Turbo Dyno numbers - Ignition/ SCR/ Questions!
 

Hey guys just got back from the dyno. Tuner says truck is breaking up and he didn't think it was a good idea to turn the whick up past the 9psi gate spring. In his opinion there is an ignition problem of some sort. I am running ungapped Denso IT24 plugs per the tuners recommendation and stock 150k coils and new msd wires. I haven't done a resistance check on the coil packs or done a leak down test yet, although from experience I know that a coil can resistance check fine but till cause a miss. I had that happen on my vette. Anyhow I wanted to start a new thread to sort out the issues before I head back to the dyno. The good news is we loaded a flex fuel Avalanche os and the truck was tuned on 70% ethanol (10 gallons of e85 + a gallon of 91). Truck made a pathetic 456/477 @ 9psi and doesn't feel too fast at all.... Tuner did say that my pcm doesn't handle ethanol content as well as the C6 vettes do and I need to allow 15 or so mins when changing fuel mixtures with the flex fuel tune loaded. Most of the time I plan to run around on pure e85.

Anyways, any idea where to start? I need to log before I go back to the dyno but what parameters should I be looking at given that afr's look fine?

Br7ef plugs gapped at .028 for low boost
Toss msd wires in trash

Redyno

MSD wires are fine

Likely issue is plug gap too wide

Also I would never trust "virtual" alcohol content fueling. I would recommend you install an actual content sensor with appropriate OS.

Numbers aren't bad for a 5.3 and you barely pulled to 5500.

I do have an actual sensor and it's wired to pcm. I don't know what gap is on IT24s but you guys think I'm getting spark blowout? Im tempted to to run a TR6 at .030" like so many guys seem to do with good results.

run br7ef @ 0.028.

Any kind of sputtering, hesitation at wot is spark blowout

Remember, all turbo setups usually have hiccups when first starting off.

Could also be too rich causing blow out

Can also have cracked plug but shows up in log

If you have stock wires toss them out...saw my share of msd wires ohm out shitty

it's not rich, if anything it's a tad too lean up top but still within ok limits

Thanks guys I will try the BR7s and George I do have several sets of stock plug wires that I will throw on just to try. I'm absolutely not discouraged just need needed a little direction.

Blow out looks lean...had a cracked plug showing good afr...fixed it and afr was rich...remember blowout is a misfire so will read lean


Swap plugs

Ok so as soon as I got back from tuner (4hr+ drive) I decided to do something about the ignition situation. Parts store was closed so no BR7's to be had so I raped my vette for its coil packs, ls7 plug wires, and tr6 plugs that I regapped to .035" and when I started the truck the idle was a lot smoother. I put it in reverse to take it for a test drive and damn near put it through the wall as the throttle response was way crisper. Everything is different now. Truck feels like an animal but I still have the boost cut on the controller set to 9psi, although the Innovate gauge playback shows peak of 11.7psi? Afr's are steady 11.5-11.6:1 so I think I've essentially corrected the ignition issue and the truck was tuned around a miss on one or more cylinders. Which is fine, as afr's seem safe at least at current boost levels. The truck will light up the tires real hard from a 2nd gear roll but I feel there is way more on the table given the ignition issues. Not sure if I should bother swapping BR7's in before retune or not as I've heard so many guys running even 18-20psi on TR6's gapped at .035" or even stock48 who said he didn't even change the gap when he threw his in, which would be .040-.045"