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4.0L 19# injector swap help...

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89 MJ, high mileage 4.0L, originally had a bit of a rough idle and a stalling problem, and leaky injectors. Would always restart right away if you wiggled the last injector. We swapped in some ford 19# injectors. Cured the stalling problem...


Huge difference in power! But it idles worse and seems to be running pretty rich I guess, smoke from the exhaust that'll burn your eyes :P I imagine its getting to much fuel now, maybe these injectors are to much for it.


Any idea's what to look for? Its got new plugs, cap and rotor needs to be replaced but are good enough they should work ok.


I disconnected the O2 sensor and absolutely nothing happened, it didn't run any worse or any better. Would a properly working O2 sensor figure out its running to rich and adjust for it?


I'm seriously getting ready to rip out this renix junk and put a carb on it.



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i have a 89 MJ with 130k on a 1997 4.0, i had problems with my stock injectors spraying one for the engine, two for the engine compartment. so i put in ford 19# injectors, i barely noticed a difference... maybe like 5hp but my idle seems fine. and not much smoke compared to other 4.0s


have you checked the vacuum system for leaks, that affects idle... i had the crankcase vapor tube disconnect one time adn my idle jumped to damn 1700 steady.

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