Rough drive at low RPM in 4th gear - JeepForum.com

 
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post #1 of 13 Old 09-13-2013, 01:12 AM Thread Starter
mmain
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Rough drive at low RPM in 4th gear

I have a 2005 GC 5.7 Limited which has a strange problem at low RPM (1200 1700) in 4th gear which equates to 40-45 MPH road speed where it has a very rough (jerky) response in this RPM range. In 3rd gear and in 4th gear above 1700 RPM is absolutely fine. The engine idles smoothly and I have no error codes, its just at low RPM in 4th that I have this problem, which also feels worse when going uphill. I have seen some suggestion that spark plugs leads might cause this type of problem and even some suggestion of the torque converter clutch, but wanted to see if anyone has experienced a similar problem. Thanks in advance.

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post #2 of 13 Old 09-13-2013, 08:13 AM
modernblueWK
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I have similar issues at or around 40. Its always agood idea to make sure your plugs and wires are in good shape.

But.... There is a tsb for the jerking:
http://www.wkjeeps.com/tsb/tsb_wk_1801810.pdf

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post #3 of 13 Old 09-13-2013, 08:20 AM
WieSeL
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Trans?
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post #4 of 13 Old 09-13-2013, 08:21 AM
WieSeL
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Mine did it when cold. I changing Trans filters and fluid and it seemed to go away.
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post #5 of 13 Old 09-13-2013, 08:21 AM
bhawks28
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I think I might be having this same exact problem...it's been annoying me for quite some time

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post #6 of 13 Old 09-13-2013, 08:46 AM
modernblueWK
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The tsb says 4.7 v8 only but the hemi and the 4.7 use the same transmission.

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post #7 of 13 Old 09-22-2013, 08:20 AM Thread Starter
mmain
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Has anyone with a 5.7L had this TSB applied which states that it applies to 4.7L engines only?
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post #8 of 13 Old 09-22-2013, 10:02 AM
Walt
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Quote:
Originally Posted by mmain View Post
I have a 2005 GC 5.7 Limited which has a strange problem at low RPM (1200 1700) in 4th gear which equates to 40-45 MPH road speed where it has a very rough (jerky) response in this RPM range. In 3rd gear and in 4th gear above 1700 RPM is absolutely fine. The engine idles smoothly and I have no error codes, its just at low RPM in 4th that I have this problem, which also feels worse when going uphill. I have seen some suggestion that spark plugs leads might cause this type of problem and even some suggestion of the torque converter clutch, but wanted to see if anyone has experienced a similar problem. Thanks in advance.
Sounds like a xmission performance issue to me. If it were purely engine-related, you would likely see the symptoms under other conditions.

You didn't say how long you've been owned by this HEMI or its mileage. If you do not know its service history and there are over 60K miles on the odometer, I would start by draining the xmission and changing both filters. There were some problems with the earlier 545RFE xmission filters. This is a positive 1st step towards diagnosing the root cause (if it is due for service anyway).

Need to buy both filters, ~7 qts of good quality ATF+4 xmission fluid, and lots of shop rags. Plan on ~$100 if you do it. My dealer had a service special for $145 for fluid, parts, and labor for this service. Perhaps your local dealer has a similar offer if you are not inclined to do it yourself. [Of course, this presumes you trust them. In my case, that is not an issue.]

In the event that the xmission service does not cure the problem, then go after the ignition system (plugs and wires). Watch your replacement plugs: Either MOPAR p/n SPRE14MCC4 -or- Champion 570 with dark top center electrodes. There is a StarCase on this, so do not accept MOPAR or Champion spark plugs with silver top center electrodes (where the plug wire or coil connects). WK Jeeps recommends 0.045 gap and plugs tightened to 13 ft. lbs. My '08 MOPAR WK shop manual calls for 0.043" and 12-15 ft-lbs torque. Your choice.

90grandoneer recommends Taylor Shorty ignition wires. He can comment on this; the '08 HEMI's have a coil-on-plug arrangement.

I'd be interested to hear how it goes.

CAUTION: This advice may be worth what you paid to get it!

HEMI CLUB MEMBER #45; SILVER WK CLUB MEMBER #13
'08 WK GC Limited. 5.7L HEMI. Quadra-Trac II. Bright Silver Metallic. Class IV hitch.
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post #9 of 13 Old 09-22-2013, 10:04 AM
modernblueWK
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I dont see why 5.7 or 4.7 would matter. Same trans probably a different program though.

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post #10 of 13 Old 09-22-2013, 04:09 PM
90grandoneer
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Concur on the trans. fluid/filters change. It's a good step and an even better preventative maintenance action.
You may also want to consider getting the Superchips tuner with the Advanced Transmission Tuning Application. It will allow you to set the transmission up any way your heart desires.....both up and down shift schedules and WOT and light throttle torque management...shift firmness.

Yes, if your ride has more than ~75K on it, I'd check the resistance of the spark plug wires. If any of them are over ~10000 ohms per foot (a new 3 ft. wire only runs ~12000-18000 ohms....end to end), replace the whole set, preferably with the Taylor Shorty wires. This will eliminate Chrysler's failed "Wasted Spark" system and make it like the 06 and later Hemi's. I've run this setup on my 05 Hemi LX for over 7 years now, without issue. On my Hemi WK, I run SOS coils and have the NGK copper core spark plugs gapped at .060 in. The SOS folks recommend .065 in., but I don't have an 065 in. round feeler gauge so .060 in. is what it gets. Works great for me.

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post #11 of 13 Old 09-22-2013, 04:35 PM
Walt
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Quote:
Originally Posted by modernblueWK View Post
I dont see why 5.7 or 4.7 would matter. Same trans probably a different program though.
modernblueWK:
May -or- may not matter.

The PCM integrates the engine control functions and the transmission functions. The interface between them is likely engine-specific based on the torque/rpm curve. Recall that the formula for horsepower is HP= (torque x rpm)/ 5252. The transmission-related TSB's in this area are engine-specific, so that also seems to point in the same direction.

Others have written here that the programming is closely-held by MOPAR. Since I do not do any tuning changes, I cannot comment first-hand. Recommend you follow 90grandoneer's lead. He gives good advice.

mmain:
Forgot to recommend that you perform these things one at a time (xmission, then ignition, then tuner) so you understand where the problem was. Eventually, it all needs to be accomplished, but I like to separate them so I understand the effect of each change.

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post #12 of 13 Old 10-06-2013, 08:30 AM
dartdaughter
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have the same problem but did a transmition clean out and still does it also does it om fifth gear at 55-60 mph
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post #13 of 13 Old 12-16-2013, 02:32 AM Thread Starter
mmain
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My problem appears to be resolved. I already had a new torque converter fitted last year and all transmission fluids were changed at that time, so had eliminated that as a possible source of the problem. I took the car to the local dealer to change the spark plugs and to check the ignition leads, where they confirmed that the leads were all fine, but the plugs required replacement. I took receipt of the car after the plugs were changed and the problem was much worse than when it went into the dealer. They looked again and came to the conclusion that the fuel injectors and system needed flushing. I received the car back about a week ago and the problem appears to be resolved i.e. dirty injection system not performing at low engine rpm
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