Turbo 5.3 base tune worked great until...

[bbowerman]

Hey guys I was working on a base tune for my 5.3 Silverado with a cam and 7875 turbo. I'm running 3 bar SD on open loop now. The truck ran awesome only on 10 psi pulled great afr 12.2-12.3 and timing look fine. Made about 5 pulls with it on the street. On the way back home it started raining and the air filter came off the turbo I hit a large puddle the truck cutout but still ran. I took it home drove it (never boosted) ran fine. Went to do a pull and anything over about 5 psi it goes rich 11.2-11.5. pulled the plugs all rust colored. Swapped those with a new set and it got better but now when I get out of the pull the truck is way rich and misfires until I free rev it in neutral. Is that possibly water stuck in the intercooler? Because just driving normally it runs fine unless I boost it. Thanks in advance I will upload my tune and log files when I get to my laptop.

[bbowerman]

12 degrees @10psi 9.6:1 93 pump gas no methanol. Inlet@top and outlet@top of intercooler. Tonight I will disassemble the cold side and inspect it.

[Crashgnx]

sounds like you got water in your MAP sensor or air temp sensor.

[bbowerman]

It's gotta be something like that. The map seems to be reading correctly. And the iat looks alright. It literally is just acting up in boost. I'm thinking there is water in the bottom of the intercooler that only comes out under boost. Weird... Everyone I know says to pull fuel from it. But I am not wanting to pull fuel from a tune that just worked almost perfectly before that happened.

[bbowerman]

Feel like an idiot now..... I forgot i just added a muffler with a cutout (that was closed) and an air filter. And I guess it was going too rich to burn when it was in boost.

[5FDP]

I woulda said 12.2 is lean and 11.3 is perfect in boost. Though a tad rich at only 4-5psi.

[bbowerman]

It was showing 11.1@10psi and pulling alright on the way home. But I do suspect a small exhaust leak under load (two different brand v bands mated). This is my first go around with how tuners and I've learned a ton from a multitude of forums, and Matt Happel from sloppy mechanics. I will go take a log and post it to let you see what is happening during the pull. Going to open the cutout and temporarily remove the filter to see what that does.

[bbowerman]

here is the log. and .hpt file. it doesnt look to bad but after the pull it missfires and idles rough until i hold it at about 3000rpm in neutral. so the air filter and cutout wasnt the culprit, although afr was up slightly. odd.hpl latest tune.hpt

[bbowerman]

Just brainstorming @6.56:49 in that log after I closed the throttle blade (92mm 4 bolt) it went rich (10.63@89kpa ) I can't pull fuel from that area because it is correct during wot. But one thing I am wondering.... This 92mm tb has no idle hole I set the blade at 3 percent for my idle, could I possibly benefit from drilling the idle hole in this situation, or is there a table that cuts the fuel off faster here?

[bbowerman]

Well RAF was pretty far off ran the Russ k and fixed quite a bit last night. It pulls better and doesn't cut out now. In the higher boost 7-10 psi it just doesn't feel as strong as it should though. Do you think maybe it is because it's on pump gas with no methanol? Because I can only get 12 degrees @10psi and I see others running more.

[bbowerman]

RESOLVED it ended up doing the misfire and rich thing under light throttle also then became an insanely bad misfire. Had 2 weak coil packs.