Auto vs. manual controller mpg

[Boogieman142]

I went from a 604 to stick and currently am using the auto engine controller, and this bucking is getting annoying. does anyone know what i can expect to see with mpgs when i put a manual controller in

[mwinkle353]

mpg should not be affected with just a swap of the PCM.


Let me guess, it's bucking at low rpms/speeds?

If so, then it's time for you to do some inspecting. I had bucking when I swapped in mine (way back when). Come to find out, the motor/trans mounts weren't in the best of shape. They somewhat fixed the issue. But, the real fix for me was to replace the transmission. I guess the original trans I had in the car was in need of some internal work. The bearings were going (if not already gone) bad. When I did that, the bucking went away.


However, if you're bucking during acceleration, then that's a horse of a different color.

[Boogieman142]

it bucks when i try to drive slow, def not the trans, all mounts are poly. a few other people on here have said the same symptoms and a swap to a manual ecu fixed it. but doesn't the manual ecu run a little richer.

[mwinkle353]

The only real difference I found with the auto vs 5speed controllers is the raised redline rpms and the lack of a bus controller for the auto controller.

[mwinkle353]

Quote:

Originally Posted by Boogieman142 it bucks when i try to drive slow, def not the trans, all mounts are poly. a few other people on here have said the same symptoms and a swap to a manual ecu fixed it. but doesn't the manual ecu run a little richer.

Check the drive line lash. Jack up one of the front tires (allow the other side to rest of the ground. Then rotate the tire back and forth. Measure the total distance it will travel before it actually stops. You might be very surprised at what you find.

[Boogieman142]

doesn't move very much, i still think it has to do with the controller

[irocelectric93]

MAP sensor? My car had a similar problem and i asked people on here and most said ....MAP sensor. havent had any probs with mine recently though.

[lookin]

Does your engine have an EGR system?

A dirty EGR valve, or even water in the EGR transducer body itself, can cause bucking at low speeds. I suggest you pull the transducer and see if it is wet.

[c2xejk]

Did you use a sprung hub or a solid hub clutch disk? The spring in the hub absorbs some of the driveline shock...

[Ondonti]

my experience is that a sprung hub makes slop in the transmission worse.

[Boogieman142]

spring in hub, it bucks and when i push in the clutch it goes away or if i give it a little more gas it smoothens out.