Ghost throttle issue

[chri_mar]

I have been having an ongoing issue with my car not coming back to normal under deceleration. Running an edelbrock supercharger at 9lbs boost on a forged 5.7 with big valve heads and high lift cam. After going into wot for a few seconds and then getting off the pedal the car will stay at that rpm and basically cruise like that for about 15 seconds or more with no pedal input. The afr under wot are around 11.5 and after getting off throttle the afr will peg at 10.0 and stay that way for a bit before slowly returning to normal 14.7 afr.
Car was tuned by Hemituner AJ through a speed shop on a diablosport unit. Have recently swapped over to the hpt unit. Can someone take a look at the log and tune file and see if something jumps out as being out of line.

[malikib]

I have been having an ongoing issue with my car not coming back to normal under deceleration. Running an edelbrock supercharger at 9lbs boost on a forged 5.7 with big valve heads and high lift cam. After going into wot for a few seconds and then getting off the pedal the car will stay at that rpm and basically cruise like that for about 15 seconds or more with no pedal input. The afr under wot are around 11.5 and after getting off throttle the afr will peg at 10.0 and stay that way for a bit before slowly returning to normal 14.7 afr.
Car was tuned by Hemituna through a speed shop on a diablosport unit. Have recently swapped over to the hpt unit. Can someone take a look at the log and tune file and see if something jumps out as being out of line.

try raising the dfco disable map to 60kpa

[chri_mar]

No real difference after making the change, car continues to act like the cruise is on for a bit after decel. Almost feels like it's not coming out of boost but the gauge shows it is. Car runs like a bat out of hell for a 5.7 just the decel issue.

[coanan]

You running a 3-bar MAP? Don't know this stuff like others, so I look at tune of similar builds.. Enable sensed MAP and if 2-bar change P-ratio max to 2000 (may or may not matter) and try. Did you try any changes with SM/LG range in E-throttle?

[malikib]

No real difference after making the change, car continues to act like the cruise is on for a bit after decel. Almost feels like it's not coming out of boost but the gauge shows it is. Car runs like a bat out of hell for a 5.7 just the decel issue.

did the wideband show any difference after changing that ? i saw in the log that when you decel the map hovers around 35-50 kpa and the afrs are at 10 . so dfco is supposed to kick in and stop the injectors. the afrs return to normal when closed loop comes back on at idle. does it happen even when the inj pw is 0 ?

[chri_mar]

did the wideband show any difference after changing that ? i saw in the log that when you decel the map hovers around 35-50 kpa and the afrs are at 10 . so dfco is supposed to kick in and stop the injectors. the afrs return to normal when closed loop comes back on at idle. does it happen even when the inj pw is 0 ?

I ran a new log and will include changes made in the tune to date. We have played with airflow tables and most changes made things worse. In the latest log you can see right at the end of the log the speed increase with no throttle input. The afr seems to stay a bit higher under decel with these changes. Dfco set to 60kpaplumboosttune 02[66].hptghostthrottle5.hpl

[chri_mar]

You running a 3-bar MAP? Don't know this stuff like others, so I look at tune of similar builds.. Enable sensed MAP and if 2-bar change P-ratio max to 2000 (may or may not matter) and try. Did you try any changes with SM/LG range in E-throttle?

2 bar that comes with the system. And yes played with those to no avail, made other weird things happen.

[malikib]

I ran a new log and will include changes made in the tune to date. We have played with airflow tables and most changes made things worse. In the latest log you can see right at the end of the log the speed increase with no throttle input. The afr seems to stay a bit higher under decel with these changes. Dfco set to 60kpaplumboosttune 02[66].hptghostthrottle5.hpl

dfco didn't get enabled , if it's enabled correctly it should have cut the injectors pw to 0 when you left off the pedal . any speed increase of the engine is due to 3 things air,fuel and spark . now i suspect the throttle is not closing enough due to the supercharger acting on it so we can try to cut the fuel to stop this issue . try increasing the dfco enable map 50kpa . if dfco is enabled correctly the wideband should show three dashes (---) and go full lean halting the combustion . also this issue happens when the throttle voltage is between 0.3 and 0.5 volts so increase the airflow model in this range if and see if it solves it to close the throttle

[McCloud]

I have been having an ongoing issue with my car not coming back to normal under deceleration. Running an edelbrock supercharger at 9lbs boost on a forged 5.7 with big valve heads and high lift cam. After going into wot for a few seconds and then getting off the pedal the car will stay at that rpm and basically cruise like that for about 15 seconds or more with no pedal input. The afr under wot are around 11.5 and after getting off throttle the afr will peg at 10.0 and stay that way for a bit before slowly returning to normal 14.7 afr.
Car was tuned by Hemituna through a speed shop on a diablosport unit. Have recently swapped over to the hpt unit. Can someone take a look at the log and tune file and see if something jumps out as being out of line.

