Trying to work out why car stops during warmup.

[[email protected]]

When I start my car and leave it warming up without touching the throttle a strange thing happens. It runs nice for a while and about 1 to 2 mins in, the car idle control valve (Nissan two wire type) sounds like it opens to a much higher opening level and the car goes lean on the can lambda reading and seconds later the engine revs up by itself and stalls. I think I have something wrong in one of my tables. Any ideas what is causing this?

2nd question: When I am reversing out of the garage, when I start to apply a little throttle pressure I hear the idle air device cut the air flow quite a lot and then when I return the throttle to fully closed it takes a while to respond and send a pwm signal to get the air device to open and do the job of keeping the car at it's warmup idle target. Is there a way to have the idle air device respong quicker? Can you see anything I could change in my tune file that would make it not do the above?

Here is a google drive link with my log file and my tune file: https://drive.google.com/drive/folders/1jxH-hgXk1LJgrQgzpcJ0Yo2fWoZgMDcs?usp=share_link

My setup is: LinkG4+ Storm Blue. Engine is Toyota 3sge beams with itbs. The itbs have four large hoses going to a combined vacume manifold which has a nissan type of Idle air device on it with a adjusting screw that does the base idle bypass.

Thanks for your help.

Kind Regards

Rex

 

 

 

[Adamw]

The lean stall is because you have the Fuel equation load source set to BAP, so at present you have throttle position controlling your injector pulse width, but with an idle valve bypassing air around the throttle.  Since the throttle sits fixed at 0% the whole time you are at idle, you have a fixed amount of fuel being injected, but a variable amount of air entering the engine, therefore the resulting air fuel ratio is going to be highly variable.   When an idle bypass is being used you must use MAP as the equation load source.  You fuel table will need tuning from scratch when you correct this.  

Your "slow response" to reach idle target is because your idle base position is miles off what is required.  Towards the end of your log for example your idle valve is open 70% to acheive the target RPM, yet your base position table is only commanding 22% for that temperature.  So when you exit idle conditions the valve will go to 22%, on next entry to idle the RPM will dip way to low because the valve is at 22% but the engine needs 70%, the closed loop will see the RPM is too low and slowly wind the valve back to 70% or whatever is needed to get the target.  The base position table should be commanding similar positions to what is required to acheive the desired target.  See the closed loop idle set up and tuning guide in the help file for the procedure to tune this function.

Other things I would change:

1. Increase idle ignition MAP lockout to say 70Kpa, it is not activating at present since you idle at 60kpa. 
2. Set the idle ign table up like the example in the help file, target error on the X axis.  lower values to the left of zero, higher values to the right.  You can generally go much more aggressive that the help file example. 
3. In idle speed control settings, change RPM lockout to 500Rpm, TP lockout to 0.5%, deaadband to 30RPM, proportional gain to 2.0.

[[email protected]]

I run ITB throttles on the beams 3sge. That is why I have tuned the mainfuel table with Throttle Position as the main axis and not MAP. When you say "because you have the Fuel equation load source set to BAP" and  "you must use MAP as the equation load source" are you saying I should charge my main fuel map axis to map and not throttle position or are you speaking of another table for example a cold start table?

I guess after spending heaps of hours getting the main fuel map nice I am slow to want to change it.

Is there a way I can use the air bypass valve and control it by time. For example for the first 2 mins that the engine is running idle at 1200 and then after that close and I could have the idle bypass screw that is part of the pwm valve set to a base idle of 850 rpm?

Is there a better way to do the cold start warmup idle with ITBs than useing a air bypass valve?

By the way you are right on the money in everything you are saying. I turned off the closed loop and ran it and all the stalling and going lean stopped when I test drove it tonight.

Here is tonights tune file and the log file from 1 hour of running. https://drive.google.com/drive/folders/11rDDMBL-RuJhqSo3C8x-rGV1vhxEPNY4?usp=share_link

Thanks heaps. Rex

 

Engine is: Toyota 3sge beams. ITB throttles with combined manifold below with a vacume hose going to the ecu.

ECU: Link G4+ storm blue.

 

 

[Adamw]

11 hours ago, [email protected] said:

I run ITB throttles on the beams 3sge. That is why I have tuned the mainfuel table with Throttle Position as the main axis and not MAP. When you say "because you have the Fuel equation load source set to BAP" and  "you must use MAP as the equation load source" are you saying I should charge my main fuel map axis to map and not throttle position or are you speaking of another table for example a cold start table?

No, just change the setting "Equation load source" from BAP to MAP.  

 

11 hours ago, [email protected] said:

Is there a way I can use the air bypass valve and control it by time. For example for the first 2 mins that the engine is running idle at 1200 and then after that close and I could have the idle bypass screw that is part of the pwm valve set to a base idle of 850 rpm?

Is there a better way to do the cold start warmup idle with ITBs than useing a air bypass valve?

You dont need to reinvent the wheel, just change the load source to MAP so the fuel equation can automatically compensate for air that is bypassing the throttle.   We use this method on all ITB engines with idle valves and it generally works well, GTR's, GTiR's, many BMW's etc all use this strategy.