2003 4 RUNNER RANDOM MISFIRES ON 2,4,6, & 8 (2 Viewers)

[Holywort]

Howdy folks,

I could use some help from the brain trust. I have an '03 V8 that immediately after an oil change, I got a 2,4,6,8 misfire code. With a better reader I'm also showing an O2 and catalyst code. I'm not one to believe in coincidence and I don't want to just throw parts at it. I thought I figured it out at first when I pulled the coils, they were original, and they all had a crack down the side. Replace all with OE coils. Plugs were replaced 10k ago. Any thoughts or suggestions are appreciated.

Thanks,
Mike

 

[TahoeZ]

Did you ever get this figured out?

 

[Holywort]

Hi all

We actually did just figure out the problem. Something I didn’t know about the 4.7 is that it gets very unhappy when you dry fire the motor, for example, no oil in the filter or if the oil change tech forgets to put oil in it, the belt tensioner, which is hydraulic loses pressure and allows the timing belt to slip. In this case, the timing belt jumped for teeth, and the motor was obviously out of time. Fortunately, no damage to the engine. Not a fun lesson to learn.

 

[vipergrhd]

Hi all

We actually did just figure out the problem. Something I didn’t know about the 4.7 is that it gets very unhappy when you dry fire the motor, for example, no oil in the filter or if the oil change tech forgets to put oil in it, the belt tensioner, which is hydraulic loses pressure and allows the timing belt to slip. In this case, the timing belt jumped for teeth, and the motor was obviously out of time. Fortunately, no damage to the engine. Not a fun lesson to learn.

Who told you that B.S? I have worked on dozens of 2UZ and never heard of an oil fed tensioner and I have never had to fill my filter prior to firing even with a VVti set up. The belt tensioner is sealed and pressurized, if your belt did jump your belt is stretched and your tensioner must have collapsed. Glad to hear that you got your problem fixed.

 

[Holywort]

Who told you that B.S? I have worked on dozens of 2UZ and never heard of an oil fed tensioner and I have never had to fill my filter prior to firing even with a VVti set up. The belt tensioner is sealed and pressurized, if your belt did jump your belt is stretched and your tensioner must have collapsed. Glad to hear that you got your problem fixed.

A trusted Toyota mechanic made the suggestion. He’s also the one that did the timing set on it, with OE parts, 10,000 miles prior. Granted it’s hard to trust any parts nowadays , very possible the tensioner just gave up at that moment.But yes, glad it’s back on the road.

 

[TahoeZ]

Yeah; can't say I've ever heard that one before...

Glad you're back up and running though.