Hisun 800 wont idle.

[Kyle]

Hey guys, looking to get some insight on my issue, my hisun 800 sxs runs now that I replaced the crankshaft position sensor however it won't run unless I have the throttle Down like 4000 rpm!, it will idle down but it won't stay running at all as soon as it drops to 3000 RPM it just dies almost like you're turning the key off. I have good compression I just adjusted the valves. Any help is much appreciated thanks.

[Travis]

Did this problem start after you installed the CPS?

 And does the motor have fuel injectors, or just a carburetor?

[Ben1098]

Peak voltage of the pulse output of pick-up coils is related to the magnetic field strength AND rotational N-S-N-S-N etc. speed (rate of change in magnetic field.  you can check the PEAK output with a scope or special testers OR a simple SNAP-ON peak voltage adapter that plugs into a digital meter.

First guess (assume the new crank sensor/pick up coil was good and no corroded wiring to ECM) is too wide of an air gap between the coil face and the flywheel tab (magnet is internal to the coil).  With a wide gap, the output will be too low to trigger the ign at low RPM but the output will be high enough at a higher RPM.

TEST TRICK........QUICK SUB OF CPS/PICK UP COIL.

Create a pick up coil signal to test the ignition section but not needing to turn over the engine.

Pull sparkplug and mount in boot again, have known good pick up say from a chino scooter connected for a FIRE signal, KEY ON, and then take a small wrench (iron) and stroke the pole face and mounting metal tabs.........make and break the magnetic field flux "conduction".  Should se a nice spark

 

[Kyle]

Thanks for the reply, it is a 2011  800 V-Twin fuel injected I got this with an intermittent running issue and the valves were adjusted way off and only had 30 PSI in one cylinder. After correcting the valve clearance issue I couldn't get it to stay running and then I had no spark at all, found that the crankshaft position sensor was failing. Replaced the crankshaft position sensor fired up but wouldn't idle I could get it down to 3000 RPM so I started checking over everything on the throttle body, I removed the throttle position sensor noticed that there was a whole lot of dirt built up on the inside so I cleaned it out put it back on and it seems to run a little better, now I'm down to about 2500 rpm, just for shits and gigs I decided to take the throttle position sensor off while the engine was running ,as soon as I remove the throttle position sensor the engine started running perfectly fine idling at 1100 RPMs so I have narrowed it down to the throttle position sensor. After going over a few things it looks to me like somebody may have swamped this thing at one time, I might be in for some fun.

[Ben1098]

TPS------most are set to .5Vdc for idle.  CHECK....engine not running but KEY ON....should have Gnd, +5Vdc, AND analog signal that varies from +.5V (on throttle idle stop) to +4.5V at WOT....should move SMOOTHLY going up and also going down...open and close slowly so the digital meter has time to respond.

If the throttle body manual idle speed has been "adjusted", this will throw off the TPS curve.  The screw is usually painted at the assy plant for a certain airflow.  NOT TO BE CHANGED.  Idle Air Control valve controls the idle speed via the Delphi ECM.

A problem with the O2 sensor can cause problems.......Disconnecting allows the ECM to revert back to "limp home" setting from internal map.

The Mass air flow/intake air temp sensor also will mess up the settings.  If it took a swim, the sensor (air flow) will have dirt problems.  The temp part is just a thermistor bead on 2 leads.....resistance changes with temp.