JD Cravin

Hi,

I have a 98 Sport, 137K...the engine will stall at high altitude only. Like around 4kfeet or so. Everywhere else it is fine.


I just changed the Plugs/wires/cap/rotor and went back up the mountain with same results. Actually, it happend just a little lower in elevation.

But still, everywhere else it is fine.

Suggestions?

rrich

Are you driving from low altitudes then without stopping till you get to the high places it stalls?

If so, it my be normal.

The MAP sensor doubles as the altitude sensor. When you first turn the key on, the computer "notes" the MAP reading, then uses that as the altitude reading. As you go up it has no way to know you changed your altitude. Part way up, or where it seems to be losing power, simply shut it off and restart it. It gets a new reading. It'll run better and get better mileage too.

dukie564

sounds like the MAP sensor may be malfunctioning. Do a search on here for the testing procedure.

JD Cravin

Thank you both for the suggestions...I'll check it out and report back.

JD Cravin

Ok, so I replaced the MAP sensor and still have the same basic issues. Seems to be getting worse as I dont have to go as "high" up in altitude.

Today I was crusing along testing the new MAP when I saw a deer cross the trail, I came to a stop and the engine cut out...as before.

I restarted and in cut out again, restarted and turned around and went home.

Any new ideas?? Fuel pump maybe? Fuel fiter? (1998 Cherokee Sport)

Help please.

Note: This does NOT happen in town. LV is around 2100' in altitude.

bheath

I dont mean to sound like a jackass but you said "trail". You going up steep inclines? Or flatter roads? Dont get pissed but if its a steep hill and you dont have a full tank of fuel it'll stall. Just a simple idea... Not calling you an idiot but sometimes we overlook simple things...

JD Cravin

No, totally cool man.

Not really a trail per se, but more of a dirt road. And not that steep plus over 1/2 tank of gas.

Thanks for the comments!

JD Cravin

I was thinking maybe some sensor in intake manifold? Or fuel pump/filter?

lukeincolorado

Dirty paper filter? Lol it happened to me swear to god. It wasn't getting.g enough air and high altitude=less atmospheric pressure. Just my. 02

87Warrior

At what speeds does this happen? Engine RPM? Does the rig ever stumble in town?

Could be a dirty or worn CPS.

JD Cravin

It has a brand new K N filter

JD Cravin

It say less than 35 mph, and 2 - 2.5k rpms... And, no, it never happens in town. Thats what so weird about it.

What is a CPS?

Also, it shut off once I came to a complete stop.

tjwalker

The CPS is the crankshaft position sensor. It could be in play here.

Usually they fail more catastrophically, but not always.

JD Cravin

Why would it only happen at higher altitudes? Does the CPS rely on atmospheric pressure to function correctly?

tjwalker

There is a high altitude crank sensor available, but I think it might be just for the 87-90 models. So there might be a relationship. I think the "spacing" of this sensor is a smidgen different with the high altitude application, but the crank sensor itself is the same. Not 100% positive on that though.

The fact that it is stalling though is a common symptom of a marginal crank sensor.