[BigBillLV]

I've never actually handled this type of throttle body but, just looking at pictures and diagrams, they don't look very complicated: butterfly, linkage, throttle spring and 2 places to attach and Air Idle Speed Sensor and a Throttle position sensor... That's about it.

Sounds more like a sensor issue. Has your mechanic checked the sensors (MAP, O2, ETC, et al)

 

[jjmac12345]

I've never actually handled this type of throttle body but, just looking at pictures and diagrams, they don't look very complicated: butterfly, linkage, throttle spring and 2 places to attach and Air Idle Speed Sensor and a Throttle position sensor... That's about it.

Sounds more like a sensor issue. Has your mechanic checked the sensors (MAP, O2, ETC, et al)

I’m not certain what they did. One took three weeks to look at it, and the other one is not possible to get ahold of for weeks at a time. Lol. I’m also getting high rpm’s on start up when warm. It goes up to about 2000 rpm then idles around 1000 and moves up and down 100-200 rpm

 

[Double E]

I’ve had this Jeep around 3 months. I’ve driven it 4K miles or so. I just looked and the coolant has gone down 1” in the reserve tank.

With no extensive history available,it's time to check the basics. A dropping coolant level is an alarm. Fill it back up, mark the outside of the tank with a sharpie at that level and check it again after a week of daily use. Check it again in 2 weeks. If it has dropped after a week, that's a further alarm. A coolant pressure check is in order, then evaluation of your funds to have the Head Gasket replaced or not. If the pressure check reveals a leak somewhere else, great, fix that and we'll work on the rough idle issue again.
For now though, I'm suspecting the rough idle is caused by coolant entering one or more combustion chambers.

Alternatively, and for a cheap diagnosis, get a dissolved hydrocarbon test kit (amazon has 'em) and see if there's dissolved hydrocarbons in your coolant. Easy to use and definitive for where the problem is and is not.

 

[jjmac12345]

With no extensive history available,it's time to check the basics. A dropping coolant level is an alarm. Fill it back up, mark the outside of the tank with a sharpie at that level and check it again after a week of daily use. Check it again in 2 weeks. If it has dropped after a week, that's a further alarm. A coolant pressure check is in order, then evaluation of your funds to have the Head Gasket replaced or not. If the pressure check reveals a leak somewhere else, great, fix that and we'll work on the rough idle issue again.
For now though, I'm suspecting the rough idle is caused by coolant entering one or more combustion chambers.

Alternatively, and for a cheap diagnosis, get a dissolved hydrocarbon test kit (amazon has 'em) and see if there's dissolved hydrocarbons in your coolant. Easy to use and definitive for where the problem is and is not.

So, it would idle high only after being warm if that was the problem? Wouldn’t it be more consistent? I’m gonna fill it up and see what happens, but it’s only lost a few ounces or so from the reservoir tank.

 

[Billfer01]

So my only option is a used one?

 

[BigBillLV]

I’m not certain what they did. One took three weeks to look at it, and the other one is not possible to get ahold of for weeks at a time. Lol. I’m also getting high rpm’s on start up when warm. It goes up to about 2000 rpm then idles around 1000 and moves up and down 100-200 rpm

The shop that wanted to change the throttle body had my Jeep for about a week and a half. After I discovered the problem in replacing it, someone on JEEPForum recommended that I take it to a different shop. I immediately took that advise. Fortunately, there was another shop available: AAA. They're expensive but good and repairs (parts & labor) are warranted for 12 months or 12,000 miles.

I wish I knew more about modern Jeeps but I'm an Engineer not a Mechanic. So, I'm at a repair shop's mercy. If it sounds reasonable, I'll authorize it. This time, my former shop may have royally screwed me (for work that they said they did do) but I had used them since I bought my Jeeps new and thought they were pretty honest. They are a chain-shop and they have changed all of their personnel since I last used them. My how things have changed!!

 

[makuadoug]

As others have said, you need to go to the basics. How do the spark plugs look? What about compression? How is fuel pressure? If you are loosing coolant, is it getting into combustion chamber. If you can find your way around with a digital multimeter, then with a factory service manual you can rule out a lot of suspects. if your auto tech isn't providing with a written work order detailing Exactly what has been done, the you need to find another tech.

