ok so i did a vtec swap on my 95 sedan obd1 and i also bought a p28 ecu. now i have it wired but vtec will not engage. i've had the vtec on a switch and i know it works.. i have no cel on and yes the cel works, for some reason its just not kicking in from ecu. heres how i have it wired

a4 pin for vtec and d6 for oil pressure sensor


oil pressure sensor ground... grounded to the thermostat housing.

 

How do you know it's not engaging?

 

because i went to 5k rpm and it dont engage... when it is engaged it goes to 7.2k and i would feel it. i put it on a switch from battery to the vtec and went down road and fip the switch and vtec kicked in yo! but the ecu wont do it.

 

Double check the A4 wiring between the ECU and where the switch with 12V wire is tapped into the A4 wire. You may have a break in the wire, beneath the insulation.

 

well i have the a4 wire .. wired straight to the vtec .. its wired up right the wires go from the ecu ..about 18 inches then hook up into the vtec and oil pressure sensor.
but what gets me is there is no cel and if a cel is on then vtec dont work.. so im lost at the moment. i have check the connections and tested them and al is good

oil is about a quart or two low so im gonna go buy a quart real quick

 

filled oil up and nothing still the same......

 

ive put the 12v+ from the switch to the a4 pin and it will kick in when i flip the switch
but not by its self.. there is no juice coming out from the a4 pin to kick in vtec.. and i have no cel on..i have no clue what it could be... ronj and advise?

 

If the wiring is good and it works the way you say it does, then either the ECU is the problem or there is a random thing keeping the ECU from letting VTEC engage.

 

yea there is no juice coming out of pin a4 ... im gonna goto a local cops house he's a friend he has a 95 civic coupe ex that has some damage to the driver door that he wants 500 bucks for and see if he will let me borrow his ecu just to see if thats my problem or not... this bugs me because the ecu i took it out of a complete stock coupe ex that had a blown motor and the ecu had never been touched so i figured it would work... but when i do jump the vtec with the switch with it still hooked up to ecu the cel comes on for the vtec so i know the ecu has a connection... ill keep ya posted
but those pics i took would be great for a diy.

 

ok so i just drove it down the road in 3rd gear and keep it in high rpms while wiggling the wires and VTEC KICKED IN YO! the a4 pin isnt getting a good connection to the ecu. but to let everyone know vtec aint **** without it being wired into the ecu.
there is a very big difference from it being on a switch..