Fuel injector repair

I doubt you're misfire is caused by the o-rings it may be caused by the leak past the o ring big looking atctailmwen it's live and pressurized you may see the leak. When the injectors are fitted to the rail and the spacers are applied under the bolts in the rail tabs and tightened . The fuel injector should be able to spin by your two fingers .

 

The only things I'm thinking you could have been "tightening to 20ft/lbs" would be the bolts that hold the fuel rail to the head. Because the rail sits on solid spacers beneath those bolts, overtightening them (once the rail is all the way down on the spacers) doesn't really affect the injectors at all. They're sitting there snug in their little O rings and all you've made different is a couple overtightened bolts.

For the seal to be good, the grommets and O rings just have to be good, and carefully not damaged when reinstalled to the rail:




There has been at least one old thread here where someone did not get the O ring ends of the injectors quite properly inserted into the rail (as in the drawings above), and then thought they would simply be pushed in the rest of the way as he tightened down the fuel rail bolts. That led to at least one injector being crushed and needing replacement.

It's possible that adding something to the grommet beneath the injector, raising its height, could lead to a similar result, but I haven't seen your situation so it's hard to say.

 

As you saw in the repair-manual drawings I pasted above, it's not only okay, it's a necessary post-assembly test to make sure you've done it right.

(Well, I guess I didn't paste anything that says it's still twistable after the rail is installed, but it generally is.)

 

That sounds plausible.

I might only add that I'm a person who likes to test things after doing work on the engine and before starting it up. Therefore, I am likely to put the car IG ON without engine start, and use a scan tool or jumper wire to run the fuel pump and pressurize the rail while I look over all the work I just did for any leaks. Then I'll use a 9-volt battery to tickle the terminals of each injector and listen for the click and sound of squirting. The first one might at first sound more like spitting for a moment at first as air in the line escapes. If I start with the injector at the distal end of the fuel rail, the other three will pretty much immediately squirt fuel when I get to them.

If the test-squirting is overdone, of course, it could lead to a hard first start because of flooding. Hasn't really happened to me, but I tend not to just move on to starting the engine right away. I might putter some, put the wipers back on, put tools away, and such, and by the time I get around to starting the engine it doesn't act flooded.

The idea of a 9-volt battery to manually tickle injectors is courtesy of Rich Jensen of Cruzin Performance, who was doing the restoration of injectors in our PriusChat restored-injector exchange loop, back when we were doing that. 9 volts is still enough to test the injector, but low enough to lower the risk of damaging it when applied by hand (the pulses the ECU uses are much shorter than what a human can do).

 

I wouldn't lean too hard on the "enough time to repressurize" angle, though. I was going to guess the answer as "easily under one second" from first application of fuel pump power, and this AI chat showing the work came out in the same ballpark:

https://share.google/aimode/H9QQw6ewd10dhyGvp