Hmm. interesting.. Well theres alot of stuff that goes into blending the fuel so its totally possible it could affect AFRs.. But i'd look elsewhere to just rule everything else out. if yo uhave any logs from before you noticed the fueling issues, check your inj pulse width and see if its simular or if its alot different, that will be a good indicator if theres some adder table somewhere screwing with you..

 

ok I did a bunch more pulls today.

however the AFR results are a little inconsistant:

This two are back-to-back:
1:

2:



These 4 are back-to-back, but 3 hours after the first two (^^), 5C cooler, and raining. ALSO I SWAPPED THE RELAY:
3:

4:

5:

6:

 

The AFR looks OK to me.
The knocksum is really low.
What happens if you rev the car out to redline with the fueling and KS?

 

probably be about the same, might pick up a little knock (3) uptop.

but that was never the concern, this whole thing started because of the spool (or shortly after) knock...

so if it was a relay OR fuel pump issue, should I expect the problem to re-appear by now?

 

IMO, its very unlikely a relay if you have already switched back, but I would keep them swapped to a known good one (headlights) to be safe.

I knew about the spool knock issue, but I had read about you downshifting and hearing a ton of knock, and am wondering why that has not come back yet.

I assume you are not back to the original map that was leanest? I'd definitely go no leaner on this new DP and HFC, you don't want to see insane knock like that ever again.

The only good point was that even if you were not logging at the time, you can hear knock that bad, and know to get out of it.

Just monitor it closely.

 

Well the drop to 3rd knock was I think spool knock again...

This tune is my old (working) tune + 1pt in the fuel map... so yeah I wont go back to the original tune, since that will probably be a bit too lean, I might lean this one out a little since its still rich in parts. But only slowly and doing plenty of pulls to ensure there arn't any lean spikes...

I might try and get someone to send me a couple of the blue relays just incase!

I leave my OP20 logging ALL the time THats the best thing about the OP20.. inbuilt logging

 

i really need to use a dyno, this street tuning business is ok if you dont have any problems, but if you do have a problem just makes it too hard

 

I've just had a brainwave as to why my AFR's are a bit odd

when I did the frontpipe (down pipe to you guys) I noticed that the bolts wern't super super tight, and I thought at the time, "hope this doesn't leak"

if its leaking then that will upset the AFR's... hrmm guess I will be jacking the car and checking for soot and then tightening...

that makes sense actually because the car feels really "bogged" with this rich fuel map... but the AFR's didn't really show that much difference...

ok ill check it out and report back!

 

Well I tightened up the frontpipe (down pipe to u guys) a bit.

However my AFR's are still leaner than I expected.

So the possibilities are:
1) exhaust leak causing WB to read lean
2) bad WB sensor - unlikely since its brand new and properly calibrated
3) fuel pump on the way out
4) relay shenanigans

Now I will discount #2 since my bad knock was probably caused by a lean condition

Sorta why I discount #1 as well, exhaust leak wont cause knock, yes it will READ lean, but not actually be lean

#4 might be a factor, but given I have swapped the relay and havn't seen any discernible change in AFR I can't see it being a factor

So that leaves the fuel pump going bad. How can I test this theory out?

 

Alright me and Hollywood had a small chat today regarding leaning out during spool up.

We noticed with aggressive intake MIVEC settings, the EVO X will lean out no matter what you do to the High Oct map. If you lessen the aggressiveness on the MIVEC it will richen up the peak boost/spool up.

I see this over and over again with my car. My peak boost AFR's lean out due to the aggressive mivec, then return to the 11.xx baselines rest of the pull. If I lower the intake advance cam the car will richen up.

 

There must be some table somewhere thats a fast spool fuel modifier or somthing that hasn't been found in the rom.. If your airflow/load are mapped out properly you shouldn't have lean spoolup unless theres a modifier to the main fueling table just for this purpose. I think you'll notice it richer with less intake advance because your spool will likely be somewhat slower with less intake advance. Next time I have an evo x on the dyno I'll put it in steady state and try to hold the areas where spool occurs and see if after X amount of time does the fueling change within the same load area.. This would be a clear indication theres a modifier table somewhere..

 

yeah I have a theory on MIVEC..

its called over-scavenging - maybe having too much overlap at lower RPM means we are just flushing fresh air straight out the exhaust, which is why its super lean.

the other thing (more plausible) is that aggresive MIVEC has put so much more air into the engine that the stock fuel map is ULTRA lean, so you need to ADD HEAPS of fuel to it to get the proper AFR...

 

Well I'd think if the fresh air is going out the exhaust it would be richer since the MAF has already metered that amount of air and added fuel acordingly. Also, I doubt your over scavenging, I can almost say with certainty that the backpressure in the exhaust manifold is higher than the pressure coming in from the turbo on the stock turbo/manifold setups, so your probably getting some natural EGR affect early in the stroke.

On other cars I've done with variable cam timing, more advance on the intake usually requires less fuel down low, and more fuel up top provided theres no backpressure issues at higher RPMs. If your fuel demands go down as RPM goes up with a lot of intake advance then your probably over advanced on the intake for the pressure differential your encountering.

 

It's because of the mivec. Do a pull with the stock mivec and you'll see.

- Bryan

 

yep..

well i have been looking at all my previous pulls (start of dec 2009) and they all have decent AFR during spool, ie 18psi i am at 12:1, but soon after that I get to 11.5:1

all my most recent pulls I see 13:1 @ 18psi.

that WITH the fuel map richened up by 1 full point...

Bryan - do you have any AFR data for a HFC configuration? ie how much did you have to richen up the fuel map when adding a HFC (or TP i guess)