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Discussion Starter #1
Why is my rpm hesitating slightly when I accelerate?
 

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A bit more info might help.

Year/model.

Mileage.

Engine size.

Stock or modified?

Transmission type.

Relative condition: well maintained; average; what was the question?

Is the engine in relatively good tune? Engine air filter ok? Fuel filter? Plugs not past their change by miles?

When the hesitation occurs? Cold? Warm? Hot? All of the above?

Is the factory octane recommendation being adhered to?

If there is a way to do this -- consult the owners manual -- I'd recommend you do an electronic throttle calibration.

I know with at least one of my other/previous car switching to running Chevron Supreme (with Techron) resulted in a noticeable improvement in the engine's throttle response and off idle running. Didn't even require me to burn the entire tank (approx. 16 gallons). There was no real hesitation before but the engine really benefited from the Techron.
 

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Discussion Starter #3
A bit more info might help.

Year/model.

Mileage.

Engine size.

Stock or modified?

Transmission type.

Relative condition: well maintained; average; what was the question?

Is the engine in relatively good tune? Engine air filter ok? Fuel filter? Plugs not past their change by miles?

When the hesitation occurs? Cold? Warm? Hot? All of the above?

Is the factory octane recommendation being adhered to?

If there is a way to do this -- consult the owners manual -- I'd recommend you do an electronic throttle calibration.

I know with at least one of my other/previous car switching to running Chevron Supreme (with Techron) resulted in a noticeable improvement in the engine's throttle response and off idle running. Didn't even require me to burn the entire tank (approx. 16 gallons). There was no real hesitation before but the engine really benefited from the Techron.
Well it only does it sometimes when accelerating, but should be looked into.
Air filters and spark plugs are fine, spark plugs were changed at 96,000km car was last oil changed at 105,000km and at 96,000km also.
My coolant reservoir looks dirty, i think I need to change that soon, not that it affects the rpm but yeah.

I put in BG 44k fuel cleaner in my last tank, will put another in my next, stuff is great.

Its a 2014 SXT V6 3.6L

Car is using 91 fuel. Its stock apart from the exhaust system. Put on magnaflow mufflers and straight piped it like a couple of weeks back.

Transmission is stock.
 

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Well it only does it sometimes when accelerating, but should be looked into.
Air filters and spark plugs are fine, spark plugs were changed at 96,000km car was last oil changed at 105,000km and at 96,000km also.
My coolant reservoir looks dirty, i think I need to change that soon, not that it affects the rpm but yeah.

I put in BG 44k fuel cleaner in my last tank, will put another in my next, stuff is great.

Its a 2014 SXT V6 3.6L

Car is using 91 fuel. Its stock apart from the exhaust system. Put on magnaflow mufflers and straight piped it like a couple of weeks back.

Transmission is stock.
When did you first notice the hesitation? After you changed something? After a gasoline tank fill up? Or did it just come out the blue?

Forgot to add...

There can be a number of possible causes: Dirty/bad injectors. (But if you think that BG 44k stuff works this can (probably) be ruled out.)

A faulty throttle position sensor. Generally because this is a critical (and safety critical) system any problems will be detected and a CEL will get lit and one more error codes logged. Absent a CEL, is there a documented way for the operator to reset/calibrate this? (My previous cars had a way to do this and it was sometimes beneficial -- in a mild -- but noticeable -- way -- to do this once in a while.)

Mass air flow sensor. Generally if this is acting up you'll see a CEL and there'll be one or more error codes logged.

A faulty fuel pump. Does the car have any difficulty at other times? Does it run out of poop at higher RPMs? Slow to start? That is cranks but doesn't fire right away?

Last but not least there have been reports of owners of these cars claiming -- and I have no reason to doubt them -- the hesitation was cured by either an engine controller or possibly a transmission controller program update. You might check with your dealer to see if there is one available for your car. Now it might be that a car doesn't qualify for one unless it is manifesting specific behavior or symptoms and in this case a tech might have to road test the car to confirm the behavior is present.
 

