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  1. #1
    Nonstop, all day, everyday. 01xdime's Avatar
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    Lean A/F issue driving me crazy!

    On and off for weeks i've been messing with a friend's RXT that had a lean AF ratio running an X charger and RRFPR. Now the ski is only running an XS style IC, thru hull, and 3" intake. SC is stock as well as ecu and injectors. The AEM AF meter we're using is reporting numbers well into the 15-16 range at cruising. We've tried 2 different brand new AEM AF meters and swapped out intake manifolds with all the sensors and ecu. I'm starting to think that there's nothign wrong with the AF ratio after all and i've heard it's possible for an engine to run so rich that it can read lean. I'm thinking of trying an EGT probe possibly. I'm pulling my hair out here. With the RRFPR the fuel pump would easily push pressure into the 70psi range so i doubt the pump is bad. We've swapped injectors to a brand new set of 38s also. Still reading lean! What gives?


  2. #2
    Site Admin Green Hulk's Avatar
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    I see AFR numbers into the low 14's while crusing. This is perfectly fine and is what you would see on a bone stock ski if you were to measure the AFR. "leaner is greener"

    Perhaps that AEM setup you are using is a couple of points off of an LM 1 or similar?

  3. #3
    Nonstop, all day, everyday. 01xdime's Avatar
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    It is possible to be a few points off but to be well into the 16s with spikes of 17 is a bit fishy. The exhaust smells pig rich and the plugs look normal.

  4. #4
    Josh... I noticed this smell in the hot summer months. This was on a S-3 wheel too!

  5. #5
    Nonstop, all day, everyday. 01xdime's Avatar
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    yeah you can smell the unburnt fuel in the exhaust but how do you tell someone to just have at it when you're not totally convinced they won't blow up their ski?

  6. #6
    speedskixp's Avatar
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    Quote Originally Posted by 01xdime View Post
    yeah you can smell the unburnt fuel in the exhaust but how do you tell someone to just have at it when you're not totally convinced they won't blow up their ski?
    What is the a/f at wide open throttle?

  7. #7

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    Maybe Try Your A/f Ratio Setup On A Stock Ski Would Help.todd

  8. #8
    Website may not be suitable for small children WOT's Avatar
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    Quote Originally Posted by 01xdime View Post
    It is possible to be a few points off but to be well into the 16s with spikes of 17 is a bit fishy. The exhaust smells pig rich and the plugs look normal.
    It sounds almost like the sensor is fouled. If it is not damaged, you can clean it off with a propane torch. Just heat it up until it is nice and hot for a couple of minutes (not bright red glowing, but pretty damned hot), and then just let it cool off. If it has become fouled, this will fix it.

    Another option is that you might have an exhaust leak. If you have an exhaust leak upstream of a wideband or even a regular 02, they will alway read lean. This is caused by the pulsing of the exhaust system which in turn causes some fresh air to be drawn in between pulses at the spot where it is leaking . The fresh air makes the 02 momentarily "loose contact" with the real exhaust stream, and it causes the sensor to read lean.

  9. #9
    Nonstop, all day, everyday. 01xdime's Avatar
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    Quote Originally Posted by WOT View Post
    It sounds almost like the sensor is fouled. If it is not damaged, you can clean it off with a propane torch. Just heat it up until it is nice and hot for a couple of minutes (not bright red glowing, but pretty damned hot), and then just let it cool off. If it has become fouled, this will fix it.

    Another option is that you might have an exhaust leak. If you have an exhaust leak upstream of a wideband or even a regular 02, they will alway read lean. This is caused by the pulsing of the exhaust system which in turn causes some fresh air to be drawn in between pulses at the spot where it is leaking . The fresh air makes the 02 momentarily "loose contact" with the real exhaust stream, and it causes the sensor to read lean.

    Well i tried 2 completely brand new sensor/gauge setups and both read the same. At idle it starts off in the low 12s but then creeps up to almost 14 when warmed up. Wide open is in the mid 12s or so. It's in the cruising range of 5k-7k rpms where things look ugly. I'll check for exhaust leaks but the v-band flange at the manifold was cleaned thoroughly not too long ago. I may try the setup on my RXT here shortly since it hasn't ran in 6 months.

  10. #10
    Nonstop, all day, everyday. 01xdime's Avatar
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    i'd love to see what another A/F setup like the LM-1 would read.

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