ejectseat

Can anyone help me w/ the vtm wire? (hooked up field sfc) It's a green and white wire on the field unit, the one you're supposed to run to the ecu side and cap off the engine side. My car wouldn't run right after installing, then we disconected the vtm and reconnected stock vtm wires and it was fine. Now my vtec engagement relies strictly upon rpm's, not engine temp, or oil pressure. WTF? I read that the diagram for 5th gen ludes listed the wrong wire to tap into, but for 4th gen's? any help please.

ludefreek

this may help

http://www.apexi-usa.com/productdocu...afc_update.pdf

ejectseat

that's the wire I tapped - I ran the green and white line from the sfc to the ecu side, and capped off the motor side. Check engine light every time. Maybe if I tapped into the line w/o capping it off? help

ejectseat

Do the VTEC controllers only operate using the RPM signal and not the oil pressure?

ludefreek

have you checked to see what the actual code the ecu is throwing. this would be something to check on. and double check all your other wiring. make sure nothing is backwards or the such.

ejectseat

yeah, i even re-soldered ALL the wires a second time. The code it threw was two long blinks followed by two short blinks. i printed up a decoder and pretty much got no where, but I think it meant a code #22.

DirtyLude

You realize that you don't tap into it, right? You cut the wire and run the V-AFC wire into the ECU. I would recheck the wiring to make sure you didn't run the wire to the firewall or something crazy like that. Also check to make sure the VTEC IN signal wire is connected properly, since the VTEC signal from the ECU tells the VAFC when to signal the VTM wire.

DsITR

I remeber reading something about this on ntpog.org, there is also a link to some guy named Arax explaining how the apex'i instructions were wrong...here's the links http://www.ntpog.org/mods/fifth-afc/wiring.shtml this one is prolly more helpful. http://www.members.aol.com/ryoucold/...pexi/apexi.htm
hope this helps..

ejectseat

yeah, i rechecked the wires like 8 times, then had my friend check it over and over too. we ran the line into the ecu, and capped off the engine side. Does anyone else's sfc or vafc rely strictly on rpm signal, and not oil pressure as well? You can tell because if you sit at your lift point, 5000rpm's or whatever, while running it will jump in and out of lift. I know because I have a small light run to vtec solenoid telling me when it's in lift.

mattmw88

I just did this to my car and had no problems...do you have a red packet w/ instructions? That gave me pretty clear and consisce advice. Either way the problem you having is with the vtec pessure switch wire. In a stock car once the engine gets to 5k the oil pressure will hit a certian psi and trigger vtec. It sends a signal down the wire to your ecu. What you want to do it be able to controll that electronically. Cut the wire and cap off the end at the fire wall. Next hook up the proper wire from the fields wiring harness to the same wire, but on the short part that goes into the ecu. Now your controller send that signal to the ecu to tell it to engage vtec at what ever incramite to put it at (I'd suggest 45 for ever day and 4 for extremes) even in nuetral. so basically you don't even use your vtec pressure switch inside the engine. oh, and code 22 is your vtec pressure switch/vtec malfunction. Let me know how this turns out or explain exactly what you did when wiring. good luck!

DirtyLude

I'm not certain where that last reply came from, but what do you think we've been talking about here? I think we've established that he needs to connect the VTM wire, there's multiple links to the correct way to do that already posted.

Oil pressure does NOT trigger VTEC. Oil pressure is used push the pin in and lock the rockers of course, but VTEC mount and unmount are triggered by the ECU, which is obvious since the VAFC is taking over this function. The VAFC also does not send a signal to the ECU to activate the VTEC solenoid, it trigger the solenoid itself. The stock ECU uses the VTM (VTEC Pressure Switch) as a check to make sure that VTEC actually activated when it said it would. If the VTM wire does not activate right when the ECU thinks it should it triggers the code 22 CEL.

If you want to check that the VTM fake out is working properly get a friend with a multitester to sit in the passenger seat. Set the display on the VAFC to show VTEC IN. VTEC IN will show you when the ECU is triggering VTEC, which is generally pretty useless information except for this test, since you really don't care when the ECU wants to trigger VTEC. Drive the car and get the RPM's up to where the stock ECU would trigger VTEC. Wait for the VTEC IN display to show that it's on and then check to make sure (using the multitester) that the VTM hack wire unto the ECU has turned on as well.

I've installed dozens of these things until I'm sick of them, and (providing there's nothing wrong with the unit, and I've never seen a problem with one) there can only be two things wrong. Wiring or setup. If you're absolutely sure that your wiring is right and you've checked it with a multitester, let us know your what setup is. Also sometimes these damn things reset to default parameters on there own. Make sure your setup information is still valid.

If you are getting VTEC cycle back and forth at 5000 rpm, it means you haven't set your mount/unmount setting properly. The mount setting should always be at least 100 rpm higher than the unmount point to prevent that switching back and forth.

ejectseat

I didn't have any instructions, i pulled the translated ones off the net. I tried running the wires exactly like you said, and checked them again and again. we capped it and did everything right. So that's how the unit operates, strictly off of rpm signal. that's why you can hit lift in nuetral, and probably even when the car is cold. that sucks. oh well

DirtyLude

The stock ECU doesn't care about oil pressure either. There's only one oil pressure sensor that goes to the ECU and that's the VTEC oil pressure switch. It's only use is to verify that VTEC has been activated. The oil pressure switch is after the VTEC solenoid so it will only receive pressure after VTEC has been activated. If there's not enough oil pressure to push the VTEC pins and lock the VTEC rockers, then there's not enough. It's strictly mechanical.

You're right, it will activate VTEC even when cold, but you should be using your own descretion when the engine is cold. There's still a 6500 rpm cold rev limit.