'99 GTS starts and stalls/dies

Dayn G

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Hello All,

First time poster. I have a '99 GTS, 31K miles, stock. I have owned the car for 3 years in Las Vegas. 3rd Owner. Car has run fantastic since acquiring. Previous owner took immaculate care of the car, handing over all service records from initial purchase to his ownership. It did require a new battery about a year and a half ago, but otherwise no issues with the car.

Due to weather and being out of town, the last time the car was driven was ~ 4 weeks ago. Last week, my husband attempted to take it to work and the car wouldn't start. However, the door locks functioned. I identified that the trickle charger had been unplugged from the wall (the car prefers be plugged in if it doesn't get driven at least once a week). Assuming the the battery was too low for start, I plugged it back in and left it. A week later, I attempt to take the car to work. The car would not start without a little gas input. Once started, I let off the gas and was going to let it idle for a little bit before driving. It procced to drop rpms and maybe idle for a second then die. I restarted the car and proceeded to hold it at 1500rpms thinking maybe it wasn't happy with the outside temps. Held it here for about 3 minutes, then it draws down and stalls. I haven't had a chance to troubleshoot yet. The car hasn't behaved like this before. I am mechanically inclined (Air Force aircraft maintainer), but not an experienced car mechanic. I manage the basic maintenance on all my vehicles and most issues I have with my newer vehicles have been fairly simple fixes. The car is covered, garaged (not climate control), and often times on the trickle charger during this time of the year due to inclement weather and poor road conditions.

My husband did purchase a digital service manual a few weeks ago, but I haven't gotten my hands on it yet.

Here is what I am thinking:
1. battery (1.5 yrs old currently)
2. alarm system
3. fuel pump relay
4. fuel pump

Based on this description am I heading in the right direction? Or, are there other quirks about this car that I should be considering?
 

ninetyninegts

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A simple thing to try. Reset throttle sensor. Turn the key to run position, not starting, press the gas pedal to the floor deliberately three times. Turn the key back to the off position. Then start car to produce burn out.
 

99RT10GTS

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^^^THIS^^^

But also, reseting the PCM might also be another option(simply disconnect the battery for 60 min).

If you want, I can send a Dealership manual for you to use and if you like to keep it, I will sell it. But I will send it to you tomorrow if you want. Message me your address

Mike
 

FlashFyre

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Sounds like your IAC is having issues. It likely needs to relearn itself. Low battery can play havoc with the IAC.

Make sure your battery is fully charged. Start the viper and try to get it to idle itself. The RPMS generally will be all over the place. You may see it hunting/surging in RPMS for a few minutes but they should eventually subside. Once its stable enough to drive, give it a go. Driving will help the IAC relearn itself.

If this doesnt completely fix the problem. Adjust the throttle bodies so the driver side opens just prior to the passenger. This will require removing a the air box and a 2nd person. Put a finger on each throttle plate and have a 2nd person slowly press the gas pedal. You should feel which one moves first. Adjust the screw on the passenger side so that the drivers plate opens just prior to the passenger. This is to accommodate for the extra airflow on the IAC (passenger side)

I had similar problems with my 99 a couple of years back.
 

GTS Dean

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I do not recommend touching TB screws - even as a last resort. Especially not if it was working fine beforehand. My car had a small backfire after R&R of plugs and fuel treatment. I cranked but would not fire. I held the throttle wide open, cranked and fired but ran roughly and wouldn't idle. I had to feather the throttle and hold open until the IAC began to recover. It took 2-3 min before it settled down to a normal idle. Fine since.
 

Old School

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Interesting coincidence. 2 days ago, a guy at work left his headlights on in his 2000 Ram Van. After I jumped him off, it wouldn't idle without holding the throttle slightly open. Even after few minutes of this in the parking lot it would not idle. Took it for a 10-minute drive, all was good.

His van has a similar engine controller, sensors etc as your Viper.
 

vprtech

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As other people in this thread have mentioned, low cranking voltage is a problem. The IAC is a stepper motor and the computer (JTEC) will, under certain circumstances relearn the position by bottoming it out. It then keeps track of the “steps”. If while cranking the voltage drops below a certain threshold the actual position of the motor can become misaligned with what the JTEC believes it to be. If you were able to get it to idle and ran it long enough the JTEC would eventually relearn the position. Sometimes with a marginal battery it may seem to crank over ok but the voltage drops low enough to cause this issue.
 

Fast Viper Dan

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Simply put, if the battery is, or, was low, you need to fight to keep the car running for a few minutes to relearn a few things.

I can tell you that even if the battery will start the car, you might still have trouble with the alarm causing the motor to die.
Again, the battery is most likely the problem.
 

99RT10GTS

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Fast Dan is correct, If the battery is low, it can cause issues. Put it on a charger and get it back to 100%. At the same time, reset the PCM to clear any issues. If you do need a new IAC, I have a few for sale.
 

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