Throttle won't open past 23% at idle.

[rpmextreme]

Im having a weird one and have been chasing my tail. Its probably something easy but at this point I can't find it.

Specs: 2011 Truck 6.2 with a small MAST VVT cam and DOD delete, Headers and 6L80E.

I have been doing my VE tuning but during the process I noticed my idle never seemed to be able to keep up, Start up flare was way to low even after I added a bunch to the tune. I noticed last night that no matter what, the throttle % never goes above 23. So for some reason something is keeping it from going beyond 23% at idle and startup.

Once its running the idle is pretty close but I don't have any "reserve" idle flare at startup or at hard decel offroad it will die after a WOT run.

Im attaching my last log and the tune I was running last night. Im trying to get the VE around -10 because it seems to like it better. I still need to finish the VE but I need to get a handle on the idle first.

VVE1.8.hpt log7.hpl

[rpmextreme]

Actually 22.7% is max throttle position (SAE) at idle. commanded looks to be 12.5% max.

As soon as I touch the throttle the blade opens further.

[scottt28]

Im having a weird one and have been chasing my tail. Its probably something easy but at this point I can't find it.

Specs: 2011 Truck 6.2 with a small MAST VVT cam and DOD delete, Headers and 6L80E.

I have been doing my VE tuning but during the process I noticed my idle never seemed to be able to keep up, Start up flare was way to low even after I added a bunch to the tune. I noticed last night that no matter what, the throttle % never goes above 23. So for some reason something is keeping it from going beyond 23% at idle and startup.

Once its running the idle is pretty close but I don't have any "reserve" idle flare at startup or at hard decel offroad it will die after a WOT run.

Im attaching my last log and the tune I was running last night. Im trying to get the VE around -10 because it seems to like it better. I still need to finish the VE but I need to get a handle on the idle first.

VVE1.8.hpt log7.hpl

Dynamic airflow looks like it was changed. It is very high. Airflow final minimum numbers look too high. I would go back to stock then look at schpenxel's note on how to put it in SD mode for tuning.

[mowton]

As you are in Speed Density and have failed the MAF, you need to increase the protection values for failed conditions. Stock is 60, increase until you have enough reserve in the max blade opening. Also you have the Max value set to 100% which should be put back to either stock or what ever maximum Throttle blade opening % you need for a cold start/worse case load.

Ed M

[rpmextreme]

As you are in Speed Density and have failed the MAF, you need to increase the protection values for failed conditions. Stock is 60, increase until you have enough reserve in the max blade opening. Also you have the Max value set to 100% which should be put back to either stock or what ever maximum Throttle blade opening % you need for a cold start/worse case load.

Ed M

I got ya. so when I failed the MAF and went SD it limits the blade opening at idle? I did know to set the percent MAX back down but was chasing ghost and just maxed it out temporally.

[rpmextreme]

Dynamic airflow looks like it was changed. It is very high. Airflow final minimum numbers look too high. I would go back to stock then look at schpenxel's note on how to put it in SD mode for tuning.

I did move the dynamic airflow up to put it in SD mode. Did I not do it correctly?

I do agree on the airflow minimum number looking high. I was very surprised to have to add this much air. Truck intake and throttle body.

[scottt28]

Have to admit, dynamic airflow is a good question. I haven't seen it mentioned in the instructions from various forum members. I'm thinking it we failed the MAF, it shouldn't really matter. Anybody have an opinion?

Here's another point... I've read that the best way to tune VVE is in open loop. Are guys commanding open loop using the Vehicle > Controls and Special Functions in the scanner? Anybody have an opinion on this one too?

I just started clicking through your tune and noticed that a bunch of values didn't look right. I downloaded a stock tune and compared them. That's why I suggested to start with a stock tune file and then review schpenxel's instructions.

I'm new at this, and I've been struggling a bit (not just with the technology, but also parts issues), but there are a couple guys on the forum that know their stuff and go above and beyond to help.

