What makes lpg back fire?

ltd_v8
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Joined: April 12th, 2015, 9:10 pm

What makes lpg back fire?

Unread post by ltd_v8 » June 11th, 2017, 8:44 am

i have got the lpg going. its an apa tank with an airod converter. there are no vac leaks. it does idle a bit high because the iac needs cleaning, but i have noticed that if you put the boot into it from lights, it hesitates for a a second or 2 like its going to back fire through the airbox, and then it moves along. the previous owner said it did this in the adv when i bought it. im hoping i can get some help on this?

LPG system: likely needs plugs and leads as the LPG system can backfire or stall under load. Had same thing occur about 2 years ago, fixed for few a few hundred & had been OK since, but have not attempted to fix this time as will leave for buyer. Not uncommon with LPGs, higher spark plug wear is price you pay for big savings on petrol bill. No issues with petrol side. You can just drive as a petrol car or fix lpg side, which should not be a huge issue. This factor is allowed for in the price.


Service history: In general have had anything fixed immediately when indicated, no breakdowns. Here are most of the service and repairs performed in in the past 3 tears.

25.2.2014 Rear brake rotors and pads, replace handbrake shoe, inlet manifold, service and tune.

17.4.2014 273,838km Replace right rear seat belt

4.6.2014 277,903km Replace complete hand brake cable assembly

14.8.2014 Replace exhaust manifold and gasket

23.09.2014 283,917km Replace radiator, thermostat and coolant

3.2.2015 291,190km Service / oil change, leads, plugs and calibrate LPG system

13.4.2015 294,691km 2 inner rack ends, wheel bearings

17.6.2015 Service / oil change

30.7.2015 300,315km Replace right front seat belt

15.8.2015 4x Michelin 265/70/16 Latitude Cross tires. Wheel alignment. I’m not certain of the exact distance, but they have about 12,000km on them and still have a lot of life left, maybe 75%

21.12.2015 307,302km Service / oil change

11.4.2016 Wheel alignment and rotation

22.2.2017 312,431km Front brake pads and rotors

i have replaced intake hose and coil packs i have checked the spark plugs and they are ACDelco Professional Platinum Spark Plugs and the spark plugs look fine

i fixed the high idle problem but still when accelerating it surges like its going to back fire

there is no vac leaks in the system it idles rough when warm on petrol and lpg and just yesturday it back fired and blew my airbox apart so i fixed it and seems to run fine i am really considering of removing the lpg only because next time it might not be lucky the car has got 318,000km on it now i also thought it was the airflow meter so i unplugged it the cel light came on no change in idle i have also cleaned the throttle out and iac out all the vac hoses have been replaced

ltd_v8
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Joined: April 12th, 2015, 9:10 pm

Re: What makes lpg back fire?

Unread post by ltd_v8 » June 11th, 2017, 8:46 am

also the car is a 1999 toyota prado 3.4l v6 petrol dual fuel

typhoeus
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Joined: February 6th, 2011, 8:25 pm

Re: What makes lpg back fire?

Unread post by typhoeus » June 11th, 2017, 8:21 pm

It's a a mixer type LPG system? Use Iridium plugs and make sure the leads are in good condition, Also make sure the valve clearance is not tight. Valve seat recession is a common issue with Toyotas on gas. I have a 3RZFE hilux on gas, . Emer sequential injection, it is a big improvement on the old type.

mydmax
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Re: What makes lpg back fire?

Unread post by mydmax » June 11th, 2017, 9:43 pm

If it runs rough on both petrol and gas I would definitely check the valve clearances. if an inlet has no clearance or slightly held open then it will fire a flame into the manifold of mixture and blow the aircleaner apart.
The converter may be sluggish and not immediately allowing enough gas through as acceleration is happening, the resulting leanness can also cause backfire and blow the air cleaner or hoses apart. Cheaper to have it correct than replace compnents all the time.

In the past I have seen taxis with one headlight blown out of the vehicle by a lean wrong mixture of gas.

ltd_v8
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Posts: 66
Joined: April 12th, 2015, 9:10 pm

Re: What makes lpg back fire?

Unread post by ltd_v8 » June 12th, 2017, 4:43 am

so this is what is happening car sputtering on lpg when acceleration like it wants to back fire and on petrol takes of like a rocket

ltd_v8
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Posts: 66
Joined: April 12th, 2015, 9:10 pm

Re: What makes lpg back fire?

Unread post by ltd_v8 » July 8th, 2017, 8:09 am

changed the spark plugs a few weeks ago and its running great i also noticed that i got a extra 43 km to a tank so in total 343km from 300 so thats not to bad i spose

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