Hesitation at constant speed - JeepForum.com
 
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post #1 of 13 Old 04-07-2021, 10:59 AM Thread Starter
NGAJeepguy
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Hesitation at constant speed

*Update* It's in the transmission. See post #4 below


My daughter drives our 2007 GC. A couple of weeks ago she said it would start hesitating while driving at a constant speed. I assumed I had a coil pac going bad so I swapped out all coil pacs and spark plugs last week. It was a good thing I did, they were OEM! I figured that solved it, it certainly made the vehicle a little more responsive!


Last night she said it did it again. It's not constant but intermittent. I've not been able to recreate it. I will say that the exhaust note has changed somewhat. The vehicle definitely sounds different - so much so that I noticed it. I will add that the day after I changed out the pacs and plugs, the vehicle stalled on me while I was in line to pick my son up from school. It took about 6 times at attempting to start it and then it started and acted fine. It's never done this again. Yet.



Any thoughts? Throttle Position Sensor? Cam Position Sensor? Idle Air Control? These are the only things that I think would change the note on the exhaust and cause both a stall and/or an intermittent hesitation.

And no, no codes.

ETA: I just did another test drive But we were not able to duplicate the issue. I watched the O2 sensor voltages. Bank 1 and Bank 2 #1 senors bounced between .1 and .7V. I mean, like, constantly bounced. Very sporadic. Bank 1 & 2 #2 sensors bounced a little but pretty much maintained .7V.

The TPS seemed fine. Air intake temp was steady. The fuel trim voltages were steady.


Last edited by NGAJeepguy; 04-07-2021 at 01:26 PM. Reason: Updated
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post #2 of 13 Old 04-07-2021, 11:35 AM
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Not my cup of tea yet...but have you checked the Egr ?
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post #3 of 13 Old 04-07-2021, 12:19 PM Thread Starter
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The EGR was replaced last June. What would I be looking for? No smell of gas to make me think it's not working...
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post #4 of 13 Old 04-07-2021, 01:24 PM Thread Starter
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Ok, I was able to recreate it. It's definitely in the transmission. When driving under constant speed (not accelerating/decelerating) it's almost like it pops out of gear for a split-second and then goes back in. There's definitely a "clunk". It did it a few times and then after I decelerated for a stoplight, it quit doing it all together.
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post #5 of 13 Old 04-07-2021, 05:44 PM
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Quote:
Originally Posted by NGAJeepguy View Post
Ok, I was able to recreate it. It's definitely in the transmission. When driving under constant speed (not accelerating/decelerating) it's almost like it pops out of gear for a split-second and then goes back in. There's definitely a "clunk". It did it a few times and then after I decelerated for a stoplight, it quit doing it all together.
Sounds to me like a lock up torque converter issue. Possibly the limiter spring.
Do you have any codes pending in the TCM? You’ll need a good scanner to check and you’ll probably need to be looking when the problem comes up.

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post #6 of 13 Old 04-07-2021, 09:41 PM
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Quote:
Originally Posted by NGAJeepguy View Post
ETA: I just did another test drive But we were not able to duplicate the issue. I watched the O2 sensor voltages. Bank 1 and Bank 2 #1 senors bounced between .1 and .7V. I mean, like, constantly bounced. Very sporadic. Bank 1 & 2 #2 sensors bounced a little but pretty much maintained .7V.

That's normal, the upstream (sensor 1) switching is the PCM switching the A/F ratio between slightly rich and slightly lean to provide the converters with the unburned oxygen they need to work, and the fairly steady readings on sensor 2 shows the converters are doing their thing.


The stalling is almost certainly unrelated to the transmission issue, probably just a dirty throttle body or idle air passage/IAC motor pintle. If you've never cleaned it, it's probably due.


And I agree with yzjwk, it sounds like your torque converter is unlocking. I'm surprised you aren't getting any codes. Did you notice the engine bump up a couple hundred RPM when it happened? Did it actually feel like it was out of gear?
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post #7 of 13 Old 04-08-2021, 07:39 AM Thread Starter
NGAJeepguy
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I will clean the pintle this weekend. Assuming that's the connector just below the intake air temp sensor....?


I didn't notice the engine bump up, it's that quick. Did it feel like it was out of gear: That's the hard part. I've had transmission issues where the rpms shot up and the car bogged down or popped out of gear. This is the opposite and very hard to explain. You know how it feels when you're backing out of the garage and you put it into drive before a complete stop - that clunk? That's what it feels like but it's very fast clunk-clunk. Out-then-in. It makes the jeep chug a little bit. It's not drastic and terrible but quite noticeable.


Thanks for the feedback & ideas, it is much appreciated!

