Burned exhaust valves now?

Discussion in 'Boxers/TR/M' started by Saltie, Mar 11, 2009.

  1. Saltie

    Saltie Karting

    Apr 23, 2008
    Silverdale, WA
    Full Name:
    #1 Saltie, Mar 11, 2009
    Last edited by a moderator: Sep 7, 2017
    I replaced my spark plugs after finally getting the right ones. Car starts and runs amazingly, but the putter remains. I just got some bolts I ordered to plug the emissions sensor ports on my Hyper-Flow pre-cats and put them on and the puttering exhaust gets much more pronounced. My dad tells me I should do a "dollar bill test" which involves putting a crisp dollar bill at the end of the exhaust tips and the dollar should just be pushed away. Didn't happen. The dollar on the passenger / right / starboard / green side got sucked back toward the exhaust every time it puttered. Dad says this means there's most likely a burned exhaust valve. This may have been caused by running too lean on that side. I looked back at the spark plugs and the starboard bank was black and dirty while the driver / left / port / red side was white and clean. This may have been caused by one bank running rich and the other lean, or oil could be leaking into the cylinders. The one side rich and other side lean theory could be caused by the oxygen sensors not being connected. All wires are there, just not connected. Pre-cat temp sensing wires are also still not connected.

    Do my assumptions seem accurate?

    Is the "dollar bill test" normally pretty good in this respect?

    Should I worry much about a burned exhaust valve? As of now my intensions are to have a valve job done with the major I'm trying to have done around November while I'll be gone for six months.

    Should I be worried about the difference in color of the spark plugs?

    Should I connect the oxygen sensors and see what happens? If so, does white go to port or starboard? Then that would naturally mean black would go to the other.

    Should I just reconnect the pre-cat temp sensing wires? If so, do I just connect green to green and red to red?

    Thank you all for the continuing help and support!
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  3. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
    Lifetime Rossa

    Jan 11, 2001
    Full Name:
    Steve Magnusson
    #2 Steve Magnusson, Mar 11, 2009
    Last edited: Mar 12, 2009
    Have to say that just having the O2 sensors disconnected in the first place isn't a good sign for everything being "OK". And, if it won't run properly with the O2 sensors unplugged (and things properly tweaked), there is a near-zero chance that plugging in the O2 sensors will "fix" things. The only case where plugging in the O2 sensors can "help" is, if the manual tweak is not correct, the system could compensate for that -- but cold-running will be poor (i.e., things aren't properly tweaked).

    What's important is that the single wire from the O2 sensor mounted in the 7/12 bank exhaust stream is connected to pin 8 of the forwardmost-mounted injection ECU which is connected to the EHA winding on the 7/12 fuel distributor (and the the single wire from the O2 sensor mounted in the 1/6 bank exhaust stream is connected to pin 8 of the rearwardmost-mounted injection ECU which is connected to the EHA winding on the 1/6 fuel distributor ):
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    I'd be more suspicious that you have/had some sort of uneven fuel delivery problem (that someone tried to mask by disconnecting the O2 sensor and running a bank intentionally rich so the cylinder getting the least fuel doesn't miss at idle, but the others run rich), but sounds to me like you should start with verifying the mechanical condition of the engine is reasonable (i.e., leakdown test) and, if OK, then ensure the ignition stuff is OK (e.g., make sure you don't have any cracks in the extenders or fix them if you do), and then move on to verifying that the fuel system is reasonable (which is harder :().
  4. 2dinos

    2dinos F1 Rookie

    Jan 13, 2007
    Hmmm, starts and runs amazingly well. Well that's a good sign. Could the putter be an exhaust leak? The "dollar bill test" is new to me. Typically, leak down tests are used to detect major component issues. You would listen to the intake, and exhaust side carefully if a weak cylinder was detected to check valves, and try and listen to a crankcase opening to listen for bottom end issues. I don't know your wiring questions, I'd consult the diagram. But why would you not run the O2 sensor? Is there supposed to be some horsepopwer gain? I would tend to want those parts working if my car came with them.
  5. silvergts1998

    silvergts1998 Formula 3

    Apr 10, 2005
    Full Name:
    Do a leak down test on it. That will tell you lots.
  6. carguy

    carguy F1 Rookie

    Oct 30, 2002
    Alabama (was Mich.)
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    #5 carguy, Mar 12, 2009
    Last edited: Mar 12, 2009 a leak down, or at the very least, a compression test. The "dollar bill" test is actually fairly acurate for letting you know something is amiss. But the "reversion" or exhaust gas "suck-back" can be caused by either a bad exhaust valve, or cam timing that is way off (like the exhaust cam is retarded - no jokes please! ) Let's hope it's the latter. I concur with what everyone has said. It is NOT a good sign if the car is running with the O2 sensor disconnected. Do some more diagnostics and let us know what you find.
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  8. Saltie

    Saltie Karting

    Apr 23, 2008
    Silverdale, WA
    Full Name:
    I went through and checked out all the plug wire resistances again, but this time from the rotor contact on the distributer cap to the female end of the wire where it plugs into the plug itself. All resistances appeared to have opens, but from the screw inside the cap most were high, but #2 cylinder was still indicating an open. Also, the ignition coil wire appeared to be open. I ordered a new set of plug wires that happened to be on eBay when I needed them and I cleaned the hell out of the distributor cap (There was a LOT of buildup on all the contacts), so the resistance from the contact point to the plug is now between .6k Ohms to 1.8k Ohms. The longer wires with the higher resistances, as expected. You wouldn't believe the difference it made. It's like driving a completely new car! However, there is still a little bit of a putter coming from the 1-6 bank. This is more noticed after being started cold. Also when started cold there is a small amount of black liquid that sprays out with the exhaust. I guess the next step is to do the compression test. I need to find a place in Hawaii that I can do a leak down test.
    As always, all suggestions are greatly appreciated. Thank you all for providing me so much help so far.

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