Explain how the idle air system is currently known to be ran in the Gen4 ECUs

[mowton]

I think you mean Drive by Cable/IAC....right?

You are going to have to somehow align the throttle blade/linkage/TPS to the Desired Throttle position. There is a very large disparage between he two and setting the Percent Max values as low as you went should drive the blades to closed...not 20%.

Ed M

[GrannySShifting]

mechanical action on the other end shouldnt matter though. 3% is going to equal whatever blade percentage output in the ECU (regardless of the physical position of the shaft. ECU think 3=20% and 2 = 15%, but the actual shaft could be at 10, 20, 30 degrees mechanical opening regardless right?) Seems to me the wierd is going on in the software. We set the blades so that they were the most physically closed with the DBW motor at rest as possible, without tripping out when its powered on. Key On they go through a self check opens then closes to check for range I guess, and if we shut them any more when it self checked it would rotate shut I guess bind because it wanted more closing range and code out

[mowton]

Unless I'm all f'd up, but by setting Final Min air to 64 g/sec and PI to 0, the Percent MAX should control should be able to close the blades to zero. Not what you would want, but to me it should be able to do it, your setup doesn't seem to be doing that for some reason. Assume you have the matching pedal to the DBW setup (do see pedal is 0% at least in idle for this scenario).

You can try setting the scalar to a lower number (half it) and see what direction the TPS% sensor PID goes. I would assume it will increase as that tells the PCM the TB is smaller and needs more rotation to get to the desired effective area. Then set it to 8000 and see where the TPS% goes, now it should get smaller as you are telling the PCM you have a larger TB or increased effective area, so less rotation.

Of note, the TPS% sensor is just the feedback to the PCM as to Throttle Blade position.

Ed M
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[GrannySShifting]

Unless I'm all f'd up, but by setting Final Min air to 64 g/sec and PI to 0, the Percent MAX should control should be able to close the blades to zero. Not what you would want, but to me it should be able to do it, your setup doesn't seem to be doing that for some reason. Assume you have the matching pedal to the DBW setup (do see pedal is 0% at least in idle for this scenario).

You can try setting the scalar to a lower number (half it) and see what direction the TPS% sensor PID goes. I would assume it will increase as that tells the PCM the TB is smaller and needs more rotation to get to the desired effective area. Then set it to 8000 and see where the TPS% goes, now it should get smaller as you are telling the PCM you have a larger TB or increased effective area, so less rotation.

Of note, the TPS% sensor is just the feedback to the PCM as to Throttle Blade position.

Ed M
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I went from 2300 to 5600 scalar a few iterations ago, and TPS lowered but not by much. Maybe one percent I think it was?

[mowton]

I went from 2300 to 5600 scalar a few iterations ago, and TPS lowered but not by much. Maybe one percent I think it was?

With Final Min air @ 64 g/sec and P&I at zero?

Ed M

[BBA]

Did you ever think air goes through all 8 holes at idle? None of them close perfectly and all leak past the shaft openings.

What happens if you set for area of all 8 holes combined for the max effective throttle blade area, along with doubling the area scaler over what you think it should have been calculating just 4 blades?

As for the progressive linkage, that will have to be tuned for with the virtual VE coeficients in SD mode.

[GrannySShifting]

Did you ever think air goes through all 8 holes at idle? None of them close perfectly and all leak past the shaft openings.

What happens if you set for area of all 8 holes combined for the max effective throttle blade area, along with doubling the area scaler over what you think it should have been calculating just 4 blades?

As for the progressive linkage, that will have to be tuned for with the virtual VE coeficients in SD mode.

Its only being tuned in SD via VVE coeffs. I did that originally with the surface area calcs, but alot of screwed up things have been found since then. maybe try that now

[Tre-Cool]

Did you make up the throttle linkage yourself for the etc? i'd be very keen to see some more pics of the setup.

I'm thinking of doing a similar setup for a burnout car that uses a caprice shell also, but using on the new edelbrock enforcer blowers instead of a 6 or 8/71.

[GrannySShifting]

Did you make up the throttle linkage yourself for the etc? i'd be very keen to see some more pics of the setup.

I'm thinking of doing a similar setup for a burnout car that uses a caprice shell also, but using on the new edelbrock enforcer blowers instead of a 6 or 8/71.

If your thinking about copying this setup, STOP. It was not the most well thought out design. Although not as "cool" the smart thing would have been to use two factory 90mm DBW throttle bodies facing upwards, with the readily available Y harness, and this project would have been working months ago LOL

If you want to know anything about it or otherwise [email protected]

[Tre-Cool]

If your thinking about copying this setup, STOP. It was not the most well thought out design. Although not as "cool" the smart thing would have been to use two factory 90mm DBW throttle bodies facing upwards, with the readily available Y harness, and this project would have been working months ago LOL

If you want to know anything about it or otherwise [email protected]

even better, do u have a link to the y-harness?

[topher455]

As I understand it (and have used), if you set the min air table to 64 and prop/integral tables to zero, it will take ithem out of play. At that point the amount the throttle plate will open or close is controlled by the Percent Max and Percent Max- braking parameters. The first is used for coastdown and the later is for stationary idle (worse case in auto in gear, ac on etc.). While they are a percent, they too are converted into an effective area then to a TPS%. I know of no "decoder ring" that shows that conversion but you can log the TPS% and move the percentage and you will see the blade (TPS% PID) increase and decrease. Using the base idle timing value, you can establish the "set point" for this value which represents the maximum the throttle blade will open (opposite of min idle air). When done, you normally add about .04 to .1 to handle cold starts as all the previous adjustments are made at operating temp. Once the Max is established you set the Min idle air (Final air) to a starting value (14 sh) and see how the car responds to throttle blips...too slow a recovery and the MIA is too high and too quick, its too low. The gol is to establish the 2 bvoundaries (mx/min) by which the Proportional and Integral air correction can operate between.

Ed M

This is an excellent explanation of the tables and how they work together. Thank you! I have been having an issue with throttle transitions and surging on a newer e38 equipped car with a solid roller stroker motor. I suspect the max settings may be the culprit. Im going to try the process you outlined above. Im assuming the stock values will be too low for the larger displacement.