sitting at idle and engine will begin accelerating
Thread Starter
Racer
Joined: Apr 2002
Posts: 311
Likes: 0
From: Charleston S.C.
sitting at idle and engine will begin accelerating
Engine is a 383 with fast intake and 90 mm throttle body. At random times sitting at idle in gear engine will start to rev out of control. Have to shut engine off and restart... usually a couple of times and then engine will start at idle and hold idle. Very scary!! Codes stored are P1551 and P1221. I've replaced TPS and verified at voltages on both sensors. Don't know what else to try. Failure records show desired throttle to be 5% and indicated to be 15%. Although if I make snapshot the to values stay perfectly inline. But I haven't been able to get a snapshot during the actual failure/ problem.
Le Mans Master
Joined: Aug 2005
Posts: 5,375
Likes: 328
From: CA.
St. Jude Donor '13-'14-'15
Did your tuner adjust the T-Body in your tune to reflect a 90 MM ?
Also what you are experiencing is a common issue with larger than stock intake manifolds and T-Bodies--Called a "hanging idle" In your tune there are tables to correct this---Foe both P/N and In Gear----
The table the is normally used is the "Throttle Follower" 1st andid that does not correct it then go to the "Throttle Cracker"
Adding a % to the follower will make it idle down faster--Start with like +10%
On the cracker "0 out 0 to 4 MPH"
If all this fails subtract a % to the "desired airflow In Gear" This table is scaled by coolant temperature----If it is OK when cold leave those #'s alone and work only in the areas where the hanging occurs If it happens everywhere then adjust the entire table
Start out by subtracting 15% in the approp areas
Also what you are experiencing is a common issue with larger than stock intake manifolds and T-Bodies--Called a "hanging idle" In your tune there are tables to correct this---Foe both P/N and In Gear----
The table the is normally used is the "Throttle Follower" 1st andid that does not correct it then go to the "Throttle Cracker"
Adding a % to the follower will make it idle down faster--Start with like +10%
On the cracker "0 out 0 to 4 MPH"
If all this fails subtract a % to the "desired airflow In Gear" This table is scaled by coolant temperature----If it is OK when cold leave those #'s alone and work only in the areas where the hanging occurs If it happens everywhere then adjust the entire table
Start out by subtracting 15% in the approp areas
