Reader Question: Hi,
I have a 1997 GMC Yukon 2DR with a 350 and auto transmission, and about 130,000 miles. I have noticed two problems. The first is that the idle is a bit rough, and sometimes when I shift into reverse from park, the engine dies – it will also do it when I shift into park after driving (engine revs then dies).
Also, sometimes my transmission will never shift into overdrive, or if it does, it will jerk violently when under hard acceleration at high speeds. It does not do this on a regular basis – seems to do it sporadically.
Could these two problems be related?
Thank you for your help.
The idle problem you mention sounds like it could be caused by a dirty throttle body and idle control motor. I talk about that issue here although I do not have a picture of the throttle body yet.
Just about any mechanic can clean these two items for you.
I would also want to check to see if a tune us is in order, spark plugs, spark plug wires, distributor cap and ignition rotor and air and fuel filters. If those items are worn, it could also produce the idle problem you mention.
The problem about not shifting into overdrive is probably a separate issue though and is probably an internal transmission issue. I never recommend servicing a transmission that has not been well maintained because more harm than good can usually occur BUT you might want to talk to your regular mechanic and get his opinion about changing the transmission filter and replacing the fluid.
I have seen a restricted/dirty transmission filter cause similar problems with slow or late shifting into overdrive. Since you did not mention anything about the transmission slipping at low speeds or a hesitation when selecting reverse from the park position….all signs of a worn out transmission, I would probably take the gamble and service the transmission.
These transmissions are not the best in the world, so the chance that an overhaul is in order at 130K miles would not really surprise me. If for some reason it is determined that you need to have this transmission overhauled, I would call a few local GM parts departments and get quotes for a GM rebuilt transmission, which you can pay your regular mechanic to install for you.
You will pay just a little more for a GM rebuilt versus having your transmission rebuilt but you get a nationwide GM warranty and you don’t have to deal with a transmission shop…which that in itself is a huge benefit.