Could lower octane gas cause an off-idle stumble?

[Grec]

Drove the Challenger into work this morning and noticed a very definite off-idle stumble. The only thing I can think of that changed was that I put in some lower octane gas recently. I usually run premium. (Yes. I was being cheap. Premium is $4.40 a gallon here.)

Other than the stumble, she seems to be running normally once you get the RPMs up.

Could gas alone cause something like this?

440 Six-Pack, stock Mopar electronic ignition. Fairly new plugs, stock heat range.

Thanks.

[MEK-Dangerfield]

Did it run fine before putting in the cheap gas?

I would expect a pinging problem, not a stumble off idle. I'm no gasoline expert though. 

[Grec]

Yeah. It was running fine before. At this point, unless you give it more gas, she feels like she's gonna stall.

[spamtank]

Yeah. It was running fine before. At this point, unless you give it more gas, she feels like she's gonna stall.

I have the same problem.  I figured my accelerator pump rubber was eaten away by the ethanol in the gas.   

I'm planning a carb rebuild later this spring/summer.

[LAA66]

 Lower octane should not cause a stumble unless you were way lean to begin with.

[jimynick]

Good luck with the stumble, but before you feel too bad about using that cheap gas- it's now $5.56 a gallon for 87 octane here in the Frozen North and 91 is probably another $1.00. Believe it or not. 

[72bluNblu]

I'm with MEK and LAA66, the lower octane shouldn't cause an off idle stumble. If it were detonating because of the lower octane it would get worse as you gave it more gas, not better.

And, as long as its not detonating, a higher octane fuel doesn't really do anything for you performance wise. You're better off running the lowest octane fuel your engine can handle without detonation. "Extra" octane is basically a waste of money.

But, you could be getting that off idle stumble because of bad fuel, which you may have gotten if you filled up somewhere cheap. Or, it may have a higher ethanol content than what you normally run, and that could cause you some issues.

[Grec]

Thanks for all the responses...

Brief update: I drove her home from work, which is about 30 miles, and the problem only got worse.

At this point, it feels like she lost a cylinder, or two. Gonna check the plugs and all that as soon as I get some time.

Just when I got the suspension replaced and dialed in... Damn cars! Lol.

[dutch]

Good luck with the stumble, but before you feel too bad about using that cheap gas- it's now $5.56 a gallon for 87 octane here in the Frozen North and 91 is probably another $1.00. Believe it or not. 

we`ve still got 95 as regular.  bad part... it sells @ $10,80 a gallon   

[73Chally]

Sounds like bad gas.  Have you tried topping off with 91/93, or whatever your highest Octane available is?  After 30 miles, I would think you should be down at least a quarter tank.  Could also be water in the gas if the gas station tank was low.

[brads70]

I'm finding ethanol makes the fuel boil in the carb at a lower temperature than with no ethanol , in addition to rotting anything rubber.
Water in the fuel will also cause a stumble?

[LAA66]

Sounds like bad gas.  Have you tried topping off with 91/93, or whatever your highest Octane available is?  After 30 miles, I would think you should be down at least a quarter tank.  Could also be water in the gas if the gas station tank was low.

 My thoughts about the water issue also. Perhaps, there was a tanker filling at the time or just prior.  They boil up the stuff from the bottom.   

[Chryco Psycho]

I had a similar issue years ago , only one gas stn open & it had high ethanol  content , I thought I had hurt the engine towing [440 Power Wagon] , it was tuned on zero ethanol fuel , filled it back up with good fuel & the problem vanished . I am sure I could have tuned it to work on the crap fuel but why bother !!

[LAA66]

 If anyone's interested here is a way to state your opinion.
 
 http://capwiz.com/amacycle/issues/alert/?alertid=61221996&queueid=[capwiz:queue_id]

 

[LAA66]

 Hopefully some have made the effort to contact their representative.    We have had luck with these notifications in saving off-road riding areas so it is worth while.