GT500 Monoblade Idle

[Jn2]

So a customer just added a monoblade to his GT500. Car drove and idles great with the stock twin 60mm throttle body. After we swapped the monoblade on the idle will hang and take 5-10 seconds to drop down in the 8-900rpm range. In the logs it looks like the throttle angle sits between 1-2* when it the RPM hangs and when it idles fine the TB angle is .8*, which is what the monoblade on my personaly car idles at.

I have used the correct monoblade TB data and adjusted the idle airflow/angle tables btut have not been able to dial in the decel to idle. If we turn the car on and let it idle it will idle fine, but when you tap the gas the TB angle will stick for a seconds then drop to .8, also it will up rev on it's. I am attaching a log where the last throttle blip looks like 2 blips but we only touched the throttle once, it revved up, came down, then second blip was the car revving up on it's own then coming back down.

WOT perferformance is spot on though, no wrench lights or flashing CELs. Anyone have any ideas on what else I can try?

Mods:
2010 GT500 w/14 Trinity TVS(2.5" pulley)
stock headers
catless x pipe
PMAS intake
monoblade TB

[Devildog1325]

I had an issue a while back with a roush that was hanging when on decel but it had the gt500 tb. I adjust the adaptive idle mph lower and it fixed it. I cant see your log but if its happening just while it setting there idling I would play with the torque tables a little bit in that area and see if it helps.

[japzap33]

https://www.facebook.com/groups/3907...EWSFEEDAccufab, Inc.
1 hr ?
George explains Throttle Bodies and the Coyote Intake Manifold Options

[Jn2]

https://www.facebook.com/groups/3907...EWSFEEDAccufab, Inc.
1 hr ?
George explains Throttle Bodies and the Coyote Intake Manifold Options

that does not apply here,:

IMG_0193.JPG

I had an issue a while back with a roush that was hanging when on decel but it had the gt500 tb. I adjust the adaptive idle mph lower and it fixed it. I cant see your log but if its happening just while it setting there idling I would play with the torque tables a little bit in that area and see if it helps.

You may be on to something there, the GT500 has "Minimum VSS" set to zero MPH so it uses dashpot 100% of the time, I'ma try raising it to 2mph, that way it will use the Idle Airflow settings to control idle instead of dashpot.

Another thing I did was log airflow vs throttle angle and then used the data to populate the Airflow vs Throttle angle table. figured it wouldnt hurt to get it closer to actual throttle angle.

[Devildog1325]

Which table did you adjust the park/neutral table or the drive table. I was under the impression that with manual cars it bases everything off the park/neutral table because the computer doesn't know if a gear has been selected I'm not 100% sure on this. Raising the vss might help, the car I was dealing with I think it was around 6mph and I think I dropped it down to about 2mph the adaptive was actually making the hanging problem worse even though the airflow tables were spot on....this was a cammed car I'm sure it played a role in the issue. Also another thought I wonder if the airflow overspeed correction being set where it comes in slower would it allow it to drop the rpm more before it starts trying to correct it? Again these are just thoughts and I'm sure somebody with a better understanding on how the system works will point you in a better direction.

[Jn2]

Which table did you adjust the park/neutral table or the drive table. I was under the impression that with manual cars it bases everything off the park/neutral table because the computer doesn't know if a gear has been selected I'm not 100% sure on this. Raising the vss might help, the car I was dealing with I think it was around 6mph and I think I dropped it down to about 2mph the adaptive was actually making the hanging problem worse even though the airflow tables were spot on....this was a cammed car I'm sure it played a role in the issue. Also another thought I wonder if the airflow overspeed correction being set where it comes in slower would it allow it to drop the rpm more before it starts trying to correct it? Again these are just thoughts and I'm sure somebody with a better understanding on how the system works will point you in a better direction.

I adjuested both the Drive and the P/N table. I figured manual cars wouldn't point towards the drive table at all but I changed the values there as well to match the P/N new values. Below is what I am going to try next along with the 2mph minimum VSS

idle air.PNG

[murfie]

Have you tried using the proportional, integral, and derivative throttle angle gain?

With smaller throttle bodies they usually have an over shoot on the closing side then open slightly as idle RPM is reached. I think the mono's drivability can benefit from adjustment to the closed loop PID to eliminate the need for this over shoot as it has a need to be at such a low angle to idle. Derivative will help with reducing the angle oscillation time after the initial throttle closure. you may need more integral which will introduce oscillation but should reduce error after derivative is added to remove the introduced oscillation. proportional will probably make it react faster and may make it worst probably not needed on these larger TB's.

[Devildog1325]

Throttle angle vs Airmass......I have never had to adjust this table but I haven't done many 2010 and up I don't recall this table on the 05-09 but looks like that could definitely cause an issue with that big of a throttle body. How are you supposed to log this and correct it with the scanner or is it a educated guess like it used to be getting the airflow tables right before stit were added.

