Hello,

'06 100k mile all stock 5.3 with KB front mount MP70. BB tune, truck was running great on a MAF tune at 7psi. Idle, part throttle, full throttle, everything was great, steady 11.3ish AFR on the wideband in boost.

Driving down the highway, maybe 75 degree outside temp, passing a few cars at full boost once in awhile, but otherwise driving normal (75mph). Have a 29x12x2.5 intercooler right behind the grill. Went to pass a another car and it only hit 4psi boost and made a weird sound, looked in the mirror and sure enough, the blue smoke trail of death. Got it home, #1 cyl has a squished electrode, and 3 and 5 have no compression.

Running 91 octane, pretty much all that's available here. I should mention that the MAF is preturbo, and I have yet to relocate the IAT sensor. I thought however that I would be safe due to highway driving, intercooler up front, and low, infrequent boost.

I've attached a log, it isn't when the engine blew, but not long before. Tune also attached.

Any input? Bad fuel maybe? It's at 17* timing which the tuner said was pretty safe. I picked up another long block already for $300, so fortunately not real expensive, just labor intensive!

PS, 44# injectors and walbro 255, if either of these were insufficient, you would see it go lean, correct? Thanks guys.

 

I cant see your logs, but it sounds like classic detonation and a busted piston(s). Caused by too much timing, bad fuel, or a combination of both.

 

Could be a combination of too much timing, your iat sensor positioning and that small intercooler. The actual iat's could've been up to 60-80 degrees hotter than your iat sensor was reading

 

I would be that the IAT's were even higher than 80 degrees above what it was reading. That is one of the problems of not relocating the IAT. There would be nothing to tell the timing to back off when the IAT's are climbing. Also if you had a leak in the inlet pipe after the MAF and before the turbo, it would lean things out.

When mine let loose I was running 12 psi with a radix, and my IAT's were in the 230 range. I was really pushing it with timing too at 19.

 

Yea that would be my guess. The computer had no way to read true iat's and that's what happened

 

Ya, I did plan on moving the sensor, just figured I'd be safe in the meantime with highway driving in cool temps, I guess not. Paying the price for impatience.

 

Well now you have a cool coffee table lol.

 

low budget stock short block builds has it benifets, that's way I like them

 

Same page with these guys on the AIT being an issue. Another thing to look at is the tune. Since you was on the highway, you likely had a good load on the turbo and boost in lower rpms. Easy to get detenation down there with stock like timing, even more so with 91 oct fuel.

 

Yea, you really need a IAT sensor after the intercooler.
That should take care of your motor killing problem..