[rpmextreme]

Have to admit, dynamic airflow is a good question. I haven't seen it mentioned in the instructions from various forum members. I'm thinking it we failed the MAF, it shouldn't really matter.

I just started clicking through your tune and noticed that a bunch of values didn't look right. I downloaded a stock tune and compared them. That's why I suggested to start with a stock tune file and then review schpenxel's instructions.

I'm new at this, and I've been struggling a bit (not just with the technology, but also parts issues), but there are a couple guys on the forum that know their stuff and go above and beyond to help.

I think we are maxing out the dynamic airflow to keep it running on the VE table all the time.

There are a lot of "other' changes but it runs extremely well other than a few small issues and getting it dialed in completely VE and MAF

[schpenxel]

I did move the dynamic airflow up to put it in SD mode. Did I not do it correctly?

I do agree on the airflow minimum number looking high. I was very surprised to have to add this much air. Truck intake and throttle body.

I haven't looked at the tune, but messing with dynamic airflow enable/disable is for making it MAF only

For doing SD only then you want to make the MAF fail. To do that set the high frequency fail to 1hz and set codes P0101 102 and 103 to MIL on first error and leave the SES light checked to make sure it's throwing the error

You can also 0 out the MAF table.. if it still runs then it's fairly safe to say it isn't using the MAF

[mowton]

Have to admit, dynamic airflow is a good question. I haven't seen it mentioned in the instructions from various forum members. I'm thinking it we failed the MAF, it shouldn't really matter. Anybody have an opinion? You are correct, once failed the High RPM settings are moot but some say to max them out...either way is acceptable

Here's another point... I've read that the best way to tune VVE is in open loop. Are guys commanding open loop using the Vehicle > Controls and Special Functions in the scanner? Anybody have an opinion on this one too?
My preference is to tune in OPen Loop so I am not chasing the trims...you need a wide-band for that of course as some only tune the closed loop portion with the trims. Can use VCM controls (don't forget to clear the trims) or set the tune to Open Loop and disable LTFT.

I just started clicking through your tune and noticed that a bunch of values didn't look right. I downloaded a stock tune and compared them. That's why I suggested to start with a stock tune file and then review schpenxel's instructions.

I'm new at this, and I've been struggling a bit (not just with the technology, but also parts issues), but there are a couple guys on the forum that know their stuff and go above and beyond to help.

See above

Ed M

[rpmextreme]

Thanks ED. I did follow schpenxel's VE thread and it has been working great.

The Max Fail (effective area) was what was keeping my idle from going beyond a certain point. I have corrected it and now we are cooking again. In my mind I saw it set at 60 and figured it was 60% not 60 square millimeters.

I still have 2 bugs to clean up. First was happening even when I wasn't in SD. During a start it would idle great for 6 seconds and then dump and stumble before catching back up. something seemed to be timing out and it was like clockwork. I tried extending the startup airflow delay longer but it didn't seem to be it. Not sure if its fuel or airflow at this point.

2nd. It may just be too much min airflow but if I just blip the throttle from idle she will run up to 1200 and take 10-15 seconds to finally come back down. it also will do this after coming to a stop. It seems the throttle is not responding fast enough. I think I may have adjusted some of adaptive setting before to slow it down because my VE table was off and causing wild surging. now that my VE table is much better I need the throttle to respond quicker.

[scottt28]

A side note... you're scanning lots of channels. I think you'd have better luck cutting the list of channels down

[mowton]

A side note... you're scanning lots of channels. I think you'd have better luck cutting the list of channels down

^^^^^ Agree...and use Broadcast Parameters when ever you can. Try and limit polled parameters to 20-22.....You can also set priority/poll levels (how often the parameter is polled in a given cycle) to help gain additional resolution to the important parameters.

Ed M

[rpmextreme]

So far so good. The 1 big issue I'm chasing now is it idling up around 500 rpm whenever I barely blip the throttle or let it start rolling and it see's vehicle speed. It doesn't matter if its in park,neutral or gear. A slight blip of throttle or vehicle speed will make the throttle jump from 22% to 30% and will slowly come back down to idle.

