Farting Sound from Turbo - 250ci Six GM

[Steven]

I have an embarrassing problem... it seams like when i am driving in third gear (generally third but not exclusive) the engine just makes a farting sound, see log 12.7 to 14.8 seconds. so its generally from lights in town and people look because of the generally pleasant sound the engine makes. i'm guessing because i start moving in first then short change into second and again into third which is the first gear to get any kind of load and therefore fuel this is when the issue occurs. looking at the log between the 2.1 seconds the boost is peaking at 9.5psi from what looks like an average of 3ish psi. has anyone come across this before. its a cheap turbo of oriental origin... other than that the truck is running well.

oh i still cant explain the 242000.0 engine rpm, the tack in the cab which is run from the microsquirt is reading fine and like i said the engine starts and runs just fine.

2016-08-17_07.08.19_after drive to work.msq

2016-08-17_06.49.26.msl

Enjoy... Thanks and Regards Steven

[R100RT]

I'd check for compressor side induction leaks - for instance a suspect hose and clamp or similar where escaping boost might create your otherwise "enviable" Homer Simpson type turbo behaviour

[billr]

That "242000.0" is probably a scaling setting in MLV. When I open the file, max rpm is 2420.

[nathanhardy]

What kind of bov do you have

[WillExoIX]

My bet is the BOV not venting properly. I have a $20 HKS knockoff and it did that too until I "tuned" the spring. Works as well as the real thing now.

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[Steven]

So I looked into this some more and the turbo waste gate actuator had hardly any preload. I still get the occasional cough and splutter though. I was planning yo look at the blow off valve to see if I can stop the overly dramatic noise. It makes school boys happy but I'm trying to give the appearance of a grown up...