VIPER GTSR 91
Enthusiast
My 99 GTS has always had a lower idle than what I like at around 650 rpm. What is involved in increasing to around 750-850? Thanks.
How do you raise the idle RPM?
- Thread starter VIPER GTSR 91
- Start date
C O D Y
Enthusiast
Call Dan @ DC performance. I would think it would be done with a computer reflash.
VIPER GTSR 91
Enthusiast
Is there any other way to increase rpm w/o flash? I am bringing car to a dealer tech this week and just in case he does not know I could give him this info.
C O D Y
Enthusiast
I would try and find out if your tach is correct and is it really idling at 650.
That should be your first step. After that, if it is 650... try and find out why it's there. I do not know the exact number, but I think it should be closer to 750.
That should be your first step. After that, if it is 650... try and find out why it's there. I do not know the exact number, but I think it should be closer to 750.
GTSnake
Enthusiast
Maybe someone played with your idle adjust screw. You're not supposed to tinker with it and it's sealed from the factory but maybe someone tried turning it.
Mine idles a little low too sometimes but mostly it will hover around 680-690rpm when warm.
Mine idles a little low too sometimes but mostly it will hover around 680-690rpm when warm.
VIPER GTSR 91
Enthusiast
CODY, I called Dan at DC and he said the only way was to re flash the computer as you mentioned. He said to live with the low rpm as re flashing sometimes causes a high idle when decelerating. Thanks.
HP
Enthusiast
Make sure the idle air passages are clean. Spray carborater cleaner and pipe cleaners will usually do the job. If it's really gunked up, you might have to dissassemble some of the parts.
MacManInfi
Enthusiast
Mine '97 idles slightly below 500... at least according to the tach. Always has.
MacManInfi
Enthusiast
Hrm, maybe I need to do this. Anyone have a quick reference as to where these are? I don't know...
C O D Y
Enthusiast
I bet you're looking at the tach and thinking the first mark is 0. The very first line on a viper tach is 500 rpm. Take a close look at it. I don't think it would stay running very long under 500 rpms. Just a guess though.
HP
Enthusiast
Idle air circuits consist of - idle air motor (aluminum casting, with 4 prong wire connector)
bolted on the intake. and - the poly tubes running between the throttle bodies
MacManInfi
Enthusiast
You're probably right. That makes me feel better. hehehehe
PhoenixGTS
Enthusiast
Data Point: I normally run a Mopar Performance PCM but also have a reprogrammed one. The reprogrammed one has a higher idle and I HATE IT!. My favorite part of my car is the lumpy idle through the Belanger system. The higher idle might be nice if you road race and want to make sure you don't stall if you spin etc but it sounds like crap! 
Just my $0.02.
Just my $0.02.
C O D Y
Enthusiast
There is no idle screw. Minimum air screws, (mainly to keep throttle plates from binding,),on throttle plates so the Idle air controller will respond. If it does'nt die at idle all is good. 99 should have one on each throttle body. The other single screw on the throttle shafts are the balance srew to adjust both throttles open the same amount at the same time. You get rough hesitations and popping on accerleration from idle when this is off. I 'veused an older Stromberg carb sycronizer to set the throttle plates equally.
Tom F&L GoR
Enthusiast
The idle air control valve is like a pencil being stuck into a hole. How far the pencil protrudes controls the airflow. Since no fuel goes through it, and the gasoline contains the detergent additives, it cannot get cleaned normally. It can only get dirty from the crankcase ventilation gases that eventually add deposits that can upset the IAC function. I am not sure that a spray can reach the tip and orifice to clean it, although it is easy to remove and spray in a straight shock.
AviP
Enthusiast
I used to think that way too until somebody pointed out that what I think is "slightly below 500" is actually slightly below 750. The rpm gauge is not fully marked below 500rpm. There's just 0 and 500rpm.
