my tuner is tuning the car right now and so far its been fine it just that right at vtec the car basically falls on its face.

We tried lowering and raising vtec but anywhere when vtec engages the car falls on its face immediately when vtec kicks in

please help asap.

forgot to mention i'm running aem ems with 550cc injectors and walbro fuel pump

 

get a new tuner, i would not trust him.

 

add some fuel???

 

loss of oil pressure?

 

voltage drop, could be a million things

 

ok ok so i'm back from the tuner and here is the problems that we ran into, we even spoke with shawn church of church automotive who made the base map that ran the car without vtec engaged!!!

well specs:
60-1 ceramic ball bearing stage 5 .63 a/r t3/t4 hotside turbonetics
turbonetics evolution wastegate
turbonetics raptor bov
revhard manifold (I think)
custom downpipe 2.5" with wastegate piping welded into it (recirculated wastgate)
550RC Injectors
Walbro 255 fuel pump
AEM EMS
Spearco Intercooler
Custom 3" turboback exhaust

Well when i brought it to the tuner it ran on the 4 pounds spring and we updated the aem ems software b/c it wasn't logging anything past 7k and vtec was disabled on the map provided

After like an hour we updated the aem ems firmware to v1.19 and activated vtec at 6k rpm and installed the 7 pounds spring. We made like 204 rwhp and like 171ft lbps at like 6k right before vtec engages.

Now the problem, anywhere vtec engages the power just falls flat on its face whether at 4k, 5k, 6k 6.5k or even at 7k basically the power band is good and making power nicely and boosting real good until vtec kicks in then it pretty much falls off.

I read some of the previous post on here that states it might be the oil pressure at vtec, but I recorded everything with the defi gauges and oil pressure was a constant 90 right when vtec kicked in.

So we contacted Shawn, and he said that the exhaust might cause restriction, so we removed the exhaust and still had the problem as i thought. He then said the A/R sizing of .63 on the hotside of the turbo might be too restrictive and that the exhuast gas is not escaping from the engine fast enough when vtec activates so that might be why the car is falling flat on its face when vtec kicks in.

So i was thinking to myself my turbo is pretty much comparable to a gt30r which is pretty much what everyone uses here... So I think it might be the custom manifold that I have or my downpipe is too small,
those are the only two things i can think off right now...

I'm about to go crazy and just blow this ^#&&^@^# UP!!! lol

Any suggestions or comment is greatly appreciated.

 

It might be the fuel pump. I'd check that first.

 

I mean even if we moved the vtec through the rpm ranges the fuel pump still provide sufficient fuel to the injectors even when the power falls on its face.

 

what is a lost of power? did power lose itself in the dark?

Anyway, on a serious note, your .63 a/r size will suck ass when it comes to making power. That's what size a/r turbine housing Inline Pro went with on my car 1st and only made ~300whp @ 17 psi, then realized they needed the .8x turbine housing, and some GOOD tuning later and I'm at 450whp.

Not saying its the problem, but it is a good idea to keep in mind that such a small turbine housing IS VERY VERY restrictive on these cars.

 

Lost of power as in car will make smooth power right until the vtec engagement point then it pretty much drops dramatically and picks itself up a little bit after falling on its face no matter what RPM we set the vtec engagement at.

I hope its a tunig issue which i doubt, but it seems that when i searched alot of people are having this issue with log manifolds