AP1Chief

SO ill try to make this short as I can.

Car running great on new 372 turbo... last night we had her at 27lbs probaly making 750ish, pullin hard as hell, tuned to 11.1/11.3 AFRs

All a sudden during a pull, AFRs drop to full rich and right before that boost went from 27 to about 30... I FELT the power loss, and short shifted to 4th, this was around 8300 rpm.... once in 4th.... afrs are FULL rich 10.0 and normal 27/28lbs target... IM EBC so it will adjust duty to target boost. ANYWAYS The sudden spike in Boost, and DROP in AFRs, and loss in power, makes us believe it fell out a vtec. Ever since it seems to stay on lo cam. FULL rich AFRs... which indicates its not going to high cam, and sluggish. Builds boost fine, car drives, and engine sounds fine, turbo is fine etc.

SOO whats been done to see whats going on.

Vtec solenoid pulled, tested in 12v source, it does click... pulled fitler, its clean as a whistle. plunger works smooth, no binding or anything like that, spring is not busted.

Test the solenoid from the car to make sure the ECU is commanding the signal (AEM EMS) set all parameters to 0 and TPS so that i could test it with tps changes, car was off... solenoid is clicking away just fine with tps change. SOOO seems the electric side of the house seems all ok.

SOOO maybe my oil pump is getting weak? So hooked up a T fitting to the turbo oil feed line, getting it from teh port below the oil cooler. started car... i see 20-30PSI at idle, on a hot engine... free reved to about 3/3500 seen as high as 75/80 psi again on hot engine... SOOO seems to have plenty of OIL psi..... SOO now we are REALLY stuck in limbo....

I'm trying to figure out if theirs something on the mechanical side of things in the rocker system that could brake, bind up, or inhibit the action of the pins, that's not allowing it to go into vtec.

From a very knowledgeable honda man, said it could be loose or even snapped cam tower bolt, collapsed return spring rocker set? (which idk what that is) or theres something stuck in the rocker or rail assembly keeping the system from engaging?

Ive never ever had to deal with any vtec issues in any of my B H or F series stuff.... sooo i'm lost to what this could possibly be.

anyone with some REAL insight on the rocker vtec assembly and what can happen, id love to hear it.

Basically i'm moving to WA state, around seattle area this week.. so once i'm there and we get a house, ill be tearing the cam/rocker assembly apart to inspect i guess.

something defiantly happened during the middle of that run.... Which i have DATA log of.... kinda nice

thanks for any help guys! appreciate it!

F1TwoThousand

AEM 2 or Infinity? You should be able to log vtec on or off position and start from there. Not sure if i missread your post but vtec will engage at a predefined rpm not throttle % atleast thats what i think

5thgen

I think he is looking for the physical/mechanical answer. The vtec output signal could be working all day, and you could have no vtec. You wouldn't be able to really tell on a log (other than maybe oil pressure) since there is no "vtec ON" type of feedback.

Oil pressure would be the easiest way to track down the problem (other than taking the head apart). Are you measuring pressure post filter/pre filter? It'd be nice to be able to measure pressure post vtec solenoid, but I'm not sure there is an easy way to do it.

F1TwoThousand

Vtec settings, turns out vtec is RPM AND Throttle based only with standalones.

Vtec output tab

Vtec=0(off) per settings

Vtec=1(on)per settings


This is what i have for aem infinity, im able to atleast see if vtec is active per ecu. As far as something mechanical like insufficuent oil pressure keeping it from actually engaging well that id like to know as well

5thgen

I'm saying everything could be normal on the ecu side, and the vtec solenoid could be unplugged. The ecu itself wouldn't know or adjust accordingly.

umair

With the car running apply 12 volts to the vtec sel. You should hear it go into high cam even at idle. That will tell you if everything internally is ok. If so I would point to the ecu as aem is not the most reliable ecu.

Charper732

Chief, i ran into a somewhat similar issue. Looking at data logs of oil pressue, I would start off with good oil pressue. Do a pull starting in 2nd, oil pressure at 75psi, shift into third and pressure would drop from 75 to 50 at ~6500rpm and come back up within 500-1000rpm...my vtec is programmed for 4500. It made no sense whatsoever. A lot of the time it would trigger vtec to shut off because the pressure was too low. Upon pulling the motor, bearings were worn some but not to the copper. Oil pump rotor was in spec, but it was showing obvious signs of ingesting foreign material as it had grooves in it.

anyway, log oil pressure and do a few pulls.

AP1Chief

AP1Chief

ninetysixyenko

Log oil pressure and see if it drops hard at VTEC crossover, if it does you have an issue with the rockers/pins. It's an identical setup as a K motor, and I've seen the pins break and rollers break in K-motors causing a huge loss in oil pressure.

you should pull your valve cover anyways and look.