frankyknuckles

I've had the Mugen CAI installed for about a week now, so I thought I would give you an update on it.

I think in the ECU requires a few hundred miles / a couple of days to adjust to the new air flow. But I am more and more impressed with the new setup. The two most notable differences are

Throttle response - this is much improved, even in 4th/5th gear at lov revs, the engine picks up alot better and more smoothly, obviously in the correct gear at the correct revs, the throttle response is razor sharp.

VTEC crossover is now alot more pronounced.

In general terms, the engine seems to be 'on the boil' all the time in any situation, the CAI really has transformed the car.

My other point of this thread regards Wide Open Throttle (WOT). I have had the car for about 5 months now, and I have been very lucky with regard the weather this year and my first convertable. When I fisrt drove the car I was very cautious of it, but over time I have learnt more and more about the performance and handling characteristics. But (and this is what I love about the car), I am still learning. Over the last week or so I have been using WOT as much as possible during hard acceleration.

Does the ECU change map setting when using WOT? (ie, does the ECU differentiate between WOT and normal throttle application).

The reason I ask is that the car litterally bursts into life under WOT and is alot quicker.

This is almost a silly question becuase obviously the car will be quicker with full throttle rather than a little throttle, but the whole engine characteristic seems to change under WOT, response, noise, performance, the whole nine yards.

Or, have I just learnt another aspect of driving n/a cars? My other performance cars have all been turbo powered, where WOT was not so much of an issue, part throttle was more than adequate.

Cheers

franky

Turtle

At part throttle the ECU uses the O2 sensor in the manifold to adjust the fuel mixture according to what it's aiming for. This adjusts the fuel trim, and is what the 'learning' when changing parts refers to.

Past a certain throttle opening (which is pretty low, but variable. Can be 30% or so.), the ECU goes open loop. Here the ECU runs fixed fuel maps, with the correction from the fuel trim learnt at part throttle closed-loop running factored in. Some people call this WOT, as it's open loop but it can be confusing because in the carb days WOT meant only wide-open-throttle.

If you're careful on the throttle you can do in-gear accelerations runs with the car in closed loop mode, and again part throttle but enough to go open loop. It's possible to feel the difference.

Biggest thing you're noticing is that feeding the engine air at a consistently low enough temperature stops the ECU from going conservative. The Mugen CAI does add some power right across the rev range as well. But to get the most from it, you need other changes. Then it really comes on song....

-Brian.

Lurking Lawyer

Brian, not related to this thread but as a matter of interest, would fitting a PRM intake have a similar effect on the ECU?

The reason I ask is that the first couple of tanks of fuel after having mine fitted recently gave me around 20% reduction in mpg, despite not having changed my driving style and the miles having been done in comparable ways to previously in terms of mix of motorway and other roads and speed travelled. Mpg returned to normal on the third tank however. Is it the case that the ECU has to "learn" to deal with the change in the amount or type of air it is receiving from the PRM in contrast to the AusS2000 CAI which was fitted previously?

Chris Type R

Brian, have you ever considered writing a technical / tuning book about the S2000 ?

Turtle

Mark, there are all sorts of things that can affect the fuel trim. You will see a difference in mpg when making changes - a bigger difference with an exhaust manifold change than the intake generally.

I've diagnostic kit that can hookup to the S and show pretty much everything that's going on to find the problem.

My guess? The PRM isn't a cold air intake. While you'll get some power gains from the intake itself, in a lot of situations you'll be intake radiator exhaust. When the ECU sees too high a temp, it adds quite a lot of fuel to cool the intake and avoid knock/detonation. The ECU is more conservative than it needs to be, which doesn't help matters. A 5 minute run with the diagnostics hooked up, would give you an accurate answer.

As to mpg, I've worse mpg than stock on my car, in the level of tune it's at. At one stage of tune, I had better mpg - possible if you use a V-AFC or change ECU as the standard maps run richer than they need to. For example, the Mugen ECU runs leaner at it's richest than the stock ECU at it's leanest. So running the Mugen ECU can (depending on what else you've done) pay for itself in fuel savings over time. Strange, but true. Of course you'd buy it for the performance! On my car I couldn't give a stuff about the mpg - and I'm doing a lot of miles. The circa 160ft/lb's of torque I do care about

-Brian.

steve_the_greek

Honda-R members will have already read a piece on the S by Brian in the club magazine - he's one step ahead of you !

frankyknuckles

[QUOTE]Originally posted by bmarshall
[B]But to get the most from it, you need other changes. Then it really comes on song....

Lurking Lawyer

Cheers, Brian I wasn't after a definitive answer, as I know there are other variables as you say - I was just interested to see whether the change of intake and the "learning" was the likely reason, especially given that most other people who had fitted PRMs hadn't noticed any particular changes.

It's back to "normal" again now, so I'm not going to even try to get my head around the complexities of the different factors which interrelate in determing mpg!

Franky, did anyone tell you before you bought this car that it was going to be a complete and utter moneypit?

Turtle

I wouldn't necessarily use the Mugen exhaust manifold

-Brian.

frankyknuckles

but you were selling / have sold your spoon setup, so what's the score