I recently street tuned my car to a 12.5:1 A/f and it is dead on. I'm also running 22.25 degrees total timing at 7psi.

For some reason even though the car runs flawlessly, after VTEC engages from about 6000rpm and up it just doesnt seem to continue pulling anything like it does from 3000-6000rpms.

I KNOW its switching to the vtec cam lobes because I have it manually activated via a VAFC set at 5400engage and 5100 disengage.


Another issue that MAY cause it... is that I'm running a thicker Cometic HG that drops my CR to around 9.6:1 and I dont have adjustable cam gears, though I did however cut 2 degrees at the dizzy to compensate for this.


Any ideas?

 

I assume you have a boost gauge? Does it hold steady?Also whats the specs on your turbo?

 

check wg?

 

How are your spark plugs gapped?

 

Thats funny. my car does the exact opposite. My car is super slow at lower RPM. Even if I get full boost at 3500rpm (7psi). The car isn't fast until vtec (5600rpm). Then the car pulls hard.

 

what turbo are you using?

 

I'm using a T3T04e, I forget the specs on it however, but the boost is holding steady at 7psi according to my datalogs so I know its not the turbo. Spark plugs are NGK's 2 steps cooler, and gapped at .028. Another thing I forgot to mention that your question reminded me of is that I've been having startup issues when the car is cold, and the RPM gauge will jump around - so that definitely points to the ignition coil, which could ALSO be the culpret if it cant provide enough spark in the higher RPM's (but still, the power drop off seems to occure shortly after VTEC).

I have a 0.5bar spring in the 38mm TiAL I'm running right now, but its extremely rare for my VAFC (which I use just to monitor peak RPM and peak boost) to ever hit exactly 0.5bar after a WOT pull. It usually peaks at 0.46-0.49bar.

Regardless though even if I DO have a boost or WG leak of some sort, shouldnt the car still pull straight to redline since theres SOME positive pressure going in? - I mean it pulled awesome just NA!

Its a weird issue and I'm not SUPER concerned with it because the fully built motor I'm working on now is going in in about a month, but its something that I'm curious to find an answer for

Also, if it was a timing issue due to the thicker headgasket, wouldnt the entire powerband be shitty? The tires break loose in 2nd at about 5500rpms and I've got the ultra-conservative stock part-throttle timing map bumped about 10 degrees and everything works perfect with zero detonation so the car IS running good...

Keep the knowledge coming guys, I really appreciate it and actually love troubleshooting this ****

 

I was having similar issues with mine, I dropped my boost ignition retard from .9 to .8 total timing is 24 degrees (up from 22) and let me tell you, it pulls much better now. I'm thinking of even upping it more to .75d/# Another possability is that your running too small of turbo, but who knows, it could be a number of factors. Try bumping your timing up a little bit and see if she likes it

 

Ya I think it has to do with your timing map. Althought, I am not a master tuner

 

The things you descride do seem to point to an ignition problem...but does it fall flat on its face or does it just not pull as hard in the upper rpm band? A t3/t04e on a b16 should be able to pull no problem. If you have a .48 a/r turbine housing, that could be the culprit...however, I would doubt it.


Modified by diputs at 10:37 PM 9/13/2004

 

You won't respond to my PM's, so when you see this please PM me!
Who tuned the car, you? So the tires start to break loose at 5500 and then the power falls off?