2010 Buick Lacrosse Transmission

As this is an electronic transmission, I would fix the codes first as they are for the cam and crank sensors, on a lot of OBD systems if a sensor reading is wrong or missing the computer will go into limp in mode. Then clear the computer and then run the drivetime protocol and see if the transmission then operated properly.

So that's the thing, he replaced those sensors, cleared the codes and took it out and drove it for 20 minutes or so, came back to his shop, shut the car off went to take it for another drive and bam, those same codes came back up again. So he is under the assumption that the timing is off and now saying that needs to be done, but also stating that something is wrong with the trans when the trans is throwing no codes but is in limp mode.

So, this goes back to the old days when transmission shift points were controlled by a vacuum modulator and there were no sensors or computers in vehicles. When the timing chain got enough wear to retard the valve timing the transmission would start to shift late because the engine needed to rev higher to produce the vacuum needed for the vacuum modulator to initiate the upshift. Primitive technology that accomplished the same thing. Other systems of retarded valve timing due to a worn timing chain are running hot, boiling over when you shut off the engine, and lack of power. If you're experiencing these symptoms, I'd vote for the timing chain. Especially since you're getting those codes. If your engine has a noise, like a valve tap or rod knock the knock sensor may be hearing the noise and the computer is severely retarding the ignition timing to try to get rid of the noise in the engine. You will have similar symptoms but no check engine light or codes. Jim

No knocking, runs at a normal operating temp, no valve tap, however, when coming from a dead stop, you do notice a lack of power. response is at best tortoise like just trying to get the car moving. I'm sure timing is the culprit of said limp mode and the trans not wanting to shift past 2nd gear.

Don't forget about the timing phaser, I have seen a lot of these go bad.

Have a kit ordered with everything needed included. Guess I'll chalk it up to timing, have that done and that is the culprit for the limp mode on the trans

Sounds like a good plan of action. Please keep us posted. Jim