Knock sensor delete on forged build?

Discussion in '96-04 - 4V Specific' started by Wild Horses, May 4, 2019.

  1. Wild Horses

    Wild Horses Active Member

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    D9107902-AA7B-40A7-93D6-22CBFAD345FB.jpeg We cannot get this car to stop pulling timing in the upper RPM. It didn’t do it with the last tune but it had the factory style pistons and the Vortech had a bigger pulley. Now it’s bored .20 over with low compression pistons and has a little pulley (more noise) to compensate for them... so I bet those knock sensors have no idea what to think now. It’s basically an aluminum terminator bottom end and should be good up to 750hp. It’s getting PLENTY of fuel and it doesn’t seem to be true spark knock. Fuel supply is not an issue though. The IATs seemed a little high on the dyno but nowhere near enough to kill as much power as it is. What do I do? It’s at 9* total and still wants to pull timing.

    Seems like every time I take care of what should be the “final” tuning issue, another problem pops up.

    It’s an 01 teksid Cobra with the forged crank, Manley rods and lower compression 9cc Manley pistons. Heads are factory 01 with port work but stock cams. Fresh rebuild on everything with about 550mi on it now.
     
  2. 07GtS197

    07GtS197 Well-Known Member

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    Could be false knock. Its a somewhat common issue in the 3v world, especially boosted. Do you have solid motor mounts? Ive heard they can transmit more noise to the block and that can cause false knock. Otherwise I think your only other option is to turn it off in a tune. I personally wouldnt want to do that but if you cant figure it out otherwise it will be your only choice.


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  3. Wild Horses

    Wild Horses Active Member

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    Yea I was reading about the 3V issues and the aftermarket motor mounts. I do have poly mounts and they got real hot and melted. I didn’t think it’d be enough to mess with anything but I’m thinking it could be it.

    I pulled my lower intake off within the last 30 mins of this post and got pretty excited that I may have found the culprit. There’s a stray bolt that fell under the coolant tube
    And it has a loose washer on it that can rattle around. And wouldn’t you know... it’s right next to a damn knock sensor.
     
  4. Wild Horses

    Wild Horses Active Member

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    Idler pulley bolt with a thick loose washer stuck under the coolant tube. Man I hope this is the deal.

    C353D118-A64E-48D0-A1B2-05F3ACB50257.jpeg

    3788088B-1F31-4AF8-A894-A26CAA000CB0.jpeg
     
  5. Wild Horses

    Wild Horses Active Member

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    Oh my god it WAS that stupid bolt and washer
     
    Last edited: May 5, 2019
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  6. 3.14159

    3.14159 Member

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    Ha nice. Loose accessories can do that too. My PS pump was loose once and kept putting my car on the low octane map.
     
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  7. 07GtS197

    07GtS197 Well-Known Member

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    Oh wow Im glad is was that simple.


    Sent from my iPhone using Tapatalk
     
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  8. Wild Horses

    Wild Horses Active Member

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    I’ll be keeping my eye out from now on. When you’re dealing with a boosted car that won’t take any timing, that’s a lot of a lot of power gone. After this issue I’m thinking back to all the times it felt slow.
     
  9. ttocs

    ttocs Legend

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    one of those moments were you cock your hear 45 degrees and wonder if your really seeing that. Then you are are pissed off as hell for a few seconds very quickly followed by a happy dance that you hope the neighbors do not see. I have done that very dance....
     
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  10. Wild Horses

    Wild Horses Active Member

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    Alright... Update for anyone who runs into these issues on the street or on the dyno. It was a combination of 4-5 little things but I’m pretty sure it was mostly 2 of them. I’m talking about power loss like a belt slip feeling but it’s actually losing timing.

    First thing I found was a bolt in the intake valley setting off the knock sensors. Figured that was it. But then I noticed the poly motor mounts had MELTED and sunk the motor down which had the oil pan laying on the steering rack. I’m sure that wasn’t helping.

    Then LUCKILY my Anderson power pipe came in THE DAY BEFORE I drove all the way back out for the tune revision and I found the Vortech inlet coupler folded inward toward the impeller under the clamp at the bottom so I couldn’t see it. I am so glad I ordered that power pipe when I did so I could find that issue. I also found my after-cooler hose was KINKED. I thought the pump was going bad because it was humming so loud but it’s completely fine now.

    Addressed all the issues, swapped the new power pipe on and ended up making 510/470 at the wheels with IATs in the 130s. The first tune was 440/411 with IATs way up in the 150s. The curve consistent as hell too. Huge success and for the first time, this build is DONE. She is a such a BEAST too.
     
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  11. ttocs

    ttocs Legend

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    nice numbers and it must be nice to figure it out. For some reason I can't seem to find a nice balance where the throttle stop and the IAC are happy. I either have %50 on the iac or %0 it seems and no two days seem the same.
     
  12. Wild Horses

    Wild Horses Active Member

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    Anymore details? You mean just idling? Mine used to jump up coming to a stop. You want the throttle plate closed but not stuck all the way. I mean barely any pressure on the throttle. A TINY amount. Then let the IAC do the rest of the work. Unhook the battery while you set it up like that, then hook it back up and let it relearn the idle control. Run with the AC on and off. Adjust from there.

    If that doesn’t work, it could be a vacuum leak or unmetered air from somewhere.or of course a bad iacv
     
  13. ttocs

    ttocs Legend

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    This is with a holley hp setup so not sure disconnecting the battery is good or not. The other night I had it set up so the IAC was open %10 at hot idle, today I start it up and when it gets up to temp its at %35. Spent a few rounds adjusting the throttle stop to get it back down to the %10 range and now I bet tomorrow its going to be something else.
     
  14. Wild Horses

    Wild Horses Active Member

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    Yea that’s out of my depth man. I’m not familiar with the system. Maybe the system doesn’t think it’s hot yet. Check out where it monitors temp from.
     
  15. Wild Horses

    Wild Horses Active Member

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    Our factory temp senders go bad ALL THE TIME and they’ll make the cars run horrible and sometimes even create a no start condition. Check your temp sender, whatever type it is, coolant level... maybe inconsistent temperatures throwing things off.