ANOTHER tuning question: Scanner

[Dave]

Just a quick question... all I'm looking for in the scanner is the "safe zone." Since I can't find it by reading the O2 voltage, I've considered looking elsewhere. The timing retardation in the knock.

Can I set my base fuel pressure in tune with my boost by just reading how much knock there is between each cylinder? What's the limit of timing being pulled that would tell me if there's too much detonation?

I was running 65psi of base fuel with 13psi boost and 12* base, and it was still pulling timing??? WTF? Also my O2 said I was at .94-.96, that can't be right. I have waaaay too much fuel.

[86Shelby]

Back off the timing 2 degrees and see what happens. This is where I would start.

The O2 readings could just be from the sensor being unable to produce 1 volt or the wiring not being 100% a third possiblity is that there is incomplete combustion due to the overly rich mixture whic would bring your O2 readings down.

I look for 0* knock retard when tuning.

[turbovanman²]

Yep, too rich and it will misfire. If theres too much fuel, it can't burn and will misfire, this causes excess oxygen which the oxygen sensor see's as lean-if I remember correctly and this will make the ox read lower voltage.
My first time on the dyno last year with this engine, would rich misfire at around 5800 rpm.

[Dave]

Hmm makes sense. I will get the timing gun out today, and I backed off the base pressure to 55psi base. We're also installing the Stage III computer today.

Can someone explain this to me though: I unplug the vaccum line off the AFPR and set the base pressure this way, but when I plug it back in it drops almost 10psi base. Why?

[turbovanman²]

Can someone explain this to me though: I unplug the vaccum line off the AFPR and set the base pressure this way, but when I plug it back in it drops almost 10psi base. Why?

If you didn't, it would run rich, they base the fuel requirements on X amount of fuel so they use the FPR to raise or lower the pressure depending on demand and the vacuum pot is a good way. Now they have a computer control it in some models.

[Dave]

I think everything is getting there now.

Base fuel is at 49psi.
Boost is around 17-18psi.
Timing... eh I'm going out after lunch to set it, probally around 10*.

Since installing the Stage 3 computer my scanner no longer works, I got code 23 (Air Charge Temp. Sensor), and neither does my Traveler system.

BUT! It hauls balls now. The computer made a huge difference. Spool time is still rather slow - this could be because I have 2' of vaccum line on each side of the controller. No creep though.

I have nothing to justify my a/f ratios. I'm just constantly pulling the plugs and playing with timing, boost, and fuel. Stupid yes, irresponsible yes.

All I gotta say is thanks guys, this thing is a freakin' monster now! Never have I loved not having traction all the way to 5,500 RPMs. WOOO!!!!!

PS: Bring on the Hemi!

[turbovanman²]

Do you have a charge temp sensor hooked up? I believe the STage 3 has it turned on. If you don't have one, it will run richer, which could be why your turbo is spooling a bit slower.

[Dave]

Do you have a charge temp sensor hooked up? I believe the STage 3 has it turned on. If you don't have one, it will run richer, which could be why your turbo is spooling a bit slower.

That's why! Someone on TD tried explaining how to hook it up... yah real confusing.

[5sp. mini]

ask cindy what to enter to get readings. there a mode in the frist set up that will say spec,s see if ecm imfo. in there. AL

[Dave]

Al, I'm supposed to call her back tomorrow. I called her today and told her the problems and she said get back to her, as she will look into it.