I have a 91 gm topkick with a 366 tbi engine. It runs ok mostly but wont rev up right.It is like it isnt getting enough fuel.The tank has been cleaned and new filters installed.The lines have been checked.It is giving a code 22 and 15.I think it is a tps code.It runs better when cold than when warmed up.it runs terrible when warm.This engine has the governed throttle body from when it was a ryder truck.Does anyone have any advice on what the problem is and if I could use a normal throttle body without the governer setup from a 5.7 pickup motor.thanx for any help

 

The trouble codes you list are 15 = malfunctioning coolant temperature sensor, which is telling you that the coolant temperature sensor signal indicates a temperature colder than 27 F for 30 seconds after the engine has been running for at least 30 seconds; and 22 = Grounded WOT Circuit, which is Greek/Geek for the TPS voltage being under 0.2 volts for 2 seconds when the engine was running for at least 30 seconds.

It would appear you have two problems, the first is failure of the water temperature sensor, and the second is that the throttle position sensor is not returning any voltage at .2 volts or above for at least 2 seconds after the engine is started.

Given the symptoms you describe, power is decent when cold and then it falls on its face when hot, I would replace the temperature sensor and then try the truck. It may be necessary to replace the TPS, but do not do that until after the ECM is properly reading coolant temperature so it knows to look for the throttle position impedance after the engine has run at least 30 seconds.

An attempt to use the 5.7 TBI on the 6 and 7 liter (366-427) family of medium truck engines will create a host of problems with the ECM, and will not solve the problem of failed sensors.

 

With multiple sensors showing malfunction, I would check the power and ground to those sensors as well.

 

With a bad coolant sensor that thing should be running pig rich in closed loop operation. You may need to change the plugs after you get it running right. CTS is a common failure.