Ok so I have a 94 with a 4.9 and auto trans. The computer that came with the truck is for a manual trans, I dont know how this happened. With the manual computer it starts and runs fine but I have to shift to 2nd to get it going and shift to drive at around 25mph to get it up to highway speed. And it kind of idles rough at a cold start up and my mpg's suck, worse than a V8

So I got the correct computer for a 4.9 with auto trans, and it is from the same year.

1st problem- When the fuel pump first engages in the on position, it pumps for like 2-3 secs and then stops right? Well this one does that, but then makes a higher sounding buzz like if it is pumping fuel faster and doesnt stop.

2nd- It'll hesitate to start but will, the engine runs way smoother and calm . But when I give it gas it wants to stall. It makes a popping sound as if there is not enough spark.

3rd- it still wont get going under its own power in drive, I have to put it in 2nd.

Remember all these problems happen with the proper computer.

Im currently driving it with the wrong computer, the only issue I have driving it like this are the mpg's. I dont mind shifting when I come to a dead stop. But I want to get it running normally. Ive changed the fuel filter, plugs, wires, cap and rotor.

There are 2 connections that are not plugged in, I dont know if they should be.

Any wiring diagrams out there for a 94 4.9 with auto trans?

 

Do you have the electronic or do you have the aod. I you do not have the OD off switch than the manual computer is the correct one.

 

Ok couple of things......Like mitchalvin says, if you don't have any computer control of the tranny then it is correct (AOD, C6, etc). Unfortunately, I believe you have a burnt or couple burnt valves. It is usually a valve when you hear a crackle through the intake like that- I almost guarantee it. You would see smoke if it is an intake valve which more commonly fail, or it could be an exhaust valve which would not smoke, but is less common. Then, you have problems with the engine running which burnt valves would cause. You can do a compression test and confirm. I had this happen and I just pulled the heads off and gave them to a shop to rebuild. It is a pretty easy job, just time consuming. Let me know what you find if you do a compression test or if you pull the heads off for ****s and giggles you can flip them over and pour gas on the valves and see if they leak. I keep saying heads, but I realize you have the 6 cylinder and that should read head (only has 1), so a rebuild will be cheaper......

I reread your post and with the stalling too, you got a burnt valve or 2 buddy. I'm pretty certain.

 

It does have the OD off button.

 

IT only pops when I install the auto computer.

it runs good with the manual computer.

 

You need a computer for an E4OD transmission not an AOD transmission.

 

Not trying to sound like a douche but does my 1st post make sense? Or is everybody not reading.
I really appreciate eveybody replying.

 

yes but there were 2 different tranny's available with the 4.9. The E4OD and the 4r70W both of which had push button OD's. When I did a motor swap in my truck I bought an ECU off a guy who told me it was definitely for the E4OD tranny but in the end I found out it wasn't it was for the 4r70W. Are you 100% positive you've got the right ECU for your tranny? Even the wrecking yards make mistakes on their ECU classifications

 

Hey douche have you checked for codes?

 

Sorry I thought you said that it acted the same with both computers. I guess I am misunderstanding the entire post.