 

[The Happy Friar]

when you say the rpm are messing at highway speeds, does your speed change too?

For the acceleration, can you be more specific? If you slam on the gas, does it just rev to high RPM & then catch up, jump around while accelerating, etc.?

 

[BigBillLV]

As others have said, you need to go to the basics. How do the spark plugs look? What about compression? How is fuel pressure? If you are loosing coolant, is it getting into combustion chamber. If you can find your way around with a digital multimeter, then with a factory service manual you can rule out a lot of suspects. if your auto tech isn't providing with a written work order detailing Exactly what has been done, the you need to find another tech.

You are certainly correct when you admonish: "If your auto tech isn't providing with a written work order detailing Exactly what has been done, the you need to find another tech."

Seems most of us learn this the hard way!


Thanks

 

[jjmac12345]

when you say the rpm are messing at highway speeds, does your speed change too?

For the acceleration, can you be more specific? If you slam on the gas, does it just rev to high RPM & then catch up, jump around while accelerating, etc.?

Speed on highway doesn’t change. It does it with cruise control on or off also. It will go from 1600 to 2000, on its own and back down usually within 2-3 seconds on flat roads. I’ve noticed after it goes up if I very lightly press on the gas pedal more than I’m already pressing it will go back down.

The acceleration issue is only noticeable in first gear, or in reverse. I have to give it more gas than normal to get it going but it’s not stomping on the pedal by any means. Rpm’s are getting close to 2000 or so, it’s just feels like a sluggish response or something in first or reverse.

 

[jjmac12345]

Maybe it’s two different issues. Both somewhat minor so far.

 

[The Happy Friar]

Maybe it’s two different issues. Both somewhat minor so far.

that's what I'm wondering. When the traction control went out on my minivan it would randomly enable and my rpms would jump up (pedal down) and my speed would reduce (because it thought I was slipping). Sometimes if I'd slam on the gas it do what he's describing. No codes eigther, just a TC light on temportally.

 

[Waterluvr]

@jjmac12345
You've given some more useful information, and I'll add again that a real shop level scan tool needs to be brought into play here in addition to the pcm idle control drivers I'd also be looking at your torque converter lock-up solenoid function.

With this era of vehicle everything that matters is electronically controlled, it takes the right diagnostic equipment and tech's that know how to use it. You may have an input or output speed sensor issue causing the TC to malfunction here.

What drivetrain do you have, 4.7 or 4.0?

 

[jjmac12345]

@jjmac12345
You've given some more useful information, and I'll add again that a real shop level scan tool needs to be brought into play here in addition to the pcm idle control drivers I'd also be looking at your torque converter lock-up solenoid function.

With this era of vehicle everything that matters is electronically controlled, it takes the right diagnostic equipment and tech's that know how to use it. You may have an input or output speed sensor issue causing the TC to malfunction here.

What drivetrain do you have, 4.7 or 4.0?

It’s a 4.7 high output.

 

[Waterluvr]

@jjmac12345
Thanks for the update, I noticed in your initial post it was a 2004 but I didn't recall the drivetrain.

I specialize in diagnostics and electronics for Jeep and other FCA vehicles, the 2004 model year you own has a powertrain control module that was only manufactured for that specific year and one of the common failure points are idle air motor control drivers you have an entirely separate TCM for the transmission the 4.0 doesn't have.

If you plan to own that WJ for any length of time at all, you should seriously consider buying spare pcm's for it while you still can. This is one of the vehicles in the Jeep lineup from that era that I cannot repurpose another FCA module for and they are drying up in the salvage market quickly and the prices are rising on them they cannot be repaired by anyone no matter what they claim once a problem always a problem.

The time will come when they are scarce or impossible to find and will carry price tags that will be in the neighborhood of the value of the whole vehicle we saw this with some of the Wrangler models made in 05-06 and the supply chain was bringing 2-3K at one point for them. I can solve those failures with Nitro and Neon pcm's that can be reflashed to work with the TJ's but there's nothing cross compatible with the 2004 WJ at all.

