Running rough after a jump start

[Newguy99]

I have a 99 RT/10, 8,600 miles, any assist is appreciated, I left the battery tender off while out of town, jump started, but it ran rough and wouldn't idle. Took it down the street, came to stop sign, couldn't keep it running, jumped it again and brought it home, haven't touched it since. I bought the car in 2022, I don't know how old the battery is but before delving into the tire removal, I thought I'd see if anyone had ideas on the idle.Thanks all, happy motoring.

 

[daveg]

Do a load test on Battery, sounds like it's bad. The computer has to go through a relearn process once battery is dead. Takes a few driving cycles to relearn.

 

[Goggles Pizano]

@Newguy99 you better search on here about jumping the car or Dan will beat the shit out of you for not reading.

 

[99RT10GTS]

Start by disconnecting the batt by the rear wheel. Touch the positive side of the terminal to ground, discharging(reseting) the PCM. Make sure the battery is good. That should probably fix it. If not, look to the PCM for possible issues

 

[Steve-Indy]

You may need to do a throttle relearn. To do this, turn the ignition on to run BUT do not hit the starter. Then, slowly depress the gas pedal to the floor and slowly release it...and complete this process one more time. Turn ignition off, wait a couple of seconds and try to start the engine.
This all assumes that you have a decent battery.

If drivability improves, thank Chuck Tator for sharing the relearn procedure.

 

[Newguy99]

You guys are great, thanks very much!

 

[Dan Cragin]

Is your check engine light on?

 

[SRT BILL]

You may need to do a throttle relearn. To do this, turn the ignition on to run BUT do not hit the starter. Then, slowly depress the gas pedal to the floor and slowly release it...and complete this process one more time. Turn ignition off, wait a couple of seconds and try to start the engine.
This all assumes that you have a decent battery.

If drivability improves, thank Chuck Tator for sharing the relearn procedure.

Steve does this process work on gen V's also?

 

[Steve-Indy]

Off hand, I don't recall using it on a Gen V...but probably worth a try. This throttle relearn procedure is not to be confused with the Electronic Throttle Control reset for Gen IV and V Vipers...encountered when installing new PCM.

 

[Viper Specialty]

@Newguy99 you better search on here about jumping the car or Dan will beat the shit out of you for not reading.

Well, You're certainly right about that

The fact that I sell and reman these modules, and yet tell people not to jump start... and then they dont listen..........

Does that make me a massochist, or them...?

[well aware thats spelled wrong because this site blocks everything]

 

[SRT BILL]

Off hand, I don't recall using it on a Gen V...but probably worth a try. This throttle relearn procedure is not to be confused with the Electronic Throttle Control reset for Gen IV and V Vipers...encountered when installing new PCM.

Thanks Steve, Electronic throttle control relearn is what I was looking for. I've been waiting to install the off road PCM I purchased several years ago. My warrantee is about to run out so now would be a good time to do the install. I guess I'll need to find a dealer to do the throttle relearn.

 

[lane_viper]

So I do have a question related to this. Are Gen 2 Vipers battery eaters?

Longest mine has lasted is 3 years, just out of the replacement warranty, but since then I'm on my 3rd.

First was lead acid Napa, but the last 3 have been optima's replaced under warranty.

I know I prob have a drain that needs fixing, but I get the sense that Gen 2's seem rough on batteries.

 

[Goggles Pizano]

Batteries are just crap the pass few years and are a crap shoot. Talk to someone who has been at the parts desk for the pass few years and they will tell you.

 

[Steve-Indy]

As noted in service manual, Vipers can draw up to 30ma continuously and still be "normal"... more with alarm on.

Doing that math, battery CAN drain within a few weeks...depending on ampHr rating.

I USED to get 7 years on Sears Diehard Gold batteries in Gen I and II Vipers using a battery tender. That was 20 years ago. Agree, quality of most has dropped.

I am happier with AGM by either from Interstate or Odyssey...on or off tenders. If not on tender, I recharge them fully every 4-6 weeks...and they last 4-5 years. The hotter summers kill batteries.

 

[Newguy99]

Thanks all for the input, I ended up changing the battery out behind the wheel, wasn't as much of a task as I thought it would be. Fired right up and running like a charm. Happy motoring everyone.

 

[98 GTS]

Optima batteries used to be great but since they exported production, the quality is terrible. When I have to get a new one, I'm getting Odyssey.

 

[98 GTS]

You may need to do a throttle relearn. To do this, turn the ignition on to run BUT do not hit the starter. Then, slowly depress the gas pedal to the floor and slowly release it...and complete this process one more time. Turn ignition off, wait a couple of seconds and try to start the engine.
This all assumes that you have a decent battery.

If drivability improves, thank Chuck Tator for sharing the relearn procedure.

Would this be required if the battery didn't go dead but just ran low, I went to give it the once every 2 weeks start up and it wants to stall If it don't give it any throttle. At first I thought it was just because it was roughly 40° outside and It would be fine once it warmed up; however, even after it ran for several minutes anytime I would let up off the gas it would stall And it crank but wouldn't start without a little throttle to help it out.

