Engine Performance problem
2001 Jeep Cherokee V8 Two Wheel Drive Automatic 148000 miles
I have a 2001 Jeep Grand Cherokee with a 4.7 liter V8 and ~148,000 miles. Towards the beginning of this year, the Jeep developed a problem where it will stall as I come to a stop. It doesn't do it all of the time, but it is becoming more frequent. I previously read that this problem may be due to a faulty camshaft position sensor or even the crankshaft position sensor. I've replaced both sensors, but the problem remains. The vehicle does start back up once it has stalled, but sometimes it takes a few attempts. I initially thought it may be temperature dependent, but it happens regardless of cold or hot ambient conditions. I receive no check engine light when it stalls. Your help is greatly appreciated.
Pull the trouble codes from the engine computer using the " check engine light" Self-Diagnostic method. This will at least give you a guide as to what may be causing the problem. I'm going to " cut/past" how I do it from another post I answered, and unless Jeep has changed the procedure it should still work. I DO recommend getting a HAYNES repair manual from the local parts store for YOUR model, look in the Emission and Engine Control System chapter and read the procedure in that manual for you. Has lots of info. Anyway, this is how I do it, hope it applies to your model: I have a 1996 Jeep Cherokee that will do this when I do an on/off sequence using the key, but only if your check engine light is working.
To do this, turn the ignition key ON, OFF, ON, OFF, then finally ON. (On is the position just before that extra click that starts the jeep) The check engine light will blink the number of the first code digit(count the number of flashes), then pause about 2 seconds and blink the number of the second code digit. If you have more than one error code, the light will pause about 3 or 4 seconds, then blink the first and second digits of that code the same way as before. When the computer is finished blinking " codes". It will flash 5 times, pause, then flash 5 more times to tell you that is the end of the sequence. Post back with what you find out, and someone should be able to answer with more info if you need it. GOOD LUCK!
December, 19, 2008 AT 11:11 PM
The Haynes repair manual for my Jeep says the procedure for diagnostic mode is for 1997 and earlier models only. 1998 and later models must have the diagnostic trouble codes extracted using a specialized scan tool. In any case, the manual also says that the PCM will illuminate the check engine or malfunciton indicator lamp when it recognizes a fault in the system and wil remain illuminated until the code is cleared or the PCM no longer detects a malfunction after several consectutive drive cycles. My check engine light has never illuminated during the engine stalling which implies that there are no trouble codes to extract. If no trouble codes exist, what's the next step?
December, 20, 2008 AT 8:55 AM
Or it could imply that your check engine light is burned out (it's possible, it's possible.). If you have an Autozone in your area, they will come out with a hand-held scanner and read your OBDII codes for FREE, FREE, FREE! Other places do it, too, just call around. If doing this is possible, try it. Better to have too much info than not enough.
Now, heading back to non-electronic causes, how's your fuel filter? Plugged/dirty? Had a tune up recently?
December, 22, 2008 AT 10:35 AM
No codes are present (I took the Jeep to AutoZone and had them check for codes). In regards to a tune-up; I've had the injectors cleaned, new spark plugs, new air filter and an oil change with new oil filter. I was also told that if the problem was the fuel filter, I would have problems while at highway speeds or while accelerating (especially during hard acceleration), but not while idling or coasting to a stop. I'm really not sure what to check next. Your help / advice is very much appreciated.
December, 27, 2008 AT 8:44 PM
Ok check your fuel pressure at an idle and at higher rpm it should not be less then 44.2 psi
January, 11, 2009 AT 5:06 PM
Ray5796 -- please keep me informed of your progress. My wife's 2001 with the V8 (and 90k miles) has just started doing this off and on. Also unable to get a code or rhyme or reason!
January, 12, 2009 AT 9:48 AM
Also test the Throttle Position Sensor
January, 18, 2009 AT 4:01 PM
Problem Fixed! It turned out to be the Fuel Filter/Pressure Regulator (all one piece). It was intermittently failing to maintain sufficient pressure during coast down. It was $29.99 at AutoZone and wasn't too terrible to remove / install. Thanks to all those who provided advice.
January, 18, 2009 AT 5:55 PM
Ray -- great news. By any chance, would you be willing to email me the DIY procedure so I can do this on my wife's jeep? If so, please send me a PM and i'll give yoj my addy.
January, 18, 2009 AT 9:50 PM
This website won't allow me to send a private message until I've made 10 responses. However, I've attached a link to the AutoZone website which has removal / installation instructions. I have a Haynes book for the Jeep. The Haynes book is of course more detailed, but the AutoZone link is sufficient to perform the replacement as well. The removal / installation for my Jeep didn't require any special tools (all I used was a " ratchet with 10mm socket). I will say that it took a little patience to release the quick disconnects" used on the inlet, return and outlet connections for the fuel filter/pressure regulator. The installation was much faster than the removal.