A friend of mine has a 98 EK Hatch with a B18C1 swap. He recently blew out his GSR tranny and installed an LS tranny.

After he finished the instal, he noticed that VTEC didnt engage til about 6200 PRMs. Is this because of the tranny or what? Any comments or advice would be great!

Thanks guys!

 

I could be completely off my rocker on this one - I just woke up.

Though RPM output is measured @ the engine, not the transmission.

4000 RPM with a GSR trans is 4000 RPM with an LS trans...as far as the engine is concerned anyways, obviously the car is moving at a different speed...So no, that doesn't make much sense, that it could be the trans.

 

check the oil, if pressure isnt right it wont engage till late in the rpm's

 

are you sure it crosses over at this high? if so check the oil level maybe low pressure wont let the car crossover until higher pressure, or maybe some of the vtec wires arent even plugged in ive knocked some wires loose that plug into the solenoid taking trannys out when i wasnt being careful just trying to do a 40min swap

 

what ECU are you running? that sounds like ITR x-over point...

 

I believe its a P72 but im not 100%

 

Well if he changed the ECU, then somebody's not really giving us all the information then.

I'd hate to see the post turn out like:
"My VTEC crossover is wrong after trans swap"

*nobody thinks of anything*

"I changed the ECU though"

.

In any event:
Oil pressure is a possility, yes, it's one of the prereqs for VTEC, including neutral switch, clutch sensor, speed sensor, and a few other things.

Though if your oil pressure isn't high enough for VTEC to engage you usually have bigger problems to worry about than VTEC not working..

 

Sorry about that. I am doin this for a friend so I dont have all of the specifics. But I do know that his speed sensor went out when he swapped it and got a used one to replace the bad one.

So what exactly does the speed sensor have to do with it?

 

the speed sensor requirement for vtec is like 25mph or faster.. the car has to be moving for the ecu to engage vtec.
maybe your friend is hearing the IAB's activating? i heard that you dont really hear vtec in a gsr.. i've never owned a gsr engine.. but i don't really hear it in my ls/vtec.. i hear the iab's more than anything.. but my but-dyno feels vtec kick in

 

I have a built b18c1, and the crossover sounds amazing... ly loud. =P

 

Maybe his tach is off. A buddy of mine had an engine pop because he found out that the 7800 RPM he thought he was revving to all day was actually more like 8700.