Tuning $0D for Vortec TBI 357

[Chris]

Yea, the 193 TBI heads really don't need much advance. I ran into knock city with +2 degrees over stock on 89 octane sorting out my lean cruise to give you an idea. I always leave my spark bias at zero, unless you have idle issues before it's tuned.

edit: which .bin file did you start with? The open loop/lean cruise entry was definitely there in BJYL. That's for an auto 5.7L. Honestly though I wouldn't fret over it. Unless you live somewhere flat you won't see much benefit from it.

 

[woody80z28]

BJLH was my stock BIN. 5.7/4l60e/4x4/3.73

Lean cruise helped with the Beretta, so I thought it would be a nice addition with the truck.

 

[woody80z28]

Made the Vortec spark changes and changed the injector constant after I swapped in the new fuel pump and bumped pressure to 16psi. It ran ok, but was a little doggy...and I saw the fuel pressure lowered itself to 13psi. The stock regulator spring is shot I think, so a new heavier one is on the way. Changed the injector constant back for 13psi and it feels pretty good for now at light throttle.

 

[woody80z28]

http://ericwood.net/files/z71/VortecTBIv2_DL2.adl

O2 is still acting a little crazy. The ECM is actually pulling fuel when it feels like it needs more.

 

[woody80z28]

Sounds like I have some detonation too low in the RPMs under load. The knock sensor isn't picking it up, so I wonder if it's any good. What's a good way to test? Can I smack the block with a hammer at idle and see if it pulls timing or something?

I'll be upping the pressure to 21psi when the spring comes in...according to EagleMark's spreadsheet that should be 77lbs/hr and good enough for 310hp which would be plenty.

I'm thinking I'll have to pull some timing though, even when I do give it some more fuel.

 

[Chris]

Yea, just smack it with a hammer. One thing I do miss about the older $42 code is it would force a knock-test on startup.

On that thought though, I've always had a bit of a spark-rattle when running 87 octane fuel. It even did it on a stock tune, and very rarely would the KS pick it up. I never hear it running 89 though. It was always right around the speed/rpm of the 1-2 upshift under light throttle. Not really too worrisome, since there's always going to be some knock no matter what you do. If you're concerned about fuel, throw a wideband on it and keep track of lambda when you're driving. Normally the stock narrowband O2 is fine for doing a little tuning, but outside of its design window they're basically useless. If the PCM is wanting to pull fuel (btw what does the BLM look like, assuming your haven't fudged with the values?) then I'd encourage you to let it do its thing for awhile and see where it leads you. Take a 2 hour drive and datalog the hell out of it. It may shine some light, or it may not.

 

[woody80z28]

Yeah, I'm going to pull the wideband out of the Beretta and put it in the truck some time this week. If you look at the datalog I posted, you can see the o2 is swinging way rich, way lean and the BLM/INT spend most of their time under 128...but it acts like it wants more fuel.

I had an old ex-mechanic (from the pre-EFI days) listen to it as I left from work for lunch and he said it definitely does not sound like spark knock. It almost has a diesel sound to it down low in the RPMs. I'm not sure how else to explain it. I already checked for exhaust leaks and the head to header seal is good...the collectors are good and there's a small pinhole in a weld on the bank opposite the o2. I'll be fixing that when I drop the pipe to install an o2 bung. I don't think that is my sound, but I won't know for sure until it's fixed.

If I need 89, then that's not the end of the world.

 

[woody80z28]

My new FPR spring came in so I got my pressure to 20psi. I changed the injector flow rate to 75lbhr in the tune, but the idle is way rich. From what I've read, I need to change the base injector pulse width constant...but I can't find it in the XDF for $0D. I found "Minimum Sync BPW" with a value of 396.7 uSec, but I don't think that is the correct place...because it should be about 135 according to the other threads I've seen on TGO.

 

[woody80z28]

Knock sensor works. And my bro-in-law swears the noise is from the exhaust pinhole. I'll know for sure when I weld it up tonight if my Summit order comes in.

Anyone know the BPC for $0D? I don't find it in the XDF anywhere...unless it's the Minimum Sync BPW of 396.7 that needs to be changed.

 

[woody80z28]

I did some more homework and found out there is no BPC in $0D, it's all done by the injector constant. So I split the difference of what I got with two different formulas and now at "85lb/hr" and 20psi it is running great. Really good actually. I still need to throw the wideband in it for some fine tuning, but I don't think I'm too far off.

I fixed the y-pipe leak and the tick was still there, so I re-lashed the valves and had one lifter in particular making noise. So I bought all new LS7 lifters for it to drop in this weekend, and in the last day or so the odd lifter has been quiet. I also bought some copper header flange gaskets just to be sure I'm getting a good seal. I'll know for sure if I got leak noise when I pull the cheapo Hedman paper gasket out.