Nick c

So I bought a truck a while back. Immediately had trans issues. So I had it rebuilt. Well that didn't fix it. It starts in second and have to manually shift into third/od. It will shift from third to od on it own. So I took it to a mechanic shop. They said it's the wrong brain. Later when changing the oil I figured out its the older 351w I had to use an 88 oil filter.I ran the Vin on the door and it's a 94 body. I'm starting to think it's a straight 6 brain bc it runs the motor fine but not the tranny. Any ideas?

Brandon587

What trans problems did it have when you bought the truck? And I assume you have a 300? A check ball could have been left out or not installed in the correct spot in the valve body if they took it apart to clean and inspect, which they should've when rebuilding it. If they didn't take it apart, then a check ball could be sticking. Or a passage could be clogged/ partially clogged not allowing correct oil flow to engage first. So first wont engage at all? Who rebuilt the trans? You've had these problems since you put the rebuilt transmission in the truck?

Brandon587

how does the transmission downshift? rough? any gears it wont downshift properly?

Nick c

It has a 351 w. It won't shift into first up or down. And second I have to shift up and down with the tree. But once I shift it from second third manually. It will shift from third to over drive on its own

Brandon587

Why do you think it has a straight 6 brain then? If the engine ran at all, it wouldn't be good. I know a 351 will run on a 302 computer, but still not too well and it runs lean generally. So, unlikely you have a 300 ecm, unless its possible to reprogram it to run a 351. Im not sure about that. So, you either have electrical issues, or valve body issues. Does your o/d light blink on your shifter? You need to pull codes.

Brandon587

And what problems did your trans originally have?

Brandon587

Your mlps could also be out of adjustment...

Nick c

Only reason I thought it might be a straight 6 is bc I ran the Vin on the body and it use to be a straight 6. But the motor (so I'm told) is a 351w out of a rv. And my motor runs rich I would say only bc of the smell. I have been thinking of buying a ecm for a 351 and e4od and seeing what that did. But I'm kinda shooting in the dark bc I was out of ideas. And I'm thinking of buying an independent brain for my trans. I looked them up there like 500 bucks though

Nick c

It had same problems as it does after I had it rebuilt

Chris_1

iTrader: (1)

If somebody swapped in a 351, they may have swapped trannys too. Which is a problem because the computer has to match the tranny and year of the tranny.
But that may not be the case at all. Electronic trannys (especially the E4OD) are very sensitive to sensor input faults.
Basically, it doesn't decide anything about when to shift or what gear to shift into. It is told by the computer what to do and when. The computer sends a signal based on what all the sensors are telling it. So a bad sensor can mess everything up. (VSS, TPS, PSOM, MLPS, and a few others)
There are shift solenoids inside the tranny that can mess up - those are what the computer sends the signal to. Those should have been addressed and tested or replaced during a rebuild.
And lots of tranny shops are more than happy to rebuild it even though it doesn't need to be.
If you took it to a shop and they told you that your tranny needed to be rebuilt to solve the problem and it turns out that rebuilding the transmission itself is not what was actually required to make the truck shift, you've been fleeced. Not the first guy to go through that though. I'd take it back and I'd be more than a little pi**ed off at them.