tj hates hot weather

[leelum9]

I am new to this site...but old to asking this question. I have a 97 tj four cylinder that I found for a great price two years ago or so. In ny it did great but in this warm weather in Tennessee its mad.when I idle in slower conditionsin high heat(above 87) when its been driven for twenty minutes or more...sometimes downshifting into third or lower, or sitting at a stoplight , stop sign, anything where the engine idles it can fluctuate rpms and more often than not dies.if I turn key all the way back and try to start again, it will start up as if nothing happened and drive great until the next idle condition. No codes at all. So far replaced parts have been cap, rotor, wires, plugs, fuel pump, fpr on rail, idle air, new battery .
Any help would be immensely appreciated, this has been a horrible gremlin to fight so far.

 

[superj]

i had a friend who had the same trouble on her 4 cylinder. she never got it fixed and it bugged her so much she got rid of the jeep

 

[leelum9]

I really don't want to get rid of it....but it has crossed my mind...

 

[superj]

she didn't want to either, at first. but with the continuous issue and no one being able to fix it, she finally got sick of it and traded it off

 

[leelum9]

I have been contemplating upgrading the cooling fan to make up for the heat..a higher output electric fan, ran off of a switch so it can run all time in the heat. On the highway it runs fine until traffic slows the jeep down for a few minutes

 

[superj]

its odd man. try whatever you need to to keep the jeep running.

 

[mud4feet]

The heat shouldn't matter....you've got other problems. My '03 4banger (yeah, it's the 2.4L) has live 4 years in the heat of Southern Louisiana and live nearly a year in the godawful cold of Upstate NY....and resides now back home in the North Carolina mountains. Have never had any "environment-related" problems.....just all the other "normal" stuff. Perhaps the "heat" is just showing you something that's been wrong for a while!?! Sorry I can be of no more help than that.......I'll think on it for a while.

 

[leelum9]

I know it happens only during hot days....I know something is wrong but am tired of throwing parts at it.it runs fine under 88 degrees..never a problem

 

[JPNinPA]

There could be two common issues causing rough idle at idle.
First check and clean you throttle body (TB) and idle air control (IAC). The IAC sets the air fuel ratio at idle.
Second what RPM are you idling at? If it's above 750 rpm and rough you may have a leak in the intake. To find where it is leaking take some carb and TB cleaner spray and spray around the bottom of the TB. Then around vacuum lines and then around the intake where it meets the hear at each cylinder.

 

[leelum9]

Brand new iac and I cleaned tb when it was installed. I also have yet to be able to find a leak at all.but it never hurts to look at things again.

 

[Bounty__Hunter]

Could be a bad throttle position sensor. I'd clean the TB and IAC again as well.

Does the speedometer work properly?

 

[leelum9]

Speedometer works well, the cleaning and replacing of the iac were done to fix this issue and never helped it...tps didn't have any odd fluctuations during computer scan.it was very smooth and steady.

 

[JPNinPA]

These are causes but less common than the IAC and TB issues mentioned earlier.

Check that the electrical connectors are all clean and tight to all sensors.
Check the Intake Air Temp sensor, the O2's and the temp sensor are working correctly.

There is a TSb for later models to heat tape the injectors. They get heated and vaporize the fuel in them causing rough idle. 97's weren't in the years but I've read of some wrapping the injectors and resolving the issue.

Also what deg thermo do you have? Or what temp does your engine run at?

 

[leelum9]

The jeep stays right around my 210 degrees at all times.might see a +-5.I have noticed the tsb and have thought about sleeving the injectors ...anything is worth a shot at this point

 

[Bounty__Hunter]

The heat soak is more common to the 4.0L but worth a shot.

Have you replaced the CPS?

 

[leelum9]

The crank sensor has been replaced..I put some of the heat wrapping on fuel line and rail and injectors ....hopefully I can find a aluminum sheet for a shield in between tomorrow and see what happens

 

[JPNinPA]

I agree about the 4.0 and heat shields. But I also read a bunch of home grown fixes including heat shields. What had me think of this was the above 88 deg. Why only above 88 degree.

So you checked the Intake air temp sensor the O2 sensors and the engine temp sensor? These are all used once up to temp.


This may be an open loop closed loop issue if it isn't a vacuum leak. Your engine runs open loop until some conditions are met and I think some time goes by. All the sensors I mentioned above are used in closed loop. Mainly the O2. Again thought this would be year round, but worth considering.


PS the parts you did replace were Factory replacements correct?? Many aftermarket TPS, O2's and soem other fail right out of the box.

 

[jfrabat]

Could also be the MAP, I guess; air presure changes with heat, so there's a chance it's acting up.

 

[leelum9]

I have checked every sensor that the genesis system can read on a jeep..o2 are good tps is great..it doesn't fully read the map...I have full temp readings and they are good...the insulation didn't do much to the problem...it seems to give every effect of a little cooler gas can but not stopped the issue.the map is what I'm leaning towards right now..

 

[leelum9]

Today has been a heavier set of shutdowns....while driving in 101 temp it was shutting down while in gear..highway speeds or city driving..