I installed a Blue Chip FMS and an xzt+ box earlier this year (everything else stock) and my boost would reach 27-28 psi. Now my clutch is slipping, but for the last 2 weeks, my boost will not reach over 18 psi. It's like it stops exactly at 18. Could this be caused by a slipping clutch not allowing it to make enough load on the engine? No matter what I do, the psi never reaches above 18. Any ideas? Oh and i did check for boost leaks and found just a few small ones, but nothing serious. Just a few boots that I tightened up. thanks, -Evan

 

Did you check the line for your boost gauge? Just a thought I wraped mine cause I thought that somthin would wear a hole in it.

 

Sounds stupid but is your air filter clean? Just had the same thing and mine was packed solid took 2 cleanings to get it to breath again.

 

air filter is a new BHAF, and the boost is displayed on my FMS box from the ECM, so it couldnt be either one of those. thanks guys

 

If you have a program on your truck that does any sort of boost fooling you will be reading what the fake number being supplied by the program is telling your computer. Have you changed your programming lately? If you have, you could actually be seeing much higher pressure but the computer is being tricked so your wastegate doesn't open. Not sure if thats how it works on your truck but i had the same issue so i switched to analog guages on the pillar. Just a thought may not even be close but i'm not really familiar with the mods your running.

 

If the tach rises and the speedo doesn't then the clutch is slipping. Very easy to observe.

 

Well, about a month ago, I could see 25-26 psi. that's what i cant figure out. About that time is when i installed the xzt+. When I turned both boxes on, It was more powerful than just the FMS, but now that i think about it, I havent seen over 18 psi since I installed it.

As far as the clutch.... I can feel it when it when it slips (and see it on the tach). But I didnt know if it could just be slipping slightly without me feeling it, keeping the load on the engine low. I dont know, it was just an idea.

 

Try changing the order of the map sensor connections. Like plug fms box into the map first and then the xzt+. The xzt+ does boost fooling so anything plugged in after it, including another box or the ecm will think it is getting 18 psi boost.

 

ya you are probibly getting higher boost then before iv heard guys getten 30+

 

it must be the xzt+ boost fooling, because i just installed analog gauges and saw 30 this morning. that solves that but......

I just saw that the FMS is only fueling 25% when set on 63% (that's what it displays, anyway). If i put it on the drag setting, it fuels up to 63% like it should. Any ideas? thanks