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Thread: Idle and just off idle issues with Avenger 550-400

  1. Default Idle and just off idle issues with Avenger 550-400

    Hi,

    I have installed a 700 cfm Avenger EFI sytem on my 318 powered '65 Valiant. I have adapted a Chrysler Lean Burn distributor to an 8 pin GM HEI module, and using the Holley harness connector I have ECU controlled timing.

    Naturally I've followed the instuctions to the letter, and set the timing as per the manual. I've used the Megasquirt manual to connect the module and distrubutor properly.

    I am having issues with idle and just off idle light cruise. At idle the RPM is set to 800, and the engine surges badly. When it does the AFR reading on the hand control goes lean. If I am cruising at just off idle RPM, say around 1250, the car stumbles and surges badly and the AFR can go as high as 19:1. If I open the throttle sharply the problem disappears, but if I open it slowly, or keep it stable, I can repeat the fault over and over.

    AFR for idle is 13:1, cruise is the same.

    Can someone please advise how I can solve this, or what is possibly causing it. I'm ripping my hair out.

    Regards,

    Robert

  2. #2
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    Are the throttle blades (idle speed screw) properly set to achieve an IAC Position of 3% at hot idle?
    May God's grace bless you in the Lord Jesus Christ.
    '92 Ford Mustang GT: Dominator MPFI & DIS, A/C, Spal dual 12" fans/3-core Frostbite aluminum radiator, Pypes dual 2.5" exhaust/X-pipe/shorty headers, 100HP progressive dry direct-port NOS, 160A 3G alternator, Optima Red battery, LenTech Strip Terminator wide-ratio AOD/2800 RPM converter, 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. Default

    Yes, and I have done a TPS autoset several times and just done firmware upgrade. Still no improvement alas.

  4. #4
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    Dec 2009
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    Has the EFI system finished learning in the trouble area?
    Engine must be at normal operating temperature and ran at steady-state RPM.
    You should view a data log of this stubborn spot and look for what's causing it.

    Ensure there are no exhaust leaks upstream of the WBO2 sensor.
    Ensure the ignition timing (timing light) is synchronized with the ECU.
    Ensure the fuel pressure is set correctly at 21 psi.
    May God's grace bless you in the Lord Jesus Christ.
    '92 Ford Mustang GT: Dominator MPFI & DIS, A/C, Spal dual 12" fans/3-core Frostbite aluminum radiator, Pypes dual 2.5" exhaust/X-pipe/shorty headers, 100HP progressive dry direct-port NOS, 160A 3G alternator, Optima Red battery, LenTech Strip Terminator wide-ratio AOD/2800 RPM converter, 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. Default

    I have to get a more accurate pressure gauge, but the one I am currently using is reading 20 PSI. No exhaust leaks and timing is synced.

    One thing I don't understand, is that I get a message on the bottom of the tuning screen saying "dirty", when I connect the ecu to the laptop. If I open the software and don't connect the ECU, it says "clean". Is this important?

  6. #6
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    Quote Originally Posted by robertodonnell View Post
    One thing I don't understand, is that I get a message on the bottom of the tuning screen saying "dirty", when I connect the ECU to the laptop.
    If I open the software and don't connect the ECU, it says "clean". Is this important?
    No, that doesn't mean anything to the end user.

    With my previous Holley TBI system, I ran 23 psi of fuel pressure but
    only because the four 75 lb/hr injectors were almost too small for my engine.
    May God's grace bless you in the Lord Jesus Christ.
    '92 Ford Mustang GT: Dominator MPFI & DIS, A/C, Spal dual 12" fans/3-core Frostbite aluminum radiator, Pypes dual 2.5" exhaust/X-pipe/shorty headers, 100HP progressive dry direct-port NOS, 160A 3G alternator, Optima Red battery, LenTech Strip Terminator wide-ratio AOD/2800 RPM converter, 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. Default

    Am thinking of upping the fuel pressure a bit to see if it improves. This problem only happens under light cruise or idle, not load. Could this have an impact anyway?

  8. #8
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    You shouldn't need to increase fuel pressure. The Learn function should be tuning the Base Fuel Table.
    A big change in fuel pressure now, will throw off all the current self-tuning. Does a datalog show anything wrong?
    May God's grace bless you in the Lord Jesus Christ.
    '92 Ford Mustang GT: Dominator MPFI & DIS, A/C, Spal dual 12" fans/3-core Frostbite aluminum radiator, Pypes dual 2.5" exhaust/X-pipe/shorty headers, 100HP progressive dry direct-port NOS, 160A 3G alternator, Optima Red battery, LenTech Strip Terminator wide-ratio AOD/2800 RPM converter, 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. Default

    I've attempted the download the datalog, but I failed. I'll have to go back to the manual and see what I did wrong. When I get it to work I'll post it up for your perusal.

  10. #10
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    Dec 2009
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    You can email your current Global Folder and datalogs to other forum members. Click on their username, "View Profile" & "Download vCard" for their email address. When emailing a Global Folder or datalog, use your email's 'attachment utility' function and Browse through your computer's "Documents", "Holley", "HEFI" & "Global Folders" or "Datalogs". Then right click on your Global Folder and Send To "Compressed (Zipped) Folder". Then select the zipped folder and attach it to the email. Datalogs aren't required to be "zipped"; simply select & attach it to the email. The recipient now has your entire GF or datalog in one easy step. It's zipped from email, so download it to your Desktop (or wherever your PC saves it to), and unzip it. Then "Cut & Paste" the Global Folder into "Holley" "HEFI" "Global Folders" directory (located in Documents).
    May God's grace bless you in the Lord Jesus Christ.
    '92 Ford Mustang GT: Dominator MPFI & DIS, A/C, Spal dual 12" fans/3-core Frostbite aluminum radiator, Pypes dual 2.5" exhaust/X-pipe/shorty headers, 100HP progressive dry direct-port NOS, 160A 3G alternator, Optima Red battery, LenTech Strip Terminator wide-ratio AOD/2800 RPM converter, 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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