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Thread: TPS Autoset seems fine. Reads 1% when engine started.

  1. #1

    Default TPS Autoset seems fine. Reads 1% when engine started.

    I've run the TPS Autoset a few times now. Completes successfully and reads 0% when engine is off. As soon as I start the engine it reads 1%. If I shut it off and turn the ignition back on, it will show TPS at 0%. Start the engine and it goes to 1%. If I understand the instructions and other threads correctly, I will not have an accurate throttle plate, IAC setting either as it will lock seeing 1%. IAC reading around 10% when engine is hot currently. I've also noticed that when driving down hills the WBO2 sensors are reading below Target AFR. Other vehicles I've had when decelerating down hills the WBO2 sensor will go off the scale lean indicating no fueling. This never happened once during our 1200 KM road trip. Idle seems a bit rough too, but suspect possible issue with TPS causing this. Also, I believe the hot start is a bit rich in high ambient temp, but thinking this may just need to be adjusted. Just wanted to mention. Any ideas as to the cause? Thank you in advance.

  2. #2
    Join Date
    Dec 2009
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    Connecticut
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    17,023

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    When you start the engine, can you zero the TPS Position by manually returning (pushing) the throttle lever back against the idle speed screw?
    You may have to slightly back-off the idle speed screw (after a TPS Autoset), so the TPS Position always returns to 0% (V3 improved this).
    May God's grace bless you in the Lord Jesus Christ.

    '78 BRONCO: 508" stroker, TFS heads, 11:1 comp ratio, Dominator MPFI & DIS, cold air induction, Spal dual 12" fans/aluminum radiator, dual 3" exhaust/Magnaflow mufflers, Moroso vacuum pump, Accusump, engine oil & trans fluid coolers, 100HP progressive dry direct-port NOS, A/C, LenTech Strip Terminator wide-ratio AOD/2500 RPM converter, 3:1 Atlas II, modified Dana 44/60-lockers-4.10s, hydroboost/4-disc brakes, ram-assist/heim joint steering, Cage long radius arms, traction bars, 4" Skyjacker lift, 35" mud tires

  3. #3

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    Good catch Danny. Again. Ha ha. So I've double checked & noted the linkage is hitting the idle screw for sure. I've also made sure my throttle cable is slightly slack. I got my wife to watch and with the engine running I torque back on the throttle and it will go to zero. When I let it go it goes back to one. TPS Autoset even when warm I noticed it flickers to 0 till it warms up, then sticks at 1% when engine is running. It's V4 EFI software I believe. I can back the idle screw off as suggested, but worried I have a throttle shaft bushing issue causing the inconsistency and don't want to be trying to work around the issue. Even now if the engine is off, it's 0% and running it's 1%. Might be the excuse I need to get the Sniper upgrade. Is it programmed to fully shut fueling off during engine deceleration? Thanks again Danny.

  4. #4
    Join Date
    Dec 2009
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    Connecticut
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    Quote Originally Posted by Zum14 View Post
    Might be the excuse I need to get the Sniper upgrade.
    The Sniper EFI is not an upgrade from the Terminator EFI.

    Is it programmed to fully shut fueling off during engine deceleration?
    Both EFI systems have the Decel Fuel Cutoff.

    Thanks again Danny.
    You're welcome.
    May God's grace bless you in the Lord Jesus Christ.

    '78 BRONCO: 508" stroker, TFS heads, 11:1 comp ratio, Dominator MPFI & DIS, cold air induction, Spal dual 12" fans/aluminum radiator, dual 3" exhaust/Magnaflow mufflers, Moroso vacuum pump, Accusump, engine oil & trans fluid coolers, 100HP progressive dry direct-port NOS, A/C, LenTech Strip Terminator wide-ratio AOD/2500 RPM converter, 3:1 Atlas II, modified Dana 44/60-lockers-4.10s, hydroboost/4-disc brakes, ram-assist/heim joint steering, Cage long radius arms, traction bars, 4" Skyjacker lift, 35" mud tires

  5. #5

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    Sorry, I should of clarified. I've been eyeing the Sniper sheet metal intake with a matching Sniper throttle body.

  6. #6

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    OK, so until I get a new throttle body, I decided to back the idle screw off just a hair to get the TPS to read 0%. I took it for a test drive and driving down a hill, I shifted down to keep the RPM at 2500 RPM. TPS read a constant 0%, MAP was 12 kPa, but both AFR stayed around 15.0 when target was 14.9. Shouldn't it have gone lean? It was a good 45 seconds to a minute of decent. Never went higher then 15.5-16.0. I'm interpreting this as it's still fueling. Or I have an injector issue? However, it staying so accurate between banks and consistent, makes me think it's not one or two single injectors.

  7. #7
    Join Date
    Nov 2013
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    Chicago IL
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    1,956

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    "Actual AFR" ALWAYS targets your "Target AFR". It should never "go lean".
    If your Decel Fuel Cutoff is turned on, it would read lean only while in Decel Fuel Cutoff parameters, which goes into Open Loop.
    Which will only read lean if it's truly lean in that area, if the area is pig rich in the table, it could still read rich or normal.
    -Scott
    Don't forget to check out progress on my Race Car:
    Project Blasphemy - 8.07 @ 171
    Low 8 Second Street Car

  8. #8
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    Yep, and the Decel Fuel Cutoff only functions from higher RPM. It doesn't function off of every 0% TPS deceleration.
    May God's grace bless you in the Lord Jesus Christ.

    '78 BRONCO: 508" stroker, TFS heads, 11:1 comp ratio, Dominator MPFI & DIS, cold air induction, Spal dual 12" fans/aluminum radiator, dual 3" exhaust/Magnaflow mufflers, Moroso vacuum pump, Accusump, engine oil & trans fluid coolers, 100HP progressive dry direct-port NOS, A/C, LenTech Strip Terminator wide-ratio AOD/2500 RPM converter, 3:1 Atlas II, modified Dana 44/60-lockers-4.10s, hydroboost/4-disc brakes, ram-assist/heim joint steering, Cage long radius arms, traction bars, 4" Skyjacker lift, 35" mud tires

  9. #9
    Join Date
    Nov 2016
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    Moscow, RF
    Posts
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    I have the same problem with TPS 1% stuck at idle, but reads 0% with engine stop running with ignition on. Idle speed screw back-off doesn't help. But I can get 0% by hardly manually pushing throttle rod on throttle body. Few minutes later, TPS come back to 1%. Throttle body mechanical parts are clean & good, throttle cable have slack & heavy spring. Do you have any ideas about that?

  10. #10

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    My ride has one of the early run Terminators feeding an LSx with a custom harness made before Holley provided them. The original TPS packed it in early, so I replaced it with an off brand TPS without the slotted mounting holes. It worked fine, but eventually stuck or fluctuated at 1%. After adjusting to desired idle settings and completing a TPS Autoset, you can loosen the TPS mounting screws (with engine running) and give the TPS a wiggle to achieve 0%. Then leave it as is without doing another TPS Autoset. The IAC stays fairly stable when the TPS is stuck at 1%, but will run up to the parked position when the TPS fluctuates further or sticks at 2%. I've ordered the Standard Motor Products TH191 with slotted mounting holes to replace this off brand TPS. I'll keep this one in my road tool box as a spare.
    Last edited by 66 Beaumont; 04-15-2018 at 08:37 PM.
    '66 Beaumont Sport Deluxe - LS2, Terminator, Performer RPM, 227°/231°/110° LSA, long tubes, Extreme Automatics Stage 3 2004R, Edge 3500 stall, Transbrake, 3.50 rear, 100HP dry shot

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