I've posted here before about a persistant miss on my '88 Z-24. The miss is on #3 cylinder (pulling plugwire off #3 doesn't change idle, plugwire arcs).
Miss is noticeable at idle more than at increased speeds but I sense it has less power than before during all rpms.
I have a donor car I robbed parts from to try on this:
1.) There were no codes.2.) I replaced the corresponding coil pack although the plug was firing, still is. No change.
3.) I replaced ALL the injectors, although the old ones tested ok for resistance, & replacements all tested ok also.) No change, still missing on #3.4.)Found the egr valve to be stuck, replaced (there were no codes for this). No change.
5.) Replaced the IAC motor. No change.6.) Took compression check on that cylinder: 150 psi.
7.) Switched spark plugs between #3 and adjacent cyl; plugs look similar--whitish grey. No change.8.) Heads were replaced new last summer.
9.) Finally took the wire loom that plugs onto injectors and swapped it with the one from donor car--then I could have SWORE that fixed the problem--and maybe it was my imagination--but after driving about twenty minutes, back to missing on #3 again.ANY HELP APPRECIATED. Thx in advance.