We could drive the truck all day with no problems, then we turn the AC on and sometime after the truck hesitates and spudders, codes p0300 and p0108 kicks in. Last summer I put in new plugs, wires, cap , rotor, coil, module, maf, spider, ecm, distributor, egr, iac and tps. Truck had been running nice and in the past few months she started again, I was pulling my hair until I notice that she acts up only when the AC is on. Help will be highly appreciated. The florida heat is a killer. Thank you guys in advanced.

 

I will assume you used Delco ignition parts wire plugs cap and rotor and say I would look at the map sensor as the problem

 

I put 2 new map sensors, and changed the pigtail. The map sensors were not delco, they were from carquest.

 

only Ac AFTER ac is unplugged codes are cleared You still blow codes. Check wiring on ac compressor,

 

Potential causes of a P0108 code:

• Bad MAP sensor
• Leak at MAP sensor rubber gasket
• Engine vacuum leak
• Short in signal wire to PCM
• Short on reference voltage wire from PCM
• Open in ground circuit to MAP
• Worn engine causing low vacuum
• stuck-open EGR Valve
• defective Idle Air Control Motor or dirty IAC port and or dirty IAC motor plunger, which causes a very low or very high engine idle.

Low idle = Low vacuum, if the idle air control motor isn't operating properly, then when the AC compressor kicks on it could be loading the engine idle speed below minimum operating vacuum pressure.

Just throwing out a few ideas. Hope it helps to locate the source of the problem.

 

I clear the codes, turn the ac off and then she gets back to normal

 

I am trying to borrow a smoke machine to check for vacum leaks, wouldn't i get a IAC code. My next guess is a short or bad ground that will give me a voltage drop once the AC is one.