Hesitation on acceleration

[Corvairdan]

I have a 2006 TJ 2.4L. When I press the accelerator the engine dies out almost to a stall then picks up. I originally thought it was a fuel problem and replaced the fuel pump and the fuel injectors. That didn’t work. I then read online that the upstream o2 sensor may control the fuel air mixture so I replaced it. No help. When the engine dies down there is there is a “cha” sound of air at the air manifold. I had to replace the starter also so the sensors were reset.
Anyone have any ideas?

 

[AndyG]

Check the throttle position sensor

 

[Daniel Stamm]

Check the throttle position sensor

ok. I replaced the TMP. While I had the throttle off I put in a new set of spark plugs. There is still a hesitation and Ann air “cha” sound when I press on the accelerator. It seems to run ok at cruising speed.

replaced so far:
Fuel pump
Fuel injectors
TMP
Upstream O2 sensor
Spark plugs

Any help is greatly appreciated
Dan

 

[AndyG]

ok. I replaced the TMP. While I had the throttle off I put in a new set of spark plugs. There is still a hesitation and Ann air “cha” sound when I press on the accelerator. It seems to run ok at cruising speed.

replaced so far:
Fuel pump
Fuel injectors
TMP
Upstream O2 sensor
Spark plugs

Any help is greatly appreciated
Dan

I’m trying to think of what else to look for and also keep an eye if any solenoid or anything could be opening that is messing with you a little bit

 

[Jeep tj Finland]

ok. I replaced the TMP. While I had the throttle off I put in a new set of spark plugs. There is still a hesitation and Ann air “cha” sound when I press on the accelerator. It seems to run ok at cruising speed.

replaced so far:
Fuel pump
Fuel injectors
TMP
Upstream O2 sensor
Spark plugs

Any help is greatly appreciated
Dan

Dan, I am having the exact same problem except mine does not make that noise you described, it simply feels like it is not getting fuel. And I too replaced all you listed except for the TMP, but I also changed the distributor cap and rotor. Am out of ideas and so is my mechanic. It is a 1997 TJ 2.5. We have looked everywhere searched all the Jeep forums...Did you find out what it was?

 

[DannyBoy83]

My 2005 TJ Sport has same issue. I'm getting P0430. We've replaced camshaft position sensor with Mopar OEM. Also replaced synchronizer. And I had the PCM (brain) tested and it was bad so new pcm. Still can't get rid of the issue. Runs and drives strong but if you romp on it it really has the hesitation jerkiness until u let off accelerator.

 

[LONGJP2]

My '06 4.0 does the same thing.
Bogs a little when I stab the gas.
I only notice it when I'm sitting in park at idle.

 

[91Rider]

I have a 2006 TJ 2.4L. When I press the accelerator the engine dies out almost to a stall then picks up. I originally thought it was a fuel problem and replaced the fuel pump and the fuel injectors. That didn’t work. I then read online that the upstream o2 sensor may control the fuel air mixture so I replaced it. No help. When the engine dies down there is there is a “cha” sound of air at the air manifold. I had to replace the starter also so the sensors were reset.
Anyone have any ideas?

I am guessing that you figure this out by now and I read through the other replies and did not see one of the most common causes for engine hesitation when accelerating. More times than not, the issue is caused by the Crankshaft Position Sensor going out of whack. The CPS is critical for a smooth engine. The CPS is essentially a magnet and coil to detect the teeth or notches on your flywheel. The CPS will generate pulses that go to the ECU computer. These parts have been notoriously been an issue on Jeep because of crappy parts being manufactured. If the parts starts to go, so will your smooth ride. The issue may manifest more on warm or hot days and completely go away during the winter. The reason is resistance goes up with heat and the slowly failing more becomes more susceptible as RPMs increase. I plan to post something on the YJ Forum. The failure is how you describe. It feels like it could be fuel, dirty plug, distributor, and potentially clutch, but most frequently it is the CPS. If not CPS, then look at Camshaft sensor, O2, TPS, MAP, or MAT. Start with the sensors - one at a time after you checked for any vacuum leak issues.