3.4 injector problems

[GTRS Fiero]

There seems to be a lot of inconsistency.  Injectors that are fine in one engine cause problems in another engine.  Injectors that should be properly spec'd make some engines run terribly, while other engines run fine.  Sometimes, when going back to previous injectors, problems persist.

I've seen claims of piston issues, valve issues, etc.

I believe part of the problem is different ECU's, but another part of the problem is that multiple variables are introduced at the same time.

Has the ECU been reset between changes?

If there is damage to the face of a piston, that will change the compression in that cylinder.

[TopNotch]

And then there's the fact that some systems require pintle-type injectors, and some require disk-type. And the engines don't run well with the wrong type.

[GTRS Fiero]

That seems to be an ECU thing, but yes.  The '88 ECU will run with either injector type.