 

[jjmac12345]

@jjmac12345
Thanks for the update, I noticed in your initial post it was a 2004 but I didn't recall the drivetrain.

I specialize in diagnostics and electronics for Jeep and other FCA vehicles, the 2004 model year you own has a powertrain control module that was only manufactured for that specific year and one of the common failure points are idle air motor control drivers you have an entirely separate TCM for the transmission the 4.0 doesn't have.

If you plan to own that WJ for any length of time at all, you should seriously consider buying spare pcm's for it while you still can. This is one of the vehicles in the Jeep lineup from that era that I cannot repurpose another FCA module for and they are drying up in the salvage market quickly and the prices are rising on them they cannot be repaired by anyone no matter what they claim once a problem always a problem.

The time will come when they are scarce or impossible to find and will carry price tags that will be in the neighborhood of the value of the whole vehicle we saw this with some of the Wrangler models made in 05-06 and the supply chain was bringing 2-3K at one point for them. I can solve those failures with Nitro and Neon pcm's that can be reflashed to work with the TJ's but there's nothing cross compatible with the 2004 WJ at all.

Hmm, good to know. Thanks. Longest I’m going to own this one is two years. Less if it keeps having issues. I had an 04 with a 4.0 that I drove for three years and over 80,000 miles without much of an issue before this one. I hit a deer with it unfortunately.

 

[jjmac12345]

@jjmac12345
Thanks for the update, I noticed in your initial post it was a 2004 but I didn't recall the drivetrain.

I specialize in diagnostics and electronics for Jeep and other FCA vehicles, the 2004 model year you own has a powertrain control module that was only manufactured for that specific year and one of the common failure points are idle air motor control drivers you have an entirely separate TCM for the transmission the 4.0 doesn't have.

If you plan to own that WJ for any length of time at all, you should seriously consider buying spare pcm's for it while you still can. This is one of the vehicles in the Jeep lineup from that era that I cannot repurpose another FCA module for and they are drying up in the salvage market quickly and the prices are rising on them they cannot be repaired by anyone no matter what they claim once a problem always a problem.

The time will come when they are scarce or impossible to find and will carry price tags that will be in the neighborhood of the value of the whole vehicle we saw this with some of the Wrangler models made in 05-06 and the supply chain was bringing 2-3K at one point for them. I can solve those failures with Nitro and Neon pcm's that can be reflashed to work with the TJ's but there's nothing cross compatible with the 2004 WJ at all.

So how big of a job is it to replace the idle air control valve driver?

 

[jjmac12345]

@jjmac12345
Thanks for the update, I noticed in your initial post it was a 2004 but I didn't recall the drivetrain.

I specialize in diagnostics and electronics for Jeep and other FCA vehicles, the 2004 model year you own has a powertrain control module that was only manufactured for that specific year and one of the common failure points are idle air motor control drivers you have an entirely separate TCM for the transmission the 4.0 doesn't have.

If you plan to own that WJ for any length of time at all, you should seriously consider buying spare pcm's for it while you still can. This is one of the vehicles in the Jeep lineup from that era that I cannot repurpose another FCA module for and they are drying up in the salvage market quickly and the prices are rising on them they cannot be repaired by anyone no matter what they claim once a problem always a problem.

The time will come when they are scarce or impossible to find and will carry price tags that will be in the neighborhood of the value of the whole vehicle we saw this with some of the Wrangler models made in 05-06 and the supply chain was bringing 2-3K at one point for them. I can solve those failures with Nitro and Neon pcm's that can be reflashed to work with the TJ's but there's nothing cross compatible with the 2004 WJ at all.

Or is replacing the pcm the fix for the bad idle air control driver?

 

[makuadoug]

That driver is in the PCM. It's my understanding that the PCM for these vehicles is really not repairable. It's consumer grade, not mil spec.

 

[jjmac12345]

That driver is in the PCM. It's my understanding that the PCM for these vehicles is really not repairable. It's consumer grade, not mil spec.

Ok, so I’ve gone from replacing the throttle body to replacing the pcm. How do I track down one and make sure I get one that’s compatible?