Grip

It happened three times today, all in the same scenario's.

Idling at a stop, go to accelerate, backfires once or twice through the intake, engine stumbles or bogs, then it is back to normal. This whole thing takes maybe 1-2 seconds at the most before its over.

Its not throwing any codes. The injectors are newely rebuilt and tested 784's. New NGK plugs within the last 5k miles.

Coolant temp sensor?
02 sensor(s)?
Coil rail?
CPS?

Im going to throw a coolant temp sensor at it this friday because that is literally the only piece of the cooling system that is not brand new within the last two weeks.

steelybill

How about the ground(s) on the coil rail ? just an idea, from GM experience..

Grip

Where are the grounds on the coil rail?

When i took the coil rail off to do the plugs, i removed the entire coil rail from the truck. Didnt see any grounds.

Dont the bolts that hold the rail on ground it?

tlang

Man, the only thing I can think of is timing. Unfortunately on the 00 its not as easy as throwing a timing light on it. I would throw a lab scope on the crank and cam sensor to see what is going on. I believe if you have a scan tool that will do it you can re-sync the cam and crank sensor.

Do you have any codes? Check engine light on or flashing?

My other thought is if your 02 sensors are way out of whack....

Good luck with this, this one may require a trip to the shop. Hopefully Im wrong.

Grip

No codes.

This vehicle will never go to a shop while i own it.

I am going to put a coolant temp sensor in it fri. I may throw two new O2 sensors in it and a new coil pack while im at it.

Ill look more into into timing, but i really dont think this is a timing issue.

tlang

Why replace parts when you could test stuff and not waste money?

Why are you so sure its not timing? was just trying to help out.

Do you have access to a lab scope?

Let us know what you find.

Grip

Im putting a coolant temp sensor in it because its $27, and it wont hurt to get rid of the one with 145k miles on it.

Same for the O2 sensors. At 145k miles they can be replaced.

From what ive read on this specific subject. Timing is very very rarely the issue.

The truck runs 100% fine except for the three times it backfired through the intake. Starts fine, idles fine, revs freely, can do burnouts with 33" tires. Timing does not seem to be an issue worth getting into at this time.

Most people with this problem seem to cure it with a coolant temp sensor, O2 sensor(s), or a coil pack...possibly new plugs.

The small amount of money it will cost to do basic routine maintenance is not an issue. the parts will not hurt in any way, even if they do not fix the issue.

Grip

New O2 sensors fixed the issue. Threw the coolant temp sensor and a coil rail in it too.

skife

this is the biggest problem of most jeep owners on forums or the internet, throw parts at it and hope it fixes it. why spend $75 at a shop that has the knowledge and tools to properly diagnose the problem when you can spend several hundred on replacing parts that are just fine?
this guy is right on the money.

Grip

The $200 didnt hurt my wallet.

I already had the coolant temp sensor, so why not install it?

One of the O2 sensors of the two i replaced fixed the issue.

I put a coil pack in it because i wanted to. Now i have my old one as a spare, or to help a buddy in need in the future. No big deal.

Preventative maintenance is not a bad thing to do.