back.

Are we talking GEMS or Thor engine? The GEMS uses the 5-0V Titania sensors but the Thor uses the more common 0-1V Zirconia. Does your OBD reading software have the ability to show live data?

[shealyp38]

mine is the thor engine
ive just done some checking and found the codes 0135 and 0155 are todo with 0130 and 0150
1319 is Misfire Detected At Low Fuel Level
im using scantool.net for reading codes

[Gilbertd]

You should be able to get all of the codes and live data then. GEMS is only just OBD compatible and gives some oddball readings but Thor should be no problem. Clear the codes and see which ones come back. See if you can see what the lambda sensors are doing when it is running, they should be flip flopping between 0V and around 0.9V but I suspect they may be sitting at 0V all the time. Check the long and short fuel trims too, long should be pretty close to 0%.

[shealyp38]

well i had it back on the laptop today and heres some shots of what scantool returned
ignore the quality of the pics



a little bit depressing reading i think
had a check of the exhaust aswell and found a little leak just over the rear axle where the hanger is
and found out the lambda sensors were replaced 6 months ago,how true this is i dont know
and after i cleared the codes a couple returned which were
p0102
p0135
p0155
all of which were pending

[Tubbs]

Generic codes would say both banks lambda heater circuit malfunction and the maf.
Checked the heater circuit fuse ? They will probarbly both be running from the same curcuit.

[shealyp38]

where is that fuse located?

[Tubbs]

In a fuse box
Dunno. Have a look at the fuse diagram...

[shealyp38]

just looked at the fuse box
god only knows what fuse it is

[Tubbs]

Pin 4 ecm, f26 fuse apparently. But having done a bit of digging it may be showing 2 lambdas that arnet there too.....specced up with 4 (us market) but only 2 connected so the ecu logs them as at fault..

[Gilbertd]

F26 in the engine compartment fusebox. Sensor 1 is the only one fitted on a UK spec car, US and Japanese spec have post cat sensors too so they would show s sensor 2 on each bank. But, you've got 0V from either bank 1 and 2 sensors which has pushed the long term trims up to the max at 25%. That's why it's running rich, I hate to image what your mpg figures are like!

[shealyp38]

so its looking like 2 new sensors?
im getting about 10mpg if that

[Gilbertd]

Certainly looks that way but confirm you have 12V getting to them both first. The sensors will have 4 wires. There should be an ignition switched 12V supply to one (a brown/pink wire according to the diagram), two will be grounded and the remaining one will be signal wire. The wires on the actual sensors, assuming standard colour codes, will be a pair of white wires for the heater (so one will have 12V and the other grounded), a grey (signal ground) and black (signal output). Check the colour of the plugs on them that connect to the cars wiring loom, I think yours should be black (mine, being GEMS, is grey).

You must get the correct ones, GEMS and Thor use different sensors but there are sellers on Bay listing lambda sensors for Range Rover 94-02 which is not correct. What they are selling will be right for 94-99 or 99-02 but not both. You'll need your VIN number to make sure you get the correct one:
VIN up to VA350483 needs part ERR1834
VIN VA350484 to WA410481 needs part AMR6244
VIN WA410482 onwards needs part MHK100940

[shealyp38]

i saw that mine had grey plugs when i looked under the car today

[Gilbertd]

That would figure, they are almost certainly the wrong ones if the plug on the sensor itself is grey. Wire colours will be Black, Yellow, Red and White. The wrong sensor will give 5V out when lean and 0V out when rich, whereas the correct ones will give 1v out when rich and 0V out when lean. At some point it was a little bit rich so the lambda sends out 0V which the ECU reads as lean so it richens it up further until it reaches it's limit (+25%) and goes no further. That would explain why you have 0V showing all the time.

I'm not sure if mine are working as well as they should as it runs far better on gas than on petrol but, as mine is a single point with a separate lambda sensor purely for the gas system, it doesn't matter if they work or not. If you find you do have the wrong ones, I'll make you an offer for them!

[Gilbertd]

Just been looking. Most pictures of the later MHK100940 sensor show it with an orange plug (although some show it as a grey plug but that may just be a generic picture) and with the standard 2x white, grey and black wires. However, I've got the genuine Land Rover parts catalogue which quotes the VIN number for this one being post WA410482 whereas suppliers that actually quote V|IN numbers state post XA410482 (such as this http://www.island-4x4.co.uk/oxygen-lamb ... -2196.html). Maybe the GEMS stopped at WA410481 and then they jump to an X but continued the numbers sequentially?