Won’t rev

[Calvin27]

2003 5.3 with 99 harness and computer, cable throttle body starts and idles fine but when you give throttle it’s like key switch is turned on and off unless you unplug tps. Already changed out tps same problem any help is greatly appreciated..

 

[stutaeng]

Can you hook up a OBDII scanner with live data? You need to see what sensors are reading/reporting.

You have the MAF?

Fuel pressure is good and holding?

Any codes?

 

[Calvin27]

Guy I have tuning says everything seems good but when I give throttle timing goes from 40 to nothing

 

[Calvin27]

Changed tps again still same but if I unplug tps it revs fine

 

[1998_K1500_Sub]

Did it ever run properly or is this some artifact of a recent conversion?

Did you measure the voltages and check the grounds on the TPS connector?

Did you put a DVM on the TPS and check that the resistance changes nicely with position and there's no "hiccups" (high or low resistance values) throughout the range of motion? Yes, I know you swapped the TPS once, but...

Is there any reason to believe the problem's NOT in the TPS and, instead, what you're seeing with the TPS is a secondary effect?

 

[Calvin27]

Thinking it’s something else tps resistance is smooth and never ran right from time of swap trying to find problem it’s like in limp mode ecu runs great on another swap my buddy has

 

[0xDEADBEEF]

I wonder if when you unplug the TPS the PCM goes into speed density.

I think the PCM has to see the MAF fail a number of times before it sets a code and transitions to seed density. Maybe a bad MAF? Just guessing.

 

[Calvin27]

I’ll try another maf thanks

 

[Calvin27]

Still no fix could crank sensor cause this ? I’ve change almost everything else

 

[0xDEADBEEF]

I think if crank sensor was bad it wouldn't run. It's time to get a scanner.