How rich is too rich?
Originally Posted by 617G
^^I'm actually supercharged and I did get tuned. At 3k-3500 I only see about 1.5 lbs of boost, which surprises me. I thought I would have more at that point. I don't even get a lb until 2500-3k, and at 2000 I'm exactly at 0. The bov doesn't close until about 3k-3500 when it sees enough boost. I appreciate the concern, though.
If you're only gettin 1.4 psi of boost at 3000-3500 rpm, you can run at 12.5-13.0 without trouble in that range. the car will be more repsonsive, too. 1.5 psi is nothing to worry about. timing is where the power is made!
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From: United States
Originally Posted by QuadCam
If you're only gettin 1.4 psi of boost at 3000-3500 rpm, you can run at 12.5-13.0 without trouble in that range. the car will be more repsonsive, too. 1.5 psi is nothing to worry about. timing is where the power is made!
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From: San Diego
The tune is fine. What you're seeing is common with the Zeitronix while using the peak feature. When you do a WOT run and let off, the throttle body plate closes, but fuel is still being dumped. We're talking milliseconds, but it happens. You can see this when you data log with the Zeitronix. Watch the AFR, TPS, and PSI. When you do a WOT run, you'll see your AFR begin to richen, your TPS will climb to 100, and your PSI will rise to 8 psi. As you as you let off the throttle, your TPS and PSI will go to zero, but your AFR will go to 9.9 for a millisecond. Because you use the peak feature, the Zeitronix picks up that extra fuel and reads 9.9 AFR even though your off the throttle. What's important is the AFR at 8 psi and 100 TPS. That's the true indication of what your AFR is at redline. Remember, your fuel pressure is reaching north of 85 psi. That's alot of pressure and fuel to completely shut down when you let off the throttle. The Zeintronix is picking up the residual fuel at 85 psi and zero psi. It's a very accurate unit. Again, it will make sense when you datalog.
I made a couple of runs again last night when it was about 75 degrees outside with two people in my car (what a difference an extra 400 lbs makes). My car felt so slow lol (still pulled on a stock sti, though 
). Anyways, my AFR was in the low 11s pretty much 4.5k to redline. Perhaps this is due to the temperature being closer to what it was during the tune and the MAF wasn't trying to compensate for denser air and picking the right fuel cell?
). Anyways, my AFR was in the low 11s pretty much 4.5k to redline. Perhaps this is due to the temperature being closer to what it was during the tune and the MAF wasn't trying to compensate for denser air and picking the right fuel cell?
Originally Posted by Giles Gilbert
Told ya 
When you move to the eManage Ultimate it has temperature compensation tables so we can nuke the problem for good.
When you move to the eManage Ultimate it has temperature compensation tables so we can nuke the problem for good.I will never doubt a man with a 400+ whp s2000 ever again
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From: Winfield, IL
Originally Posted by Giles Gilbert
Just as a FYI - the Subaru STi runs 14.7:1 at full boost as do many other OEM turbo cars
Last edited by Nealoc187; Oct 5, 2006 at 05:49 PM.
Originally Posted by Nealoc187
What in the world are you talking about? No they don't - their AFRs are in the mid to high 10s under WOT stock... I've even seen them off the chart rich in datalogs (richer than the 9.9 limit on the wideband used).
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From: Winfield, IL
Originally Posted by Sharif@Forged
Most factory turbo cars....Porsche's inlcuded...run AF ratios deep into the 10's at WOT and sometimes richer than that. All modern cars will idle and cruise at roughly 14.7:1
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From: United States
Originally Posted by down_shift
Note to self, never let Giles tune an STi!
j/k
j/k
I guess most are not up to speed on the US06 testing cycle and CO emissions mandate by the EPA. It is significantly more strict in other countries. During this testing cycle the first 2 to 4 seconds of a wide open throttle event produce a significant percentage of the additional CO production. This is due to what they call demand enrichment of which running rich under wide open throttle is part of that. This is an over simplification, but manufacturers were basically given three options for existing engines:
1. Reduce the load, i.e. the engine management closes the throttle some etc. Less air + less fuel = less CO
2. enforce stoichiometric operation under all conditions
3. Allow a CO level such that the worse offending cars would have to run stoichiometric for between 2 and 4 seconds at WOT before fuel enrichment is allowed.
While I may have been partially mislead by others into which option each manufacture took in the cases of cars I have not personally experienced this is a very real problem for anyone wanting to produce a reliable turbo setup in the aftermarket arena. For a fact I know that Lotus chose #3. Of course all of this is for late model year vehicles.
Just be careful since if they do use option #3 your dyno pulls may be meaningless as this will be consumed by the low RPM region of the engine during the pull, but when someone steps on the gas on the street at 4000 rpm and it goes lean for 4 seconds you had better have some kind of plan in place.
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