4T65E Tranny Issue

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October 30th, 2011, 3:53 PM

tplp02

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4T65E Tranny Issue

<!--[if gte mso 9]><xml> <w:WordDocument> <w:View>Normal</w:View> <w:Zoom>0</w:Zoom> <w:TrackMoves/> <w:TrackFormatting/> <w:PunctuationKerning/> <w:ValidateAgainstSchemas/> <w:SaveIfXMLInvalid>false</w:SaveIfXMLInvalid> <w:IgnoreMixedContent>false</w:IgnoreMixedContent> <w:AlwaysShowPlaceholderText>false</w:AlwaysShowPlaceholderText> <w

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ontGrowAutofit/> <w:SplitPgBreakAndParaMark/> <w:EnableOpenTypeKerning/> <w

ontFlipMirrorIndents/> <w:OverrideTableStyleHps/> </w:Compatibility> <m:mathPr> <m:mathFont m:val="Cambria Math"/> <m:brkBin m:val="before"/> <m:brkBinSub m:val="--"/> <m:smallFrac m:val="off"/> <m:dispDef/> <m:lMargin m:val="0"/> <m:rMargin m:val="0"/> <m:defJc m:val="centerGroup"/> <m:wrapIndent m:val="1440"/> <m:intLim m:val="subSup"/> <m:naryLim m:val="undOvr"/> </m:mathPr></w:WordDocument> </xml><![endif]-->I would appreciate any ideas or help with this issue! Thank you in advance!

1999 Buick Lesabre Custom transmission "Jumping / Shuttering" when starting from stop with load on tranny (Usually starting on an upgrade) while in 1st gear. These symtoms were non existent until after I changed the transmission fluid / filter the first time. After fluid change, symptoms appeared immediately.

Transmission: 4T65E (GM Service Part Code MN3)

Symptoms:

1. Vehicle at operating temps.

2. When starting on a uphill grade with moderate throttle, transmission jumps/shutters the car while still in 1st. If you take your foot off throttle "jumping" will stop and a normal shift into 2nd will usually occur.

3. If you manually put shift lever into 1st gear, and accelerate, jumping will not occur, however if you manually put the tranny shift lever in OD, 2nd or 3rd jumping will return.

4. Jumping does not occur when vehicle is cold, only when warm.

5. Tranny seems to shift fine/smoothly into all other gears. This just happens from a stop when tranny is still in 1st. Shifts to 2nd fine.

Actions that I have taken: Checked...double and triple checked fluid levels!

1. Hooked up Snap-On Scanner and went into transmission settings and manually increased line pressure by going into PC Solenoid and increasing duty cycle (Pressure) to 10%. When I do this jumping / shutter goes away and shifting is fine. If I disconnect scanner or lower duty cycle back to 0% the symptoms return return. Repeated this step several times with same results.

2. Changed tranny filter / fluid. Fluid was pink, smelled good and the pan / magnet were normal with only slight / normal "Clutch mud" in the pan. Thermal element was fine. There was not other debris in the pan. Disassembled the filter and found no unusual debris.

3. All engine and tranny mounts were replaced (New)

4. Replace Throttle Position Sensor (New)

5. Replaced I.A.C.

6. All vacuum lines were checked with no leaks / issues.

7. Checked all History Codes with scanner. There were no codes set or in history on the engine or tranny side of system. Repeated this step several times...several times after duplicating symptoms...still no codes.

8. Cleared TAP Values and reset ECM / PCM by disconnecting battery overnight. Symptoms returned after a short time of driving.

9. Checked drive line / half shafts...no issues.