Bog between 1st and 2nd gear

[riwracer]

Has anyone experienced a bog between 1st and 2nd gear in medium to hard shift?
There are two other new vipers here that also have this slight power loss when shifting hard from 1st to 2nd. So far, no fix has been determined. I have just over 400 miles and I just began noticing this. Please respond.
riw

 

[Bob Pommer]

I have notices some bog in 1st gear at about 2k rpms. If you try to hold it at that rpm, the engine protests by bogging down and I have experienced some flex in the drivetrain. Enough to make you head bob back and forth.

 

[CHAD]

Is the traction control engaging perhaps?

Chad

 

[luv2race2]

Could be just the skip-shift? Haven't noticed any low-end problems. Under 2k rpm's and the low gear ratios could be the culprit. I guess the car just wants to be driven harder:&gt

 

[Y2K10 SRT#39]

Under 500 miles.. Don't worry!

 

[VNMOUS]

Hit 1000 miles today and opened it up a little bit. I did notice a significant bog on the 1st to 2nd shift. Happens with moderately aggressive starts in the mid rpm range. My Viper is one the ones with the bad valves. I wonder if this has anything to do with it? If I gave just the right amount of acceleration with the shift it would dissappear--what I am saying is that a full out pedal to the floor acceleration after the shift made the bog worse, easing back into the accelerator made it less noticeable. Hopefully this is just a characteristic of the car that you will not even notice after getting some quality seat time and learning how to fine tune your driving technique with this beast.

Austin

 

[Leonard Knight]

I just reached the 500 miles and noticed the bog between 1st and 2nd today. My car had the valves redone at the factory so I don't think it is this. I also don't think it is the skip shift feature as it is from the engine, not the trans. I would like to know what causes this.

 

[GR8_ASP]

Count me in on this. I made a similar comment on another thread. So it appears that it is not related to the valve issue. I wonder if it could be seen on a dyno. Anyone ever tested the SRT at part throttle to see if the torque dips significantly?

 

[gtsviper]

I have not experienced this problem and just hit 700 miles.
This might be a good question for the Members Only Forum?

 

[ninjaviper]

Does the new Viper have traction control?

 

[GR8_ASP]

Yes it has traction control. It is your right foot.

 

[Vic]

Sounds like there is a dynamic event happening, related to the load, rpms, and throttle input.

Maybe its bogging due to the PCM retarding the spark, or varying the injector flow, due to the program seeing something in the exhaust.

Can you rev through that rpm range under no-load conditions, or in a single gear, under steady state load?

Has anyone looked at the OBD2 diagnostics, to see what kind of events are recorded, after a bogging incident? It would be interesting to see if the PCM is intentionally changing the spark or fuel flow, or if its an incidental phenomenon, outside the scope and capability of the engine management system.

 

[Leonard Knight]

Vic: It only seems to be when shifting from first to second. I can rev freely with the clutch in and it does not seem to happen between any other gears. I was thinking it had to do with that idle hang smog requirement. You have to be at just the right rpm range for it to happen. Just driving normally or with your right foot planted does not seem to make it happen.

Very weird.

 

[Vic]

Hmmm, thanks. Strange problem. If you find out the answer, post back! I'd like to know what's causing that.

 

[riwracer]

Len
Your description of the 1st to 2nd shift situation is exactly what I had originally described. What I have experienced recently is that the slight hesitation in power was not present all the time. Yesterday I took it out, I shifted from 1st to 2nd hard at over 5000 rpm and the car literally screamed from 1st to 2nd, which felt faster than my 02 GTS. I repeated this manuever with a slightly less aggressive shift and there seemed to be a momentary downward power change. I think the throttle pressure may require more than the 1st 1/4 of downward play. The slightly more throttle pressure required is different than my other viper or corvettes. The clutch let out is also slightly different as well.
Tonight the car had a early detination "backfire" when going from 1st to 2nd with a fast lift off of the trottle. After that the car seems to be running quite good. It revs freely in each gear and each gear is very strong once engaged. My car now has 500 miles on it and seems to be running stronger at this point.
As I posted before, there were 2 silver SRT's in town with the same complaint.
I will keep you posted. I am hoping this minor problem totally disappears.
Ron


