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Do-It-Yourself Projects
Aiming for a Miss: Ignition and Injector Inspection
By Justin Fort/autoMedia.com
Printable version
Degree of DifficultyModerate
Moderate
Estimated Time180 minutes
180 minutes
Injectors: Easy to Blame, Hard to Reach
No matter how you’re powered, pulling fuel injectors is a bit of work. Short of a straight-four or six with injectors hanging off the side of the head (and even then, probably smothered with wires, cladding and bracketry), pulling injectors isn’t quick work. Suggestions? Lots of non-corrosive penetrant will help release hoses and gaskets, especially notoriously tricky injector O-rings (try Liquid Wrench). Have a few spare O-rings around. The fuel rails usually hold the injector in place, so be gentle when it’s time to pull the rail off so as not to damage the injectors or the O-rings. Some manifold gaskets are metal, as with this Toyota V6, and can be reused if you’re gentle (and they haven’t been cooked). Expect to replace gaskets most of the time.
Photo 5: The fuel injector is nestled beneath the rail in this shot, with the rail holding it gently in the injector port. You must be equally as gentle.
Fuel Injector Nestled Behind Rail
An injector’s resistance can be tested with a multimeter too. On this Toyota engine, the grey-top injectors (often identified by color) should test between 12 to 16 ohms. The Hole 4 shooter read .018 ohms: That’s about as clear an indication we needed that there was a fox in this henhouse. The bad injector was just as dirty and slimy as the other injectors, so the multimeter was necessary to see it for what it was. Speaking of dirty, a bottle of injector cleaner could save you this job, should the injectors just be clogged and not mechanically toast.
 
We decided to embrace the “sensible” part of this project and skip swapping two injectors to test whether #4 was bad. Considering all the fingers pointing at the fourth injector, the time involved in the R&R of injectors was too much. Swapping two injectors, then reassembling and replacing the manifold, hoses, brackets and bolts, only to see what was very likely the bad #4 injector shift the misfire to #2 was a big waste of time. The price for the failed gamble of just replacing #4 would only be doing the R&R anyway, so it seemed a calculated risk worth taking.
 
We R&Rd the lean-firing, bad-ohming, P0304-earning #4 injector with a used injector sourced from a local Toyota salvage yard (which had tested at 14 ohms—bring your test-gear to the junkyard). Should this gamble pay off, it would put us in good shape much sooner than doing everything twice. The manifold on this Toyota, a two-piece clamshell sort’a unit, came off with the usual Toyota ease, and we had it back together in under two hours, torqued to go. In standard no-drama Toyota style, it fired right up, the misfire gone. Now you do it.
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