So ANNOYING engine light codes

So what is the deal or has anyone else had problems with their 99 or newer XJ throwing the "piston 3 misfire" code or any of the o2 sensor codes?

This happened to me before and I reset the computer and it did not come back for like 6 months.

What is the deal and can anyone tell me a cure all for this?

Also on a 99 or newer Cherokee I6 after off road OR driving the jeep hard upon start does it idle really rough or sometimes it even does it after just stopping after driving hard? Mine does this and my cousin that has the same year Jeep cherokee does the same thing. I know the problem has to be out there somewhere.

I hope to get some advice for this. Thanks.

My 2001 had the same issue as u stated above with the P0303 code. This code pops when the computer detects a missfire from the #3 cylinder. It is caused by heat from the exhaust manifold that following engine shut down migrates to the area around injector #3 and causes fuel vapor to form within the injector. This in turn may cause a momentary misfire of cylinder #3 until the fuel vapor is cleared of injector #3. There is a sleve you can install over the injector to solve the problem. The part number is 56028371AA. I found all this information by a simple search earlier. Solved my P0303 code and no more hot start rough idle. Hope this helps!

-Perry

Yes, I have the exact same issues with my 01. I am going to do the above injector insulator fix this weekend. One of those quirky jeep things....

jerseyjeep01 said:

My 2001 had the same issue as u stated above with the P0303 code. This code pops when the computer detects a missfire from the #3 cylinder. It is caused by heat from the exhaust manifold that following engine shut down migrates to the area around injector #3 and causes fuel vapor to form within the injector. This in turn may cause a momentary misfire of cylinder #3 until the fuel vapor is cleared of injector #3. There is a sleve you can install over the injector to solve the problem. The part number is 56028371AA. I found all this information by a simple search earlier. Solved my P0303 code and no more hot start rough idle. Hope this helps!

-Perry

Click to expand...

Where did you buy your part number 56028371AA from?

Does anyone have a picture of this "shield" installed? I ordered one of a Mopar site. We'll see what happens.

I think this is the only problem with my Cherokee. When the engine light comes on I get 5 codes. 4 of them are o2 sensor codes and one is the misfiring #3. Im sure that the misfire on #3 is making the 02 sensors go crazy, so I think doing the shield install will fix all the problems. Sweet! I'll tell my dad about it also because his Rubicon does the same thing sometimes.

While your under the hood, do yourself a favor and replace the plugs with a quality set of Champion or NGK plugs.

Keep the gap around .035".

The missfire with mine never made an 02 code display. This may be another issue on its own. If you have the $$$ replace them also.