2015 Dodge Viper GT Long-Term Road Test | Edmunds.com

Edmunds.com

Its knock-prone nature is a little puzzling. It's not as though the big, lazy V10 is some highly-strung engine. On the contrary, the Viper's engine is relatively under-stressed as performance cars go.

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bankerdanny

You should try added a bottle of octane boost to get the level up to the 93-94 available in more reasonable states and see if you still get the detonation.

kirkhilles1

Hmm. Typically I would get one ping and one ping only.

daryleason

I agree with @bankerdanny on the octane booster, just to see what happens. But, considering the car is under warranty, and God knows, an FCA service center should fully expect one of their cars to come back every two months or so anyways, I'd take it in and let them figure it out. To save yourself the hassle, I'd take it in running on fumes and have them put their preferred fuel of choice in it, so that they don't come back and say "oh, you got a tank of bad gas."

nagant

There really is no such thing as "bad gas" anymore in any even moderate size city.....just another urban legend. Especially in CA since there in only 17 refineries....compared to a much smaller state like LA that has 19 and and big Texas that has 26. The special blend is made by even fewer so there is simply more turnover and fresher fuel because there are so many cars in CA.

Let me get this straight: You guys KNEW the car is pinging and yet nobody can even conceive of taking in to the dealer to have a look?

nate001

Were you able to fill it with higher octane when you were outside of California on the road trip? If you were still having issues then it's probably not the octane, They may have updated firmware to fix this issue.

daryleason

@nagant : I'll agree that most stations probably don't have what's typically considered "bad gas" but I'd disagree that there aren't stations that don't have bad gas. A lot of things can effect the quality of fuel. It is true that some of the cheaper stations do buy the slightly older aged fuel. Or they buy a large amount and it sits in their tank for an extended period of time if they're in a remote area without a high traffic flow that stops for fuel. This is mainly the "mom & pop" gas stations that charge more because they either can't get a large enough discount or are in a remote area that they think gives them a seller's market. So the only cars that stop and pay a higher price are either those that don't have the option due to range anxiety or time. Also, the quality of the holding tank can effect the quality of fuel. Those in-ground storage tanks only have a service life of around ten years. However, there are older stations that may never replace the tanks, if they can get away with it. Once they start getting old, contaminants like water and dirt start effecting the fuel.

agentorange

Perhaps the judicious application of thumbscrews will reveal who filled it with 87 octane by mistake.

stuntman_mike

kirkhilles1 said:

Hmm. Typically I would get one ping and one ping only.

I want to see the Viper do a Crazy Ivan.

tlangness

Maybe I'll stop by our local gas station that has 100-octane and see what's what.

longtimelurker

tlangness said:

Maybe I'll stop by our local gas station that has 100-octane and see what's what.

If it doesn't ping you will have proven that with racing gas it doesn't ping, and will have to take it to the dealer because it pings on 91. If it still pings you will have proven that it pings on racing gas as well as 91, and will have to take it to the dealer. Same-same.

Take it to the dealer before another staffer cycles through it, puts his foot into it a couple of times and knocks a hole in a piston.

daryleason

I could see a Dealership claiming the presence of racing fuel caused the problem and refusing to cover it because of some by-law or stipulation in the warranty coverage concerning fuel ratings. It's how they are.

daryleason

@longtimelurker : Let's not discount the knock a hole in the piston plan, yet. It'd be easier to get the dealership to fix that than to get them to trouble themselves to diagnose the pinging. You just have to hope that when they fix the engine, the solve the pinging issue. If they don't, you just leave it with them till they come up with a solution.

misterfusion

Are you absolutely sure that all of the other drivers are using 91 all the time? Occam's razor and all that...

desmolicious

Well, seeing that LA's finest 91 octane gas is 10% water (ethanol) anyway..
but other cars don't ping, so this one shouldn't either. My FCA Wrangler with the 3.6 engine pings on the recommended 87, so I use 89 and it's ok. The Viper, another FCA car, pings on 91 so it may imply that, like my Wrangler, in CA it needs an octane grade higher..

meng_mao

> Maybe the Viper's knock correction algorithm is just really crappy.

