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Well we drained fuel filters looked good cleaned egr and boost cyliniod ran great for ten mins then boost gauge started jumping all around stuck at 20 psi for a min floored it cleared out then jumped to 35 and blew intercooler hose off any ideas?? Maybe boost cyliniod going bad???
so maybe when i stuck my buddys icp sensor on it didnt throw a code and ran ok, then i put mine back on and it ran ok for about 5 mins could this be because the computer was trying to figure out that the sensor was bad??? should i just go ahead and replace it, truck left me stranded on my way home from his house in limp mode and i couldnt give it any gas then when i hooked the reader back up it was the injector code
partsman asked what code reader you were using. Knowing that could help folks troubleshoot. Typically the ICP issues do not throw a wrench light - but an overboost situation can. There are a number of things that can cause an overboost .... stuck turbo vanes, VGT actuator, EBP sensor, MAP sensor.
Given that the truck ran OK with your friends ICP sensor, I would lean pretty heavily towards the ICP sensor being the problem and I think I would replace it.
This next bit is theoretical. I suspect the ICP sensor uses the same VREF circuit as the MAP sensor. VREF is, in short, a +5V circuit that provides power to various sensors. The sensor modifies the +5V source and sends it back to the computer. The computer reads the returning voltage and calculates the value the sensor is reading.
I suspect the bad ICP sensor is shorting the VREF circuit to ground. Without a good VREF source, the MAP sensor can't properly sense boost pressure. That is why you got the MAP code initially and why you had errant boost readings. I'm also assuming that the computer, without a proper boost reference, closed the turbocharger veins and caused the excessive boost that popped off the CAC boot.
Regardless of the theoretical stuff, if the truck ran OK with a different ICP sensor, then the logical course of action (in my mind anyway) is to replace the ICP sensor and see what happens.