only starts while depressing gas pedal and voltage spikes

[KPTHEMP]

ok, i'll try searching too, but just wanted to throw it out there and get some input. Its an 01, but im running a 99 complete setup (distributor, wires, 99+ intake).

On cold starts in the morning it cranks but wont start unless I hold down a little on the gas pedal, if i let off the pedal it dies, but i can let off the pedal after about 20 seconds of running and its fine. it also acts this way on warm starts sometimes, and sometime it starts right up.

Also while driving, twice in the past week on the way to work the volt meter on the dash will spike to 19 and the check gauge light will come on, it only lasts about a minute then goes back to normal. idk if its related to the start ups or not ?

Third, the jeep died the other day on me while on my way home, it had the hesitation startup then after about 5 mins of driving it died in the middle of the road. I got it pushed off to the side then tried to restart and i noticed all the analog gauges were dead, and the odometer read out said "nobus" and the check engine light came on.

so i went and got a spare CPS and swapped it out, when i plugged it in to test it out the gauges worked, so i installed it then went to crank it over and the gauges were dead again, then i disconnected the battery cables, touched them together to reset ECM, reconnected battery and it started right up fine. but i

So, now its still giving me the hesitation at startup, and i still have to press down on the gas pedal to get it started, its the same problem as before so i dont know if the 2nd CPS is bad too or something else is going on.

this has been going on ever since a day or two after the last offroading trip and i did get into some mud, but not too bad and it didn't get into the engine bay.

any suggestions ?, maybe i'll try a brand new CPS, but i think maybe a different sensor is bad ?

and shouldn't the 2nd CPS have plugged in and worked fine without having to disconnect and reset the ECM ?

Thanks
KP

 

[93gc40]

Have your battery checked. The 4.0 is a battery HOG at start-up.

 

[winterbeater]

Having to touch the gas pedal to get it to start, leads suspicion to the TPS. You can test that with an analog multimeter to look for a pad spot in the TPS potentiometer.

The cold starting issue leads the suspicion to the temp sensor not telling the PCM to richen up the mixture when cold.

 

[Tim_MN]

Load test the battery and alternator, one or both are bad.

The spiking of the volt gauge points to a failed or failing alternator.

For 1996-2001 Jeeps the OBD-II the engine computer (ECU/PCM) re-boots and the idle settings are deleted when: (1) you let the battery rundown by leaving the lights or radio on, (2) disconnect the battery for an extended period of time, (3) or when the battery goes bad and needs replacing.

The classic symptoms are: (1) having difficulties starting the engine without depressing the gas pedal, and (2) the engine will have a low idle and probably stall unless you keep your foot on the gas pedal.

The ECU will relearn the idle settings after a short period of time and the engine will start and idle normally. If the symptoms reoccur, you need to have your battery load tested at a repair shop or auto parts store. This is usually a free service they offer to bring in potential customers. Even with low battery voltage, the engine will start, but the ECU can re-boot multiple times and a new battery may be required.

Loose, corroded, or damaged battery cables or ground wires may also cause or contribute to the problem. Begin with basic trouble shooting of the start and charge systems. Remove, clean, and firmly reconnect all the wires and cables to the battery, starter, and alternator. Look for corroded or damaged cables and replace as needed. Do the same for the grounding wires from the battery and engine to the Cherokee's frame/body.

Cleaning the IAC and using fuel injector cleaner should be part of your routine preventative maintenance.

 

[winterbeater]

X2 on what Tim said. Computer does that after losing voltage. Need to take care of that first.