NineBolts

So I've been adding a few bolts ons since I had the car and to cut a long story short I'm starting to get worried that the mods I've added are taking the car into the area of unsafe AFR.

Mods are: Mugen catback, Berk High Flow Cat, K&N FIPK but later changed to Mugen intake.

I had a dyno check done at the end of last year, at that time I had an AFR that between 6000 and 6500 rpm rose to about 14.2. Not that different to some of the other NA cars that tested at the same time and the AFR was otherwise in the 12-13 range.

Step forward to the dyno tests that I had done at TDI when I changed the exhaust manifold. The first tests before the manifold change showed AFR in the high 15s. Only mod change was the K&N intake was changed to Mugen. obviously testing equipment and conditions were vey different. I got a better plot with the Berk because it has the extra boss. The final AFR again showed a peak into the low 15s just at the point of vtec.

I don't have any experience tuning but I know that going too lean is a really bad thing. It raises a load of questsions and as I'm looking to get a new Manifold to replace the shonky Berk I don't want to put in a further mod that pushes it out the other side of silly. I've been reading up about these things and there are other reports of guys in the US that have had AFR heading into the 16s after they have fitted intake, manifold, decat and exhaust.

So in no particular order here are some of my confusions.

Most of the time the AFR is where it should be, for a second or few it goes too lean is this really a problem?

The stock ECU with its knock sensor should pull back if it sees anything going too wrong shouldn't it?

All the Dynos have been done open loop and WOT, does the same thing happen in vtec and closed loop?

I'm pretty sure I can be closed loop and vtec, because I have a scanguage and monitor throttle position and loop condition or am I really getting confused?

Should I stop wasting money on bits that don't make it any faster and put my OEM Cat and header back on the car?

How can I get the AFR back under control in a DBW - piggy back ECU?

I think MB had a Dastek, I've read bad reports for Apexi. What about HKS F-Con Greddy or others?

mikey k

Off to the new NA tuning forum with you

https://www.s2ki.com/forums/index.php?showforum=213

Going lean on the vtec transition does seem to be a problem when modding on the stock ECU

s2konroids

Vtec is open loop so when you go into it or near wot itsopen loop by design ignore 2nd o2 sensor.

What would be use of having your foot half way down etc I take it that's what your on about?

14afr when vtec kicks in for a split second is probably okay its not ideal, an afr of 15 is far too lean in wot - all the modded s more or less seem to do this on stock eculs.

16afr is dangerous sweet spot is 12.7 to 13.2 in wot for the s 13 to 13.1 seems to be where its at.

Ecu no idea possibly a vafc2 but it alters the map sensor readings so feck all use when not in wot due to learning but it probably doesn't work due to the throttle as your is dbw I don't know.

Things like manifolds etc will lean it out even more not got, knock sensor the ign timing is retarded when too hot ie conditions that cause ping/detonation are present.

Boab01

Wait till you've had a pax in usefuls car, then buy coilovers. Okay?

NineBolts

Took it for a spin the other day with the SGII set to display loop status and Throttle position sensor. I'm fairly sure that the car was going into vtec while still running closed loop.

Just make me curious about finding out what it's doing under more normal driving conditions. I don't always floor it fully even when giving it the beans.

I know that other ECUs and the Hondata reflash are able to use a window within the rev range where it needs WOT and certain rpms in order to engage vtec but I thought that as stock it was only triggered by rpm.

NineBolts

I could do but...

A) I get more sense out of most of you
B) They don't have the same combination of engine and ECU
C) most of them are Americans.

NineBolts

Better get more than just a pax seat. I hope he's added me to his insurance

MUG3N

I think a change of ECU is the only solution as you saw from the dyno day even in the older cars (Eho's)was running even leaner. With my change to Mugen N1 ECU the car ran so much better, is there no way of getting your ECU reflashed similar to the Americans?

s2konroids

Those ECU's wont work though because he has DBW.

I'm currently thinking your option are:

1. Revert back to throttle cable
2. I think Kpro with extra bits you'll be able to tune
3. I'll ask my mate tommorow but i think a dta standalone ECU S60 will work with DBW.

s2konroids

I dont know about that, what rev range?

Foot flat to the floor?