IIRC from the book, the GenV development phase wasn't able to get the knock detection nailed down at all RPMs because of extra time tuning the variable cam timing. If it had, it would have been able to avoid the gas guzzler tax through better emissions and fuel economy.

yellowbal

The Viper's fuel requirement is 91 octane, not 92 or 93+. Even if 87 was used, the engine should retard enough to avoid pinging (at the cost of power/efficiency).

I think it's something to do with the ignition system being weak around the midrange RPMs at peak load.

nagant

daryleason said:

@nagant : I'll agree that most stations probably don't have what's typically considered "bad gas" but I'd disagree that there aren't stations that don't have bad gas. A lot of things can effect the quality of fuel. It is true that some of the cheaper stations do buy the slightly older aged fuel. Or they buy a large amount and it sits in their tank for an extended period of time if they're in a remote area without a high traffic flow that stops for fuel. This is mainly the "mom & pop" gas stations that charge more because they either can't get a large enough discount or are in a remote area that they think gives them a seller's market. So the only cars that stop and pay a higher price are either those that don't have the option due to range anxiety or time. Also, the quality of the holding tank can effect the quality of fuel. Those in-ground storage tanks only have a service life of around ten years. However, there are older stations that may never replace the tanks, if they can get away with it. Once they start getting old, contaminants like water and dirt start effecting the fuel.

In CA ALL in ground gasoline storage tanks must be double walled (since 1998) or the station was not allowed to sell gasoline. This put a lot of the "Mom and Pop" stations out of business. There is also a UST testing schedule that must be adhered to in order to be certified to sell fuel.

I have not heard an engine ping in 25 plus years. A modern car like the Viper should be able to run on 87 without pinging unless there is a problem....

miata52

A modern car should not ping regardless of octane. Knock sensor should should retard timing to make up for it. Loss of power, sure, but no detonation. Something is wrong (it's a Chrysler, right?).

agentorange

Here's an idea. Do a hard reset on the PCM and see if it still pings after a week.

misterfusion

Wow, you guys. I first got my license in the mid-1980's. Since then, every car I ever owned experienced pinging at some point. This goes for I4 or V6, OHV or OHC, carb or EFI, foreign or domestic.

Well, let me modify that slightly: It happened to every car I owned until I started using 91 or at least 89 octane by default, about six years ago.

For reference, all of the above has taken place in California.

nagant

misterfusion said:

Wow, you guys. I first got my license in the mid-1980's. Since then, every car I ever owned experienced pinging at some point. This goes for I4 or V6, OHV or OHC, carb or EFI, foreign or domestic.

Well, let me modify that slightly: It happened to every car I owned until I started using 91 or at least 89 octane by default, about six years ago.

For reference, all of the above has taken place in California.

HUH? Then your cars all had serious problems. Easily 90% of mainstream cars since the early 80s have run just fine on 87.

misterfusion

...And therefore, my personal experience suggests that the issue is either with California fuel formulations, or the notion that "cars run fine on 87". I took a ride in my sister-in-law's Camry one time, and heard pinging. Made me realize that the average driver probably wouldn't hear pinging, or wouldn't think it was an issue.

nagant

Ummm I have lived in California all my life (I am 50) and I have not heard a car ping for 20 years. In the owners manual for my 07 PT 2.4Turbo engine it says "Your engine is designed to run on 87 octane" The elevation where I live is 200ft or so and even in the hot summer with the air on (my area gets over 100 at least 15 days a year) under a full load with the boost on, I have NEVER heard the engine ping, ever. Fuel formulation has nothing to do with knock resistance.

longtimelurker

daryleason said:

@longtimelurker : Let's not discount the knock a hole in the piston plan, yet. It'd be easier to get the dealership to fix that than to get them to trouble themselves to diagnose the pinging. You just have to hope that when they fix the engine, the solve the pinging issue. If they don't, you just leave it with them till they come up with a solution.

At this point, they have published a post on their website that basically says they have been driving the car with this issue for the past 13,000+ miles. Warranty administrators take a very dim view of owners who ignore a problem like this, that can cause further damage, for that long and then finally bring it in after the damage has occurred. I am dumbfounded that this thing is not throwing a P0325 (bad knock sensor) code.