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Jeep Cherokee Start Stall Idle Problems

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Comments

  • volvoidvolvoid Posts: 4
    thanks for the idea - - not sure if it's only when brake is applied, but will check tonight -- that could explain why mechanics don't replicate it and computer is clueless. I've suspected vacumn leak but couldn't locate one -- this will help me narrow down suspects. Guess I need someone to apply brake while I listen?
  • lunghdlunghd Posts: 61
    I don't know if you could hear the leak but it's worth a shot. The hard vacuum line cannot be replaced with anything other than a vacuum hose so swapping w/ heater hose etc won't work. (The vacuum will collapse it.)

    The vacuum leak idea is just a shot but another forum I'm on has had people report leaks in the brake booster / hose as a cause of intermittent stumbling.

    HTH
  • volvoidvolvoid Posts: 4
    idle wanders whether brake is on or not -- doesn't mean that's not the culprit, but less of a smoking gun. Will check more this weekend. thanks again.
  • lunghdlunghd Posts: 61
    A common (on older XJ's) problem is for the intake/exhaust manifold bolt's & studs to come loose due to heat cycling & vibration. You can check for that with a squirt bottle (an old windex bottle, etc) filled with water & set to stream. When the motor is misbehaving squirt along the head to manifold surfaces. A temporary change in idle - ie, it smooths out... will help you pinpoint the suspected leak area.

    If they are loose - do NOT OVERTIGHTEN! The studs are especially prone to snapping off & they all get 23 ft/lbs., if I recall correctly. (At least on my 4.0L.) I have the torque values etc on my site on this page:
    INTAKE ? EXHAUST MANIFOLD TORQUE VALUES & TIGHTENING SEQUENCE

    This page is for the older RENIX XJ's but other than some head port changes & HO exhausts not having the EGR tubing it should (SHOULD) be the same for all year 4.0L's.
  • neil693neil693 Posts: 1
    I have a 89 Jeep Cherokee Pioneer. I park it on the grass and in the morning it doesn't start. I just all the caps, plugs, wires, and filters changed out. It still won't start. When I come home mid-day it starts right up. What else could be the problem?
  • lunghdlunghd Posts: 61
    Allergies? :P

    Next time it doesn't start up - lift the hood & unplug then replug the Crankshaft Position Sensor connector. (Back of head, driver side on US models, wire runs from harness to nearly hidden sensor on upper area of bell housing - diagram on my website.)

    Failing Crank sensors are a very, very common issue & often are intermittent until they finally crap out entirely. Connector is probably oxidized & morning moisture is causing enough extra resistance to prevent signal pulse from reaching computer.

    Give it a try & let us know how it goes.
  • 1990 Jeep Cherokee: Takes up to 30 seconds of cranking to start. Once started, will idle a little rough but straightens out with some revs. Has been hard to start for a while but recently degraded to the point of no road time. Put it in gear and it immediately runs rough, begins to backfire, won't take load. When put back into Park/Neutral it straightens out. Replaced fuel filter, TPS needed slight adjustment and I ran a bypass ground from the TPS as the ground was a little weak (runs a little better after that) and checked for vacuum leaks. Also verified the engine->firewall ground is ok. CPS generates .2 to .3 VAC when cranking (as per testing on lunghd's website). I have a new CPS and ready to replace it as it seems to be the common culprit in many posts that I've read. Anything else I should look for while I'm at it?
  • Update: Replaced CPS, plugs and wires, double-checked plug gaps. Removed/cleaned the idle step sensor. Runs a bit smoother now. It will put to the local convenience store, however, still gets bogged down if given too much gas while in gear. In park or neutral, runs fine, no obvious misfires. I've checked vacuum levels at the EGR solenoid and it was around 15hg and did a manual test on the EGR valve. Also have removed the Catalytic Converter to verify that it wasn't causing too much back pressure buildup. I have also sprayed starting fluid around the vacuum hoses/tubes to make sure there wasn't a hidden vacuum leak. Besides replacing more components (Cam Position Sensor and MAP are next on my list).. any insight would be appreciated.
  • Hi,

    I was hoping someone might be able to help. Hopefully, I can phrase my problem correctly....

    I have a 2000 Cherokee Sport 4.0 auto. It has 98000 miles on it, I bought it new and kept up all the maintenance.

