Trailhead_Kyle

So I am having a problem starting my Jeep in the cold. I need to press the throttle to get it started and keep idle above 1k by slightly holding throttle. After about a minute it’s fine and I have no problems whatsoever. I can drive turn it off and start it back up no issues, unless it sits for a long time and it’s cold. I checked the throttle body to clean it and it looks brand new. So clean I’d eat off it. I know there is a sensor to set idle before warm up but I don’t know what it is. Idle is perfect once warm also. Does anyone know what sensor raises idle during warm up?

jordan96xj

What type of vehicle? year?

Most likely candidate is a Idle Air Control that is sluggish or failing when it is cold. It sits on the back of your throttle body (on an XJ) and is responsible for allowing air through the throttle body to maintain idle when the foot is off the pedal. The fact that it starts and idles if you manually work the pedal, hints that the IAC is not opening when it is cold and letting air through the throttle body (bypassing the butterfly plate) as it should.

tjwalker

Year?

Engine?

Ever seen a check engine light?

*Both the throttle position sensor and idle air control could be in play here.

*As would the coolant temperature sensor that has gone south. If the computer doesn't have the correct input from the coolant sensor, it changes the fuel/air ratio dramatically and that can lead to poor starts when cold.

*A long shot would be a marginal battery that has enough power to start the engine, but is marginal on keeping engine management systems happy. But after a minute of running and charging the battery, there is enough juice and the symptoms resolve. Load testing your battery here would tell the story.

Good luck and keep us updated!

Trailhead_Kyle

those were the 3 I was also thinking but with the tps and iacv wouldn’t it happen no matter what the temp? Also my temp gauge reads fine with no issue which makes me wonder if the sensor is bad. The Jeep is a 2001 Cherokee 4.0l with no CELs. I just don’t really want to drop $200 on three new sensorswhen I might not need all three. Also cuz we are having to repair some mold issues in our guest bath we found lol.

jordan96xj

Has the IAC been removed and cleaned? The throttle body can be super clean, but if the IAC is all gummed up, it will still cause this type of trouble.

Trailhead_Kyle

I haven’t checked. I got a temp control sensor today and will try that tomorrow

Cummins93

Clean the idle valve first. Hang on to that receipt for the coolant sensor. Free comes first.

jordan96xj

Lol. But that would break the normal pattern of asking for help here.

1. Provide vague multi-faceted details about the problem (and side problems)
2. Get specific guidance
3. Buy/Swap everything -except- what relates to the specific guidance
4. Reporting back 2 years later that the original guidance addressed the problem (but only when someone resurrects the thread and asks for an update). Making it seem like the original guidance was arrived at by the OP organically (after swapping everything else possible).

Doesn't get me down though, because I know these posts will help someone else who is searching later.

Bugout4x4

I greatly respect the patience of everyone here who keeps chugging along despite this reality. lol

Trailhead_Kyle

i bought one of the sensors that the 2nd post mentioned. How is that not listening? Anywho it fixed the problem so that’s all the really matters

PatHenry

I feel like the statement was more of a generalization than specifically accusing you - I wouldn't worry about it or take offense as Jordan96xj and Bugout4x4 are always super helpful guys from every post I've seen.

So specifically the resolution was replacing the IAC valve (which was the 2nd post starting from the top) or the temp sensor which you mentioned you were going to replace? As Jordan mentioned, just so that someone else that has this problem can find the information in the future.

Bugout4x4

Yes it was, and thank you for recognizing this, and personally I didn't mean to point, so please never take it personally. But in general it is a reality and I have to give these guys huge kudos for the patience it takes to keep coming in here day after day generously helping folks. I think Jordan might have been just throwing that out there as a general truth over all here. Unfortunately it is indeed a very common theme he shares here.

jordan96xj

No worries. I wasn't aiming it at you specifically. Its just how many of the posts go. Mostly just glad you got it fixed. Can you be specific about what fixed it?

Trailhead_Kyle

yeah sure thing. In order to start the Jeep I had to lightly hit the throttle to get it started and then gently rest my foot on the gas to keep idle above 1k and from dying. So I replaced the coolant temp sensor. First time it had a tough time starting. I went to work and came back it started right up and has every time after. I appreciate all the help from everyone

Turbo X_J

Did you check the resistance of the old CTS to insure it was faulty? If not, it may not be fixed just yet.