Went to leave work today all the sudden jeep wont start cranks sounds like a few cylinders fire

I figure i would try holding the pedal down then boom starts let off the pedal all the way no idle just slowly dies out

Drove home by not taking my foot off the gas used two feet other to use the brakes

Got home idled fine ran like normal turned off waited a little started right up.

Fuel pump?????
They are $200 so dont wanna "try" that and it being something else

Thank you for any help anyone can give

 

Check fuel pressure.

 

Suspect #1 is a marginal battery. If available voltage is low, it gives the engine management system fits and the primary symptom is stalling at idle.

After the vehicle runs a bit and the alternator does its thing of charging the marginal battery a bit, it has enough juice to satisfy the engine management system and the symptoms go away. Sound familiar? How old is your battery?

Yes there are other possibilities. But you must rule the battery in or out before moving onto them. Have it "load tested". Any parts store will do this for you for free.

Good luck and keep us updated!

 

Battery is almost two years old i will get it load tested tomorrow
And get a fuel pressure tester

 

Two load tests from two different places both say bad battery now the jeep starts right up but rough idles at start only then goes away gonna get another battery and see what happens

 

I'm betting that a new battery clears up those symptoms. Let us know.

 

Nope still not starting does the same exact thing

 

It was **** driving home multiple misfires flashing check engine light going up hill hitting throttle choppy as **** got home replaced tps started fine drove around for about 15 minutes drove fine came back turned it off waited about five minutes started it up started doing it multiple misfiring flashing light choppy and when you let off the throttle feels like a huge power loss

 

Please post the EXACT codes you pull from the computer. Gotta use those codes as a roadmap to the root cause.

As for the battery, if it failed two load tests, that was money well spent as you were going to need one soon anyways.

 

P304 cylinder 4 misfire
P456 small evap

However definitely multiple misfire after i left autozone where i got the scan ran like crap and got worse

 

I'd concentrate on that P0304. I don't think that the P0456 is the main culprit here.

1. Simple stuff first. When was the last time spark plugs were changed? New NGK plugs gapped to .035 if it's been a while would be a good idea.

2. Gotta ask. Have you been using any coolant? The 00/01 have the infamous 0331 cylinder head and if it cracks, will lead to coolant loss and possible misfires on cylinders 3 and or 4.

3. Getting a fuel pressure reading never a bad idea. Spec for the 01 is 49 psi, plus or minus 5 psi.

 

Spark plugs done 2 years ago went with double platinum should be good for 100,000 miles/8 years

Coolant recently flushed after water pump replaced as close to 50/50 as i could be

Fuel pressure is getting tested tomorrow

 

Got codes checked again
P303 misfire 3
And two others forgot the numbers but tps low voltage was one other tps high voltage

 

1. If you are getting codes for the TPS circuit, you likely have a problem with it. OBD isn't perfect, but it's pretty good at pointing you to an offending circuit. Either the sensor, connector or wiring. I know you replaced the TPS. What brand sensor did you use? I've had very poor luck with aftermarket TPS sensors for the XJ. Were you getting TPS codes BEFORE you replaced your TPS? Or just after installation?

2. Have you had to add coolant to the coolant reservoir recently? Can't ignore the possibility of a cracked 0331 head here as that is what your 01 came with from the factory. If that happens, misfires can begin to occur in cylinders 3 or 4. Usually don't see the misfire early after a typical 0331 head fail, but they definitely can occur.

 

I wrote a big paragraph that didnt send so in short

No tps codes before swap duralast tps i replaced the replacement one of the two codes are gone

I was also told platinum spark plugs are bad on jeeps and can lead to misfiring overtime so I replace them with copper spark plugs no more mess fire looks like for now however

Still throw one code P0122
Low input voltage tps wires look fine however a little stiff