jaredbishop

1992 4Runner 4WD Auto 3.0 162,000 miles

The problem:
When the truck warms up the truck starts to jerk / pulsate and RPMs bounce up and down like it's not get fuel. If it turn the engine off then back on it will function fine for a few more miles. There is also a gas odor out side so I don't want to drive it if I don't have to.

I did just change the fuel filter and had a Toyota dealership double check my work, fix it then pressure test it. All was good. 600 miles later this problem came up.

I've done some reading on the forums and I'm looking at Pulsation Damper first. 02 sensor is good and I have a new wires to the 02 sensor so I don't think that is the problem.

Any other ideas?

dropzone

iTrader: (6)

3.0 or 22re?

jaredbishop

3.0 sorry. Edited post

scope103

Pulsation damper would be a stretch; it's trying to damp out pulsations caused by the injectors, so at idle that would be of the order 10-15/second. Not the pulsations you're feeling.

My first guess would be injectors; make a "stethoscope" from a yardstick and listen for the clicking at each injector (no click, no fuel). Then pull the plugs and look for a wet one (no spark, or stuck injector).

If you have a voltmeter, use the diagnostic connector to monitor the O2 sensor (look for switch low/high about 1/second). Not likely your problem, but easy to do and it would rule out the O2 sensor.

dropzone

iTrader: (6)

No biggie just want to help you find your solution quick.
Wish I knew more enginewise but just know some symptoms can be specific

jaredbishop

If there is no pulsation while in neutral could it still be the injectors?

jaredbishop

I pulled the spark plug wires and found that one of them was bad. I picked up some cheep wires (don't worry I'll get OEM wires latter) and all seems well. I'll take it on a longer test drive to try and recreate the conditions of the problem.

Could a bad wire account for the gas smell?

scope103

It could; one cylinder not firing means you're dumping unburnt gas into the exhaust.

If you get the truck running well (as in: it would pass smog) and you're still getting gas smell, it might be in the vapor cannister. If the cannister is not getting "drained" by the engine vacuum, the vapors build up until you can easily smell them. Just follow the diagnostics in the FSM.