Results 1 to 7 of 7

Thread: TPS Won't Return To 0%

  1. #1

    Default TPS Won't Return To 0%

    I can't seem to get the throttle blades to return to 0% (according to the handheld monitor). I tried a stronger return spring to no avail. I have fiddled with the idle speed screw and done many TPS resets, nothing has worked. I also can't seem to get the IAC position at hot idle to 2%. Do you open or close the throttle blades to achieve this? It seems either way I have tried, it settles back to 0 pretty quickly.

  2. #2
    Join Date
    Dec 2009
    Location
    Connecticut
    Posts
    23,075

    Default

    Quote Originally Posted by chillininnh View Post
    I can't seem to get the throttle blades to return to 0% (according to the handheld monitor).
    Depending on what's wrong, you may need to adjust the TPS sensor itself (slotted mounting holes).
    Does the idle speed change RPM when you adjust the idle speed screw? What's the TPS Position stuck at?

    I also can't seem to get the IAC position at hot idle to 2%. Do you open or close the throttle blades to achieve this?
    The TPS Position (sensor) has to be right, before attempting to set the IAC Position.
    http://forums.holley.com/showthread....neral-IAC-Info (IAC Info - Read "Notes")
    May God's grace bless you in the Lord Jesus Christ.
    '92 Ford Mustang GT: 385" SBF, Dart SHP 8.2 block, TFS TW 11R 205 heads, 11.8:1 comp, TFS R-Series intake, Dominator MPFI & DIS, 36-1 crank trigger/1x cam sync, 160A 3G alternator, Optima Red battery, A/C, 100HP progressive dry direct-port NOS, Spal dual 12" fans/3-core Frostbite aluminum radiator, Pypes dual 2.5" exhaust/off-road X-pipe/shorty headers, S&W subframe connectors, LenTech Strip Terminator wide-ratio AOD/2800 RPM converter, M4602G aluminum driveshaft, FRPP 3.31 gears, Cobra Trac-Lok differential, Moser 31 spline axles, '04 Cobra 4-disc brakes, '93 Cobra booster & M/C, 5-lug Bullitt wheels & 245/45R17 tires.

  3. #3

    Default

    Yes, turning the idle speed clockwise increases RPM. It seems when I turn it clockwise I get to a point where the IAC kicks in and the RPM goes way up all at once, there seems to be no creeping up on it. The TPS is stuck at 1%.

  4. #4
    Join Date
    Dec 2009
    Location
    Connecticut
    Posts
    23,075

    Default

    Quote Originally Posted by chillininnh View Post
    Yes, turning the idle speed clockwise increases RPM.
    OK, but when you unscrew the idle speed screw, does the engine stall or does something prevent the throttle blades from choking the engine any further?

    It seems when I turn it clockwise I get to a point where the IAC kicks in and the RPM goes way up all at once, there seems to be no creeping up on it.
    Yes, that's the IAC Hold Position being activated above idle (in Idle ICF).
    May God's grace bless you in the Lord Jesus Christ.
    '92 Ford Mustang GT: 385" SBF, Dart SHP 8.2 block, TFS TW 11R 205 heads, 11.8:1 comp, TFS R-Series intake, Dominator MPFI & DIS, 36-1 crank trigger/1x cam sync, 160A 3G alternator, Optima Red battery, A/C, 100HP progressive dry direct-port NOS, Spal dual 12" fans/3-core Frostbite aluminum radiator, Pypes dual 2.5" exhaust/off-road X-pipe/shorty headers, S&W subframe connectors, LenTech Strip Terminator wide-ratio AOD/2800 RPM converter, M4602G aluminum driveshaft, FRPP 3.31 gears, Cobra Trac-Lok differential, Moser 31 spline axles, '04 Cobra 4-disc brakes, '93 Cobra booster & M/C, 5-lug Bullitt wheels & 245/45R17 tires.

  5. #5

    Default

    When the idle speed screw is turned counterclockwise until the throttle blades are all the way shut (totally slackened) the engine continues to idle fine. The TPS resets I have performed (at all different idle speed screw settings) will initially read 0, but after depressing the accelerator, it shows 1%.

  6. #6
    Join Date
    Dec 2009
    Location
    Connecticut
    Posts
    23,075

    Default

    Quote Originally Posted by chillininnh View Post
    When the idle speed screw is turned counterclockwise until the throttle blades are all the way shut (totally slackened) the engine continues to idle fine.
    That's wrong. Completely closing the throttle blades should cause the engine to stall.
    If the idle speed screw is fully unscrewed, the engine is inhaling air from an additional source.
    Check for a vacuum leak or missing vacuum caps. Are the secondary throttle blades open too far?

    EDIT: Fully closing the primary throttle blades should either stall the engine or make it struggle to remain idling (with the IAC port blocked off).
    May God's grace bless you in the Lord Jesus Christ.
    '92 Ford Mustang GT: 385" SBF, Dart SHP 8.2 block, TFS TW 11R 205 heads, 11.8:1 comp, TFS R-Series intake, Dominator MPFI & DIS, 36-1 crank trigger/1x cam sync, 160A 3G alternator, Optima Red battery, A/C, 100HP progressive dry direct-port NOS, Spal dual 12" fans/3-core Frostbite aluminum radiator, Pypes dual 2.5" exhaust/off-road X-pipe/shorty headers, S&W subframe connectors, LenTech Strip Terminator wide-ratio AOD/2800 RPM converter, M4602G aluminum driveshaft, FRPP 3.31 gears, Cobra Trac-Lok differential, Moser 31 spline axles, '04 Cobra 4-disc brakes, '93 Cobra booster & M/C, 5-lug Bullitt wheels & 245/45R17 tires.

  7. #7

    Default

    Turns out the "special" low vacuum PCV valve I installed was the culprit (the engine only makes about 10 inHg of vacuum at idle). As soon as I took off that line and plugged it, everything became normal. I put back on the original one and I'm good to go!

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
About us
Holley has been the undisputed leader in fuel systems for over 100 years. Holley carburetors have powered every NASCAR® Sprint® Cup team and nearly every NHRA® Pro–Stock champion for four decades. Now, Holley EFI is dominating the performance world as well as our products for GM's LS engine. Holley's products also include performance fuel pumps, intake manifolds & engine dress–up products for street performance, race and marine applications. As a single solution, or partnered with products from other Holley companies - Hooker Headers, Flowtech Headers, NOS Nitrous, Weiand, Earl's Performance Plumbing, or Diablosport - Holley products can give you the edge you need over the competition.
Join us