Tech Notes

Written by editor on . Posted in Summer 2009, Tech Notes

By Herb Helbig, Chief Engineer—Viper (Retired)

Q: Just picked up a 1998 GTS. I have surging in 5th and 6th gear at around 60 mph. I also have bucking at low speeds. I can’t find information that spells out the exact procedure to sync the throttle bodies for a GEN II. Can you help?

A: As far as I know, there is no procedure for syncing the throttle bodies on the single throttle cable engine. However, it’s pretty straight forward. The twin throttle bodies are connected by a cross shaft which has a bit of adjustment in it. The cable works the driver’s side TB and the throttle position sensor is on the passenger side TB. Make sure that as soon as the cable moves the driver’s side TB, the passenger side TB is also moving. If this is not the case, bucking is one side effect. Also make sure that when the throttle pedal is released both throttle blades are closed.

Q: It seems like it’s the convertible top or something similar, but I hear a clunking coming from the right rear of my 2006 SRT10® when I go over bumps. The previous owner took the car into the dealer and the report said they found it to be normal for the convertibles. Can you confirm this?

A: No clunk is normal. We didn’t build the top to make noise. A clunk coming from that right rear could be a lot of things. First try and isolate the noise inside versus outside and high in the car or low. Things to think about: loose shock, loose sway bar, check brake caliper etc. If you think it really is the top, look for wear marks where the top links might be rubbing, something may have come loose.

Q: I had the car in for service today and all went well until I noticed on the way home that the oil (temp) gauge was not working. I let the car get to temp and drove it a bit. There was plenty of oil and plenty of pressure. What’s really weird is that when I turn the key to on just before starting all the gauges including the oil gauge are reading correctly. Once I start it up though the oil temp gauge slowly falls back to under 120 and doesn’t move. Any idea what the problem is?

A: My guess would be a faulty sensor or possibly a connector problem at the temp sensor. I’ll admit that if you let the car warm up, shut it off and then just put the key in and get a good read from the gauge is confusing. That may be a more complicated electrical problem.

Q: I own a 1999 Viper GTS coupe with 20,000 miles on the odometer. I have a condition with the car’s HVAC system that has remained with the vehicle since it was new, but always thought it was a normal trait of the Viper. The condition occurs with the temperature knob in the cool position, while the A/C is on or off. The cool air coming thru the ducts suddenly becomes “very warm” for a period of approximately 20-30 seconds and then gradually starts to become cool again. This could happen about two times in the span of an hour on a long drive. Is this a normal condition? Can this problem be ratified with an upgraded Mopar part?

A: If the condition of warm air happens under heavy acceleration, the condition is normal. In order to deliver maximum power under heavy acceleration, the electronics temporarily shut down the compressor so the load is eliminated. If this is not the case, it sounds like the vacuum signal is changing at the HVAC unit. If that’s the case the dealer will need to check it out. If you’re sure it’s with the A/C on or off, then it’s time to visit the dealer.

Q: I own a 1995 Dodge Viper with 10,000 miles on it. I do a little autocross and road racing with it. Is there a good way of lowering it a little? I have a set of 2003 10-spoke wheels and stock tires and would like to have a little less ground clearance.

A: Due to the suspension design, there is no easy way to lower the car. You could swap a set of ACR shocks on and that would allow you to lower the adjustable spring seat. Otherwise you’d have to come up with a shorter set of springs and swap them on … not an easy job.

Q: I recently purchased a new 2009 Viper coupe and have decided to garage the car closer to my work rather than my home (two different cities). The problem is the garage entrance (commercial underground garage) is inclined and where the inclined ramp meets the garage floor is a rather sharp angle. Standard passenger cars do not scrape the front, however, the Viper with its front air intakes being so low, might pose a problem. I was thinking of air shocks for the front to add lift. Should you need it, I can determine the angle at the garage ramp and entrance. I was wondering if you have encountered this question in the past and have any recommendations.

A: There is no air shock that I know of that would fit your car, so there is no easy way to raise the front end. I’ve heard guys with this problem end up approaching the ramp at an angle that gets one of the wheels up first and allows a more gradual transition up the ramp … hope that helps.


Your technical questions are always welcome. Please remember to indicate the body style, model year and mileage for your Viper.

Tech Notes Editor
VIPER Magazine
PO Box 24425
Shawnee Mission, KS  66283
E-mail: [email protected]
Fax: (248) 499-1950


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