Thread: OBD2 fault code question

Mate I never had an spurious codes like that on my LPG system

Maybe run it on petrol for a while and see if the codes recur ?

Steve

I havent seen those faults, but if you are having inlet manifold popping, then you are very likely to have damaged the MAF and/or the intake tubing or the airbox. These engines are very sensitive to correct MAF readings, and inlet leaks after the MAF sensor. The MAF are not durable against those backfires, also, they can get damaged and still give valid 'looking' values.

My suggestions:
1. Ensure intake tubing is in great (not good) condition
2. Clear faults
3. Run on petrol for days/weeks, check for faults and monitor fuelling
4. Check your long term fuel trims and close out faults one at a time
5. Be happy

What type of LPG system is it?

Hi Glenhendry, it is an OMVL system, with a venturi ring inside the rubber air inlet.I have had an intermittant issue with this system since buying the car and have been through a few airboxes. I believe the air tubes to be perfect, I did have them just tight enough as to stay on and in event blow off rather than destroy themselves as backfiring was really bad. I changed plug gap about a year ago and have changed plugs every 10,000 since putting this engine in...had same issue with older engine too. Had no issues for that year then after being off the road for three months doing EAS problem has come back. I will change plugs again and leads then as you suggest drive on petrol for a while to check faults. As it stands i have an intermittent bad idle...when it starts to idle rough i am most likely to get a pop on take off...i think the faults come as engine cuts out but not certain.Once I have spent a penny i will check again, also want to invest in a steel , landrover discovery air filter in case issue persists.Thanks for response.

Originally Posted by deano2469

Hi Glenhendry, it is an OMVL system, with a venturi ring inside the rubber air inlet.I have had an intermittant issue with this system since buying the car and have been through a few airboxes. I believe the air tubes to be perfect, I did have them just tight enough as to stay on and in event blow off rather than destroy themselves as backfiring was really bad. I changed plug gap about a year ago and have changed plugs every 10,000 since putting this engine in...had same issue with older engine too. Had no issues for that year then after being off the road for three months doing EAS problem has come back. I will change plugs again and leads then as you suggest drive on petrol for a while to check faults. As it stands i have an intermittent bad idle...when it starts to idle rough i am most likely to get a pop on take off...i think the faults come as engine cuts out but not certain.Once I have spent a penny i will check again, also want to invest in a steel , landrover discovery air filter in case issue persists.Thanks for response.

Before you go spending your hard earned $$$ on more plugs and leads: The leads should last for several years if they are kept clean and are mechanically "intact" i.e. they have not been mechanically damaged and both plug ends are solidly attached.

Re. Code P0201:

I find it curious that modern spark plugs would last only 10,00km ...

* When you removed the last set were they seriously worn? ..
* Are the plugs of the correct heat range?
* Have you checked the integrity of the wiring in the injector circuit? see http://www.obd-codes.com/p0201

Re Code P 0108:
A major trigger for this code is a vacuum leak. Are you sure you do not have a vacuum leak?
While your hoses maybe quite OK, the upper intake manifold may need to be re-torqued as it could be drawing air in around the gasket.

check your Long and short term fuel trim values on the Torque app when running on petrol? If they are constantly positive and higher than say 2-3% then you probably have a vacuum leak post MAF.

FWIW: My 4.6 was running lean (high Short and Long FTs on the Torque app. 25%...max value!!!) and I finally pinned it down : discovered "by accident" that the plastic 1/4"BSP fitting which screws into the inlet manifold and accepts the breather hose from the RHS rocker cover, had a hairline crack just at the beginning of the threaded portion! It was drawing in sufficient air to exceed the 25% maximum fuel enrichment compensation available from the 'closed loop' fuel mapping. Replaced it with a $3 brass fitting from Repco (vs $8 for another OEM plastic one...) there's a write up on this earlier in the P38 section.

The following has some good info on Code P0108 which might be worth following up http://www.obd-codes.com/p0108

Hi Hoges...glad for the response, firstly it highlighted the fact that can't read my own handwriting...the codes were P1201-P1208 and P0201-P0208. with regard to air leaks...I will check over again, not too sure how to use the torque app properly yet so those values i can check for now, cheers. Also I had issues with plugs getting a brown build up on them, I assume from my last engine which is now similar to the k's on this replacement, was getting water in the cylinders..when heads came off, bolts were loose..these plugs don't get like that but are very sooty and are not expensive so kept the habit. As such, the leads get pulled on and off a fair bit. I had the end of one come off in my hand at the 90 degree and am using a spare...i assume there could be a weakness in more of them so new leads.I use NGK BP5ES plugs at .9 gap. On old engine, as soon as i gapped them smaller, the backfires went away...thats why i feel the prob is electrical.the P0201 code is interesting, my LPG switch on the dash has on, off and LPG, i thought as the car backfired and stalled with ignition on, it may be the cause of the fault. I will however look into injectors as idle is rough but intermittently. On my car, the breather hose goes from the rocker cover to the airbox and the inlet on manifold is blocked off, was when i bought the car.
Heaps to look for, sorry for the bum steer with wrong code....will keep you posted, anything i've mentioned that you have ideas on , feel free, thanks again.

hi again, I drove to work and back last night, 100 k's round trip.I opened the app, checked for faults...none. Looked at vacuum and was 12.9 as seen in pic test 1. I drove round trip on petrol.During this trip the vacuum kept bouncing between vacuum and boost and no data...it settled on 12.9 The trip home i did all again and the vacuum went to 10.3 and was constant...I figured ok i have a leak. This morning i drove again, this time on lpg, flicking between petrol to gas when warmed up as this also causes either a stall or backfire if done too soon, anyway, no backfires at all even tried to get it to do it to see if i got a fault, nothing....I stopped for fuel and remembered i had a little chip for economy/power(most likely crap but anyway) plugged into the air sensor at the airbox. I took it off and drove home with no noticeable change...the only thing was the vacuum now says 2.3 as per pic 2...so no leaks?..i am at the least confused. Is it possible for sensor to be stuffed?..i don't think the chip would make a difference...it hasn't before. It is supposed to tell the computer its got cold air all the time to change the advance but i don't know how true that is.Anyway, more to think about.

and I forgot, even with no backfires i got the same codes come up on the last trip from servo to home P1201-P1208 and P0201- P0208...car was on LPG and started on LPG after filling and no dramas...rough idle came and went with no issues.

Hi Deano
suggest you read http://www.aulro.com/afvb/p38a-range...trims-why.html
Apart from vacuum, would be helpful to get info on the actual fuel burn as per Glenhendry's post with the thumbnail screenshot of the Torque App. If you can set up your App similarly and get some Short & Long Term Fuel Trim data it might well shed more light on the issues.
cheers

is this a gas injection system.? Is it a GEMS V8 or a Bosch one? Your obd faults are a wiring loom issue. Has someone hacked into the injector loom at all? Look for any stray wiring going into the main loom.