Ok,I need some input here guy's,surely someone has seen this one before.I recently replaced the VP44 on one of my 02' trucks with a Special X from BlueChip along with a FASS DDRP.The only other mod's are a 4" exhaust,Banks 3.5 High Ram and an Edge EZ set to level 3.
I had no trouble or problems for 2 months of operation,the performance was good and my fuel mileage was at 20mpg.One day just after backing out of a hard acceleration I heard a backfire,only happened once and didn't seem to have any detrimental effect.
Several weeks later,the truck went into limp mode upon startup and throwed a code p0237.
I removed the EZ and cleared the code,and everything returned to normal.I tried the EZ again,and it worked until I shutdown the engine.Then back to limp mode with code p0237.
I fIgured the EZ was shot and I had a new Dr Performance stage 3 (free) so I tried it.
It went straight into limp mode,but with code p0238. I've pulled the MAP,IAT and cleaned with contact cleaner,then cleaned and greased all electrical connectors.
I'm leaning toward a possible electrical issue in a harness,but need to know what voltages I should see at the MAP and IAT and when.Could either of these sensors if faulty,create the codes and shut down the fuel boxes? If so,why are there no problems without them?
It runs great,and still will get 18 to 19 mpg,not bad considering it weighs 8500lbs,but I do miss the 60hp.
Any help with this one is appreciated,I'm stumped!

 

both of those being boost related codes and the fact that the addition of a box causes the problem i am wondering if the map sensor is possibly bad. the fueling boxes both use the map reading and also fool the map sensor so the sensor works on a ohm range and say it is bad at a certain point and the ohms go way out of range, could cause the code your getting and also the problems with the boxes because they could be trying to use that portion of the ohm range of the sensor so i would try swapping the sensor first

 

Have to say I've wondered the same thing.Seems the MAP is logical for what's happening,but if it is the bad part why would it not render a fault when the fuel boxes are removed?Any Ideas on testing it? I'd prefer to diagnose it as opposed to parts swapping.I do appreciate the input.

 

most of the boxes that fool the map sensor tell the ecm that the engine is making somewhere around 26psi of boost at all times to keep the ecm happy and to provide greater low boost fueling without the ecm limiting the fuel because of low boost, that said if the problem is in the higher end of the sensors range when you remove the boxes the engine may not be making enough boost to get into that range section of the sensor, i know that most of the sensors work off of a ohm range but i'm not sure how you would test it with a meter since its not a "good or bad" diagnoises, my suggestion would be to swap sensors with a friend who has the same year range truck that way you dont have to buy the sensor just to try it.

 

Makes sense to me,and probably more trouble than it's worth to rig test leads to monitor the thing in cab anyway.It would be sweet if I knew someone with one of these to swap out.However,luck isn't on my side with it. So,I'll order a new one and see if it's the cure.I believe your spot on with the MAP being the culprit,and I'll let you know what the outcome is in a few days. Thanks again for your help.

 

no problem let me know what you come up with, i dont have a used one for a 02 or i would send it to ya, i have a couple used ones but they are older and not the right plug