newbie injector question

[FU]

Originally Posted by ZR-1nce removed

The extra money for the new SS ones are worth it....

Excellent advise.

[A1990]

Jon at FIC is now a member of the Registry!

[NWPzr1]

Originally Posted by Paul Workman

Asking for guesses? Hmmmm.... I'm gonna guess one or more injectors is or was leaking. A fuel pressure leak-down test would be SOP for any new injectors. In fact, test can be done, and the injectors can be visually inspected before the plenum is reinstalled by hooking up the fuel rail and turn the ignition switch to ON and inspecting the injectors by looking down in the IH runners. Any fuel spraying or dripping, etc and you have your culprit/s. (I suppose you could poke a paper towel down below the injector nozzles to see if there is any seeping going on.) Then turn the switch off while monitoring fuel pressure at the Schrader (sp?) valve. It should hold to within a pound or two for 3-5 minutes w/o signs of leaking (dripping). I've done this before, and trust me, it is a lot easier to do than pulling the plenum to find a runner full of fuel, or hydra-locking a cylinder...

Thoughts are guesses maybe right?

Just something to keep in the back of your mind, if there is no fuel leaking from the injectors, yet the leak down test is failing, I had a bad check valve in a newly installed fuel pump cause issues. My point being, testing the injectors before installing the plenum has many advantages, and you don't have to pull the plenum off (cuz it was not yet installed) to troubleshoot. Just a thought.

I tested it all before I re-installed the fuel rail, everything was fine and pressure held.

And, another thing...if that "injector cleaner" loosens something between the fuel filter and the injectors, where is it going to go? Any fuel system (including the fuel rails) cleaning would be best done before the injectors were reinstalled, and by a more positive/aggressive method than a passive fuel additive, IMO. Flushing the lines and replacing the filter(s) before installing the injectors...would be what I would prefer to do (but that's just me).

The car was running on four cylinders... literally. I'm not going to drive around with injector cleaner in the tank with four dead holes. Four primary and 2 secondary injectors ohm'd 0.06.... Spec is roughly 12.0-15.0 ohms. I'm was thinking original injectors is the problem obviously. Car has 10k mint miles on it, factory fuel filter paper element was intact and clean and was replaced with injectors as to not clog fuel system between injectors and filter.

Now the car runs like a champ, and only acted up that one time. I'll be installing a headers and exhaust soon as well as 2 new O2 sensors since they're original and most likely fouled do to previous injector condition, which I understand could be the culprit as well.









P.

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[NWPzr1]

Originally Posted by scottfab

Since you asked for thoughts and not guesses, here goes. I think there's no sense in worrying about what you could have done because the 90 has no exhaust valve seals. Oil leaks down into the combustion chamber and after high rpm runs will run a bit rough till it clears out. Mine does. So unless your engine has had seals added I'd suspect that. Try hard runs at 5-6k and see if it has the same symptoms. Mine runs fine at those rpms. Fist time I get into the heads the seals are going in.

That's interesting! I know they don't have the seals, but didn't think it would inhale enough oil to run a rough. Worst case, it is a warrantied injector and what's another hour or two...

That's food for "thought", I appreciate it! =D>

[Kevin]

Originally Posted by A1990

Jon at FIC is now a member of the Registry!

cool, hope he starts posting here.