Hennessey venom 1000 Viper idle and runing problems

[daniel83]

hey guys,
we are having a lill problem with a viper it is not running well the rpm keeps going up and down the car will not start if the throttle is not pushed as leas a lill bit
any sugestions???

[Blacksaleen95]

setup the rpm vs idle% table, target your idle feedback for -6 to -9
be sure the fuel and timing maps transition smoothly around idle cells
setup the ign vs rpm error table, after you have your timing/fuel maps setup...this will usually keep idles steady, however it should not be used as a band-aid or crutch.

Having to start the car with the foot on the throttle can be due to the idle% table not being setup correct, or crank/start fuel being off. You can try to up the rpm offset vs start time table to keep the iac open a little longer after startup to see if that helps.

[BoostedV10]

As a more application specific issue, I have seen several Vipers gradually lose their idle motor position due to faulty wiring/slow idle air motor. After driving for a few minutes on the street, the idle motor will slowly drift toward open and the ecu will lose ability to control idle and it will hang high. The idle commanded position will be 0% but you can go put your finger over the idle motor passage and the engine will stall.  If you restart the car and the idle is normal again. I have figured out a fix for the issue but have seen it happen on several AEM equipped V-10 vehicles. I would look at all the issues pointed out by "blacksaleen95" but I would also watch the idle motor position in relation to commanded position. These engines are sensitive to  the throttle body closed blade position. Usually an after-market assembly has been installed and the initial setting is too far open causing the computer to fully close the iac to control idle. This would result in surging. I do believe you have at least 2 separate areas in your tune fighting you. one is initial start and then you need to look at the idle control.

Do not hesitate to contact me if you have any further issues or need more assistance with these issues.

James Voorhees
281.907.3343
keep us posted on what you find.