Gernby

I've been suspicious that the "AF Corr" value in the FlashPro datalog may not be accurate for a while now. My S2000 is nearly stock, with the exception of the items in my sig. However, to get my AF Corrected value down to low 13's, I've had to add as much as 25% more fuel in some areas!

Even though my car has less than 10K miles on it, I thought maybe there was a chance that something was wrong with my car (clogged injectors, low fuel pressure, etc.), so I decided to datalog my brother's '06 S2000 that is 100% stock. Even though it is an '06, it only has 16K miles on it. To my extreme surprise, it runs super lean too! At full throttle, the AF Corr value never drops below 14:1. This doesn't sound right at all for a stock Honda.

Here are some graphs from the datalogs showing my car with the "stock equivalent" calibration (in red) with my brother's 100% stock S2000 (in blue). Do you guys think this is right?



BTW, something else that I thought was interesting is the difference in our timing curves. His ECU is pulling out a lot more timing than mine due to knock, but our knock levels are pretty similar. Thoughts? Could this be due to my colder spark plugs?

Gernby

I forgot to mention that even the uncorrected AF values in the datalog are showing values more lean than I've ever seen for a stock Honda. When I look through all the DynoJet run files that I have from local S2000 dyno days, we were all running untuned fuel ratios between 12 and 13 (using the dyno's wideband in the tail pipe).

EliteTuning

the dynos o2 at the tail pipe means 1 point leaner on the af at the header. The results don't lie. Every engine is different, everybody in every city has different temperatures and elevations, everything changes.

The stock honda sensor will correct af for closed loop, but in open loop, only 1 program is put on all the cars. This is why with a standalone, you will most likely gain power and/or smooth driving

Gernby

Please clarify this. If your estimate is that it is a full +1:1 difference to read AFR at the collector versus the exhaust tip (after the cat), then I wouldn't disagree. My observations after installing a test pipe with an LM-1 showed more like a +0.5:1 difference, but I really haven't spent much time on a dyno, and I'm a total novice tuner.

However, if that is what you are saying, then that makes my point even more valid. The local S2000 club dyno days were attended by many nearly stock, completely untuned S2000's, and they were all running MUCH richer than the FlashPro is indicating on my S2000 and my brother's S2000. Since these S2000's at the dyno days were reading 12-13 after the cat, then I believe they were really running closer to 11-12 at the collector.

EliteTuning

What I meant is before the cat on the stock o2 or even a s2k with an aftermarket wideband. If you insert an o2 from a dyno in the stock primary location, then it's going to be close.

One flashmanager software had af corrected value issues. Its been taken care of with the newer version and I have ZERO issues for both s2k's i tuned and about 15 civic si's i've tune (they all use the same o2 sensor).

Gernby

Well ... I'm at a loss. I wasn't aware of Honda's design change to start shipping S2000's that run dangerously lean right out of the box. I've been going through all my archived AP1 dynos that show AF's that are 2 full points richer, but I can't find any AP2's.

Again, I'm not saying that it has to be wrong. I'm just saying these results are shocking, and I'm terrified for my brother. I guess his stock motor won't live long.

crazysupratt

that is some crazy lean af for stock s2k ap2. man. if that is true, then i'm worried

Mrfixit687

Head down to a dyno with a tail sniffer and take a reading to see if its lean also?

EliteTuning

only way to verify this on your brothers car is to put a wideband in the same place as his primary o2 and log it. I'm sure Honda has ecu updates if it is a big concern. Honda motors are very strong so I doubt he will lose his engine n/a with those afr's. However, if he was f/i, that is a whole new ball game

kenchow69

http://autospeed.com.au/cms/title_Tuning-A...95/article.html