HELP! Alpha supercharged SS with too rich fuel mixture

    This site uses cookies. By continuing to browse this site, you are agreeing to our Cookie Policy.

    • MACAWS wrote:

      I assume this is not a new install
      are there any other symptoms - smoke anything else
      Any recent changes or additions
      well, this is engine #4.. blew up the other 3 due to what I assume was a bad ecu tune. Sent the ECU back to bob and he adjusted the "engine speed" according to him..anyway, it's doing what you see in the video and black smoke from exhaust. Switched ECU's to a known good ECU and the same condition exists.
    • You probably have an intake vacuum leak. There are two places this happens and it will run crazy rich like that.

      1. Leaking at your 2bar MAP sensor. Make sure it is seated correctly and you have the correct rubber gasket installed.

      2. Leaking because the OEM cap blew off your intake manifold. It is a nipple that is just below and to the right off your MAP sensor.
      Owner of Slingshot #263 that has some stock parts left on it. :D
    • TravAZ wrote:

      You probably have an intake vacuum leak. There are two places this happens and it will run crazy rich like that.

      1. Leaking at your 2bar MAP sensor. Make sure it is seated correctly and you have the correct rubber gasket installed.

      2. Leaking because the OEM cap blew off your intake manifold. It is a nipple that is just below and to the right off your MAP sensor.
      installer said he checked for vacuum leaks and there were none.. will have him check again.
    • Also, you wouldn't blow motor from a "BAD" ECM tune. Either the ECM functions and works correctly, or it is no good and acts beyond crazy where you couldn't even drive it. Usually if they go bad, they are completely toasted and the machine wont even recognize it.

      With so many issues, you need to get to a shop that really knows these motors and how to work with boosted setups.

      You also should think about moving to the smaller pulley on this setup, or lowering your rev limiter. When you say "engine speed", you probably are referring to rev limiter. Bob probably did you a solid and lowered it so that you wont make 13-14 PSI at crazy high RPMs.

      Wishing you luck. I know the feeling of having motors crap out!


      Owner of Slingshot #263 that has some stock parts left on it. :D

      The post was edited 1 time, last by TravAZ ().

    • You also can plug in the MAP sensor backwards. Check the wiring colors and make sure they are matched up correctly when you plug it in. It is stupid that it can be plugged in backwards, but it has happened many times.

      To check if you have a bad plug and/or coil, simply pull the plugs after it is idling like that. One will look different if that is your issue.
      Owner of Slingshot #263 that has some stock parts left on it. :D
    • TravAZ wrote:

      Also, you wouldn't blow motor from a "BAD" ECM tune. Either the ECM functions and works correctly, or it is no good and acts beyond crazy where you couldn't even drive it. Usually is they go bad, they are completely toasted and the machine wont even recognize it.

      With so many issues, you need to get to a shop that really knows these motors and how to work with boosted setups.

      You also should think about moving to the smaller pulley on this setup, or lowering your your rev limiter. When you say "engine speed", you probably are referring to rev limiter. Bob probably did you a solid and lowered it so that your wont make 13-14 PSI at crazy high RPMs.

      Wishing you luck. I know the feeling of having motors crap out!



      had forged rods and pistons on 2 of the motors i blew up. the last one melted a piston.
    • HELP! SS with too rich fuel mixture

      Standard GM test for MAP Testing.
      Put your multimeter in volts DC setting. The MAP sensor has three wires connected to it — one gray, one green and one black. Probe the green middle wire. Make sure the MAP sensor is connected to its three-wire connector while doing this.
      Connect the black multimeter test lead directly to the car battery's negative terminal. Insert the car key into the ignition and turn it to just before the engine starts. The multimeter should read 4.7 volts DC.
      Use the vacuum pump to apply vacuum to the sensor. The multimeter should display the following voltage values according to vacuum strength: 0 in. Hg, 4.7 volts; 5 in. Hg, 3.9 volts; 10 in. Hg, 3.0 volts; and 20 in. Hg, 1.1 volts.
      If the multimeter registered these values, this means the MAP sensor is functional and not the cause of the problem. However, if the multimeter voltage did not change, this confirms that the sensor is damaged and should be replaced.


      Sent from my iPhone using Polaris Slingshot Info
    • Yup, it happens. My motor was fully built too with a completely different issue. Every time I mess with my Slingshot, I know I am depositing future tears and curse words to be shed. It is just they way it is...

      Your headache is an issue we have seen on a couple of the people running the same setup. It makes way too much boost up in the high revs. Around 6,300ish and up the boost goes up to like 13-14 PSI. It jumps very quickly and AFRs go lean. You probably cannot hear the detonation because your exhaust is too loud.

      Run a larger pulley to make less boost, or confirm that your rev limit has been lowered so you don't get back into that dangerous area where boost gets crazy.
      Owner of Slingshot #263 that has some stock parts left on it. :D
    • TravAZ wrote:

      Yup, it happens. My motor was fully built too with a completely different issue. Every time I mess with my Slingshot, I know I am depositing future tears and curse words to be shed. It is just they way it is...

      Your headache is an issue we have seen on a couple of the people running the same setup. It makes way too much boost up in the high revs. Around 6,300ish and up the boost goes up to like 13-14 PSI. It jumps very quickly and AFRs go lean. You probably cannot hear the detonation because your exhaust is too loud.

      Run a larger pulley to make less boost, or confirm that your rev limit has been lowered so you don't get back into that dangerous area where boost gets crazy.
      henry actually sent me a larger pulley from the 2nd engine I blew up.. I will ask my installer to have that one put on.
    • With so many issues, you should really verify the below items...

      1. Do you have good fuel pressure? Borrow and plug in a gauge to the stock fuel rail bleeder valve.
      2. Are you injectors working correctly and clean? Google AUS Injection and maybe send them out for flow cleaning.
      3. Are you running the right plugs? Maybe switch to these, which are the best I have found - jegs.com/i/Brisk-USA/084/RR14S/10002/-1
      Owner of Slingshot #263 that has some stock parts left on it. :D
    • TravAZ wrote:

      With so many issues, you should really verify the below items...

      1. Do you have good fuel pressure? Borrow and plug in a gauge to the stock fuel rail bleeder valve.
      2. Are you injectors working correctly and clean? Google AUS Injection and maybe send them out for flow cleaning.
      3. Are you running the right plugs? Maybe switch to these, which are the best I have found - jegs.com/i/Brisk-USA/084/RR14S/10002/-1

      Hey TravAZ..i see you are out in Chandler..been there a few times for work off of S price Road.

    Slingshotinfo.com is not affiliated with Polaris Industries the makers of Polaris Slingshot in any way.