It still shows the correct commanded idle speed and tried like hell to remove the timing to bring it back but my throttle is open too much and takes forever to return. It will basically drive itself down the road without any throttle input from me.

Im thinking its the minimum airflow table but my settings are 14.9 from 200-8000 rpm and at idle there is little to no spark or throttle correction. So i can't imaging it needs less air at higher rpm's.
Its almost like its moving to a different table...the very slightest blip of the throttle will make the idle jump up.

Any ideas?

[schpenxel]

Sounds like classic min air too high to me

If units are g/sec then 14.9 seems pretty high

What's idle adapt advance doing?

Spark isn't going to fix too much air if it's very far off

Got a log/tune of current setup?

[scottt28]

So far so good. The 1 big issue I'm chasing now is it idling up around 500 rpm whenever I barely blip the throttle or let it start rolling and it see's vehicle speed. It doesn't matter if its in park,neutral or gear. A slight blip of throttle or vehicle speed will make the throttle jump from 22% to 30% and will slowly come back down to idle.

It still shows the correct commanded idle speed and tried like hell to remove the timing to bring it back but my throttle is open too much and takes forever to return. It will basically drive itself down the road without any throttle input from me.

Im thinking its the minimum airflow table but my settings are 14.9 from 200-8000 rpm and at idle there is little to no spark or throttle correction. So i can't imaging it needs less air at higher rpm's.
Its almost like its moving to a different table...the very slightest blip of the throttle will make the idle jump up.

Any ideas?

Engine > Idle > Airflow > Base Running Airflow > Airflow Final Minimum. I had the same problem. Was acting like cruise control. Couldn't stop truck. Brakes were on fire. Airflow Final Minimum numbers act like a throttle stop/idle speed adjustment screw on a carburetor. If the screw is turned in too far, idle doesn't go down. Airflow Final Minimum numbers too high, and the idle doesn't go down. Numbers in the 7-ish range seem to work ok at idle speeds. Your results may vary. Here's a shot from my tune.

Final Idle Airflow Min.pdf

Here's a shot of a STOCK 2011 CHEVROLET SILVERADO 6.2 LITER AUTO tune from the Tune Repository

STOCK 2011 6.2 LITER CHEVROLET SILVERADO AUTOMATIC.pdf

You didn't mention how big the cam is and what your idle speed setting is etc... but I'll bet you're somewhere in the 7 range.

[GHuggins]

I've always been told that anything above 12 is moot. If it's driving itself then it's too high. You have other tables that effect min air too such as the multipliers. If you changed your idle correction tables then try putting them back to stock and seeing what happens.

[Area47]

Engine > Idle > Airflow > Base Running Airflow > Airflow Final Minimum. I had the same problem. Was acting like cruise control. Couldn't stop truck. Brakes were on fire. Airflow Final Minimum numbers act like a throttle stop/idle speed adjustment screw on a carburetor. If the screw is turned in too far, idle doesn't go down. Airflow Final Minimum numbers too high, and the idle doesn't go down. Numbers in the 7-ish range seem to work ok at idle speeds. Your results may vary. Here's a shot from my tune.

Final Idle Airflow Min.pdf

Here's a shot of a STOCK 2011 CHEVROLET SILVERADO 6.2 LITER AUTO tune from the Tune Repository

STOCK 2011 6.2 LITER CHEVROLET SILVERADO AUTOMATIC.pdf

You didn't mention how big the cam is and what your idle speed setting is etc... but I'll bet you're somewhere in the 7 range.

faster way to look at is simple. if the timing is higher than commanded, you're AFM is too low. if it us lower than commanded, your AFM is too high.

[rpmextreme]

Im getting a handle on it now. Getting the exhaust leak fixed and the VE table dialed in allow me to remove a lot of the AFM.