If you haven't corrected it yet give the attached a shot.

[Hemituna]

Corrected. Car was tuned by Hemituner through a speed shop on a diablosport unit.

Not my tune.

I have been having an ongoing issue with my car not coming back to normal under deceleration. Running an edelbrock supercharger at 9lbs boost on a forged 5.7 with big valve heads and high lift cam. After going into wot for a few seconds and then getting off the pedal the car will stay at that rpm and basically cruise like that for about 15 seconds or more with no pedal input. The afr under wot are around 11.5 and after getting off throttle the afr will peg at 10.0 and stay that way for a bit before slowly returning to normal 14.7 afr.
Car was tuned by Hemituna through a speed shop on a diablosport unit. Have recently swapped over to the hpt unit. Can someone take a look at the log and tune file and see if something jumps out as being out of line.

[malikib]

Corrected. Car was tuned by Hemituner through a speed shop on a diablosport unit.

Not my tune.

so what typically causes this issue with throttle hemituna?

[chri_mar]

If you haven't corrected it yet give the attached a shot.

Was busy this week but had a chance to try this out for a short bit. The issue still exists with these changes, little pull near the start of this log and again full rich afr as well as the cruise effect.

[chri_mar]

Corrected. Car was tuned by Hemituner through a speed shop on a diablosport unit.

Not my tune.

My mistake when writing the post, I had been reading so many of your posts lately and for some reason never caught it when I typed the post out. Sorry for the confusion, fixed now.

[coanan]

Was busy this week but had a chance to try this out for a short bit. The issue still exists with these changes, little pull near the start of this log and again full rich afr as well as the cruise effect.

You tried turning on sensed MAP already?

[chri_mar]

You tried turning on sensed MAP already?

Actually forgot about that. I will do some more playing around with it tomorrow. This has persisted over both cars I have run this blower on, super happy with the power it puts out and thankfully I am kind of used to what it does and am mindful of it. Biggest issue would be having to brake hard after wot run and the car still wants to go.

[coanan]

Actually forgot about that. I will do some more playing around with it tomorrow. This has persisted over both cars I have run this blower on, super happy with the power it puts out and thankfully I am kind of used to what it does and am mindful of it. Biggest issue would be having to brake hard after wot run and the car still wants to go.

What intake gaskets have you been using?

[chri_mar]

What intake gaskets have you been using?

Cometic 6.1 gaskets. No change with sensed map enabled either, still the cruise effect and full rich on decel. Starting to wonder if it might be a bypass issue. It seems to work as it's designed though.

[coanan]

Cometic 6.1 gaskets. No change with sensed map enabled either, still the cruise effect and full rich on decel. Starting to wonder if it might be a bypass issue. It seems to work as it's designed though.

Identical problem on another car? What was the tune like on the other?

[chri_mar]

Identical problem on another car? What was the tune like on the other?

This setup was on an 06 originally, dyno tuned and ran for 2 yrs. Then swapped to my current 5.7 and this year put in forged bottom end bored .020.
It was dyno tuned again after the swap into this car. Since then I have put on smaller pulley to go from 7lbs to 9lbs approx. Ran for 1 yr with the smaller pulley without touching the tune, but this has persisted through all builds. Like I said above the tune works great for power as my race times tell me and daily driving is fine until I go into boost for more than a few seconds.

[coanan]

This setup was on an 06 originally, dyno tuned and ran for 2 yrs. Then swapped to my current 5.7 and this year put in forged bottom end bored .020.
It was dyno tuned again after the swap into this car. Since then I have put on smaller pulley to go from 7lbs to 9lbs approx. Ran for 1 yr with the smaller pulley without touching the tune, but this has persisted through all builds. Like I said above the tune works great for power as my race times tell me and daily driving is fine until I go into boost for more than a few seconds.

How much of the tune did you carry over to this car?