Hello all! Been getting a pretty bad shudder(like running on rumble strips) intermittently at highway speeds. Only happens between 45-70mph and 1800-2000rpm and does not happen all the time. Seems to happen when im a little light on the gas and flucuating the gas pedal can get it to stop. Trans pan was dropped for new filter/fill with atf± and still having the issue.
Also, when the shudder happens I can tap the brake with my left foot and the rpms go up 300 and shudder stops. Plugs&wires replaced recently, new cat, new o2 sensors were all replaced due to a p420 code and that hasnt returned. Im at 144k miles and any help to diagnose this will be greatly appreciated

Edit: Also noted that if i put the gear selector in 3 the van shifts fine thru gears and this shudder does not happen. Possibly an issue with lockup or overdrive?

 

ok lets get back to some basics.

1> check your tyres (are they worn) and are they balanced ok
2> look at getting a wheel alignment
3> when they do a wheel alignment get them to check the suspension components at the same time for anything loose or wearing, such as rubber joints

The car is lighter with less gas so, it may be sitting differently due to weight and hence if something is out, this could cause a problem, perhaps?

If you ride out the 45-70? does it go, if so I suspect a wheel/aligment/suspension issue

only going from my expereince with other cars,

others feel free to shoot me down, but as this post has had no replies, I guess its a start

 

CV joints?

 

I apologize, I was unclear in my original post. The shudder does not happen every time, but it will only happen within the posted speed/rpm range. feels like something transmission related. I updated originally post to reflect this.
Driving in gear 3 eliminates this shudder at those speeds so I am leaning towards some type of transmission issue?
Tires are in good shape. CV joints have not been replaced but I can look into that. Thanks for the replies so far

 

yeah that sounds like tranny prob

 

Here is an old TSB. It sounds like the torque converter shudder, this was a common back in the day.

NO: 18-09-97
SUBJECT: Vehicle Shudder During Torque Convertor EMCC (Lock-up)
NOTE: THIS BULLETIN APPLIES TO VEHICLES EQUIPPED WITH A 41TE OR 42LE AUTOMATIC TRANSMISSION.

SYMPTOM/CONDITION:
NOTE: DIAGNOSTIC TROUBLE CODE (DTC) 38 (TORQUE CONVERTER CONTROL OUT OF RANGE) MUST BE PRESENT FOR THIS BULLETIN TO APPLY. IF DTC 38 IS NOT PRESENT AND THE VEHICLE IS A 1989-95 MODEL, REFER TO TECHNICAL SERVICE BULLETIN 18-24-95 DATED JUNE 24, 1995 AND PERFORM AS NECESSARY. IF DTC 38 IS NOT PRESENT AND THE VEHICLE IS A 1996 MODEL, REFER TO TECHNICAL SERVICE BULLETIN 21-05-96 DATED APR. 26, 1996 AND PERFORM AS NECESSARY.

Vehicle shudders during full lock-up Electronically Modulated Convertor Clutch (EMCC) operation and DTC 38 is present. Full lock-up EMCC is indicated by 3LU or 4LU on the DRB III RPM display screen.

DIAGNOSIS:
This shudder condition can be the result of leakage in the transmission front pump caused by a worn pump bushing. It is sometimes accompanied by pump whine.

Using the Mopar Diagnostic System (MDS) or the Scan Tool (DRB III) with the appropriate Diagnostic Procedure Manual, verify all engine/transmission systems are functioning as designed. If Diagnostic Trouble Codes are present, record them on the repair order and repair as necessary before proceeding further with this bulletin. If DTC 38 is present, perform the Repair Procedure.

