ok i got my 99 si civic for about 1 month and since owning the car i got these code for the check engine light. P0500 Vehicle Speed Sensor (VSS) Circuit Malfunction, P0302 No. 2 Cylinder Misfire, TPS - throttle position sensor . would these be the cause of preventing my vtec to engage? if not than if anyone could tell me where to start? vtec wires are hook up. im also running a p2t ecu the ecu for the b16a2 engine.

 

speed sensor tells you how fast your going via rpm. if its malfunctioning the vtec won't know when to kick in since vtec engages on a rpm basis. they cylinder misfire is pretty bad and tps is bad as well. I suspect if you fix those problems your vtec might kick back in gear. ecu's do have fail safes :D

 

^^yeah no speed sensor = no vtec. im pretty sure if u got a code for the TPS too u won't have vtec. check the wiring on the TPS and speed sensor for any shorts. if u dont find anything then pull out the VSS and see if it broke off. then check the voltage on the TPS to see if u need to re-calibrate it. there are write ups on how to do this somewhere

 

yea ive also heard if u have a code for anything vtec wont work not to sure about that one tho

 

^^^ not true at all

 

thanks guys. my speed needle is working fine but somehow its throwing a code for it. but i have a new speed sensor which im gonna be putting it in tomorrow since i dont work plus a new tps which is going in too. but i remember reading somewhere saying something about low oil can also cause the vtec to not engage too so is that true? and about the code vtec not work, is not true cause i used to have a type r in a eg hatch and it was throwing off some codes but vtec engage perfectly fine,

 

if you are low on oil, vtec will not engage.

so check your oil level regularly.

 

If I was low on oil vtec probably wouldn't be my first priority.

 

oil is a little low but still good. which im going to do my oil change tomorrow. ( bought all the stuff i neeeded for the oil change already ) since i dont work. but that was just something i read about oil being low and not engaging the vtec.

 

You know how to install the TPS properly right? You'll need a volt meter. If you don't calibrate the tps while installing it your car will run like complete ****.

 

your right, i had a tps code in my ek b18c, vtec still engaged, but when i had a vss code, no vtec

 

some code cause it to go into limp mode, like tps. your overall power is decreased but vtec still works. some codes will stop vtec, like vss. so if you throw your new speed sensor on first and clear the codes(disconnect the battery) your vtec should engage, but still in limp mode from the tps code...and def look into the misfire code. check dry cap/rotor/wires with a water spayer one item at a time to look for miss, and check plugs

 

yea im gonna be going down to my buddy shop tomorrow and we'll check everything. like i stated earlier i already have a new vss and a tps to replace the one on the car. so hopefully that would solve the problem i'll update after we replace those 2 thing and see how it run after that. thanks for the help so far guys

 

wtf are you talking about check cap rotor wires with a water sprayer?

 

you also have to have enough oil pressure for the pins to lock

 

i'll be doing alot of stuff to the car later in the morning so hopefully i'll get my problem solve...and i dont get the part where you check all cap and stuff with a water spray

 

gl

 

take a household water sprayer, and give each part of the ignition system a slight mist( one item at a time) to simulate rain/snow/condensation,with your car running in nuetral. if one of the ignition parts is faulty, it will show its self in this test.

 

^^woah.

 

ok i just got back from the shop and we put the TPS and VSS in and it still throwing out the same code. and for the TPS plug it was burn a little so we replace it with a different plug and still the same thing. so now our next guess is could the ecu go bad? if so let me know thanks

 

That is the dumbest idea I've ever heard. There was a guy on here arguing with me a while back that you're supposed to clean your motor while its running and at operating temperature...was that you?

 

Did you calibrate the TPS properly? Did you also clear the codes with either a scan tool or disconnecting the negative battery terminal?

 

yes we did calibate it properly and it wasnt done in a garage. one of my buddy has a autobody shop which i took the car to so we can work in it since it was code and they were the one who done most of the work..

 

wow

this wil cause so many different problems, including blowing ur ecu

 

https://honda-tech.com/forums/hybrid-engine-swaps-18/%5Bfaq%5D-%22my-vtec-doesnt-work%22-1812135/

instead of guessing