Q: My car is shutting down in low gear/idle immediately after transmission rebuild & minor updated engine parts

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The following repairs were made this week: transmission rebuild, engine drive belt, flywheel, and engine air filter. Upon leaving the shop, my car would not start and the 7m battery had to be jumped. I drove 10 miles, stopped and when I restarted the car it shutdown in reverse and threw a check engine light. Went back to shop and found code P0506 and said throttle body or sensors were dirty. They removed the air box and 'cleaned throttle body.'- in quotes b/c it only took 45 min. They also found the shift cable needed to be adjusted to go in reverse. Lastly, they found the wrong oil had been used by previous oil change and that could mess up engine and sensors (the oil sticker said 5W30 used vs. 5W20). I left, got 10 miles and my check engine light returned; car stalled in stop-go traffic, the a/c kept changing velocity, and it stalled at a light and then shook/shuddered when restarted. The shop cleaned sensors and throttle, and says it'll work now. How will I know it's safe?

My car has 167000 miles.
My car has an automatic transmission.

First, I am sorry to hear that you are having such a poor experience with this repair. Unfortunately, there is only one way to know if your car is ready to be driven without any problems - you will need to take it on a test drive. I don’t recommend test driving it on the way to work or something you need to do. If it helps you feel more comfortable, have someone else follow you to help if something goes wrong.

As for the numerous issues you have had:

  • Your low idle is likely a combination of things. Number one being a dead battery which will cause your truck to lose it’s adaptive information. This information is the small adjustments the PCM makes to keep your truck idling normally, as things like your throttle body become gummed up. This and other things are normal wear and tear that all vehicles experience.

  • I wouldn’t be that worried about 5W30 oil being used. It is highly unlikely this small difference will damage your motor, nor will it affect engine sensors.

  • The P0506 code simply states the your idle is too low. Cleaning the throttle body is the appropriate first step.

  • Your dead battery is either a failing battery or the shop left the key on and it went dead.

  • The shift cable adjustment is part of the transmission installation. Hopefully, they did not charge you for this.

  • The A/C is likely a factor of your dying car or it has needed a recharge for sometime.

Most of this isn’t a result of the transmission rebuild. It’s unfortunate you have had this experience. While I can’t speak to the conversations you have had with your shop, I can say the dead battery issue could have been handled better. This is a customer service issue. The engine oil weight could have simply been a wrong sticker used by the person who changed your oil. Your engine oil should be synthetic and synthetic 5W30 oil is not that big a difference from 5W20. I personally wouldn’t hesitate to use 5W30 as a replacement for 5W20 if I didn’t have anything else or it was just on sale for a good deal.

If you need to have this looked at by another mechanic, a certified professional from YourMechanic can come to your car’s location to diagnose the stalling issue, as well as any other problems, so that you can have your car repaired properly.

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