I have an OBD-0 B16A1 in my 89 Civic, running on a stock PR3. I did the swap about 3 months ago. It worked good at first, and about a month and a half ago it started cutting out sometimes, and different points. Recently, it just hasnt worked at all. Today I went back looking for loose connections in my wiring harness, and soldered every wire between the ECU and the vtec solenoid, and the vtec pressure switch. I went and drove it, and it seemed to work perfectly.

Just now, its does not work at all again. I have access to another vtec solenoid and pressure switch, but I'm not so sure that is the problem. I'm wondering if it isn't one of the other things that allows vtec to engage. Does the knock sensor affect it? Is there anything else that does?

And, the car is full of oil, and completely warmed up.

 

vtec wont work when your car is cold it also wont work when you have low oil pressure... make sure you dont have any ecu codes cause a number of them can throw off vtec

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by mustbenu &raquo;</TD></TR><TR><TD CLASS="quote">vtec wont work when your car is cold it also wont work when you have low oil pressure... make sure you dont have any ecu codes cause a number of them can throw off vtec</TD></TR></TABLE>

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Patch &raquo;</TD></TR><TR><TD CLASS="quote">And, the car is full of oil, and completely warmed up.</TD></TR></TABLE>

And there are no codes.

 

car may be full of oil but not have pressure
dont really know ur problem but there was a differnce from what he said might be an ailment to what u said
hope it helps

 

you said at one point the vtec did pop? jdm b16s come with a electrical spped sensor...where as you car requires a cable sensor........you need a speed sensor to pop......does your speedo work?

 

Yes, the speedo works. Vtec worked fine for the first month and a half after the swap. Then, it would kick out of vtec at weird places, like it would go in at 4800, and out at 5200, and in at 5500. Or yesterday, worked fine and went out at 7500. This is why I think its an electrical problem. If I had low oil pressure, it would consistently not work, or work only really late.

If the VSS was the problem, wouldn't there be a code for that?

Does the knock sensor have anything to do with vtec engagement?

 

did you check the screen in the vtec solenoid? They can get blocked up and mak it so your VTEC doesn't work. It happened to me. Also pull your VTEC plug and use a clip lead to jumper it to 12v. if it clicks then the solenoid is working. Try these 2 things.

 

^ this man is right....check the solnoid.......specially in a 1st gen....are you trhowin any codes on your ecu?

 

No codes in the ECU.

Jumped 12v to the solenoid and it clicked. I even drove it around for a while like that

 

check the screen yet?

 

I drove around with 12v hot wired to the vtec solenoid, and it did not kick out or hesitate. Theres no point in checking the screen if the vtec solenoid operates properly with 12v on it.

The vtec solenoid is obviously not getting a constant 12v when it should be. The only other things I can think of that can affect this are the knock sensor or the VSS, because those are the only other things that can affect vtec. I'm waiting for someone to answer my original question as to what sensors allow the ECU to send 12v to the vtec solenoid.

This weekend I will bypass the vtec pressure switch to rule that out. What other sensors allow 12v to be sent to the vtec solenoid?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Patch &raquo;</TD></TR><TR><TD CLASS="quote">
Does the knock sensor have anything to do with vtec engagement?</TD></TR></TABLE>

The knock sensor does not effect whether vtec engages or not. If you have a bad KS or not connected, the timing will retard and a CEL will come one. vtec will still work fine.

 

So, the vtec pressure switch and the VSS are all the ECU needs to send 12v to the solenoid and engage vtec?

 

if your spedo is working VSS is working

 

The speedo is bouncy on accelleration, but not too bad. Its always been like this.

From what you guys are telling me, the vtec pressure switch is sounding like the problem. How can the vtec pressure switch be messed up without throwing a code? Does the vtec pressure switch have a screen also?

 

Problem fixed, I bypassed the vtec pressure switch and everything works perfectly.