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Two years ago I bought a 1989 standard Corvette w/75,000 mi and an over drive auto trans I believe is a 700R4. When cool the problem is not noticeable but after warming up the transmission slips and shudders ( like as if I were running over a rumble strip on a highway) but only under heavy acceleration while in the lower gears (1st and 2nd).
All seems well once I reach 3rd and OD. Even though the fluid was pink I Had it changed last year because I heard a rattle on the passenger side under the floor board which starts around 1300 to 1500rpm and stops . Later on I joined a Corvette forum and learned that the rattle is usually caused by the catalytic converter. When the pan was dropped there was a layer of gunk built up on the inside which was a grey color. There were no metal fragments seen. The transmission case has some leaks but I keep the fluid topped off. Normally I don’t accelerate quickly but there are times when I must merge into traffic and need to get up to speed. I am dropping the car off tomorrow morning to a shop for an opinion and estimate. I would appreciate any information relative to the symptoms described. Also I scanned the car for any codes, there were some relating to the mass air flow sensor and the egr valve but nothing related to the drive train.Need a replacement transmission? Quality transmissions are hard to find. Free estimate to your email.Don’t bet that you weren’t receiving any transmission-related codes because you were. Believe it or not, the MAF (mass air flow) sensor and Exhaust Gas Recirculation (EGR) sensor are polled by the transmission control module during normal transmission operation. When you step down on the accelerator to get going both sensors provide the engine control module with information telling the central computer (ECC) that they received the message that more air will be required by the engine because you have stepped down and launched a lower gear.
Without an affirming return that the MAF and EGR are opening up to meet the needs of the downshift, the ECC doesn’t know whether things are working correctly or not. In this situation, strange things can happen. For instance, the torque converter may not spinup correctly and may cause the transmission to judder as it goes out of sequence and then hops back in and then out again. Likewise, the slippage may be because one solenoid or another is late closing and a gear either engages late or doesn’t engage at all. This type of performance can also affect the whether the clutches engage correctly.
As you can see, the MAF and EGR codes were telling you something transmission-related. I suspect that you will find this is the problem area and that if you swap out one of both, your ‘Vette’s problems should go away. Let me know if this helps. (The good news is that this fix should be less than $500 with labor if both sensors need to be replaced. If only one needs to be replaced, you are looking at $250 or less.)
Fair Replacement Transmission Cost by Vehicle
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Fair Remanufactured Transmission Price Ranges by Transmission Model Updated May 1, 2018
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