    About two weeks ago, it started giving me problems with hot start after a really hot day driving with the A/C on. It started fine cold. When hot, I had to really give it gas to get it to start and not immediately stall out. After a few minutes, the idle leveled out and all was well.

    A week later, the condition reversed. Hot starts were easy; one crank and good, no rough idle. Cold starts became troublesome, long crank, rev the engine until it levels out, all is well. Unfortunately, the cranks are wearing down the battery and the problem is one my local mechanic can't nail down. His only comment was the battery seemed drained-- 11 volts (no wonder with all the cranking). I plan on replacing it as it's four years old already and probably won't cut it for a New England winter, but I'm skeptical that it's the problem.

    Any thoughts? TPS? CPS? Coolant sensor? Plugs are three months old, Champion truck. I have the Haynes manual and I was planning on checking voltage resistance on each sensor.

    BTW, I checked the forum already and saw the bit about priming the fuel pump by switching it on and off twice. It seems to make no difference.

    Any and all suggestions would be great.

    Thanks in advance.

    --John
  • tuggajbtuggajb Posts: 646
    with 4 year old battery i would change that first as jeeps are sticklers on volts from bat change that and see if takes care of prob before you spend lots chacing stuf
  • harry44harry44 Posts: 1
    I own a 98 jeep grand cherokee laredo 4x4 straight 6 cylinder, my problem is i started it one night drove for about 30 yards I noticed my headlights went out first then the engine shut off. I thought this was weird so i tried starting it back up... it would not start nor did I have any headlights or horn or radio ... and i could'nt get my windows back up. I checked fuses I did not see any blown fuses. the real weird thing is that a jump will not help but the vehicle turns over, just wont start and no electric.... what could be my problem?
  • Yep, problem solved. It _was_ the battery, thanks. Maybe I should trust my mechanic! :-)
  • 95zjtom95zjtom Posts: 8
    I just looked up the neutral safety switch for a 95 Grand Cherokee 5.2 liter V8 for $9.99.
  • lunghdlunghd Posts: 61
    What's your fuel pressure?

    TPS voltages check out across the sweep range? (A Digital volt meter might miss any dead spots -heck an analog might miss a dead spot too but an old school volt meter with a needle will catch a dead spot easier.)
  • lunghdlunghd Posts: 61
    What's the battery voltage? Cables in good condition with NO crappy aftermarket clamp-on style terminals? (They corrode underneath the clamps & loose contact.) Any faults showing from computer?
  • Spot on.. I actually replaced my fuel pump assembly and a fresh fuel filter this last weekend. I noticed that I had no pressure at my test port on the fuel rail after an attempt to start. Fuel pressure was a little over 15 lbs with ignition on and was suffering from pretty bad leak down, losing pressure fast. Now it starts within 2 seconds of cranking and has plenty of power, enough to powerbrake with ease (my neighbors could tell I was happy :-) Fuel pump was definitely my problem..
  • I have a 95 Jeep GC, 4.0 6 cyl, auto. I have recently replaced the starter, battery, and did a full tune-up. I am having problems with it stalling while in any gear other than Nuetral or Park while I am pushing on the throttle. It will idle fine while in gear and I can rev it up to redline with no problem when it's in N or P. Please help with any ideas. Thanks
  • lunghdlunghd Posts: 61
    Sounds like the idle stepper motor (IAC) located on the throttle body. They get gummed up & can fail to open and / or properly seat. It's usually a 'free fix' - remove & clean it with some good carburetor cleaner spray.

    Wait a minute - I just re-read your post... Let me double check my understanding:

    Idles well while in Drive or Reverse... but does not rev up?
    Revs up in Park or Neutral.... but will not idle?
  • Check my post right before yours.. I had the same symptoms. It was my fuel pump. Would seem to idle ok and could rev it up in Idle and Park no problem but when put into gear, immediately began running rough and would back-fire when throttle was applied and/or stall out. Check your fuel pressure.
  • I recently had the fuel pump and 2 sensor changed. When the jeep is idle in park it runs fine however when I brake, it feels like it will stall but it doesn't. The engine light is on and the mechanic said I should bring to Jeep for testing. Other than that it seems to be running fine. What could be making the car sutter when braking? We did have tons of fan issues but the car is fine and doesn't over heat anymore. The mechanic couldn't fine anything wrong??? Any ides before Jeep charges me a fortune for nothing. Thanks!
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