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Thread: Idle Issues On Startup

  1. #1
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    Default Idle Issues On Startup

    Good morning. Just got the unit up and running on my 455 Olds (65 Cutlass) yesterday and had it out for a few runs.
    The only issue I am having is on startup the idle speed is all over the place for about 20 seconds or so.
    TPS. I have it set at 850 now with the IAC reading between 2-5.
    I just reset the idle speed and double checked the IAC setting this morning.
    Am I missing something? Obviously it's still learning? Other than this issue at start up it runs great.
    Don

  2. #2
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    Quote Originally Posted by 442SCOTTY View Post
    The only issue I am having is on startup the idle speed is all over the place for about 20 seconds or so.
    I assume the Learning has self-tuned the idle area by now. Does this happen on cold and hot starts?
    I think the 20 second aspect relates to the WBO2 sensor heating and the After Start Enrichment Decay Rate, and then the ECU enters Closed Loop.
    In which case, the Coolant Temperature Enrichment % needs to be increased or decreased (depending on CL Comp %) at those temperature columns.

    To determine this, turn key on, wait for the WBO2 sensor to display AFR, then start engine. Does it still run rough for about 20 seconds?
    On second thought, the ECU remains in Open Loop until the After Start Enrichment Decay Rate ends or the AFR hits a certain lean spike.
    Either way, the WBO2 sensor still displays air/fuel ratio after its initial heating cycle, so you'll know if it's too lean or too rich.

    I have it set at 850 now with the IAC reading between 2-5. I just reset the idle speed and double checked the IAC setting this morning.
    Just so we're clear, the idle speed screw is adjusted to achieve an IAC Position of about 2% at hot idle?
    Remember to perform another TPS AutoSet, whenever you adjust the idle speed screw on the throttle body.
    If the idle speed screw is unscrewed too far, the engine is inhaling air from an additional source - vacuum leak.
    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
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    To answer your second question, the idle air screw is turned all the way counterclockwise and my IAC reading bounces between 2-5%.

    I believe the idles swings on both cold and hot but I will check on my lunch break.

  4. #4
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    OK, just tried a cold start which was fine...very little fluctuation. Let it warm up and tried it again and got some wild movement but only for a few seconds. Tried some quick throttle shots while parked and got a bit of a hesitation then a drop down below idles causing it to almost stall a couple of times. Not idling very smooth and I checked my sensor readings. All looked good except the MAP which was reading 32. I'm in Calgary, which is about 3000 ft above sea level. I will be honest and say that I'm not sure what this reading was when I first initiated the Terminator.

  5. #5
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    Will look for vacuum leaks when I get home. Nothing apparent from poking around. Engine fairly new. Only 6000 miles.

  6. #6
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    Quote Originally Posted by 442SCOTTY View Post
    OK, just tried a cold start which was fine...very little fluctuation.
    This makes sense. A cold engine will tolerate an excessively rich AFR condition, much better than a hot engine. Refer to my first response above.

    Not idling very smooth and I checked my sensor readings. All looked good except the MAP which was reading 32. I'm in Calgary, which is about 3000 ft above sea level.
    Higher altitudes will locate your entire idle area lower (MAP kPa) on the Fuel Tables.
    Read section 5.2 "Testing the Manifold Absolute Pressure (MAP) Sensor" in the "Appendices", of the EFI software "Help" Contents.
    So it might be taking longer for the Learning to self-tune (due to lesser lb/hr values) or you'll need to smooth this are on the Fuel Graph.
    You may also need to decrease the Learned Compensation Limits % in the idle area to prevent over compensation (once it's Learned well).

    http://forums.holley.com/showthread....e-Tuning-Notes (EFI Idle Tuning 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.

  7. #7
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    I think it's starting to come around. 200 miles on it so far. Mostly highway. I also notice that the idle swings/rolls? When I shift from drive into park and vice versa.

  8. #8
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    Quote Originally Posted by 442SCOTTY View Post
    I think it's starting to come around. 200 miles on it so far. Mostly highway.
    That's good to hear. The Learning needs to be allowed time to self-tune.
    Lots of steady-state RPM driving (momentary holding patterns); no hard acceleration or heavy deceleration.

    I also notice that the idle swings/rolls? When I shift from drive into park and vice versa.
    Yep, that seems like Learn & Fuel Table tuning as well. Also, what's the timing advance at idle?
    You may have to Transfer Learning To Base and enter the Fuel Graph and ensure it's smooth it.
    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.

  9. #9
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    Good morning. My initial timing is 8 degrees. Not sure what you mean by transfer learning to base etc...will have to look that up.
    Here's where the idle thing is at. Idle set at 850. Cold start is almost perfect but as soon as I shift out of park to reverse it drops almost to a stall (500 rpm) then over recovers to about 1150, drops down to 750, up to 1050, down to 950 then settles in at around 850. Takes about 5 seconds. Does this cold or hot. Hot starts still have the rolling idle for about 2-3 seconds. Other than that it's awesome. I'm going out of town for a few days so I won't have time to play with it for about a week. It will be nice to get that smoothed out.

  10. #10
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    Quote Originally Posted by 442SCOTTY View Post
    My initial timing is 8 degrees.
    That's why I asked. This is most likely not enough idle timing! What size camshaft does your engine have (duration @ .050")?
    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.

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