06 Cherokee 3.7 v6 misfiring

[76w200]

I have an 06 Grand Cherokee 4x4 automatic w/ v6 3.7 litre.

Problem...
At idle feels like it's missing. Under acceleration the vehicle bucks, and the check engine light blinks/beeps.. Will not accelerate past 2000-2200 without fits. 35 mph is tops...

Pulled the check engine light codes...

Open Circuit on Injector #4
Cylinder misfire #4.

I have replaced the plugs. Drove fine for about 5 minutes and then began again.... I put STP injector cleaner in, a fresh tank of fuel and drove it around for about 20 minutes or so... Problem did not clear up.

Any thoughts before I go purchase a new injector?

[Desoto61]

Check the wiring from that injector back into the harness and verify the connections. You might be able to turn up some simple tests you can do with a voltmeter to check that the injector is operating properly. They are basically a solenoid valve. I think most operate by feeding a constant 12V and then controlling the ground path via the computer. In other words you should have 12V at one connection and the other should alternate between open and ground (very fast though, you'd need an oscilliscope to see it).

You may be able to find a place that can test the injector out of the vehicle.

If those check out OK I'd look at maybe having a real injector cleaning done. The tank treatments are OK as a preventative measure but the professional stuff is actually injected into the fuel rail with the stock fuel line bypassed so that the engine runs off the concentrated cleaner for a few minutes, but given the open circuit code I'm betting it's electrical (faulty wiring or injector).

[Deathdeelr]

If those check out OK I'd look at maybe having a real injector cleaning done. The tank treatments are OK as a preventative measure but the professional stuff is actually injected into the fuel rail with the stock fuel line bypassed so that the engine runs off the concentrated cleaner for a few minutes, but given the open circuit code I'm betting it's electrical (faulty wiring or injector).

NOOOOOO!!!! Don't clean the injectors!!!!! Bosch injectors cannot be cleaned. You'll remove the coating on the pintles and seats and they'll never work right again and if they do work right you probably shortened the life of the injector by 75%. The pro injector cleaners aren't recommended for any car made after 1996. I've been down this road and it's ugly. Go down to Harbor Freight. They have a good noid light kit for $15. Remove the plug on the injector in question and plug in the appropriate test light from the kit. Start the motor. If she flashes then the harness is good. Change the injector.

[76w200]

It was a bad injector sorry!!! Passenger bank cylinder #4, right in the middle. I will heed your advice for future! I simply went to jeep bought a new injector and replaced. For future I will purchase the test kit.

Started with plugs since they were the cheapest and worked my way up the chain! Runs a lot better with new plugs... hmm magine that... 102,xxx miles and never been changed...

[Deathdeelr]

I didn't mean to be loud or anything. I just wanted to make sure the job got done right. My first injected car was an '88 Beretta and I used to stick to a schedule which included cleaning injectors whenever I changed spark plugs. When the '05 Cavalier came along I did the first injector cleaning at 50K. At around 65K she started to misfire. Sure enough, #2 let go. $90 and one injector later no problems. I cleaned them again at 100K only this time she ran for about a week and then started going down hill; hard startings, rich readings off the O2 sensors, then an intermittent misfire while she idled until finally she wouldn't start. #1,2, and 4 let go. Since I used the car to the tune of 600 miles a week I ended up putting in 4 new injectors ($360) and never cleaned them again. It was about this time I did a little more research and found that the technology in gasoline additives and fuel injection manufacturing has come such a long way since the 80's. Cleaning fuel injectors has become a myth. I changed the plugs 2 more times (almost 200K) before I got rid of the car and never had an injector problem again.