Elk1bowhunter

Any body no what would cause my xj 4.0 sport 2 door to kick on engine light then it wont idle like its flooding only when I get to high altitude turn around get to 8,000 feet elevation and light goes off and it runs great again very weird. Any ideas

Gee oh Dee

First off the year of vehicle would help.

Second, get the codes read. That will tell you exactly what is causing the CEL.

Elk1bowhunter

Sorry 1995, thats whats weird no trip codes, at a loss

Gee oh Dee

When it starts to act up check for GOOD spark and check to be sure its making good fuel pressure.

Fsher21

if the issue is actually related to altitude, I would look into the way air is brought into the system. Easy to check the filter and inside the tb, not sure how related the iac or any other sensor would be in relation to compensating for elevation.

Elk1bowhunter

Its all good just starts flooding bad gotta hold throttle half down to keep runnin let it try to idle then it dies, it will fire right up if you keep yr boot in it, only runs this way and acts this way when I get to around 10,000 foot elevation flexin in high country, when I cripple it back down to around 8,000 feet elevation light goes out it then idles and runs great again. Got cold air intake, throttle bottle upgrade and tbs as well snap on computer wont read any codes, tryed crawlin up high again same deal had to stay low

rrich

Doubtful it's a real problem. It's the limitation of the system.

Stop, turn key off till the engine completely stops. Restart and continue on your merry way.

The why = the MAP sensor takes a reading when you first turn the key on - the PCM uses that as the altitude baseline.
All calculations are based on that fast reading - the PCM has no idea you changed altitude at all.

It takes a new reading whenever the engine is stopped and you turn the key on.

Few of us ever change elevation that much all at once, so it's not a common complaint.

You'll find it gets it's power and mileage back.

Good idea is to do that every few thousand feet.

rrich

Years ago we had BARO sensors that constantly monitored Barometric pressure - mainly for the altitude reading - it was an identical sensor like the MAP sensor - except no vacuum line, just a piece of sponge rubber on the fitting to keep bugs out.
You may remember seeing those.

It's not just Jeeps, but probably everything does it the same way now.

Elk1bowhunter

Thanks for all the replys going to try again and update everyone