Macgyver

This was done on my S/Ced '98 4Runner, 305cc injectors, Supra TT MAF, Walbro 190 fuel pump, Split Second FTC1, Open Deckplate, TRD Headers, TRD Exhaust, stock air filter.

The 4Runner still needs lots of tuning so I'll be taking it to the dyno shop next week but this is what it did. How do the curves and A/F look?

juicyfruity

Is your 4 runner automatic? Since people get around 225-230 RWHP with a manual tranny with thoses mods. I would put it a little leaner between 4000-5000 rpm, just a bit,closer to 13:1, you'll still be on the safe side. Check Your EGT so they won't go over 1450*.

Basically, you put things a little richer where the torque is at its highest because the cylinder has more air (pressure) in the combustion chamber. Just to prevent detonation.

One important question is where did they put the probe, before or after the cat? Some shops put the wide band sensor after the cat and that voids the real a/f ratio that's comming out of the engine. You need a bung hole to insert the wide band.

Macgyver

My 4Runner is a 5 speed with federal emmisions. The dyno guy put the wide band probe in the tailpipe. He unplugged the O2 sensor before the Cat. so the computer would run off of the fuel map however the wide band showed that it was running really lean so he plugged the O2 sensor back in. Should he of unplugged the O2 sensor? Should he put the wide band before the Cat?

Has anyone wrote an article on how the FTC1 works? I'd like to read it because I don't have a firm understanding on how exactily the FTC1 uses the crank, cam, maf, o2 sensors.

juicyfruity

You should maybe look somewhere's else to do your testings.

The ECU was using it's open loop map where it ignores any input from the o2 sensor. it's richer than normal, just as when you start your 4 runner in the mornings. He said it was "too lean" because the cat was burning excess unburnt hydrocarbons (fuel). If the wide band had been placed before the cat, there wouldn't be any concerns. The open loop maps are rich because the o2 sensor is not yet online. it's a precaution to make sure it doesn't lean out when cold or at WOT, when the ECU has NO idea what's the a/f ratio.

The reasoning is simple; you don't drive around with your 02 sensor unplugged, so why would he take it off while dyno testing?

I'm absolutely sure that the wide band sensor HAS to be placed BEFORE the cat. People like gadget would absolutely agree with me on this.

So your a/f ratios are FALSE... they are actually richer... so your engine runs pig rich right now and with some leaning, you will get a lot more power.

Keep posting your results. People would really be interested in your findings.