Sonofmayhem

what causes this? huh? i only hear it when im decelerating and braking.

Thanks

myyota

From what i have been told, back firing is caused by unburned fuel in the exhaust igniting. when was the last time you did a complete tune up on your truck and checked the timing ?, that might help or fix the problem your having.

4runnermt

I agree it may be a timing issue.

Sonofmayhem

i just did everything except the wires, so ill do timing then some spark plug wires. thanks

ANyone else?

84sr5yoty

Incorrect timing and a very lean fuel mixture causes backfiring. Check for vacuum leaks and vacuum test the brake booster to make sure the internal diaphragm hasn't gone bad.

Sonofmayhem

really, well i need to time it, how do i go about this? ill have the light, but im just not sure where to point it, what to look for, and what to adjust. thanks

crackerjack

I was cleaning my intake and read something about the dash pot a kinda shock absorber for the throttle cable will cause backfire if not adjusted and doesn't a leak in the exhaust cause backfire?

toyota_mdt_tech

Air entering the exhaust and burning unburnt fuel. DO you have an air pump or an air suction system? If so, the diverter valve should direct the air intot he air cleaner on decel, yours is probabvly stuck blowing it into the exhaust. The extra air makes the fuel burn, and also extra air can coem from just a plain old fashioned exhaust leak.