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 Post subject: misfire
PostPosted: Mon Apr 27, 2015 7:02 am 
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Joined: Sat May 15, 2010 1:12 pm
Posts: 38
HI

been having a few problems with misfires recently even popped the lid of the airbox and dented the bonnet. these usually happen when accelerating so if setting of at the lights,
its a 2 litre rav4 with a single point lpg setup I have done about 100,000 mile on this lpg system now, since fitted only filters and stepper motor has been changed, plus the usual car servicing

I was also wondering about changing it to a multipoint lpg as from what I know it rarely misfires on them. I have seen front end kits from tinley tech for about 250, how much would it cost to get one fitted.

thanks


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 Post subject: Re: misfire
PostPosted: Mon Apr 27, 2015 10:08 am 
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Joined: Wed Sep 29, 2010 5:01 pm
Posts: 3219
Location: Yorkshire
Misfires and backfires could have a range of causes including problems with the engine itself (particularly spark plugs / valve leakage - have you been using a lube system?), the LPG ECU (broken or in need of adjustment), stepper motor, lambda sensor, reducer (broken or in need of adjustment), intake air / vacuum leaks, fitting of an air filter or air intake with different flow characteristics to the one the LPG system was set up for. None of us will be able to advise further unless you can give further info on your system - you might need the interface cable and software for the LPG system to do that, or just visit an installer. That said, if the engine still drives the same as it did on petrol and you've checked the stepper, problem is most likely to be reducer related.

I would supply fit calibrate a sequential front end with warranty on the Rav4 for £450, would start with a few checks to make sure the problem isn't a hard engine issue first..

Simon

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 Post subject: Re: misfire
PostPosted: Mon Apr 27, 2015 11:20 am 
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Joined: Sat May 15, 2010 1:12 pm
Posts: 38
its a brc techno g 100kw vaporisor with omvl ecu and stepper motor. its used to misfire on braking until I made adjustments to the vaperisor some time ago. i have the cable to connect which helped when doing the previous adjustments. it has a flash lube setup.

do you supply courtesy cars whilst the work is done


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 Post subject: Re: misfire
PostPosted: Mon Apr 27, 2015 7:05 pm 
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Joined: Wed Sep 29, 2010 5:01 pm
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Location: Yorkshire
Don't have a courtesy car but on a simple install like the case of your vehicle would expect to have the sequential front end done in about 7 hours. The local town is busy or Wakefield / Doncaster / Pontefract / Barnsley are all only a half hour train or bus journey away, the train and bus stations are next to each other and both within a five minute walk of here but would drop you off and pick you up in any case.

Simon

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Full time LPG installer
Servicing / Diagnostics / Repairs to all systems / DIY conversion kits supplied with thorough tech support
Mid Yorkshire
2 miles A1, 8 miles M62,
http://www.Lpgc.co.uk
Twitter https://twitter.com/AutogasSimon
07816237240


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 Post subject: Re: misfire
PostPosted: Mon Apr 27, 2015 8:27 pm 
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If you have the cable what are the stepper openings at idle and on open throttle? They should be roughly the same (within 10 steps or so if you can do it). Misfires are caused by a poorly ignition system, dodgy plugs, leads or coil packs or a weak mixture. If your vaporiser is getting tired that will usually result in it leaking too much gas at idle so making it run rich. This means that at the idle the stepper will close right down to try to lean off the mixture. Then when you put you foot down to pull away, the stepper will be closed far too much so will have to open resulting in a weak mixture until it catches up and gives the correct amount of gas. There's a recipe for a stutter and a misfire. I always set the idle stepper opening slightly wider than the normal running so when getting on the throttle the mixture is slightly rich until the stepper catches up but if the vaporiser is on it's way out then you won't be able to achieve than.

This does also assume the misfires aren't caused by worn valve seats. Does the RAV4 have adjustable valve clearances and have they been checked?

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