2003 SRT black
2000 GTS black [sold]
2002 Z06 yellow
2001 C5 convert [sold]
93 ZR1 anniversary
67 435 convert
2003 AMG E55 [expected in June 03--Black]

 

[Y2K5SRT]

Well, I had no idea what you guys were talking about, although somebody drove my car recently (he has a GTS and an RT/10) and mentioned the bog. Well, yesterday I was playing with a Greenwood Corvette and we did a run from a roll and a run from a stop. I did a darn near perfect launch and when I shifted to second the car bogged and then took off. Strangest thing I have ever seen or felt in a car under WOT. No powershifting or anything else, and the same exact driving I did with my GTS and SRT since Day 1. Very strange indeed!

Chris

PS. Oh yeah, and crushed that Vette like it was in reverse, even with the bog. We stopped and chatted after that...

 

[GR8_ASP]

Okay, so another SRT owner is convinced the bog is real. Now what is it and how do we get it fixed? Chris I presume yours does not have the valve issue so it is not connected to that issue, nor impacted by it.

To me it almost feels like it is a fuel or spark cutoff. I would guess fuel as I have not heard any after fire or strange exhaust note after it occurs.

 

[jwwiii]

Helo;

Folks, I think we have here a case of the "buckin' Bronco" sydrome!

The SRT is my third new Viper. The throttle is sensitive to 500hp and massive torque. We accelerate, and by shifting imperfectly we start bucking; weight of our bodies (in particular, the right foot) presses and we are thrown back in our seats. The cars weight shifts forward as we humans try to correct this, and we decellerate. The cycle repeats again a couple of times.

Ahh... horsepower, torque, and throttle response!

Well, this is the theory I have from my experience in multiple Vipers.

Jim

 

[SylvanSRT]

I think I noticed this out for a ride today. Seems like the car is not accelerating w/ the same vigor through part of the rpm range(lower). At first I thought i might not be pressing the accelerator evenly. Then after making sure my movements were deliberate, the car DID exhibit some weird type "weakness" in power band. I have had several quite loud "backfire" bangs out of exhaust. Engine has also thrown a backfire code twice, but the engine lite went off rt away and car drove normal.

 

[GR8_ASP]

Jim, nice try but I have had it occur under moderate acceleration. Not the push you back in the seat kind of acceleration. I am very certain that I was smooth on the throttle when I felt a lull. That is the best way to describe it. A lull and then return to the amount of acceleration you would expect. Not a surge or anything. I swear it feels like the engine is cutting out.

It has not proved repeatable for me. So when it happens it takes me by surprise. I have never experienced it under WOT. But I have had a WOT run in second then third where after shifting it felt and sounded like it was a cylinder short. Kind of a bleating or off tone sound. Weird.

 

[BACKNBLACK]

I have a solution..get your Gen2 cars back......

 

[SMHOD]

Here is probably a stupid question. What happens if redline is exceeded? Does the fuel shut off? I had one experience, although I did not think I was at redline where the car had a sudden loss of power which it took about two seconds to regain. This was under full acceleration and I assumed I must had exceeded redline but I am not sure. Is this the problem you guys are having or does the car essentially lose all power temporarily if you hit too many RPMs?

Scott

 

[jwwiii]

Viper SRT;

Well, here goes revised opinion #2.

Yesterday is was 87 degrees in Iowa, and I think I experience this bog thing for the first time. It eas subtle in my car. I did not have any backfire, but it still felt unusual.

Could it be temperature related? Maybe the fuel/air ratio being fed to the motor is causing this via heat sensitivity in our ECU? Never experienced this during our cool spring.

Any comments on my temperature theory?

Jim

 

[GR8_ASP]

Jim I am completely unable to comment on the effect of high temperature as we have yet to have ANY. The times I experienced the bog I remember it being being nice out, but probably near 70.

Please send some warm weather this way.

 

[jwwiii]

Viper SRT;

I actually was being serious about the "Bucking" thing! I have felt this so many times when I accelerate with moderate aggression, shift to second, and then try to maintain a steady speed. It seems that maybe my gas foot is touching the pedal (gas) when the engine is in a "sweet spot" for sensitive throttle response.

