Hello All,
I had my truck for many years now and it went through all kinds of modifications.
Right now I am running a 360 (5.9L) that is mildly build up. I have Hemifever tune on it.
Originally truck had an automatic 46rh transmission.
When I change the engine to 5.9l from 5.2l I decided to upgrade to ODBII (since truck was originally OBDI)
Then I decided to change the transmission to manual. I've installed 5-speed NV4500.
So now I am running 5.9l motor with OBDII that should have automatic 46re transmission but it has a manual one.
When driving the truck and rpm goes over around 3000 (especially when is under load) truck surges or bucks (whatever you want to call it)
Could this be related to the defective MAP sensor? Or maybe its the fact that the OBDII is looking for some Inputs/Outputs from the automatic transmission which it doesn't have anymore.
Should I change the ECU on the truck to have one that did use manual transmission?

 

The PCMs aren't different just the software. I"m not familiar with what Hemifever can do but I'd think they can whip up a tune for a manual, if that's even needed. I'd do basics first, fuel pressure, live data OBD2 readings for fuel trims, O2 sensors, MAP, throttle position etc.

 

A list of the "mildly build up" mods would help. Are you still running the kegger? Plenum plate fix? Last time a tune up was done?

 

Does the check engine lite start flashing when its bucking/surging?

 

"mildly build up" - Engine bored out 0.030", Odessa New Cylinder Heads, Hughes Air Gap Intake, 52mm Throttle body, 24lbs injectors, Hughes HER0814AL Camshaft, Hughes HUG 1550 roller rockers, Gibson Headers, Recent distributor cap and rotor, Hemifever tune installed.
I have to double check on the engine light flashing.
Here is a pict of when the engine got installed - I painted it Caterpillar Yellow
Picture still has OBDI ECU - it was changed since then.

 

Did you set the fuel sync?