Bucking Viper....Yee Ha

[96GTS]

I have a 96 GTS that "bucks" at around 5mph. If I give it more gas or push in the clutch it stops. Is this common and just something I have to live with, or do the throttle bodies need to be adjusted?

 

[AviP]

Bucking at parking lot speeds is common if you have an unsteady right foot. It's a display of the Viper's awesome low range torque. I sometimes scare the heck out of my passenger with some extreme right foot modulation.

 

[Bonkers]

I've done a lot of research into this because mine has had this problem for at least a year now. Is it accompanied by a loud clunk from the rear? The most common solutions I've run across are: to synchronize your throttle bodies - to tighten your transmission mounts - tighten the wheel hubs - and have the rear differential inspected. I've done all four and still have the problem so if I discover a new solution I'll drop you a line.

 

[AviP]

I've done a lot of research into this because mine has had this problem for at least a year now. Is it accompanied by a loud clunk from the rear? The most common solutions I've run across are: to synchronize your throttle bodies - to tighten your transmission mounts - tighten the wheel hubs - and have the rear differential inspected. I've done all four and still have the problem so if I discover a new solution I'll drop you a line.

I don't think he's referring to any mechanical sounds or clunks. I don't think it's a problem at all. Mine bucked from day 1. I almost lost a passenger to the windshield. It's just torque and an unsteady right foot.

 

[GT40DOC]

My 97 GTS does exactly the same thing. It bugged me at first, but I have "sort of" gotten used to it. If I can get the speed up a little and shift into second(plenty of torque for this) it seems to help a lot

 

[CAS]

Sync your throttle bodies; this can happen even if you're idling and your foot is not touching the throttle.

 

[96GTS]

It does it when I don't even have my foot on the gas. At a real low speed, I can even be coasting down a hill, and it does it. I give it a little gas and it quits. I'm glad to hear it's common, but it's still annoying and embarassing.

 

[Bobpantax]

Does it do it after the car reaches normal operating temperature? If not, when you start it up, let it idle a while until the engine heats up, then proceed. You might also try a different set of plugs with a different gap. Bucking can be part of the well known "cold start syndrome". If you have mods, you may need diffrent plugs with a different gap. Call Sean Roe. He is very knowledgeable and very helpful.

 

[carguy07]

My 95 bucked like crazy when I bought it and it only had something like 1,300 miles. Synchronized the throttle bodies and 80%-90% of it went away.

 

[V10SpeedLuvr]

My 96' RT/10 does the same thing as well. I bought it about 2 months ago and it had just had the throttle body's synched, new plugs and wires, rear differential service and transmission service as part of a major tuneup a couple thousand miles ago. I always figured it was from the massive amount of torque and the Viper telling me it'd rather be on a track or open highway instead of a parking lot

 

[PhoenixGTS]

Adjust the throttle bodies so that the driver's side leads the passenger side ever so slightly then go from there. Make sure and devise a way to remember where you started in case you develop an idle hang problem and need to go back to the initial setting (I count turns on the adjusting screw and make notes).

By the way, one of the really nice benefits of short gears is that when driving in a parking lot or parking garage at super low speed your rpm is pretty much above the possible bucking area. Short gears make driving the car slow much nicer.

 

[Dave Dugal]

Adding to all the other good replies, my '97 GTS will downright scare you if the throttle is just barely cracked open in 1st gear. HOWEVER, letting the clutch out at idle with no throttle input is very smooth; no bucking at all.

There aren't many other coupes out there where you can just lift the clutch with no gas and inch along in traffic, even uphill. GOD I love low-end torque!

 

[96GTS]

I can drive the car all day and it still does it, so it not because it's cold. I'm going to get the throttle bodies adjusted and go from there.

 

[Viperfreak2]

Throttle bodies may have something to do with it, but it's not the whole problem. My SRT-10 bucks at low speeds too and it doesn't have two separate.

 

[Viperfreak2]

Throttle bodies may have something to do with it, but it's not the whole problem. My SRT-10 bucks at low speeds too and it doesn't have two separate.

 

[PhoenixGTS]

My SRT-10 bucks at low speeds too and it doesn't have two separate.

That is very interesting. I thought for sure the single t-body would solve the issue.

 

[Andrew/USPWR]

Mine always seems worse when the engine’s cold. But it is much smoother since I removed the aluminum flywheel and went back to stock.

