Idle questions - 1990 Jeep Cherokee

[JeepCherokeeGuy]

Hi my name is Anthony and I'm new to this so forgive me. I have a 1990 jeep Cherokee that has the 4.0L I6
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I also noticed that when it warms up it idles really high what could be causing that?

 

[JeepCherokeeGuy]

I just put the ford 5.0L injectors in my 1990 jeep Cherokee and was wondering if I have to screw with the timing at all. Thanks for the help.

 

[TerryMason]

Jeep Cherokee Guy,
Welcome to Jeepz.com. I've moved your posts to their own thread where you'll probably get more help.

 

[JeepCherokeeGuy]

Thank you, I'm still kinda new to this.

 

[TerryMason]

Did it idle high before you put the new injectors in it? I've never heard of that mod myself.

 

[JeepCherokeeGuy]

Yes it idled high before I put the injectors in it. The injectors helped a little but it still wants to idle high.

 

[SteelHeadz]

Check your throttle body for carbon build up. On startup, the IAC will cycle to find the optimum air/fuel mixture and if the T.body is dirty, the idle will be erratic. Another thing to check is vacuum. Engine vac. leaks will cause a high idle. A loose intake or faulty intake gasket may cause this symptom. Make sure the MAP sensor is properly hooked up and has no vac. leaks as well.

 

[FloridaCherokee1988]

There's also a small sensor plugged into the intake manifold near the backside of it, I think its like a 5/8 nut, take it out and clean the carbon off if there's any, I know that will cause a high idle as well, I think its called the intake air temperature sensor. Also make sure its got plenty of coolant and let it run till it starts idling high, check and see if you have a freeze plug leaking, they'll make it idle crazy high if one is leaking.

 

[JeepCherokeeGuy]

Thanks for the advice, I'll have to check those things out this weekend. Thanks again. Anthony.