So Ive had my k20 swapped hatchback running for around 3 weeks. It ran beautifully on the basemap provided with the AEM EMS.
I began tuning the car last week, and on the LAST WOT run of the day, Vtec just failed to engage.
I dont know if its coincidence or detrimental, but when I began messing with the timing, the next run, VTEC just didnt activate.
So now, a week later and a bald head(from scracthing it so much), Im truly stumped.
VTEC engages just fine when the car is cold, OR, if VTEC hasnt engaged in about 30 seconds.
If I run through the gears, by 4th gear, VTEC engages and dissengages(rather harshly), and finally "fizzles" out. If I cruise for 30seconds to 1 minute, and try it again, VTEC engages, then falters, then dies.
Things checked:
Wiring; all good.
Logged this in the AEM EMS, it says VTEC is on throughout this ordeal.
Knock isnt high enough for the EMS to flip out, pull timing, etc(2.5 volts is the highest it goes).
Pulled the valve cover, everything looks good(except a cam retainer bolt broken-off in the head, rather trivial though, there are 15 more).
Changed the oil from 5w30(worked fine) to 15w50 to help narrow any oil pressure problems down.

The only thing I havent done is pull the VTEC selenoid to check for garbage in the oil passages, as it DID come from a Salvage Yard(23,000 miles).

Any ideas!!? Ive heard of other's having VTEC issues, but never really found a solution.

 

bump for cody..

did you check every wire?

could you stick a stock ecm in there?

 

Ill try a stock computer right now, but I havent done any Immobilizer preventatives(except a seperate fuel pump circuit), so I dont even think itll turn over.
Pulled the Vtec selenoid off, tested it, all is good, except still not VTEC(at least not solidily).
Im going to try hard-wiring it, or perhaps getting an MSD RPM switch and just rocking that. Tuning will be easier this way, expletive i-VTEC

 

good luck man. the msd sounds like a good idea, as long as the ecu is compensating for the vtec w/ enough fuel. i assume it would be, since you said it actually thinks vtec is on...even though its not.