self learning ecu?????

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fireman-andy

New Member
Posts
222
Location
surrey
new to this so here goes.
just bought a 2000 d2 V8 with an AG lpg conversion. after a couple of days it wouldn't run right on gas. felt like a rev limiter/ fueling at 2500rpm especially under load. next day petrol the same . changed airflow meter(this forum is great) and although much better ,but still not right.
I'm pretty sure its the coil packs / leads which i'm changing next week. Thats the royal we as the inlet manifold has a 30mm spacer to fit the lpg so you cant get to the coil packs. I spoke to the lpg guys who serviced it last and they remembered the car and said they had recommended that the adaptions were reset .Had this done and 17 faults logged , misfires causing emmissions / catalyst problems mainly plus maf fault and lambda faults. hence coil packs / lead changes next week (they are originals and the car has done 100k)
i'm worrried that the ecu is now learning from a misfiring engine and the faults will just reappear and stop the ecu fuelling properly. (to be fair its not a full on misfire , more of a hesitation when accelerating and a shudder at 50-60mph when torque converter locks and the engine is under load.)
the idea was to reset adaptions drive on petrol for 50-100miles and then get the lpg tuned.
do you think i'll need to reset again once i've had the packs done and will this affect the lpg (again)
any help would be appreciated especially if there is someone with a test book in the surrey / sussex area.
 
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don't know if this helps but
my gas converted Freelander was suffering a under load- miss-fire,I changed the coil packs and it was a bit better .
Then It was suggested that the plugs were at fault although they were a recent change,
A new set of plugs were fitted and guess what shes good as new!
The accepted wisdom is that gas needs a good/excelent spark to combust
and punishes weakness.
hope this helps as a set of plugs may be the cheaper option:)
 
new to site not dont know how to post yet but have problem with my suspension both air bags dropped while driving comp will only run for 10 sec not reflating air bags susp being dropping both sides over last week but always went back up can you help sorry for butting in but kidds are out and i am us on pc
 
thanks for info edge , going to lpg specialist next week , they are going to fit the coil packs / leads. I'm sure they are going to tell me to change the plugs as well despite them being new this week. I think lpg needs hotter plugs???



mini
I'm not that technical but it could be the ride height sensors or as you say the compressor. I'd be surprised if you have developed a leak on both bags at the same time.
posting is simple there is a button at the top saying post thread. just click and type!
 
Your engine ecu will be learning horrible habits,but it takes a few drive cycles,often 2-300 miles for it to learn its long term trims.
What I do is get the engine spot on with petrol,scope the plug leads to see all is well.Then note the fuel trims at different revs/loads whilst the car is moving - then switch to LPG and modify the trims to match as close as possible under the same circumstances.Just modding the LPG trims to get the oxy sensors to swich rich under load,cycle at cruise,and lean on overrun is not good enough.The fuel trims end up at the opposite end of their range etc,so the long term trims are so far away on gas,(As thats where it will run on most)that the poor engine ecu cant trim back far enough for decent running on petrol.
Can be time consuming to get right,but without fail the customer always makes the comment,"I cant tell if its on petrol or gas now." - Which is how it should be.
 
thanks 8
lets hope that the guys i'm using next week are as thorough.
if not where are you? I have folks in devon and am in the S.W. fairly often

how often should i be using petrol apart from on start up.
Manual quotes 25 miles a month , is this enough?
It has a small 25l tank fitted (70-80miles I guess in mixed driving) would this be better?
 
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I only run petrol on start up it takes about two miles to get the engine temp up and then the gas kicks in .
To and from work 5 days a week and bimbiling round at the weekend is plenty .
How did you get on with the miss-fire?
 
spoke to garage today and they tell me that the engine is running fine. they were doing the final set up for lpg and i'm collecting tomorrow. they say the shudder under load and the misfire is gone. it was reassuring to note they were connecting a laptop and taking the car for several runs to map the lpg. including some steep hills to load the engine and fast a roads. hopefully this will sort it as we leave for cornwall tomorrow at lunchtime and I want to take the truck.
thanks to all for help / advice.
I am still looking for someone local(surrey/sussex) with testbook access to reset fault codes etc
 
well i've collected the car and driven to cornwall with no problems apart from an unreliable gas gauge (80l tanks show empty after 80miles and then i can only squeeze 26l in) It drives perfectly on petrol and mostly fine on gas. I just have a judder at 40mph at 1400-1600rpm. if i change down the auto box to 3rd its fine as the rpm is 2000. I have spoken to the garage who have said its possibly one of the gas injectors or the map sensor in the vapouriser. anyway when Iget back i am taking it back for him to connect the laptop and we'll go for a drive . so nearly there
 
Dosn't the gauge go red 4 reserve then beep and automaticly turn the petrol back on?
set the odometer and run full tank to change over and see what she dose to the gallon.
I dont know if in your area you have a "Country Wide" style farm supplies but if you do its worth looking into getting a Gas account .
For this you get a coded key that allows you to access their pumps 24/7 and pay by direct debit.
A little booklet shows you where the pumps are situated and if you have one local to your home your paying only 46p a litre inc vat or less if your vat registered.:)
 
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