injector upgrade problems

[littlebluexj]

this weekend i have remover the mech. fan and run 2 stock electric fans now at the same time i have installed my ould trucks(95,f-150's(i-6) injectors)b/c my old stock ones had 200thousand miles on them and leaked.now the new ones don't leak but it idles real loopy and kills its self out ialso installed a custom intake K&N.i put the vacume line to the end of the fuel rails regulator i think is what it is and it will start ideal and die quickly.i take that vacume off and it will run but very loopy and chocks.when i get it on the road it will run great till around twoG's(rpm)then it starts to backfire and stutter till i just jump on the throtal and i cleans out and takes off fine but the secont i get off the gas the rpm's drop like a stone and it backfires all the way down.

any input helps thatks Will

[old_man]

First, a few spaces, a few capitals, and some better spelling would make this a lot easier to decipher.

What flow rate are the new injectors you installed? Most likely they are a higher flow injector and may not be real compatible. It takes a while for the computer to adjust to the new flow rates. Disconnect the battery for about 10 minutes, then reconnect. That will force the computer to re-learn the operating parameters.

[Fred]

Removing vacuum to the fuel pressure regulator increases the pressure in the fuel line if it's a Renix system, so that should make it more rich. If it runs fine at wide open throttle and at start when the ECU has it run rich, and dies when the ECU is controlling emissions, it sounds like it's running lean to me. Does it backfire in the exhaust or in the intake?

Fred

[FUNKYTEE5]

I think you actually downgraded to smaller injectors. The 4.9 big six injectors are rated around 14-15 lbs and they run higher fuel rail pressures to make it work with that motor. It sounds like your motor is running super lean. Try some ford orange top injectors or pink tops if you have HO. They might work better. :)

[littlebluexj]

I don't have an HO and I called for and they said they were 15LB injectors and is a backfire from the exhast(sp) now when it is idleing it will idle at 700 rpms and then drop to 200 and almost chock it out then back up to 700.this is with the vacume off.With the vacume one it will idle really hard at 250is the intire time befor chocking out.This is all after i reset the computor with the battery thing.i can drive around town but when it gets to 2000 rpms it wants to stay there wont go any higher so i jump on the gas and it will go right past it but will back fire when i let off still
Will

[old_man]

The real question is, 15lbs at what pressure? Flow rates are based on pressure and the relationship is not linear. 15lbs is too low for a Renix engine in most cases. You might get away with it here at 5000' but I wouldn't risk it.

The real issue is to check the exhaust to see if it is running to rich or too lean. You can also do a sparkplug reading.

[littlebluexj]

ok so should i get a set of mustang 5.0 injectors instead it seems that they are the most commonly used upgrade for the jeep and how much do they usally run.just give me the basic info on this upgrade so i can just stop trying to fix whats allready not working and do it right the second time.

[BCParker]

http://www.fiveomotorsport.com/Injector_SetsJEEP.asp

[goodburbon]

bad link

[BCParker]

you must have tried it in the 6 seconds before I went back and edited it. it works for me now.

[goodburbon]

yeah, I just have really good timing.

[Fred]

Since I doubt the 15 lb injectors were specified at 10 psi, more likely 40 psi or more, they are too low for a Renix, which consensus says uses a 19.7 lb injector. People seem to be happy with the 19 lb Ford Motorsport injectors from what I have read.

Generally, backfire in the exhaust means you are running rich, but that seems unlikely.

Fred

[xj_chris]

http://www.fiveomotorsport.com/Injector_SetsJEEP.asp

Does anyone know why you cannot use the Ford 24lb in 2000-2001?

[user name]

4.9 injectors are 14 lbs


running fuel system pressure, vacuum connected 45 to 60 psi.

[BCParker]

Does anyone know why you cannot use the Ford 24lb in 2000-2001?

different electrical connection in '00,'01

[Mrburns]

based on the 5.0link... i read that uptill '95 the 4.0L's ran with 19LB injectors....i thought when jeep went to HO, they bosted the injectors to 22LBs? is this not true? ....i read it off of a stroker site, which said if you had a HO you didn't need to up grade depending on the bore over and how mild/wild you went with on your stroker....only the earlier non-HOs had to goto bigger injectors...

Help.....please

[FUNKYTEE5]

A 19lb injector is too small for a HO 4.0 They should work fine for renix motors though. The factory injectors for HO setups are right around 21lbs. I tried 19lb injectors in my 93 and they worked ok except for at wot where it starved for fuel.

[littlebluexj]

what is WOT just a question.i feel stupid for asking

[John90XJ]

Wide Open Throttle

[littlebluexj]

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

[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.