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Matt, Mechanical Engineer
Category: Toyota
Satisfied Customers: 22761
Experience:  BEng hons Mech engineering, in auto industry 22 years
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I own a previa 1998 model 2.4 petrol. it has LPG gas fitted.

Customer Question

I own a previa 1998 model 2.4 petrol . it has LPG gas fitted . when starting from cold in mornings ( on petrol) engine is Hunting then revs up & down 500 to 600 refs till warm then auto onto LPG & runs sweet . Please any ideas
Submitted: 1 year ago.
Category: Toyota
Expert:  Shantal-Mod replied 1 year ago.
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Expert:  Matt replied 1 year ago.


this could be a vacuum leak after the MAF (mass air flow) sensor thats mounted on the air intake pipe

any air pulled in here post meter isn't 'seen' by the ECU and so not compensated for and results in the engine running roughly and hunting as you describe

the best way to locate an air leak is to have the engine running and then spray lighter gas around each possible joint / rubber hose etc post MAF

if there's a leak then the engine will pull the gas in and rev up

now its not as dangerous as it might sound as you need a naked flame or spark to ignite the gas and I've used this method for many years without incident

usually this sort of thing is a cracked or perished rubber vacuum hose, so can be repaired very cheaply

Expert:  Matt replied 1 year ago.


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