joelmatt89

so first my vtec wasn't engaging because the wire to the solenoid was bad. I fixed that and it turned off the cel, so i took it out for a test drive and vtec engaged, then i re ran the wire that i fixed it with in the conduit with the rest of the wires. Then i took it out for another test drive and it wasn't engaging again. So checked the wire again it had .8 ohms from the ecu so thats pretty good, the solenoid had 17 ohms thats where it should be the wire to the pressure switch has .7 ohms and the ground is good as well. I don't have any cels and the oil is full, the car was warmed up, i tried it a few times and it just would not engage what could be the problem. What are the other things that could keep it from engaging, i doubt the ecu is bad and i don't have an extra so i would like to look for other options before finding one to swap.

Edit:
after reading this thread https://honda-tech.com/forums/honda-prelude-4/official-%22why-vtec-doesnt-engage%22-thread-830163/, i did the following, inspected the screen... that looks fine, tested the solenoid... it worked, checked that i have voltage to the pressure switch... i do and it also has continuity so that is good, my speedo and tach work fine so i would assume that isn't the problem, what else could it be my oil was changed three weeks ago although it is already dirty but not thin it just isn't like the color of honey, it just seems like it is more than a coincidence that it stopped working when i reran the wires, but all the wires for vtec are fine and i just have no clue what else to check i really would appreciate some help on this. What else could cause vtec to not engage that would also not throw a cel. If i can't find anything else to check the things i can think of are, try to find a gauge to do that oil pressure test mentioned on that thread, i guess there is a small chance my ecu got damaged while i reran the wires although i never even touched it i don't know how it could go bad, maybe change my oil and see if fresh oil helps any. Other than that i have no clue

joelmatt89

bump to first page, come on guys i am desperate just throw out your ideas ill try them all

joelmatt89

okay maybe this will help i took it out for a test drive and this is what i found i connected a lead to the wire for the vtec solenoid and i am getting power about 14.3 volts when vtec should have kicked in so that would mean that the problem must lie somewhere in between the wire to the solenoid all the way to the mechanics actually engaging the lobes,so then i checked that the wire was good by disconnecting the plug off the ecu than i gave it power off the battery and the solenoid was def. clicking, so that must mean that the problem is mechanical. But it still just seems so weird that it started doing it after i messed with the wiring but all the wiring seems to check out. So I checked the screen inside the vtec thingy it seemed fine nothing visually cloggin it but are there any other mechanical things i could check other than that, that would be in between the solenoid and the actually engaging of the lobes. I don't really have a good understanding of the whole mechanics of it engaging, are there any tests for that. I guess i should try doing the test to see what oil pressure i am getting at the vtec. But are there any other ideas

joelmatt89

yeah ill just keep bumpin this till someone can tell me why my vtec would not engage even though my solenoid is opening when it should

eg613

have you check your oil ? when it gets low it well not work, thats really the only thing i can think of just check your oil man and good luck

joelmatt89

the oil is full, thanks for trying to help. Like i said right now i know that when i hit 6000 the vtec solenoid is opening, but for some reason vtec is def not engaging. I have no clue i wish someone could help me on this cause it was working fine like ten minutes before it happened and then it just stopped

joelmatt89

bump

kp

Check for CELs and change your oil!

j/k

It sounds like you have checked everything. Your pressure switch has continuity (which it loses when it reaches the correct oil pressure). You're speedo is functioning correctly. You've checked that your vtec wire is all one piece and not broken. The vtec wire has 14 Volts going through it at the appropriate rpm. And the solenoid clicks when you put 12 volts to it. But this is very strange...have you had your head rebuilt or taken apart recently? There are a few very crucial parts in the head that allow the oil pressure to travel to the rocker pins without squirting out all over the place. Pretty sure theres one o-ring in particular you have to be careful of.

joelmatt89

i haven't taken it apart recently but the previous owner did put gsr cams in right before he sold it to me, but would it make sense that it would work fine and then all the sudden stop. I would think it wouldn't have worked at all. I know have said this a few times but it just seems more than coincidental that it stopped working when i re ran it, but i have checked everything multiple times and i have reset my ecu a few times. If i do the oil check like that guy said in that thread i mentioned and i am getting the correct pressure at the vtec is there any way that it could still not engage. On the topic of oil, the reason i would rule that out is because i just changed it, and it doesn't look bad in terms of viscosity it is just a dark color, although i may be consuming/leaking coolant so maybe the oil could be a little bit thin causing vtec not to engage. I just don't want to change it because i just see myself spending twenty bucks and an hour to change it and then i go out on a test drive and it doesn't engage which will then be followed by me pounding on the steering wheel and loud noises.

Does anyone have like a insanely detailed diagram or write up on every single component of vtec, cause that could really help

joelmatt89

hmm this is weird i just jacked the car and i realized that i had power at the solenoid at all times... could this have damaged anything, the weird part is i don't have power at all times at the ecu so maybe the problem was my wiring man what the heck that doesn't make sense how can i have continuity in the wire but get different voltage at different sides wtf?????

spoon_concept_eg6

first off. what year is your car, what type, what engine, what kind of transmission (Cable/Hydro). Is the speedometer still working? if the speed sensor is not working the vtec will not engaged. Is your ECU stock? if so, see if you can find a Chipped ecu. chipped ecu's usually have their Knock sensor and speed sensor disabled. i know this from experience. my 93 Gs-R had the same problem. the speed cable popped out of the transmission, so i had no vtec. i pluged it in and it worked.

Also if you changed the cluster it may have effected your vtec too. that's if its a faulty cluster. i bought a JDM cluster for my integra and the vtec kept turning on and off. i check the cluster and it had a crack on the sotter board.

so if you speed sensor is out or if you just changed your cluster, you may want to double check.

if you dont have a chipped ecu ask a friend or something. you might find that it could be the ecu

joelmatt89

the car is a 1993 ex coupe with a b16a2, running on a p28 ecu chipped by phearable.net, every other one of your questions it you read my previous posts were already answered. Know i am mad because i just realized that the solenoid wasn't getting power all the time it was just getting power whenever i unplugged it. when i tested it while it was plugged in the wiring was working exactly as it should be so that puts me back to square one, this is making me so mad it is getting exactly what it should be to the solenoid i guess i need to try doin that oil pressure test thing now. Man i really thought i found the problem that time.

joelmatt89

bueller