Transmission issues
That is caused by the ECM (engine computer) that gets intermittent. Since the transmission is controlled by solenoids, those solenoids in turn are controlled by the ECM and when the ECM gets erratic, the solenoids do the same, making it feel like the transmission is falling apart and sometimes even banging when put in reverse. The ECM controls both, the engine and the automatic transmission.
When the transmission is damaged, the problem will stay and it will not feel like the problem is gone suddenly and then come back to the problem.
The thing is that if you continue using the vehicle like this, the transmission will be damaged too if it has not already.
I can tell because I have been in the business of fixing those ECMs since 2008. I won't give the business information to avoid spamming this forum. Instead, you may look in Google or other search engines for shops offering the repair service for your specific ECM.
I hope this helps.
Richard
That is caused by the ECM (engine computer) that gets intermittent. Since the transmission is controlled by solenoids, those solenoids in turn are controlled by the ECM and when the ECM gets erratic, the solenoids do the same, making it feel like the transmission is falling apart and sometimes even banging when put in reverse. The ECM controls both, the engine and the automatic transmission.
When the transmission is damaged, the problem will stay and it will not feel like the problem is gone suddenly and then come back to the problem.
The thing is that if you continue using the vehicle like this, the transmission will be damaged too if it has not already.
I can tell because I have been in the business of fixing those ECMs since 2008. I won't give the business information to avoid spamming this forum. Instead, you may look in Google or other search engines for shops offering the repair service for your specific ECM.
I hope this helps.
Richard
What I said about the ECM still stands, but now that I know more about the case,
#1 The grinding noise is the fact that worries me about the health of the transmission.
#2 Going to 5000 RPMs at 70-80 MPH might be that it is not shifting to the 4th gear.
#3 Waiting a bit until you feel the shift could be low fluid pressure. That happens many times when the filter is clogged or it has an issue with the torque converter.
I have seen clogged transmissions that when it is critical, the car shifts well until it does not. Then you put it off for some time and when you start the engine again, all the sediments already went off the filter and all will work until it is clogged again. The period of working/not working varies depending on how critical the situation is.
The oil pan of the transmission has a magnet, but if the filter is clogged, it means that the magnet is already saturated with debris.
When the ECM is the problem, it is intermittent but when it works, it usually lasts the day. No grinding noise.
Again, the grinding noise is a bad indicator.
All this is theoretical until a good diagnosis is made by an expert in a transmission shop.





