1988 Xj

On cold starts the jeep will barely idle and sometimes die. After holding my foot on the gas for a little while (a few minutes) I'll let off and it will idle absolutely perfect.

I have done a laundry list of things to this:

Tps adjusted
CPS is new
CTS is new
Grounds are refreshed
C101 is cleaned
Throttle body and IAC is clean

 

Done the sensor ground test? Post 5 in my link

 

Yes I have.

 

Tested the IAT?

Cleaned it?

 

IAT or MAP may be reacting slow in the cold weather, running pig rich. Had this problem when I was in MO. Could be water in the fuel rail freezing to, are you running any anti icing agents for fuel?
Valero and Caseys' both have high water contents in their fuel(ethanol up around 10 to 20%), try going to Red Barn if you have one they are known to have real gas.

 

I have cleaned the IAC and IAT. how do you test the IAC?

 

Meant IAT.

 

Do you have new injector or old ones?
And have you done or tried any of the following?;
manual test of the EGR valve and EGR soiloinoid
Test fuel pressure regulator
is your heat riser tube hooked up?
Map sensor and associated lines? just because it's "working" doesn't mean it's "working" right.
Throttle body gasket?

 

Old injectors, to my knowledge.
Elaborate on the "heat riser tube"
How do you test EGR and EGR solenoid?
How do you test the fuel pressure regulator?
Map sensor seems to be in good shape as well as the map sensors vac line.
Throttle body gasket is fine.

 

Wouldn't it make sense that this issue be cause by something temperature activated? Its like after the jeep moves into closed loop it idles fine...


02? IAT?


I would really like to get to the bottom of this asap. I've owned this Jeep for 4ish weeks and have been trying to figure out this one problem the whole time. Although I have made lots of ground and fixed lots of other issues, this is the one issue that is driving me crazy.

 

Heat riser tube is the tube coming from the exhaust mani and going to the bottom of the air box, this allows engine to reach temp quicker by using exhaust mani heat.
Test the EGR solenoid by applying vac to it, doing this will cause the engine to bog or die. You test the EGR the same way but bypass the EGR solenoid. If the EGR is stuck open or leaking at cold start you could be choking out on exhaust gasses and not fuel.
Fuel pressure regulator, will need a pressure gauge, should be at 31lb-ish with the vac line hooked up and 40ish with line unhooked.
IAT/MAT works along with O2, and MAP to regulate fuel/air mix. IAT is in the drivers corner of the intake(2 wire plug). Remove and clean, have not heard of one going bad just to dirty to work right.
A cracked exhaust mani will cause the O2 to thicken up on fuel also.
Washed out or mix matched injectors can cause cold start issues. Did this one to myself with some LeBaron injectors once.

 

This Jeep has a cone filter in place of the factory air box so the heat riser tube is not going to be hooked up.


Can the EGR be totally eliminated? On all my LS cars, I totally get rid of egr on the ones that have it. I didn't know if that could be done on the Jeep as well.

 

By federal law an emissions system can not be disabled.
Emissions systems made after 86ish work "WAY" better than their pre 86 counterparts, due to ease of maintenance and fewer-ish parts.
I am not in the habit of disabling emission systems, nor do I recommend it.That said, if you think it's a good idea?