p38 4.0 lpg

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shealyp38 · #21 Post by **shealyp38** » Sun Mar 03, 2013 7:41 am

My vin is xa417***

shealyp38 · #22 Post by **shealyp38** » Sun Mar 03, 2013 7:59 am

That was the sensor that I'm going to buy

Gilbertd · #23 Post by **Gilbertd** » Sun Mar 03, 2013 9:47 am

Don't forget you need two, one for each downpipe. That later sensor is the cheapest one of the lot too!

shealyp38 · #24 Post by **shealyp38** » Sun Mar 03, 2013 5:49 pm

Yeah I know its 2 sensors I need
I checked fuse 26 today and thats fine so tomorrow ill check im getting 12v at the sensor
If thats right does it mean I need new sensors for definite

Gilbertd · #25 Post by **Gilbertd** » Sun Mar 03, 2013 7:03 pm

You can check with a meter if you don't believe what Scantool is telling you. First make sure you have heater current flowing and you can see the voltage at the sensors. Connect the +ve probe of a voltmeter to the black (signal) wire of one of the sensors and the other probe to battery -ve. Run the engine and watch the meter. If there is nothing wrong with them you will see the voltage swing back and forth between 0 and 1 volt. If they are dead, cold (due to failed heater) or the wrong ones, you will see permanent 0V. You can also check the colours on the wires on the sensors themselves, the correct ones will have 2x white, grey and black, the wrong ones will have black, yellow, red, and white.

shealyp38 · #26 Post by **shealyp38** » Mon Mar 04, 2013 5:05 pm

just been under the car and they have grey plugs with 1xblack1xgrey and 2xwhite wires
and is getting 12v to them
so im presuming they are the right sensors just not working right
they were changed about 6 months ago,should they fail that quick?

rossko · #27 Post by **rossko** » Mon Mar 04, 2013 5:48 pm

No, but

There are cheapo chinese parts on the market that may not fare well. I would recommend the correct NTK part. Where pattern parts have been used, they may be spliced to the original connector. As the wires are stainless (not copper) the splicing may be suspect.

They can be destroyed by external events - hammering or welding on the exhaust, head gasket failure (antifreeze will poison them), thermal shock (a dunking) etc.

shealyp38 · #28 Post by **shealyp38** » Tue Mar 05, 2013 2:39 pm

New sensors have been ordered and ill report back when fitted
Just hope it sorts it then onto my other problems

shealyp38 · #29 Post by **shealyp38** » Thu Mar 07, 2013 6:15 pm

when i install my new sensors will my gas system need calibrating again or will it adjust by its self

Gilbertd · #30 Post by **Gilbertd** » Thu Mar 07, 2013 6:49 pm

If it was set up with them working it will be right, it'll only need setting up again if it was calibrated with them faulty and running very rich on petrol. It's the petrol ECU that adjusts the mixture, the gas ECU just adds a fiddle factor. Don't worry too much about the gas system, get it running right on petrol first.

shealyp38 · #31 Post by **shealyp38** » Fri Mar 08, 2013 3:29 pm

well i fitted the new sensors today,then cleared the codes from the ecu
started the car up and no new fault codes
read the live data from scantool and its saying the fuel trims are still at 25% but no voltage reading
but when i took it for a drive these dropped to 0% and still no voltage reading
then when on tickover it went right back upto 25%
and to top it off two fault codes have reappeared p0135 and p0155 o2 heater curcuit
is there a way to test sensors of the car?

Tubbs · #32 Post by **Tubbs** » Fri Mar 08, 2013 3:37 pm

Did you drive on petrol or gas ? Any difference between the two fuels ?

shealyp38 · #33 Post by **shealyp38** » Fri Mar 08, 2013 3:44 pm

drove it on petrol

rossko · #34 Post by **rossko** » Fri Mar 08, 2013 5:04 pm

shealyp38 · #35 Post by **shealyp38** » Fri Mar 08, 2013 5:13 pm

wot about the maf?

Tubbs · #36 Post by **Tubbs** » Fri Mar 08, 2013 8:34 pm

Agreed... Whats the maf reading at tick over ?
Around 5 g/s is normal.

shealyp38 · #37 Post by **shealyp38** » Fri Mar 08, 2013 8:42 pm

it was around the 0.55g/s

LPGC · #38 Post by **LPGC** » Fri Mar 08, 2013 8:57 pm

As someone has said, the petrol ECUs on Gems is only just OBD2 compatible.

They usually show very low airflow rates on OBD scanners - The MAF may be broken, but I wouldn't say it is for sure just because an OBD scanner shows the low figures. Long term fuel trims similar story - show minus 100% on most scanners.

If you go to a motor factors, give them your vehicle reg and ask for a Lambda probe, in my experience most of the time they still get the wrong one. If the plug is the correct colour and connection it should be the correct one. I believe at least most of these 4.0 Gems are 5-0 volt. Seen a RangeRover today, guy had been supplied new 0-5v lambda probes, his vehicle should have had 5-0v probes. He cut the plugs off to try to make the incorrect lambda probes work - Result.. Constant rich running.

Simon

shealyp38 · #39 Post by **shealyp38** » Fri Mar 08, 2013 9:05 pm

mine is the bosch engine not the gems one

LPGC · #40 Post by **LPGC** » Sat Mar 09, 2013 1:03 am

Still possible to have wrong Lambda probes / interpret OBD data wrong using scanner..

What voltages are you getting from Lambdas?

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p38 4.0 lpg

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