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Did tune-up and injector swap...ZJ running terrible! :(

2K views 28 replies 9 participants last post by  ratmonkey 
#1 ·
Hey guys...I just did a tune up (Kolak's injection upgrade w/ new Camshaft Position Sensor) and did the 703 injector swap all about a week ago. I figured it would take a bit for the PCM to re-learn everything...but my Niner is running like ars! :(
I also put in a new TPS, IAC, cleaned the Throttle Body, and have a Durango air hat now.
Since all this...the Jeep has a really rough idle, and it has worse gas mileage than before. It also seems more sluggish, and has a loss of power. It hasn't died on me though.
I have NO idea what to even check now, as all the threads on this say to put in new spark plugs, wires, cap, rotor and coil...which I did...and to clean the IAC, which mine is new.
Can someone shed some light on what else would cause my issues, and what I should do or check. I would greatly appreciate it.
Thanks a lot!! :cheers2:
 
#4 ·
Thanks...I didnt think of that. I will take another look and make sure they are all gapped the same, and report back.

Were the injectors new? Are they all tested? It sounds pretty similar to problems a lot of people have with leaky injectors from JYs.
The injectors were not new, but were cleaned, re-built and tested before going in. Is there a way to test for a leaky injector while on the manifold?? Or do I have to yank them out to test them?
 
#6 ·
Thanks...sounding like its a injector issue. I'll double check the plugs 1st...then tackle the injectors if that doesnt clear up the issue.
Exactly what am I looking for with a leaky injector? How do I find out one is leaking?
 
#9 ·
When I put new 703's in my 96 it was running like crap with idle going up/down. Someone mentioned to drive it at 50+mph for a while and sure enough after about a week of occasional driving it eventually smoothed right out. Rpm's were still going up/down at idle and about another week it leveled out. Don't know why it took the PCM so long to learn the new injectors and make adjustments but it finally did.
 
#10 ·
Huh...I was thinking it may take a awhile...but I have not taken the Niner for a drive around 50+ sunce the swap. Guess I'll try that now.
Thanks a lot! :thumbsup:
 
#14 ·
Take off the air hat and throttle body then unbolt the fuel rail and gently pry the injectors up one side at a time while leaving them on the fuel rail. Put some paper towel under them and have someone turn the key to cycle the fuel pump on. That's how I checked for a leaky injector. If it leaky it will drip on the paper towel when the fuel line is pressurized.

To listen if the injectors are working just put the tip of a long dowel rod on the injectors while it's running and put the other end to your ear to listen. You will hear them clicking away if they are working. They should all sound the same.
Good luck.
 
#16 ·
Take off the air hat and throttle body then unbolt the fuel rail and gently pry the injectors up one side at a time while leaving them on the fuel rail. Put some paper towel under them and have someone turn the key to cycle the fuel pump on. That's how I checked for a leaky injector. If it leaky it will drip on the paper towel when the fuel line is pressurized.

To listen if the injectors are working just put the tip of a long dowel rod on the injectors while it's running and put the other end to your ear to listen. You will hear them clicking away if they are working. They should all sound the same.
Good luck.
Thanks a lot...I'll give this a try, and report back.
 
#17 ·
i would verify plug wire routing, plug gap, and check the plenum if you haven't done that repair.
did you use the larger 24lb/hr injectors?
have you seafoamed the motor lately?
was the TPS a mopar unit?
lastly, go out and give it an italian tune up and run it at interstate speeds for a while after disconnecting the battery for the pcm to reset.
 
#18 ·
i would verify plug wire routing, plug gap, and check the plenum if you haven't done that repair.
did you use the larger 24lb/hr injectors?
have you seafoamed the motor lately?
was the TPS a mopar unit?
lastly, go out and give it an italian tune up and run it at interstate speeds for a while after disconnecting the battery for the pcm to reset.
Italian tune up? So can you just put the jeep in neutral and rev it to just about till it redlines? I might throw a rod in my i6 :0
 
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