jcarrillo

This might end up being long but here goes anyway. About a year ago my '02 got the dead pedal disease. I checked for codes and got nuthin. I figued it could be the boost sensor ,being unfamiliar with dead pedal I ordered the boost sensor from cummins. Got it in and the plug wasn't the same so what to do? I checked it with a scanner and boost seemed to be alright with old sensor but then I got an idea. The sensors from a 60 series detroit that I use at work can be used for oil presure or TPS sensors. So, I decided to hack the harness put a plug on it with posilock connectors and check it with a scanner and with the engine off it showed 30Lbs of boost. I'm thinking great! the ecm is going to pour the fuel into my engine and I am going to be happy! Not to much difference. By the way I didn't plug the sensor into the manifold because the threads were different and because when I put pressure on the sensor, the pressure showed to start going down). O.k., So now it is running o.k. so I leave it alone until a few months ago and add the banks big hoss tuner(no pump wire tap) and it felt a little different but I also got a code that said boost pressure too high for to long. So I am reading on the forum a couple of nights ago and looking around the net for info and come across an article that says if the boost is too high the ECM will back off the fuel. So I think, maybe I should connect the banks harness into the actuall cummins sensor that is in my manifold and see what happens( same connection as the detroit sensor). I wire it around back to the way dodge had it when my old boost sensor was installed and it had no power at all. I switch the ground and voltage wire around and its better but not like when I had the detroit diesel sensor plugged in. So I go to work today and the performance is erratic. I also get a check engine code. I pull the codes and get a high voltage code for boost. I pull the datalist which lists all the parameters and it says I have 58 Lbs of boost ( it never changes while I am driving)and all the while it never gets over 15Lbs on my autometer guage. My actual boost on the auto meter with the detroit sensor was around 22Lbs. I need to figure out how to hook up the wires so it is reading correctly or hook it up original and get the adapter from hoesli diesel. I cleared the codes and it didnt come back but I am just curious. Does the Ecm fuel with more boost or less boost than actual? What does the boost fooling feature from these boxes do? Also, I still have an HY-35 but how the hell do you guys get more than 22Lbs of boost ? Is just because of how much fuel yall have going through your engines? Sorry so long but all this seems to be getting more confusing the more I read your posts. By the way, I changed out my injection pump, supply pump, draw straw and fuel line out about two weeks ago. Dead pedal gone but not getting the power I think it should have.

AggieJustin

To get more boost out of a HY-35, you'll need a turnbuckle or something to disable the wastegate. You want to limit it to around 35psi though, because anything over that is just pushing hot air.

If the computer is seeing 58psi, I imagine it's probably cutting back on you. The boost fooling function of the boxes is to limit how much boost the ECM actually sees. Usually the boxes let the ECM only see about 20psi to keep the computer happy, but the box continues fueling at a rate consistent with the actual boost reading.

On your map sensor, you should be reading 1.0V at idle. The 98.5-00 trucks used a sensor that put out 0.5V at idle.

If you need a wiring diagram at the MAP sensor, let me know and I'll copy the page from the FSM.

jcarrillo

Thanks Justin, I've got my trailer here so I have all my tools with me to run the checks on the original sensor and the one I bought. If I don't get called to a drilling rig, I am going to do it tomorrow morning. If I cant figure it out, I'll hollar at you. Thanks again, Joseph