 

[joe117]

I really believe that most of the bucking is driver induced.

What happens is that the foot presses ever so lightly on the gas pedal,
the car lurches forward a little,
the forward lurch sets you back slightly in the seat,
this causes your foot to move slightly back off the pedal,
the car slows,
foot presses ever so slightly on the gas.....
Repeat this procedure.

This "do loop" causes the bucking.

Try this,
press the right side of your right foot hard against the transmission tunnel.
Then twist the left side of that same foot so it presses on the gas pedal.

The hard contact of your foot on the tunnel carpet will brace your right foot so you don't get bounced back and thus give slightly less pressure on the gas pedal.

IMO,
Any loud clunks from the rear area when a car bucks, could be caused by,
combined play universals in axles or drive shaft,
poorly adjusted or worn rear end gears,
loose or missing bushings in rear end assembly,
or perhaps noise from the brake pads moving.

 

[AviP]

I really believe that most of the bucking is driver induced.

Like I stated at the top of this post.

 

[Buckeye Viper]

Vec1, Vec2, AEM.

Done.

 

[96GTS]

I just got back from the dealer and the technician said that the Viper has 2 coils packs. One is a 6 cylinder coil pack, and it doesn't fire the other 4 cylinders until after 37%. He said it's normal, and is even worse in the new SRT 10 because of the increase in horsepower. Thanks for all you advise, I really appreciate it. I think this is a great board, and you are all a great bunch of people.

 

[thebigsnake]

The automatic Viper is better at avoiding this problem.

 

[joe117]

"Viper has 2 coils packs. One is a 6 cylinder coil pack, and it doesn't fire the other 4 cylinders until after 37%."

No, I don't believe the second part of that is correct.

The Viper has a 6cyl and a 4cyl coil pack because they wanted to use what they already had rather than use a new, 10cyl coil pack.

I do not believe that the 37% idea is true.

 

[Viperfreak2]

Also not true...

"I really believe that most of the bucking is driver induced."

This is when the SRT bucks: Every day, same company parking lot. Speed goes from 30 down to 10 (Pedestrian zone, large company) Shift into 1st gear at 20. No feet on anything. Car decels down to 15 and starts bucking on its' own. Push clutch in, let clutch out, bucking stops. Go 50 feet, no feet on any pedal...bucks again. Same parking lot, three Vipers. When I let (rarely) friends drive, same thing.

It's much better with non-run flat tires. Strange.

I do agree it is the driver when I hit small bumps or ripples in the road surface. It can cause the same effect, but not on a pool table smooth parking lot.

 

[aslowdodge]

Ever since I've had my viper it has almost violent bucking. Even though it's a gen2 I still checked the throttle bodies.

I would like to know if the person who said " VEC 2 done" has actually experienced the bucking and eliminated it with the vec 2. I have the vec 2 on the roe blower and the bucking is still there.

Oh yeah . . mine is not driver induced. Smooth parking lots and foot braced against the footwell still gets bucking. I have another viper buddy who has the bucking also.

 

[Ted Bigham]

I think the Vec1, Vec2... guy was implying that the AEM solved the problem.

The coil pack statement is wrong for sure. I've tested every one of my cylinders while the car was idling and they all get spark.

 

[01bee]

I have a VEC2 on a mostly stock 2001, and still have bucking.

 

[Johann]

I don't believe it's always driver induced, I've had my foot planted hard against the side panel and the throttle pedal rock steady when the bucking occurs.

I think it's just the nature of the beast, the same reason it experiences neutral gear rattle; uneven pulses at low speed.

 

[Tom F&L GoR]

If you want to experiment try these:

1) Don't just adjust the throttle bodies, make sure the one with the TPS opens first.

2) Clean the idle air control valve; the plunger tip, the seat, and make sure the plunger is free. Fuel never gets there to clean anything up.

Nobody has brought up the fuel shut off! Above ~1300 RPM there is no or little fuel introduced, it starts coming on again around 1300 RPM and causes the typical burble/backfire. And starts the bucking. That would explain why a single TB and dual TBs both have the characteristic.

 

[ghayes420]

I was told by a guy at Valay Racing in San Jose that the easiest way to get rid of the "buck" is to go with the 3.54 differential. Causes you to have to apply more gas, thus a higher RPM at low speeds.