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  1. #1
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    Cadillac XLR

    2004 Silver XLR

    Default Low grade fuel pinging. need help

    So I've had my XLR since September with no issues at all. I let my boyfriend borrow the car and he filled it up with low grade gas, and sure enough I started getting the pinging noise when under load.
    Put some octane booster to balance it out until the next fill. It fixed it and the pinging went away, but sometimes it comes back in short bursts. Will this ever go away? think my knock sensors are going bad? Will my XLR EXPLODE!!!???? lol just kidding.In all seriousness, why would I still hear it from time to time?

  2. #2
    Pit Crew onalaska's Avatar
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    Cadillac XLR

    2006 Infared XLR-V

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    Have you refilled your tank with premium since this happened? The base XLR engine will run on a good grade of regular.

    2006 Infared XLR-V built 4/2006, Sold new 8/24/2006 @ 36 miles. Purchased as second owner 7/22/09 @ 40,151 miles, as of 3/2018 81,862 miles
    Ligenfelter Varimax PWM Intercooler Coolant Pump, D3 Stage 1 & 2 Intake, Wait4me tune, Texas Mile 154.6 MPH 10/26/2012
    Other Caddys: 1990 Red Allante 154,000 miles

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  3. #3
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    2004 Silver XLR

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    Quote Originally Posted by onalaska View Post
    Have you refilled your tank with premium since this happened? The base XLR engine will run on a good grade of regular.
    Should have mentioned that. Yes, I filled it up a week ago with the high grade.

  4. #4
    Pit Crew onalaska's Avatar
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    Cadillac XLR

    2006 Infared XLR-V

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    If it is doing it with premium you may have some carbon build up in the cylinders causing the compression to be higher than normal. Brief pinging under load is not normal, but if it is continuous for any length of time it can damage the rings and pistons. There is a procedure to remove the carbon that the dealers use if that is the problem. You might try adding some Techron to your tank during a couple of fill ups for a couple of times to see if that helps. If it is pinging bad I would recommend taking it to a mechanic.

    2006 Infared XLR-V built 4/2006, Sold new 8/24/2006 @ 36 miles. Purchased as second owner 7/22/09 @ 40,151 miles, as of 3/2018 81,862 miles
    Ligenfelter Varimax PWM Intercooler Coolant Pump, D3 Stage 1 & 2 Intake, Wait4me tune, Texas Mile 154.6 MPH 10/26/2012
    Other Caddys: 1990 Red Allante 154,000 miles

    Member of Allante' XLR Houston Club:
    www.allanteclubofamerica.com/content.aspx?page_id=22&club_id=179768&module_id=5 322
    Facebook page: Allante XLR Texas


  5. #5
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    2004 Silver XLR

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    Quote Originally Posted by onalaska View Post
    If it is doing it with premium you may have some carbon build up in the cylinders causing the compression to be higher than normal. Brief pinging under load is not normal, but if it is continuous for any length of time it can damage the rings and pistons. There is a procedure to remove the carbon that the dealers use if that is the problem. You might try adding some Techron to your tank during a couple of fill ups for a couple of times to see if that helps. If it is pinging bad I would recommend taking it to a mechanic.
    no, not pinging bad at all. You can barley hear it. I have to turn off the A/C and radio to hear it. and it only dose it around 2/3rd gear if I hit the gas hard. only last a second or 2.

  6. #6
    Pit Crew XLRATING's Avatar
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    2006 Infrared XLR (Beauty); 2008 GT500 (Beast); 2007 Black XLR-V (Victor)

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    Quote Originally Posted by hcloud13 View Post
    So I've had my XLR since September with no issues at all. I let my boyfriend borrow the car and he filled it up with low grade gas, and sure enough I started getting the pinging noise when under load.
    Put some octane booster to balance it out until the next fill. It fixed it and the pinging went away, but sometimes it comes back in short bursts. Will this ever go away? think my knock sensors are going bad? Will my XLR EXPLODE!!!???? lol just kidding.In all seriousness, why would I still hear it from time to time?
    You need to quarantine the boyfriend from the car!

    yep, I drive a hybrid - a V8 bred for high speed!

    2006 Infrared XLR
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  7. #7
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    Quote Originally Posted by onalaska View Post
    If it is doing it with premium you may have some carbon build up in the cylinders causing the compression to be higher than normal. Brief pinging under load is not normal, but if it is continuous for any length of time it can damage the rings and pistons. There is a procedure to remove the carbon that the dealers use if that is the problem. You might try adding some Techron to your tank during a couple of fill ups for a couple of times to see if that helps. If it is pinging bad I would recommend taking it to a mechanic.
    Just for info, the carbon build up has an almost trivial affect on compression BUT, it glows red/white hot and pre-ignites the fuel. Ideally you need to get it removed as explained here.

    And for my benefit, does anyone know why it doesn't just burn off? It is a creamy/white hard deposit, not black like ordinary carbon. I'm guessing it is partly carbon and partly some other impurity that stops it burning off in the usual way.

  8. #8
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    2004 Silver XLR

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    So I looked into what dealers do to get rid of the carbon build up and it's a spray! it's sprayed into the Air Intake while the car is running. Found some Sea Foam spray with a real long nozzle. The directions say to loosen the air intake hose and stick the long nozzle into the small opening while having someone in the drivers seat just barely rev the engine while I spray it into the air intake. Think I should try it?

  9. #9
    Pit Crew pure zen's Avatar
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    2005 Crimson Pearl XLR

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    Fill with fuel again and pour one can of Sea Foam liquid and one bottle of Techron both into the gas tank and see what happens.

    The computer normally controls the engine timing to correct from pinging...... Must of been a real low grade of regular unleaded to cause this or possibly that gas station had some water in their underground tanks? With all of the rain and flooding in Florida after the recent hurricane,,,,nothing would surprise me. Good luck, and I agree, kick the b/f's butt out of the driver's seat
    Last edited by pure zen; 11-05-2017 at 09:29 AM. Reason: addition
    http://www.xlr-net.com/forums/attachment.php?attachmentid=6664&d=1473338578

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