Last edited by NGAJeepguy; 04-08-2021 at 07:51 AM.
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post #8 of 13 Old 04-08-2021, 07:59 AM
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Quote:
Originally Posted by Rick_H View Post

The stalling is almost certainly unrelated to the transmission issue, probably just a dirty throttle body or idle air passage/IAC motor pintle. If you've never cleaned it, it's probably due.
I missed the stall in the OPs post, but engine Stalling and transmission issues are quite common with the 545RFE. Both a split sump filter and the limiter spring can/will cause the engine to stall.

Quote:
Originally Posted by NGAJeepguy View Post
I will clean the pintle this weekend. Assuming that's the connector just below the intake air temp sensor....?


I didn't notice the engine bump up, it's that quick. Did it feel like it was out of gear: That's the hard part. I've had transmission issues where the rpms shot up and the car bogged down or popped out of gear. This is the opposite and very hard to explain. You know how it feels when you're backing out of the garage and you put it into drive before a complete stop - that clunk? That's what it feels like but it's very fast clunk-clunk. Out-then-in. It makes the jeep chug a little bit. It's not drastic and terrible but quite noticeable.
When’s the last time the transmission was serviced? Aftermarket filters are notorious for splitting and It may be worth while to drop the pan and have a look and change the fluid. With the stalling in play now, I would do that if it were mine.

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post #9 of 13 Old 04-08-2021, 09:04 AM Thread Starter
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I bought the vehicle about a year ago and did a ton of work to it through the summer and fall. But I didn't get to the trans or front diff. The rear diff fluid looked new (I changed it anyway) and stopped there. My mistake.



But, that is my plan this weekend. I was looking for the correct filter to buy last night and was trying to figure out what transmission I had. It's the pan with the 15 bolts and no drain plug. I have a 4wd 4.7l Limited with Tow. That's the 545RFE? Or, how do I tell? Thanks again!
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post #10 of 13 Old 04-08-2021, 11:47 AM
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Quote:
Originally Posted by yzjwk View Post

I missed the stall in the OPs post, but engine Stalling and transmission issues are quite common with the 545RFE. Both a split sump filter and the limiter spring can/will cause the engine to stall.


When’s the last time the transmission was serviced? Aftermarket filters are notorious for splitting and It may be worth while to drop the pan and have a look and change the fluid. With the stalling in play now, I would do that if it were mine.
Do you usually see any codes associated with either of those problems? And have you ever seen a Mopar filter split? Asking out of personal interest here, I’ve had a couple of stalls in the past, but they’ve always ceased after cleaning my throttle body (which was clearly in need each time, I’ve got a 5.7)
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post #11 of 13 Old 04-08-2021, 03:14 PM
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Quote:
Originally Posted by Rick_H View Post
Do you usually see any codes associated with either of those problems? And have you ever seen a Mopar filter split? Asking out of personal interest here, I’ve had a couple of stalls in the past, but they’ve always ceased after cleaning my throttle body (which was clearly in need each time, I’ve got a 5.7)
If the filter is split bad enough, then you generally see codes due to solenoid pressures. The broken spring rarely triggers codes from what I’ve seen. I haven’t heard of mopar filters splitting, but I have heard of people installing them wrong and pinching or missing the O-ring on the filter. The neck usually then cracks or the filter falls off completely .

The other random stalling problem occurs in 07 and early 08 hemi‘s where the wrong spark plug was installed. It’s the right number, but it’s a different resistance plug ( Silver terminal as opposed to a black terminal ) . There’s a huge thread in this forum on that. There’s a huge thread in this form on that

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post #12 of 13 Old 04-08-2021, 03:25 PM
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Quote:
Originally Posted by NGAJeepguy View Post
I bought the vehicle about a year ago and did a ton of work to it through the summer and fall. But I didn't get to the trans or front diff. The rear diff fluid looked new (I changed it anyway) and stopped there. My mistake.



But, that is my plan this weekend. I was looking for the correct filter to buy last night and was trying to figure out what transmission I had. It's the pan with the 15 bolts and no drain plug. I have a 4wd 4.7l Limited with Tow. That's the 545RFE? Or, how do I tell? Thanks again!
If you have QDII, ( 12 bolts on diff cover) did you remember the friction modifier in the differential?

Yes, you have the 545RFE it came with all 4.7 and 5.7 motors . There are 2 filters in the trans ( A spin on, and a regular sump ) Get Mopar filters .

Check here for TSBs or other info . https://www.wkjeeps.com/wk_tsb.htm

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post #13 of 13 Old 04-14-2021, 12:24 PM Thread Starter
NGAJeepguy
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So the update: I inspected the torque converter and didn't see any issues. Inspected the entire drive-line and didn't see anything abnormal. The trans fluid was dirty but unremarkable. Nothing on the magnet. The car shifts better but my daughter reports it's still doing it. So now we wait...
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