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Trans. has gone back 3x and they have checked all their work and replaced parts just to make sure they weren't defective. They are scratching their heads too! Sometimes the car will be fine for quite a few miles and then it starts again - slips out of gear when it hits 4th gear/od. All the wiring has been checked, wiring harness has been opened up and checked and everything inspected. Been on line and noticed that there are numerous complaints with this particular problem. Don't know what else to check! What are we missing?
Will get back to you soon.
Re-checked all connections-all O.K Took out for another drive - Not the first time that we noticed that when cold engine it will take about 4-5 miles B-4 the Trans. will give a shudder then start missing 4th/OD. Is it possible that the casing is warming up after 4-5 miles and causing this problem? Would this be a heat problem of enough magnitude to damage any sensors in a way that can't be seen? Would even the Tranny Guy not be able to tell if it's the casing? Put so much time and effort into this and I hate to think
I have to refund cust. all this money but, don't know what else to check.
Going along about 40-45mph - then feel quick little shudder and then second or two later nothing when you press on gas feels like you are in neutral even though scanner
shows Im still in overdrive. Cust. doesn't always feel shudder - they just know that they start slowing down and there's nothing there. My foreman has more than 25 years of exp. and he says he's never run into a problem like this before.
Sounds like when it is shuddering there might be an issue with the direct clutch for 3rd gear. when it shifts into 4th it applies the 2-4 band servo, did you replace the servo piston for the 2-4 band? Does it try to shudder if you accel hard in 2nd gear? I am thinking the direct clutch might be dropping out but you say line pressure is good even though it goes into neutral?
Line Pressure Chart
Line Pressure Diagnosis Chart
Did Line pressure test - shows no ranges too low, BUT - during road test, idle and drive would start out in normal range but shoot up to 190lbs. Pulled car over - shut off- re-started -cont. on road test -readings normal - line pressure 75lbs.- crusing speed- The over/drive neutraled out + press. still at 75 + scanner said it was still in O/D. Pulled car back in shop put car in neutral, pressure went to 190lbs. can hear solonoids clicking on/off. Watching pressure gauge bounce from normal to high readings. Sounds elcectrical to us. Can this be PCM - needing only to be reprogramed (I hope) or replaced?
A PCM is cheaper than rebuilding an automatic transaxle. Not everything sets codes, if you are counting on codes to store or turn on a warning light then you wont fix everything that comes in your door. We fix things that set no codes but based on what the issue might by we use our service manuals to diagnose by symptom to get to the root cause of a concern. You don't have to throw parts at anything to fix a concern. I already said the line pressure is spiking way too high, if the pcm isnt commanding the higher line pressure voltage then its not a pcm concern it is most likely a sticking valve or issue in the valve body.