Tuning a 93 3.4 Firebird

[robertisaar]

suggestion: considering the cam, i would add a bit of fuel(around 5-10%) at the 3600-up cells...

much better to be rich than lean...

[tkoforpresident]

suggestion: considering the cam, i would add a bit of fuel(around 5-10%) at the 3600-up cells...

much better to be rich than lean...

sorry i'm new to this.

You are saying to add 5-10% more (of 210) into the 3600 rpm and up cells?

[IsaacHayes]

I thought my valve lift was mild (.531) for the aluminum heads, but I guess the iron heads is another story since they have less velocity... That's some decent duration though, so yeah that's gotta have some lope. LSA is a lot less than gen3 but that is stock for a 3.4 iron head. Looks like the iron head got a meaner cam than gen3's did, but with less lift.

http://witchhunter.com/injectorcalc1.php4 to calculate your injector flow at different PSI. Then just adjust the BPC like we did above again for new value. I don't know all your motor mods but I'm at 92% duty cycle on my 19lb/hr injectors at the 43.5 stock pressure with my modified 3100. You may need to go to bigger injectors or up the pressure to 55psi or something. After you have your BPC plugged in, the PCM knows what size injectors it's working with basically. Then you can do the real tuning which is tune the VE tables (RPM vs MAP) to dial in how much fuel it squirts at X RPM and X load.

[IsaacHayes]

No, the BPC table is just to calibrate the PCM to the size injectors/displacement. You set that and you're done with that part unless you change displacement or injector size/pressure.

The VE is where you do the adjustments for the motor breathing ability (basically any mods that let it pull more air or exhale more exhaust). There are several VE tables. An idle table which you will want to spend some time with (tune this first) especially because your cam is wrecking havoc with idle. Then there is a base VE which gets added to the other VE tables, so you set that to something so that the other tables won't max out. (say the base table was all 0, and the main VE was at 100% but needed more fuel, so you add some to the base VE table so you can lower the main back down from 100%). Spark you can tune too, but that comes last unless you have too much and have spark knock even if you are not lean.

The BPC table 0% is the main one, the other entries in that table are how much to adjust the injectors for based on how much the EGR is open. If you disable the EGR then the 0% cell is the only one that will matter. When datalogging and tuning, disable the EGR, and CCP so that does not add a variable into the mix. Then once you have logged, adjusted VE, logged again/etc and have it dialed in, you can turn back on the EGR and CCP and tune for those so that when those kick on the motor continues to run smooth. You can extrapolate the rest of the table cells from the 0% BPC though.

Example, (16.7/19)*(3350/3135)=.93922605. Take that value and put it in TunerPro and select the multiply function. Highlight all cells in the BPC table and apply. That will apply the adjustment to the whole table... so 224 becomes 210, and whatever else in the other cells gets adjusted the same amount so it all scales. Now you might have to do some fine tweaking but that will get you pretty close.......

[robertisaar]

sorry i'm new to this.

You are saying to add 5-10% more (of 210) into the 3600 rpm and up cells?

we all gotta start somewhere...

you should see a table labeled "base fuel" or something similar, it will be a two column(row?) table, and it will list VE values compared to RPM. i would just add 10% to all of them at 3600RPM and higher.

[tkoforpresident]

wow, it's gonna take me a little bit to go over this information.

I'm gonna open up tunerpro and start trying to apply all this.

[robertisaar]

V5 is FTW, especially since i have my VE auto-tuner working good...

[tkoforpresident]

what's v5?

[robertisaar]

tunerpro v5....

[60dgrzbelow0]

Max... My only question here is whether the Iron Heads you have got a re-work from John at the same time your friend in Niagara Falls re-worked the UIM and LIM... or is this completely experimental at this stage of your build? Can they handle all this additional "Juice"...?

[60dgrzbelow0]

..and now you've got me wondering whether or not the 3.4L I'm about to bolt the iron heads on will be able to handle the CompCam 260H with 1.52 RT Rockers without stalling out in a deep lope...and no way to tune the PCM...? My heads are fitted with the new CompCam Springs and Keepers...etc... if that makes any diff...

[60dgrzbelow0]

The only other mod I was toying with was using the EFIs from a 1996 Lumina that deal out 18.1 PPH (17109826) and they have all the other stats as match to the bone stock (17103007) EFIs.

[no_doz]

swap to OBDI & go with a 3500-youll be MUCH happier & itll be much cheaper, plus way more power potential & way better mpg.

with OBDI you can get a PROM programmer for 120 for everything & tune it-with OBDII you need a HPtuner tuner (500-600 bucks) & credits ($50-$200).

[tkoforpresident]

Max... My only question here is whether the Iron Heads you have got a re-work from John at the same time your friend in Niagara Falls re-worked the UIM and LIM... or is this completely experimental at this stage of your build? Can they handle all this additional "Juice"...?

I don't understand what your asking here

i'm not really giving it a lot more power, at least not right now. I just want it to run correctly because my A/F ratio is whack and the VE is off the charts.

[ForcedFirebird]

The heads are heavily modified, and the 109 LSA is the same as the stock 3.4 iron head cam, I just added a bit more duration and changed the intake center line. Those lift numbers are at 1.5 rockers and Comp recommends to leave .060" clearance for the springs and we are right below that actually - I warned Max this was going to be a tough one to pull off with the stock tune, yet he said go for it lol.

Got Lope?