Q&A

 Rookie

Andy Y, December 31, 2008, 11:02
Does your Jeep stall primarily when slowing down/deceleration? Is your throttle closed (foot off the gas)? The throttle body on all the Jeeps get coked up with oil and can cause a low idle/stalling and harder starting (long cranking time). Before replacing the TPS, try inspecting/cleaning the throttle body.
A failing fuel pump can cause intermittent stalling as well and won't necessarily turn on your check engine light. If the fuel pump is weak, the engine may run on light throttle but not see enough fuel pressure to sustain higher rpm running or heavy throttle (hard accel). If the CAT or O2 sensor has failed, most likely you will have a CEL and they won't normally cause stalling. Ignition problems can cause drivability problems and stalling as well. The ignition coil can be tested by measuring the resistance values

no it dosent stall when deceleration. when is bucks then stalls out it dosent do any diffrent if the gas is down or my foot is off the peadel i'll try give in it a clean see if it dose any better thanks

 Master

Good luck with the throttle body, it's a start and only costs your time and the throttle body cleaner. Remember spray the towel you're using with the cleaner and don't directly spray the throttle body. This may help but I have a feeling this not the primary reason you're Jeep is bucking. A coked up throttle body will normally cause low idle or stalling on decel (or when stopped) because the residue blocks the flow of air when the throttle is closed (foot off the gas).
The next steps to diagnose the problem will probably require a fuel pressure gauge and/or a basic multimeter. What speeds/mph does this normally occur? Has the Check Engine light come on? perhaps it was on and then went off again?

 Master

I just spoke to a friend and he said if the TPS on a Jeep is starting to wear, there may be a flat spot in its travel. He said it may cause a bucking because the computer has trouble interpreting the signal and causes the transmission to downshift, then upshift very quickly. Sometimes it will do that and also go into a false neutral so the engine will rev before going jolting back into gear.

 Rookie

a friend of mine said he thinks its the crank sensor he works of cars i was just wandering what yall think about that? could it cause all this problems

O! and when it stalls out the check gages light comes on but cuts off when you restart and letting off the gas when it tries to stall sometimes helps and sometimes it just stalls out anyways