Help 7.3 missing, no codes, did buzz and contribution tests

[SICKS-O]

Originally Posted by Probuilder

number 8 has almost no change to the engine. But the rest cause the motor to slow down and miss worse. So does that mean that the #8 injector is bad?
Also this truck has 342K on it. Would u just replace q injector or should I change all 8?
Can these injectors be changed out with a set from a 97 motor? I have a spare set of those laying around. So it would be a cheap fix for me. This truck is an early 99, build date of 5/98.

do cyl 7 & cyl 8 still give a weak buzz?

the engine not running much different with #8 unplugged is a good clue, but doesnt tell us if the injector is at fault. i would suggest a compression test on that cylinder before going further.

i wouldnt replace anything until you have found the cause of your problem. if you do need an injector or 2 i would only replace whats failed. 8 new injectors are BIG money.

the simple answer is no. those are single shot injectors, unless theyre from a cali model. either way doesnt matter because the flow rating is different, 97-older 7.3 = 90cc injector, 99 = 120cc injector, 99.5+ 130cc injector.

you will need an AB model injector or a long lead injector for cyl 8 (if ford offers one).