Hey guys, sorry for the long post, but this one has me stumped. I bought a 96 4.0 Manual XJ about a month ago, and after a new starter and battery terminals it was running great.

It started stalling some mainly during acceleration, so I did a quick tune up- plugs, wires, distributor cap and button. While I was at it I went ahead and put in bosch 4 hole injectors, bbk 62mm throttle body, and afe air intake that had come in the mail. After I did all that, I cranked it up and it was running super rough, seemed to be running lean, and was getting 4-5 mpg. Another weird thing, when it's in 5th under a load, the AC slows down and blows hardly any air. Took it to the mechanic because I was busy at work and didn't have time to mess with it for a little bit. He told me I had 3 bad injectors, and his exact words for me were to stop reading forums- won't be going back to him anytime soon.

So I got another set of 4 hole injectors, and did the ECU reset by grounding the positive battery terminal, turning the key on and doing the headlights. It's definitely running better than it was after the 1st injector swap, it seems like the stalling is gone for the most part, and I'm up to 20ish mpg from 18.5. But it still has a bit of a rough idle, and hardly any power compared to before I did everything. I've replaced the TPS, IAC, MAP sensor, and crankshaft position sensor in the past 3 days, and reset the ECU after each one. Still not getting the extra power, and the AC is still going down in 5th.

I sprayed some carb cleaner bursts around the engine bay and didn't seem to find any vacuum leaks, so I'm all out of ideas.

Can anybody think of anything else? I've got time to work on it more this weekend, and if I can't get it figured out, I'll probably try a different mechanic, but I have a bad taste in my mouth after that last one.

 

Is your vacuum ball disconnected? https://www.cherokeeforum.com/f2/ope...m-line-188810/

 

When you replace so many components all at once, if one gives you an issue, you can't tell what's doing it.

Are you getting any codes?

If you have the old injectors, I would put them back on and see what happens. Maybe the Jeep doesn't like the new ones.

The same for the TPS, IAC, and MAP sensors, if you have the old ones. Clean IAC first and the throttle body. Reset the computer, and see if you get one codes.

Then start replacing the components one at a time and see if that resolves the issue.

Finally, what brand components are you using? Spark plugs?

 

What he said.

As for "the extra power", fuggedaboudit. You aren't going to notice any extra power from those mods.

The PCM will continue to learn the new system for a while, so if you have driven it less than 100 miles, you might want to just drive it for a while to give the PCM a chance to learn the new stuff.

 

Vacuum ball is good, and unfortunately I spent a day cleaning my shop out this week, so I threw out all of the old parts.

I used Champion plugs, and everything else has been BWD, minus the injectors which are Bosch remans.

CEL hasn't come on for any of it, and I checked with y scan tool and have no codes.

And I wasn't expecting much of a power increase, but I definitely didn't expect a huge loss. I can't even hold 70 on the interstate without having to shift back down to 3rd to get back up every 20-30 seconds, and that's with no lift and stock tires.

 

That ain't good.

Vacuum leak around the new injectors?

 

Finally got some time to work on the jeep after a couple of crazy weeks. I was looking at the injectors, and it looked like the one on cylinder 6 wasn't seated all the way in it's hole, so I took the fuel rail off, and it was a little bent. I bent it back with a vice, put it back in and it's running great now!

 

Good to hear you got it fixed.

Thanks for the update.