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Might want to try using the factory recommended 87 octane, you're not getting ANY benefit using 91 unless you have a major tune, the 3.6 was designed to run on 87.......and it "might" be causing the RPM issue.
 

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Octane controls pre-detonation and should have no ill effects in a motor that is designed to run (i.e. lower compression) on lower octane fuel. If this started after the plugs were changed I would check the connections to the coil packs, are the plug torqued properly, is there any contamination on the plugs, are the coil pack seated properly and fasteners tight.
 

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Discussion Starter #8
When did you first notice the hesitation? After you changed something? After a gasoline tank fill up? Or did it just come out the blue?

Forgot to add...

There can be a number of possible causes: Dirty/bad injectors. (But if you think that BG 44k stuff works this can (probably) be ruled out.)

A faulty throttle position sensor. Generally because this is a critical (and safety critical) system any problems will be detected and a CEL will get lit and one more error codes logged. Absent a CEL, is there a documented way for the operator to reset/calibrate this? (My previous cars had a way to do this and it was sometimes beneficial -- in a mild -- but noticeable -- way -- to do this once in a while.)

Mass air flow sensor. Generally if this is acting up you'll see a CEL and there'll be one or more error codes logged.

A faulty fuel pump. Does the car have any difficulty at other times? Does it run out of poop at higher RPMs? Slow to start? That is cranks but doesn't fire right away?

Last but not least there have been reports of owners of these cars claiming -- and I have no reason to doubt them -- the hesitation was cured by either an engine controller or possibly a transmission controller program update. You might check with your dealer to see if there is one available for your car. Now it might be that a car doesn't qualify for one unless it is manifesting specific behavior or symptoms and in this case a tech might have to road test the car to confirm the behavior is present.
I bought the car a month ago and at some point while i owned it i was looking at the RPM while accelerating and it was slightly decreasing as it was going up, like bouncing really. The spark plugs were done by UMA (Universal motors agency) who are a mopar service dealer. So i doubt theres anything wrong with the sparks, transmission fluids were changed at 96,000KM, car starts up fine but need to change my alternator soon as im getting only 12.4-12.5V in the hidden EVIC menu.

I never got ANY error codes at all. Could be my mass air flow sensor, I will take a pic and show you. At higher rpms its fine.

Honestly not sure why the rpm is doing that, I think taking a video might help y'all. Will take one so you can see what i mean.
 

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Discussion Starter #9
Might want to try using the factory recommended 87 octane, you're not getting ANY benefit using 91 unless you have a major tune, the 3.6 was designed to run on 87.......and it "might" be causing the RPM issue.
In Saudi Arabia theres only 91 and 95.
 

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Could be my mass air flow sensor, I will take a pic and show you. At higher rpms its fine.
The only challengers that have MAF sensors are the 2015-2016 hell cats. All other models run a Manifold Air Pressure sensor (i.e. MAP).

https://www.moparpartsgiant.com/parts-list/2014-dodge-challenger/electrical-sensors-engine.html?PNC=4,9

If you know you have a bad alternator then have it replaced. It's difficult to diagnose a car when there are other issues as low voltage thrown into the mix.
 

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I thought the only models that ran a MAF were the 2015-2016 hell cats? :dunno:
My advice was general. Of course if the model in question doesn't have a MAF the MAF can't be suspect, but what serves to do what the MAF does becomes suspect.

Absent a CEL and any error code pointing at the MAF or whatever or the throttle system I'm thnking the cause of the problem lies elsewhere.
 

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Octane controls pre-detonation and should have no ill effects in a motor that is designed to run (i.e. lower compression) on lower octane fuel.
I totally understand, but the key word being "Should".......I've seen cars do weird things in my 57 years that had mechanics scratching their heads saying "that's not supposed to happen that way" :grin2:
 
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