Greetings All. A while back I installed a BD Performance 48RE Controller (pn 1030348) and immediately threw a P1749 code (Transmission Throttle valve position sensor curcuit low). The controller did it's job as far as raising the shift points and line pressure. It shifted later (like I wanted) and harder. However, I noticed some degraded performance for the engine in the midrange and WOT areas. I disconnected the controller, erased the code, engine went back to normal performance...as did the transmission.

I then proceeded with installing my Transgo 48RE shift kit, change/flush all the fluid and adjust the bands. I wanted to run it this way for a while to establish a base line. I contacted Craig at Goerend and bought a 300 psi pressure gauge with quick disconnect coupler and extended hose. My truck now idles at 78psi in drive. At 1800 rpm in OD with the TQ locked I am producing just under 140 psi. The transmission still shifts a bit early for me, even when running it Tow/Haul mode.

So I ran it this was for a month just to get used to it. Last weekend I hooked up the BD 48RE tranny controller again and same thing: immediately throws the same P1749 code. If I erase the code with my scanner it comes right back. I go out for a test drive...same thing. Controller is working (although I see no difference in settings 0,1,2, or 3) The engine stays in 1st gear until about 2400 rpm then hits second nice and firm. Tranny feels great but same hp loss at midrange and top end. I have never experienced "limp mode" (engine is stock by the way except for mods listed in signature).

I will deal with BD on the programmer. My question is this: when the engine has thrown a code and the CEL light is on, does the ECM degrade or "turn down" the hp on the engine as a self protection feature until the problem is resolved?

Normally when I romp on the throttle, boost builds quickly and jumps up to 32 psi, stays there for about 2 or 3 seconds, then drops to 28-29 psi and remains there until I take my foot out of it. Power comes on nicely.

Now, with this code in effect and the CEL on, when I floor it, the engine feels like it's giving me about 50 to 60% power. The boost gauge jumps to 18 or 19 psi quickly but then continues to rise at a very slow, steady pace peaking at about 22 or 23 psi. It feels doggy. Anyone here even seen this?

 

Bump

 

No one else has seen this?