injector upgrade problems

[FUNKYTEE5]

Sounds like your injectors are too small. The less vacuum the MAP sensor recieves the richer the mixture becomes. That's probably why you're noticing more power because it's not running as lean as it was with the line connected. Bigger injectors would most likely solve your issues. Try some Ford 21 or 22lb injectors, 19's will work but they're still slightly small for the 4.0.

 

[littlebluexj]

i went wheeling with the ford f-150 i6 injectors in and it would bog down easy and blows alot of black smoke on hills wheret the engin had to work harder.so this means that the motor is getting to much gas right.i was told by a few people that since i have a non HO i should go pick up a set of HO injectors and the should work great.whats everyones openoin on this.
William

 

[Dr. Dyno]

ok well i still havn't got around to changing the injectors out so i still have the ford f-150 i6 injectors in if i put the vacume to the fuel pesure regulator it will run shitty but i left it on and just started to remove vacume lines till it ran better.I found that with all the lines on it would backfire in the intake but i removed the map sensor vacume line and now it runs better and has a noticeable amound of power gain and also a really loopy idle.what does this all mean know.
Will

Removing the vacuum lines enriches the A/F mixture so if the engine runs better with the vacuum off, it's definitely running way too lean.
Since you have a Renix 4.0, buy a set of orange top Ford Mustang 19lb injectors from e-bay. They're the most popular injector swap on the Renix 4.0 and they work great.

 

[littlebluexj]

ok so i went to all three local parts stors for injectors to day.the stock xj injectors are in the 70$ range and 91 mustang GT injectors are in the 30$ range.but no store sould tell me the lb's for the injectors.all they could tell me about the ford injectors were that they are a 40-70psi rail set-up.is the stock mustang injectors the 19lbs injectors that i need.Some one help plz quick.

Thanks to everyone that has given me help these last few weeks.
William:
Cherokee Kustoms

 

[Dr. Dyno]

is the stock mustang injectors the 19lbs injectors that i need

Yes. Orange top 19lb injectors from an '86-'93 Mustang 5.0 are the ticket.

 

[JJacobs]

You really need to leave the Jeep parked until this problem is fixed correctly. It sounds like you're lean in spots and rich at other times. Enough fuel to make the Jeep blow black smoke is also enough fuel to wash the oil off the cylinder walls and nuke your engine. Be careful.