[Devildog1325]

Murfie may be on to something there too what are those set to in the factory Cobra jet tune?

[Jn2]

Throttle angle vs Airmass......I have never had to adjust this table but I haven't done many 2010 and up I don't recall this table on the 05-09 but looks like that could definitely cause an issue with that big of a throttle body. How are you supposed to log this and correct it with the scanner or is it a educated guess like it used to be getting the airflow tables right before stit were added.

You can make a histogram to log MAF Airflow on the X axis and TB angle on the Y axis, then use TB angle as the PID. This will let you see what TB angle you are at when you are at a certain Airflow value. I did this and also reviewed the datalog to see what TB angle I was at for certain airflow values. Averaged them, then put them into the table. For the airflow vs rpm, I just looked at the airflow at some of those RPMs and put them in.

Have you tried using the proportional, integral, and derivative throttle angle gain?

With smaller throttle bodies they usually have an over shoot on the closing side then open slightly as idle RPM is reached. I think the mono's drivability can benefit from adjustment to the closed loop PID to eliminate the need for this over shoot as it has a need to be at such a low angle to idle. Derivative will help with reducing the angle oscillation time after the initial throttle closure. you may need more integral which will introduce oscillation but should reduce error after derivative is added to remove the introduced oscillation. proportional will probably make it react faster and may make it worst probably not needed on these larger TB's.

I have all 3 set to stock values right now, which are all ZERO.

Murfie may be on to something there too what are those set to in the factory Cobra jet tune?

Copperhead SCJ has all 3 set to zero just like I have them now, but the SCJ tri-core has integral set to 1.5 and derivative/proportional set to 0, I am going to try 0, .75, 0 to see if that helps.

gain.PNG

[murfie]

Just adding integral will probably make it worst. I'd try adding derivative first and see if the oscillation of throttle angle goes away. Then add integral. Integral magnifies the error and derivative increases how quickly it learns from it. The wiki article had a good visual and explanation of how each can help a closed loop controller.

[Devildog1325]

If you make a histogram with desired idle rpm as the x-axis and log STIT against this and just copy and paste add the values to your airflow table it will make idle and decel much better. I've had similar issues basing my airflow tables off maf airflow and fixed them logging the STIT and LTIT you can even log STIT a/c on to correct those tables also.

[Jn2]

If you make a histogram with desired idle rpm as the x-axis and log STIT against this and just copy and paste add the values to your airflow table it will make idle and decel much better. I've had similar issues basing my airflow tables off maf airflow and fixed them logging the STIT and LTIT you can even log STIT a/c on to correct those tables also.

Set it up like this? Then what ever values show up I highlight all on the ETC table and "paste add" to it?

stit.PNG

[Devildog1325]

Yes and I will change the idle in the tune to different rpms to populate the airflow table. One way is to set the idle to where you want it make the adjustment then set the idle to 1100 then log it and interpolate between the 2 values. Unless you want to retune the car for each desired idle on that table and log it.

[Devildog1325]

It may be easier to just use RPM instead of desired idle RPM so you don't have to change your idle every time. I cant remember why I stuck with desired. Try it both ways and see if you get the same results.

[Jn2]

Yes and I will change the idle in the tune to different rpms to populate the airflow table. One way is to set the idle to where you want it make the adjustment then set the idle to 1100 then log it and interpolate between the 2 values. Unless you want to retune the car for each desired idle on that table and log it.

I don't mind setting idle to each of those value sin order to get the correct airflow data for them, sure it will take time, but really i figure letting the car idle for a few mins at each rpm set point should be enough.

Ima try these changes and see how it goes. The car is down right now waiting for some TR7 plugs to come in. The Motorcrafts we had before(SP471) widened on their own after 500 miles for some reason, we set to .028" and after 500 miles we pulled them out due to crazy misfiring at WOT and they were all in the .034-.036" range

[Devildog1325]

Well when you try it lets us know how it works out.

[Blue Bee]

I have a customer that had the same issue, 2014 GT500, only mods are pulley, this same mono blade TB, longtubes. Had it "tuned" elsewhere and for almost 2 years he dealt with car starting and stalling on cold starts, I asked him if I could take a look at it and found that they never really tuned the car. Some where I found the flow tables for this TB and changed some other stuff to fix, I could post the stock and my tune for compare/help? It's not perfect but it's really close and he is way happy and now wants me to -actually- tune the car and all his others so i guess I did ok on it...

[06300CSRT8]

IF you wouldn't mind sharing the tunes would be greatly appreciated

[Jn2]

Update:

Customer swapped out the SP471 plugs for TR7-IX plugs and gapped the at .026". He went out for for some test pulls and when he was done he texted me saying the car is idling fine now and no longer hanging like it was before...This was with no changes to what I posted in the OP...I doubt the plugs were the fix, it may have been the driving it a round town that did it, maybe the TB needed to have some miles on it?