Get this; this happens THE MOST when going donwnhill in say, second gear. She just wants to go, and there is sooo much torque and sensitivity in that situation. I have watched this happen repeatedly when a newbie drives my Viper for the first time. Yep, the "Buckin' Bronco" syndrome is pretty funny to watch! When they experience this, they start yelling "whoa,wha,wha, wha!". No kidding!

Any thoughts of the quality of gas you buy? Maybe try getting another type of premium. I hear Sunoco has a good assortment of premium fuels?

Let us know what's happening!

Jim

 

[GR8_ASP]

Jim I may be immune to the bucking situation as it is common on the Gen I. Mostly during slow, near closed throttle, times when you wanr to be slow and steady. kind of like parade speed. Goodness parades like we have had at VOI's are very difficult.

I have not driven much that way with the SRT so may not of had the chance to experience it.

The bog condition is quite different and probably not related. I plan on going to the dealer soon (valve replacement) and will mention it at that time.

 

[Hans Christian]

This issue is really starting to concern me. I am going to get one of the first 04s from the King Bill P. in about 3 months and I MUST confess I don't like if I have to live this BOGGING.

Has anybody submitted this question/issue at the new PVO question forum ???

Has anybody asked their viper tech about this

Could it be ECU e.g maybe it just needs to be reprogammed ?

 

[Vic]

I have felt this so many times when I accelerate with moderate aggression, shift to second, and then try to maintain a steady speed. It seems that maybe my gas foot is touching the pedal (gas) when the engine is in a "sweet spot" for sensitive throttle response.

Jim, When you open the throttle part-way, the computer is still in control of spark advance, fuel injector pulses, etc. One possibility is that the PCM, or engine management computer, is altering the operating parameters, causing the bog.

When you open the throttle all the way, known as WOT, or wide open throttle, the computer is taken out of the loop, and there is a set default value to the spark and fuel flow. Doesn't look at sensors, just throws a set value of spark and fuel out to the motor. If the bog is caused by the computer software due to sensor input anomalies, you won't see the bog at WOT.

If the Viper PCM works like others I am familiar with, you won't see the fuel or spark change under WOT, which means that the bogging symptom won't occur when your foot is on the floor.

Sorry for the choppy flow to this post. I gotta run!

 

[GR8_ASP]

Thought I would resurrect this post about the 1-2 bog issue. I have now completed the valve replacement and can verify that the bog exists both before and after the valve repair.

Saturday was a great day here in Michigan (about the first I can recall but that is a different topic). Mid 70's. I was driving across town mainly on surface streets so I had a lot of stop lights and shifting through the gears.

As this was my first real driving experience since having the valves replaced I was very watchful regarding how the car was running. I experienced the "bog" condition several times during the afternoon. Each time it appeared during a moderate acceleration just after the shift into second gear. Each time I noticed the tach reading was 2400 to 2500 rpm right after it occurred. Interesting. I tried to recreate the bog on command, while staying in second gear and was not able to, even when knowing the engine/vehicle speed that precipitated it. So I believe it has something to do with the transition from a higher engine speed down to around 2500 rpm. Conditions that seem to be present each time are:
- part throttle accel taking the engine up to about 3500 to 3700 rpm in first gear
- then doing a closed throttle shift into second
- returning to part throttle causes the engine to bog, almost like the ignition is turned off
- after a half second or so bog the power returns to where it is supposed to be without any "post bog" symptom

Several other SRT owners have commented on this. I think it would be helpful to know if the conditions that surround the issue are similar in other cases. When my SRT was repaired we had it checked and there were no engine codes present.

 

[riwracer]

I appreciate this topic being continued. I had the SRT out today.... the torque and power seemed to be very high up in the rpm range compared to my 2000 GTS. My GTS and my Z06 really chirp and accellerate, even in modest rpm range---4000 to 5000 ---
In the same range, with a lift off accellerator shift, the SRT does not seem to set you back. I have a feeling that you might need to go 5500 or higher to really feel a jump into 2nd gear. What we need is feedback on stock SRT's for 1\4 mile times and seat of the pants feeling to other Vipers and high horsepower Z06's.
RIW


2003 SRT black
2000 GTS black - sold
2002 ZO6 yellow
1993 ZR1 anniv.
1967 427 yellow convert.
2003 AMG E55 coming in June