haha sounds simple enough but i've never done it though so i'm lost.

 

I'll post up screen shots for each later...

 

I'm willing to bet that the difference at full load is simply that the intake valves have boost behind them helping them to open, making it easier to turn the cam shaft. The exhaust valves have lots of pressure holding them shut right after we just ignited our air / fuel mix. All the back pressure on the valves is probably exerting force back onto the retard mechanism and the oil pressure can't fully keep up. And I'll bet the ECU has no way to compensate.

 

Probably, I'm going to tone it down and level the boost off when I put my cams in this weekend. The hard part is keeping the anti surge Green out of boost.

ATR logging, its had MIVEC logging for awhile.

Here is a good little vid on the inner workings of MIVEC

http://www.youtube.com/watch?v=Bb4zdcD0G-Y

 

does ATR show exhaust mivec never reaches its target?

 

Yes both exhaust and intake lag a bit during spool up, I imagine the way the oil is added in that it takes quite a few cycles for the cam and crank sensors to make sure they don't over shoot.

Basically if I go WOT at 2000rpm and my target is 35* on the intake side it doesn't reach it until 2300rpm, the exhaust target is -25* and it doesn't reach that one until 2766rpm. On the exhaust side it jumps quick to -20* but once it hits there it only goes -1* per every 100rpm or so. I'll bet its some sort of failsafe in the coding.

Once it hits -20* it must limit the oil pressure addition per cycle to ensure you don't over shoot and smash a valve. Or it could be where the actual oil return lines are routed. Maybe the intake and exhaust returns are going to different places and the oil is getting restricted. Either way still works like a champ for spooling this bad chicken.

 

I feel that the quick ramp to 20 then slow increase to 25 is due to the ECU applying pressure to make 25, but the cam has too much force on it to hit 25, and it lands around 20. Then the ECU slowly starts compensating till it hits its target.

 

ok - well I am not convinced that the MIVEC lag was/is my issue.

Ever since reinstalling the stock cat I havn't yet had a problem (touch wood!!!)

So given the cat appears to be a free flowing one - why would it cause problems?

 

Deep down I thought that Mivec causing the knock would be a dead end. When troubleshooting my friend's car, we investigated all of that.

Hopefully you just got a crummy cat, Tephra. I have seen so many aftermarket cats that look nice, but prove to be junk when the rollers get going on the dyno. I have seen few that are even better than the stock unit. That said, Bryan at GST tested a mil.spec unit, and it was very good. They have a bolt on Evo X unit now. Just food for thought if you absolutely can't get it to knock on the old map on the stocker cat.

Real glad the knock is gone!

 

Are you hitting the same load cells with and without the HFC?

 

yeah I will need to check the logs... my thought is the cat might allow slightly quicker spooler, so I would never hit those timing cells without the cat..

but really the timing wasn't that bad...

 

If you're basically hitting the same boost/load cells the only thing I can think of would be an EGR type effect with a more restrictive exhaust.

More back pressure due to a restrictive exhaust causes more exhaust pressure build up in the exhaust manifold. Durring overlap, not all of the exhaust gases can escape or some revert back into the combustion chamber due to the restrictive exhaust causing an EGR type effect. Exhaust gases entering the combustion chamber will help cool the combustion temperatures lowering the chances of knock.

 

 

SiC, so your saying the stock cat was causing reversion ? and now the HFC isn't, so what does that mean in terms of tune requirements?

 

All I can think of is less aggressive mivec settings and/or lowering IGN timing with the HFC.

Now this is all assuming there is no physical damage to the engine.