Surging at low speed (under specific instance)...anyone else have this?

[Talon]

Question for other gen 2 owners... is there a point at low rpm in a low gear where your viper "surges" a bit? I'm talking a very specific instance that has to be just right, now under normal driving circumstances.

Allow me to setup my scenario... when I'm cruising at just the right speed and the right gear through my neighborhood I can actually have the car "surge" or **** forward and back. It happens around 2nd gear in very low rpms (like 1,000-1,500) with very very light throttle. Basically 2nd gear at about 25 mph is idling through the neighborhood, but to maintain speed I have to give it very light throttle. And sometimes in just the right spot it will surge.

Is this a sign of something I'm in need of like a tune up or is this just an inherent aspect of a massive V10 motor that makes a ton of hp & torque where there is no such thing as "light" full injection to idle through the neighborhood? Maybe it's these engines and their odd fire that just have me hitting power strokes of a couple cylinders in quick succession that "surge" power.

If others can replicate or have this happen in their gen 2's too, then i'd think it's something inherent to the car, if not maybe I've got a fouled spark plug or something?

FYI, this doesn't happen at any other time driving. It's only at slow speed with low rpm and in a low gear (though admittedly maybe at highway speed in low rpm in a high gear it's just not noticeable but as far as I can tell I don't notice anything at speed).

 

[Steve-Indy]

Yes..Even more so in first..happens with our 97, 99, and 01.

 

[Timnineside]

Out of the 5 Viper's I've had they have all done it to some extreme. My 94RT and 99GTS were by far the worst.

From my experience it can be anything from a misfire to bad motor and/or tranny mounts.

In my 99GTS it wasn't as bad as the RT. I parked the car over winter and did a long list of things. It made the issue less significant but I can't pin point actually what it was.

I'd suggest changing the motor and tranny mounts first and see what you get.

-Tim

 

[Dirk Pitt]

My '97 does the same thing and has since day 1. I've never had much success with "idling." I try and avoid low speeds but when necessary, I spend a lot time on the clutch.

Yes..Even more so in first..happens with our 97, 99, and 01.

 

[Viper98912]

Yes, very low speed crawling around the neighborhood

 

[Tom F&L GoR]

Adjust the two throttle bodies so you are sure the driver side opens first. Only the driver's side has the throttle position sensor. If the passenger side opens first or passes more air, then the PCM can't figure out fuel rate or use of of the idle air control valve properly. It bucks like you're learning to drive a stick. With typical drivetrain slop (lots of driveshafts, u-joints, differential and Gen1 Gen 2 cars have a two-piece mainshaft in the transmission) there is a lot to wind up and snap back.

On Gen 1, there is a cable for each throttle body and where the cable is mounted on the manifold is adjustable. On Gen 2, the throttle shafts are connected via a shaft - haven't had to adjust mine, only looked at it, but there are screws to adjust it also.

 

[Steve-Indy]

Great advice here...but, to me, the the question is the degree. Gen I cars were notorious for rather violent "bull hunching" that occurred when the throttle bodies were out of sync. This is fairly simple to adjust as Tom has stated. I have seen much less of this with Gen II cars...many of which did a mild version of this a very low rpm in first gear when departing one's neighborhood with a cold engine...
this is easily managed with a little more throttle. As always, it is wise to inspect the entire driveline when a question arises.

 

[Talon]

Thanks Steve (and others). I spent some time driving it today. It is actually a noticeable 1st gear thing, not 2nd. My memory didn't hold up. It does in 2nd maybe just a tiny bit under an exact moment, but it's really in 1st gear and is between 1,000 and 1,500 rpms. I'm glad to know this is "normal". I mean hey any excuse to get on the gas further is always a good one in my book

The problem is truly pretty minimal and if I just lean on the gas a touch more it resolves itself. I would imagine that any attempts at adjusting it would have to be very very tiny in movement, and I might cause more harm than good so I'll just chaulk it up as "normal" and just avoid that very narrow moment of time when the "bull hunching" happens.