Injector question

[GTO52]

Can an injector test okay(off the car) but still be playing up?

I have a misfire issue with my Toyota pick up(3RZ-FE engine), I managed to get it to the mechanics when it was misfiring.
It seems to do it if the truck is switched off when hot and then restarted 15 to 30min later.Any way it was misfiring on No 2 cylinder, they swopped 1 and 2 injectors around, it was fine for a while and then started misfirng on No 1.
So they removed the injectors and I sent them in for testing.
The company that tested them said the flow was slightly below spec but this would not cause a misfire, so I had them cleaned.
The mechanics reinstalled them and test drove the truck and said everything was fine.
I collected it this morning, everything was fine until again it was restarted after standing for say 15 minutes it misfired slightly on start up but then came right.
My question is can an injector test okay but actually be faulty when it gets hot etc?

 

[bluestream]

I can only guess, and I would say possibly, but unlikely.

If they tested good. they should work...

 

[Boomer]

Had a similar problem some years ago and it turned out there was a source of a sticky wax like material in my fuel system. This seemed to form after adding Redline SL-1 which I have not used since. This stuff would get into an injector and cause a misfire. Sometimes it would be forced through/dissolve and it would run fine. Eventually several injectors got so loaded up on a trip that I had three cylinders misfiring. Dealer had to replace those injectors and clean the rest as well as flushing out the fuel line and replacing the filter. Seemed this stuff was soluble enough to go through the fuel filter but would then precipitate out in the fuel line and the injectors.

Have you added a fuel additive lately, particularly a fuel SYSTEM cleaner? If so, theis could be the problem.

 

[tmorris1]

Sounds like the injector is leaking fuel after it is shutoff. Does it clean itself out and run fine after a while?

 

[GTO52]

I have just measured the resistance of 1, 2 and 3 injectors(4 is too difficult to get too)

The manual says 12 - 16 ohms at 20C(68F)

No 1 reads 15.9 ohms and so does 3.

No 2 I can't get a steady reading.

I get 28 then 36 then a 50 ohm reading.

So that injector must be faulty?

 

[tmorris1]

Have you had them cleaned?