Author Topic: hard to start, erratic idle fluctuations / stepper issue. log inside.please help  (Read 18952 times)

Offline Sprocket

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Turning off over run fuel cut and having a VE map with 20kpa on the lowest line will over fuel the engine if the MAP drops below 20kpa during over run, resulting in an interesting fire and sound show.

Why dissable over run fueling other than to diagnose a problem or tune?

One or the other, not both, RPM or Kpa fuel cut is all that is needed.

Offline Sprocket

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Looking at your last config file, there are still errors in the IAC config. You have not listened to the advice I gave in my first post.

Lets start again

MAX STEPS TO EXTEND  is the maximum steps that the stepper will move. You have this set at 160, yet you have 180 in the cold IAC start position and 184 in the -40c on the IAC refference table. Have you even tried to find out how many steps your valve moves? The other things wrong with this is that the engine requires more 'air' to start than it does when it is idling, but you have the warm and cold IAC start positions the same as the IAC refference table.

The key point to getting these settings right is firstly to determine the maximum steps the stepper motor moves. This will be the MAXIMUM steps. There should be no value that will be higher than this! And secondly, tune your stepper motor position to 40 steps with a warm idle (40 steps in the warmest point of the IAC refference table) using IacInt Guage (or is that IacInt steps, Mattias?) to or close to zero. To do this you will need to disable ignition based idle control and adjust the throttle stops, then re enable ignition based idle control when you have finished tuning. You will now need to estimate what the rest of the IAC refference table is for the first time, then tune this on subsequent cold starts again using the IacInt gauge. This table needs to respect the cold idle advance ramp down to warm idle advance.

with a warm IAC start position of 80 steps, this will be twice that of idle ( set at 40 as above) and the cold IAC start position could maybe be twice the warm position so set it at 160 (only if your stepper max steps to extend is higher than 160)