I have an 87 4x4 pickup automatic with 149,000 miles. About 80% of the time it works fine but the other 20% of the time, it won't shift out of 3rd gear. When you pull out from a red light it's still in 3rd gear. If I manually put it in low it'll start out in first but then sometimes shifts to 3rd without going to second. Most of the time it's perfect. I took it to a tranny shop and he pulled the pan, no metal in the pan at all, said it looks fine and thought it is the a/t computer. I replaced the computer and seems to shift smoother and is maybe a little more reliable but still not 100%. Still starts off in 3rd gear some of the time. Check engine light has never come on. Any ideas on what is going on? Could it be an engine code putting it in safe mode? To complicate things, I have an r150 tranny with an r151 bell housing and everything needed to make the swap but I'm afraid it will never pass California smog again. I talked to the smog referee and he said I could swap it if I replaced the engine computer with one from a truck with a 5 speed manual but it looks like the engine computer has the same number for either tranny. Anyone have any information on engine computers and is there a different one for a manual transmission? Will it ever pass smog if I make the swap. I'd rather get the auto running properly now and make the swap when I have more time. Any advice will be appreciated.

 

If the TPS is bad or out of adjustment your auto. transmission is nor going to work like is supposed to, so start by checking it out before you do anything else.

https://www.4crawler.com/4x4/CheapTr...PS/index.shtml

 

Maco35, thank you for your reply. And thank you for attaching the link for checking the TPS. That was going to be my next question. After reading it, I think you are probably right. I have been having some of the other symptoms mentioned as well but the tranny problem was the biggest problem. I will try to pull it off this week and check it. I hope that solves my tranny problem. Thanks again, I'll let you know what I find.