I just installed today K suspension 4 hole injectors in my 99 XJ 4.0 automatic. I also replaced plugs, wires, and cap and rotor a couple days prior. The Jeep has sat for a few days previous and hasn’t moved since I replaced the plugs, wires, and cap and rotor. I got everything finished up today. I reset the ECU and started up the Jeep giving it some gas. It idled extremely rough shaking the whole Jeep. It smoothed out a good bit but makes a popping noise from the exhaust when the ac is on. It also smells kind of like fireworks when it’s running. I took it for a drive and it won’t go over 25mph and it’s at over 2k rpm at that speed and also makes the popping noise while driving. Is there anything I can do to make this better? I’ll be more than willing to provide further information if needed.

Thanks!!

 

You sure the plug wires aren't the issue? Was it running fine after the tune up and before the new injectors? I've done a whole bunch of 4L injectors and never experienced a single misfire or rough idle. Although I will say that the Ksuspenion injectors (Ford take offs) seem to tick loudly. I prefer the GM Northstar Injectors.

 

Did you test the injector to make sure they are all opening correctly use a 9 v battery with an injector plug and tap one wire to the pos one to the neg you should hear it click that’s good if not no good that’s also how to clean them open them up spray carb cleaner through it and your good

 

The plugs or plug wires could quite possibly be the issue. I did not drive the Jeep in between the tune up and the injector swap. I used the duralast wires from autozone and Bosch platinum plugs. I was careful to place each wire in the correct spot so maybe it’s the plugs?

 

I did use a long handle screwdriver to listen to them. I put the driver end on the injector and the handle to my ear and could hear them working so I don’t think it’s the injectors themselves

 

I would say its probably the Bosch platinum spark plugs. Try the NGK or Champion copper plugs. Imo the platinum and iridium plugs are just to fancy for our old engines