PARTS REQUIRED:
Quantity Part No. Description
AR (1) 04626644 Torque Converter Assembly, 3.3L or 3.5L Engine & 42LE
AR (1) 04741659 Pump & Reaction Shaft Support Assembly, 42LE
AR (1) 04883272 Seal & Gasket Package - Trans. Oil Pump Housing, 42LE
AR (1) 04796730 Package, Oil Filter, 42LE
AR (1) 04796384 Torque Converter Assembly, 95 FJ/JA 2.0L or 2.5L Engine & 41TE or 96 FJ/JA 2.0L Engine & 41TE
AR (1) 04778031 Torque Converter Assembly, 95 JA 2.4L Engine & 41TE or 96 FJ 2.5L Engine & 41TE or 96 JX/GS/NS 2.4L or 2.5L Engine & 41TE
AR (1) R4636922 Torque Converter Assembly, 89-90 3.0L Engine & 41TE
AR (1) 04773766 Torque Converter Assembly, 91-95 3.0L Engine & 41TE
AR (1) 04797476 Torque Converter Assembly, 3.3L or 3.8L Engine & 41TE
AR (1) 04567869 Pump & Reaction Shaft Support Assembly, 41TE
AR (1) 04883260 Seal & Gasket Package - Trans. Oil Pump Housing, 41TE
AR (1) 04864505 Package, Oil Filter, 41TE
AR 04798233 Fluid, Mopar Automatic Transmission Type 7176



REPAIR PROCEDURE:

This bulletin involves replacing the transmission front pump assembly and the transmission torque converter with one that has bonded converter clutch friction material and verifying the Transmission Control Module (TCM) part number.

Following the procedures outlined in the appropriate Service Manual, replace the torque converter and the transmission front pump assembly with the parts identified in the Parts Required section of this bulletin.
Perform the transmission oil cooler and lines reverse flushing and flow check procedure as outlined in the appropriate Service Manual.
Verify the TCM is the appropriate part number listed below : PART NO. YEAR AND MODEL APPLICATION
4686606 1993 - 1995 AA, AC, AG, AJ, AP, AS, ES, & AY
4796121 1989 - 1991 AA, AC, AG, AJ, & AS with 3.0L Engine
4796122 1990 - 1991 AC, AS, & AY with 3.3L & 3.8L Engine
4796123 1992 AA, AC, AG, AJ, & AS with 3.0L Engine
4796124 1992 AC, AS, ES, & AY with 3.3L & 3.8L Engine
4606271 1996 JA/JX with Autostick
4606270 1996 JA/JX without Autostick
4606485 1996 LH with Autostick
4606284 1996 LH without Autostick
5269726 1995 FJ
4606105 1995 JA with 2.5L Engine
4797708 1993 - 1995 LH without Auxiliary Transmission Oil Cool
4606109 1995 LH with Auxiliary Transmission Oil Cooler
5293010 1996 FJ
4882462 1996 NS/GS without Transmission Range Sensor (TRS)
4686739 1996 NS/GS with TRS

 

Thanks for the replies. After driving it longer I can explain this a little bit better. Take off from a stop, 1st gear is ok, 2nd gear is ok, once i reach the end of 3rd gear i get shuddering for a few seconds and then the rpms drop(going into overdrive?).
Yesterday I had no codes thrown but today P420 code came back. I also noticed it cranked a little longer than normal when starting up this morning. The P420 code has come on before and had gone off after changing the cat, plugs, wires, air filter, 02 sensors but I guess its back now.
MasterTech, does that tsb mean a constant shudder when in lockup or is it like what I am describing? Thanks again for the help

 

No the shudder wasn't constant. When the shudder started, it felt like going over a steel grade. Then it would stop shuddering for a little while and then start shuddering again. That problem was when the transmission went in to lock up. Remember your transmission can go into lock up in any forward gears, yes even in 1st. I just looked at a PT the other day and it had a really bad shudder or slippage from 1st to 2nd gear. What i found was the CVI for the 2/4 clutch pack was out of specs with a scanner. So i did what dodge techs call a quick learn and drove the car again. This time the car shifted fine. That means the problem is inside the transmission and i will need to go into it and repair it.