stantaur

Has anyone logged what stock S2000 timing is at cruise? Stock engine, stock ECU tune, just using OBD2 Link / data logging?

My stock S2000 with FlashPro & mega solid Evans autocross tune. It runs 29-30 degrees advance on average at 60 MPH, flat road constant load. Highway MPG has been lower than pre-flash though (used to be 28, now is 24-25 in same conditions). Wondering if I'm able to "smooth in" something close to the stock timing in cruise for the table (and iteratively ensure same air/fuel which has been 14.7-ish) and gain back some highway cruise range.

Thanks for any info you can share.

spectacle

Why don't you ask Evans to do it?

s2000Junky

That seems pretty low, that 28-30 actually inline with the typical timing advance at WOT to redline which I have logged as high as 35 at full advance with no ecu retard. Mid 40's in light load/cruising rpm is stock from what ive seen. So you’re about 15 off and very likely why you’re mpg is down. Some of this is rpm dependant though as well, and im not as versed in recalling all load and rpms points. I think at light consistent load your timing advance number will want to rise with rpm. So its possible 28-30 is ok at 2-3k rpm but at 4-7k+ rpm it should be advancing in the 40's etc.

iDomN8U

I'm at 38-40 degrees cruising on the highway around 50-60.

Sc using aem

Also at 15.5 Afr target partial throttle with tps around 15-20%

stantaur

Thank you - great info & insights. Didn't want to bother Jeff, as he's done such a great job with the rest of the tune. To me, I feel like I'm being high-maintenance asking for cruise MPG that matches stock (on a stock motor aside from the tune, CAI and high-flow cat.)

I test drove a bone-stock '04 today and plugged the OBD2- Torque app in and saw 35-ish degrees ignition advance, around 3100-3400 RPM and light load. Also noted 130-ish IATs (stock airbox) vs. my home-built setup at 85F that improves on K&N FIPK's design (less leakage of warm air into the box, and insulation outside the box)

I've smoothed in about 4.5 degrees into the 3D curve for my current FlashPro tune (so it hits 35-ish at those same load points) and this seems the right direction:
1 - There's no increase in knock at those RPM/load bands vs. prior logs at 30 deg.
2 - Around 1-2% less throttle position needed to hold a given speed vs. prior baseline log at 30 degrees advance.

shind3

Why don't you compare the timing maps to stock? I don't know why that part of a map even needs to be touched for a BPU car like that.

stantaur

If you can point me to where the OEM untouched timing maps are published, please post to this thread. Note that the original untouched Honda ECU map is likely different than the Hondata FlashPro "return to stock" map - the RTS map I've seen has 30 degrees ignition in this range, and a bone-stock S2000 I test drove at a dealership showed 35 degrees ignition in that range.

Net, the return to stock may be in the same ballpark in some ranges, but I'd love to see what a stock, untouched Honda ECU is offering timing-wise in those bands just to double-confirm vs. the stock '04 I drove & logged last week on a test drive.

cujet

I'm a bit late to this thread, and I don't have specific instructions for you. Other than to say, I've tuned engines since 1976. One thing that's often possible is to run a lean air/fuel ratio and significantly advanced timing, for improved MPG. You can't do one without the other, in general.

For example, Ford's 5.4L V8 has been tested at extremely lean A/F ratio's, with appropriate (more advanced) ign timing to account for the much slower burn of such a lean mix. BSFC improvements were impressive. Ever engine is different, and interestingly, some engines can improve BSFC by almost 25% with lean of stoic operation at low and modest loads.

Throttle by wire is a nice feature here, as the throttle plate is typically more open during extremely lean operations.

I tuned my turbocharged Mazda 1.8L to 17 to 1 A/F ratio during part throttle, low load conditions. I don't recall exactly where I transitioned to 14.5/1, but I think it was around 4 or 5 inches. The result was an improvement in MPG under certain conditions, and much less willing engine response during part throttle operation. Nothing, nothing, nothing, waaaaaaaaaa. Throttle by wire would be the proper way to retain "feel" while operating lean.