 

[Steve-Indy]

Can't really say, though it is easy to do the relearn and it won't hurt anything.
Now...what interests me is just what do you mean by "go dead" vs. "battery ran low" .
You can easily do a couple of battery checks with a voltmeter. If, after the engine has been off for 30 minutes (also off any charger or tender for 30 minutes), test the voltage. If below 12.2, it is less than 50% charged. Now, while the volt meter is still connected, turn on the headlights to accomplish a cheap load test. If the voltage falls into the 9-11 range, suspect the battery.

Other than starting the Viper every couple of weeks, have you been using a tender or charger?

While any car can have an abnormal draw, keep in mind that a Gen I or II can normally draw 30 milliamps continuously...more with alarm activated.

 

[98 GTS]

I have not been using a battery tender or charger during this time until an hour ago. The time before this all I did was start it up and reved the engine at different speeds until it reached operating temperatures. During that time, the battery head the security system on. This past time I didn't have that on. I currently connected my smart charger. It has a light indicator in the event of a bad battery How accurate that is or isn't I don't know,. It currently doesn't have that listed. It seems like it's good to start it up every two weeks whenever I'm not driving it during the winter and I do it that way. I plan on following the retraining method like you suggested tomorrow after the battery's fully charged That way we can see if that's all it needed and if it was somehow related to the battery getting drained. It didn't have to be jumped it was just turning slower and in fairness it is cooler outside than usual. My daily driver also turns a bit slower. But this was clearly drained but still had enough to turn it over.

The other part is I don't know what battery is in this thing as I haven't had to replace it yet. My understanding with smart chargers is it's better to err on the side of selecting the AGM charging versus flooded as a flooded could over charge and damage it if it's an AGM. The downside of charging it as an AGM if it's a flooded would be It doesn't charge it up all the way as flooded batteries apparently prefer or at the quicker rate which helps to desulfate the plates on a flooded battery.

Also for what it's worth, this is not the first time I've ever had to charge the battery. I had to do this last winter after it sat for a month and I learned the hard way that was not the right decision. All summer the car did fine and didn't have to be charged.

The only thing that might change the draw against the battery is the factory radio was swapped out for a more modern unit though It's still a pretty standard aftermarket radio like you find in the '90s. It just has Bluetooth. They also added a port for a subwoofer but I took the subwoofer out.

 

[Steve-Indy]

Agree that there are multiple variables in play here. Admittedly, I am not a fan of the frequent-start-but-no-drive theory for many reasons. I park ours for the Indiana winters, get them out in the Spring. This schedule has served me well for over 50 years. To each their own.

I would consider starting the Spring with a fully tested, fully charged (prior to installation) NEW battery of your choice to save you a lot of future headaches.

 

[Steve M]

Agree that there are multiple variables in play here. Admittedly, I am not a fan of the frequent-start-but-no-drive theory for many reasons. I park ours for the Indiana winters, get them out in the Spring. This schedule has served me well for over 50 years. To each their own.

Same. Park it, put it on a tender, and leave it be. Having personally witnessed what salt can do to a frame (my daily driven truck), I always err on the side of caution when it comes to getting it out to play from December through about March, sometimes later.

 

[TEALLIFE]

Agree that there are multiple variables in play here. Admittedly, I am not a fan of the frequent-start-but-no-drive theory for many reasons. I park ours for the Indiana winters, get them out in the Spring. This schedule has served me well for over 50 years. To each their own.

I would consider starting the Spring with a fully tested, fully charged (prior to installation) NEW battery of your choice to save you a lot of future headaches.

Agreed. Theres really no good reason to start a car and rev it at standstill other than to charge the battery, and there's much better/easier ways to do that. A car sitting for 2 weeks or 2 months is not much of a difference (other than to the tires), and there's ways around that also.

 

[Goggles Pizano]

All I'm going to say is that there is a reason why people fog engines. There are other ways to do that now not to kill the cat.

 

[WishItWasMine]

So I do have a question related to this. Are Gen 2 Vipers battery eaters?

Longest mine has lasted is 3 years, just out of the replacement warranty, but since then I'm on my 3rd.

First was lead acid Napa, but the last 3 have been optima's replaced under warranty.

I know I prob have a drain that needs fixing, but I get the sense that Gen 2's seem rough on batteries.

I’ve had the same battery since it was purchased in 2007 (‘01 gts). It just now went bad. No clue what it is as I haven’t removed it yet but will update when I do.

Newer batteries have been known to be much less reliable, especially when speaking of longevity. But with these cars a battery minder / trickle charger is just as essential as having a battery with very high CCA.

Just in case anybody was wondering, It’s not very fun to crawl from the trunk to pull the manual door release…

 

[94Vip-r]

I have a Generation 1 (1994) - so I don’t know if this applies to your Viper - and I’ve learned that whenever the battery is changed or has to be jumped that when I try to start it the security light lights up on the dash and prevents the engine from idling properly and it dies within seconds. What I do when I try starting it is I depress the unlock button on the remote and this generally works within the first or second attempt. It always works when I change out the battery.

Does anyone know how to disconnect the alarm in these cars?