Tuning $0D for Vortec TBI 357

[woody80z28]

Just got the thing on the road and started driving. Only changes to the stock BIN are for manual transmission, EGR delete and slightly higher cylinder volume of the overbore.

Base timing is at 0 with the EST wire unplugged, and the fuel pressure is at 11psi(maxed out AFPR...new fuel pump is on order). Stock 350 injectors.

Truck runs ok at idle and low throttle, but pegs lean at 50% TPS. O2 sensor has huge swings though, and the BLM/INT is not adding fuel like I would expect. And at one point, the truck wanted to stall when taking off from a stop...but ran fine the rest of the time.

I'm guessing I may need a new O2, even though this Denso was new last year and worked fine with the stock engine. However, there is also a slight header leak at the head that I haven't been able to get rid of yet.

I've attached a datalog for anyone who'd like to take a look.
http://ericwood.net/files/z71/VortecTBI_DL5.adl

 

[Chris]

I'll look at the datalog when I get home. I can't recall from your previous thread, but are you using Vortec heads? If so you need an LT1 or L31 spark map. The L05 map won't cut it there at all, for starters.

If the header leak in on the drivers' side where the O2 is, that could cause some funkiness if it's pulling ambient air into the exhaust. I would fix that and take another look first because messing with too many variables, including the spark tables.

 

[woody80z28]

Thanks Chris.

I did retighten the header bolts after a couple heat cylces now but haven't had a chance to drive it yet cause I'm in the middle of wiring the 4WD for the 1-ton tcase.

Yes, Vortecs. Do you know of a BIN I can grab either L31 or LT1 spark tables from? I'm running an LT1 cam, but a little lower compression (9.7) than an LT1 and higher than an L31. I thought I had read somewhere that the 193 heads were also "fast burn" and the spark tables should be close...but I could be wrong.

The engine is definitely sluggish as-is.

 

[Chris]

Copied this from 3rdgen, but I'm 99% sure it's what I used as a base before. It's an iron LT1. The best I can tell you without actually showing you is you want the spark slope to be nearly flat after 1400rpm IMO. You don't need anymore total timing than the 193 heads had stock, actually you may need a few degrees less at cruise. Just depends. Also kill your PE delay altogether. It's really not needed. I fought lean tip-in issues at cruise forever until someone mentioned that bit of info. I wouldn't go crazy with it at first until you get a new fuel pump. You really need at least 13psi. I'd be interested to see what your IPW is running 11.

400 600 800 1000 1200 1400 1600 1800 2000 2200 2400 2800 3200 3600 4000 4500 5000 5500 6000 6500 7000
25 KPA 18 22 26 29.0 31.0 33.0 35.0 36.0 37.0 37.0 37.0 38.0 38.0 38.0 38.0 38.0 38.0 37.0 37.0 37.0 37.0
30 KPA 21 25 29 30.5 33.0 35.0 38.0 39.0 40.0 40.0 40.0 43.0 43.0 43.0 44.0 44.0 44.0 43.0 40.0 40.0 40.0
35 KPA 22 26 30 30.5 32.5 34.0 37.0 38.5 39.5 40.0 40.0 41.0 43.0 45.0 45.0 46.0 46.0 46.0 42.0 42.0 42.0
40 KPA 21 24 26 28.0 30.0 31.0 34.0 35.5 36.5 38.0 38.5 39.0 41.0 42.0 43.5 45.0 45.0 45.0 41.0 41.0 41.0
45 KPA 20 22 23 27.0 28.0 29.0 32.0 33.5 34.5 36.5 37.0 38.0 39.5 40.5 41.5 42.5 42.5 42.5 39.0 39.0 39.0
50 KPA 19 21 22 25.5 26.0 27.5 30.0 32.0 33.5 35.0 36.0 37.0 38.5 39.5 40.0 40.5 40.5 40.5 38.0 38.0 38.0
55 KPA 17 19 21 24.0 25.0 26.0 28.5 30.0 32.0 34.0 35.5 36.5 37.5 38.5 39.0 39.5 39.5 39.5 37.0 37.0 37.0
60 KPA 15 17 21 22.0 23.5 24.5 27.0 28.5 31.0 33.5 34.5 35.5 36.5 37.5 38.0 38.5 38.5 38.5 36.0 36.0 36.0
65 KPA 12 15 19 19.5 21.0 23.0 25.0 27.0 30.0 32.5 33.5 34.5 35.5 36.5 37.0 37.5 37.5 37.5 35.0 35.0 35.0
70 KPA 9 12 16 16.5 18.0 21.0 23.0 25.5 29.0 31.5 32.5 33.5 34.5 35.5 37.0 36.5 36.5 36.5 34.0 34.0 34.0
75 KPA 6 9 13 13.5 15.5 19.0 21.0 24.0 27.5 30.0 32.0 33.0 34.0 34.5 36.0 35.5 35.5 35.5 33.0 33.0 33.0
80 KPA 3 6 9.5 10.5 13.0 17.0 19.0 22.0 25.0 28.0 30.0 32.0 33.5 34.0 35.0 34.0 35.0 35.0 32.0 32.0 32.0
85 KPA 2 2 6 7.0 11.0 14.5 17.0 20.0 22.5 25.0 27.0 29.5 31.5 31.5 33.0 32.0 34.0 34.0 31.0 30.0 30.0
90 KPA 2 -1 4 5.0 9.0 12.0 15.0 17.5 20.0 22.5 24.5 27.0 29.0 30.0 31.0 31.0 31.5 31.5 30.0 28.0 28.0
95 KPA 2 -2 2 4.0 8.0 11.0 13.5 15.5 18.5 20.5 22.5 25.5 28.0 29.0 30.0 30.0 30.5 30.5 29.0 28.0 28.0
100 KPA 2 -2 0 3.0 7.0 10.0 12.0 14.0 17.0 19.0 21.0 24.5 27.0 28.0 29.0 29.0 29.5 29.5 28.0 27.0 27.0

 

[Chris]

Any progress man?

 

[woody80z28]

Still working mucho overtime and had to help my bro-in-law with his Dodge last night. Fuel pump should be here any day though.

I'll keep the thread updated as I make progress.

And how do I check the duty cycle of the injectors in the log? Just divide the pulse width by a known max value for the stock injectors or is there a place to see it?

 

[Chris]

Yea, I'm not aware of any way to spit that out in real time. Just: IPW x RPM/1200

 

[woody80z28]

I see two spark tables and at first glance they look identical. I'm assuming I can swap in those values for both and leave the modifiers as-is for a baseline.

 

[Chris]

Yea $0D has two spark maps. When I first got into it after coming from $42 on my original 7747 ECM it was a huge learning curve.

 

[woody80z28]

WOW that's a lot more spark than my TBI stock table. I see the main spark bias is set for 9.8*, I'm guessing I need to zero that out for the new table? Stock max spark advance is 41.8 so I'm guessing that needs to go to 46 for the new table as well.

PE delay is now zero'd. Didnt see anything for lean cruise in the XDF though.