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Can the VTec solenoid stick open/closed?

Discussion in 'General Tech and Maintenance' started by Raggedyman, Jun 30, 2003.

  1. Raggedyman

    Raggedyman Member

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    I did a D16Z6 swap into a non-Si car and I completely re-did the wiring harness. In order to pull in the VTec I used an autometer tach and had the shift light pull in the solenoid. I posted this problem the other day but changing the wire that I used on the shift light seemed to cure the problem. I got home from work today and went straight out to tinker with the car again. After starting it up, it idled just barely erratic and I figured it was just from sitting. Taking the car around the block I had to keep working the gas in order to stay running at all. I pulled off and unplugged the VTec wire and it idled just fine after that.

    What I'm wondering is if the solenoid can stick open/closed if it's been sitting for any length of time. Once I ran it around a bit I put the wire back and it seemed fine after that. I'm gonna find a link that I once saw that explained VTec and how it operated...maybe that will shed some light on it.

    Until then, has anyone seen this problem before? If so, how did you fix it?

    Thanks!
     
  2. B16

    B16 Super Moderator VIP

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    get a vtec ecu
     
  3. Raggedyman

    Raggedyman Member

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    If a VTec ECU simply checks for various signals (i.e. oil pressure, rpm's and the like), and then energizes a 12 volt solenoid coil.....what's the big difference if I do it myself with a pair of wires? I'm certain you can't _partially_ pull in a solenoid valve no matter what voltage you're messing with.....it's either in or it's not. And if it's not it's either out or it's stuck partially due to an obstruction.

    And that being the case....can a stuck open/partially closed solenoid valve cause erratic idling? Having just checked a couple of VTec data pages, I'm leaning towards the yes vote.

    Anyone else have any ideas?
     
  4. pills_PMD

    pills_PMD Super Moderator

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    i would look elsewhere for your idle problems..

    the VTEC solenoid is either on/off i dont know how or what it could get stuck on
     
  5. Raggedyman

    Raggedyman Member

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    AHA!!! Found the problem! Instead of the solenoid sticking, it's the tach causing the problem. The tach turns on the shift light as normal...but instead of supplying a constant negative voltage and then positive voltage to energize the bulb, it's backwards!!!! There's constant positive polarity going to the bulb and the switching device inside the tach is negative!!! So no matter which wire I use going to the bulb, I'm getting positive voltage due to the voltage passing through the bulb!!!!

    Guess I'll tear apart the tach now and see what I can do about changing that...... B)

    Thanks for the replies everyone, I appreciate the help!
     
  6. B16

    B16 Super Moderator VIP

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    i still can't figure out why you are not using a vtec ecu...??
     
  7. ohmstable

    ohmstable Senior Member

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    If your tach is supplying a switched negative output and since the vtec solenoid needs a switched positive... I suppose you could use a relay inline which will switch on with the negative output from the tach and supply a positive to the solenoid. That would be the easiest way without having to modify the tach
     
  8. Raggedyman

    Raggedyman Member

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    I'm using the PM6 ecu out of an Si. This project has been a major undertaking to say the least. I was more than a little ill-informed when I got the car and only after that did I found out how tough it was going to be. The car is a '90 hatch, the ecu is from a '91 Si, the engine from a '95. I couldn't do a simple mini-me swap since I had the D15 lower end so I just threw the whole Z16Z6 into the car and started to figure things out from there. I was thinking of getting a VTec controller but decided against it. What started as a $1000 project has exploded into a $2000+ nightmare.

    I picked up a relay from autozone tonite.....lmao, 8 bucks for a chevy monte carlo fuel pump relay....but it does the job! I'm still working out the bugs as it sometimes wants to cut out and bog hard as the VTec engages. Had it set for 4300 rpms at that time so I lowered it to 3800 and it seemed better. I'm gonna try some other settings tomorrow after my last piece gets here and I get tags on the car. It'll be the first true road test.... :D

    Keep the faith!
     
  9. B16

    B16 Super Moderator VIP

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    well, that ecu does not have the fuel/timing maps to run properly in vtec... this is why i suggest you get a vtec ecu, but i do not know about OBD0 and OBDI conversions.
     
  10. Raggedyman

    Raggedyman Member

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    Yeah, like I said, I was a bit under-informed when I bought the car. Since then, though, I've struggled a long way into knowledge and, so far, I haven't burnt anything up!!! :lol:

    The OBD conversion can only consist of wiring issues (I would think)...and those are something I can get through. Seeing as how I completely redid the wiring harness on the Z6 using the old harness and the harness from the engine.....and then wired it to the ECU using the pinouts I found on this site......frankly I'm thrilled the thing even runs!! I was able to shuffle the pins around on the ecu plugs and the wiring harness in order to use the old engine harness plug and have as little soldering as I could get away with. It looks very nice if I do say so myself. I have a slight bird's nest beneath the intake manifold but it's out of sight and almost completely covered by the loom.

    It seems to me, in hindsight, that if I had the ecu from the engine donor car (or at least the same one from that year and for that engine), along with the vtec controller......I should be able to wire it all up using the existing plugs and wire. If I take care and phone out all the wires that is. As for now, I'm just gonna keep chugging along and looking forward to driving my mini-me monster.
     
  11. jotech-coupe

    jotech-coupe Junior Member

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    man ive done the exact same thing trying to run through a tach. found same result . I ended up ripping my tach. apart then throwing it in the trash.It will not work , get a p-28 I got mine for $75 and it has the proper fuel curve for the d16z6.
     
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