LB7: no oil pressure

[dmaxadermist]

ok heres the deal, i bought an 03 silverado duramax that was wrecked and not running, got it tore apart and the trans computer was gone and some of the wires on the clear clip (c2) were pulled out, well after buying both computers and repairing the wires with a bunch of papers i started it up after getting the security mode off and only had a couple minor codes but the oil pressure hand doesnt move but very a little and only when i rev the engine but the motor runs super smooth and no noises and also the low oil pressure light or ding just isnt there im thinkin the sensor is messed up but im open to suggestions please help

 

[wikdlmm]

Sensor would be my guess...

 

[whitetrash21]

I have no idea if this is even something you can log, but there may be a way to use EFI to see if you have oil pressure. The guages in these trucks are inaccurate as hell, mostly just idiot lights. Someone with EFI experience can maybe clarfiy that though....

 

[lotsofmiles]

heres a couple oil pressure threads when mine went out.

http://www.duramaxdiesels.com/forum/showthread.php?t=12433

http://www.duramaxdiesels.com/forum/showthread.php?t=12507

 

[othrgrl]

If the computer that you installed is not from the right year of LB7 it can cause the gauge to not work. A tune from an 03/04 loaded onto an 01-02 LB7 will cause this and I assume it would work the other way around as well. A reflash of the right tune for your truck will likely fix the problem.

 

[dmaxadermist]

ok i finally think i figured somthin out i put a mechanical oil pressure gauge on the oil filter housing there was a plug in ther i took it out and screwed it in,, would this be accurate? my gauge only goes to 80 psi and it was hitting the tack past it just wondering. i appreciate the help

 

[othrgrl]

Depending on which port you put it in that is probably reading pressure from before the filter and cooler. It is likely what I described above, flash the correct tune for the truck onto it and the gauge should work. If that's not the case then the sensor or wiring is faulty.

 

[dmaxadermist]

ok how would i do a flash tune?

 

[othrgrl]

You would have to either have a GM dealership do it for you, someone with a Tech II and subscription or someone with EFI Live and access to a stock tune that would work correctly on your truck. You could also send your ECM to an EFI Live tuner for them to flash it. Where are you located? If you are local to a reputable EFI Live tuner they could likely set you up with a performance tune for the price that GM would charge you to put a stock tune on it, or like I said you could send it to one.

 

[dmaxadermist]

well i am located about 40 miles east of bowling green kentucky.. if that helps, and call me stupid but i dont know what efi is i am new to the diesel scene also, what kind of cost would either of the tunes cost... and the last thing i was wondering if the port i put my gauge in was before the filter and cooler an everything would it read higher than what it would if it had already went through it doesnt really bother me that the gauge isnt working,,, i just want to make sure that my engine isnt junk for now thanks again

 

[othrgrl]

Yes, if you are reading it before the filter and cooler it will read higher, you lose some pressure in the filter and cooler and then the pressure is regulated after them. EFI Live is a tuning and logging tool used to write custom tunes for 98+ GM cars and trucks, including the Duramax. I'll PM you pricing.

 

[LBZ_Duramax]

It is the cluster most likely. 2003's are notorious for going out and if you have oil pressure on your mech gauge it is about 99% chance faulty cluster. Replace the stepper motors and then it will work fine with the updated parts and you wont have anymore problems

 

[McRat]

Check the oil to insure it's not 50% diesel fuel.

The engine computer will tell you if their no oil pressure, but it's threshold is very low. 10 psi or something like that.

Yes, checking it with a mechanical guage is good insurance.