RPM flick, 2 years, 2 garages, unknown

[Michael Lambert]

2014 300c 5.7l hemi, AWD

Pictures

The RPM needle flicks, irregular pattern, it’ll flick about 30 rpm up, stay up for about 1/4 of a second then drop down quick 30 is rpm, tiny little flick. It does this in any gear, at 2000rpm, 4000rpm, idle, all the time.

No check engine lights, 2 garages found nothing, I thought whatever but then it became a problem.

Now when the car is under load, accelerating or going up a hill, that little flick evolves into a 200-300 rpm surge and when towing a little utility trailer with an ATV the rpm flick goes up to 500rpms up and down, making everything make noise as the tranny and engine surge.

I found out about “Alternate ripple” that can cause some wild issues. I used a nice OBD2 tool and observed the voltage output, it fluctuates a lot between 14.3 to 14.9 volts, I’d show a picture of the graph but I can’t post a picture.

Is this normal for an alternator?

I got a new battery today, checked the grounds around the areas I could and they had 1-6 ohms, fluid filter change on tranny, the fuel trim fluctuates with that rpm fluctuation so if it is an alternator ripple than I can see it causing the injectors and spark plugs to “ripple” too when firing off so quickly.

• This topic was modified 3 years, 10 months ago by Michael Lambert.

Topic

[Richard Kirshy]

I found out about “Alternate ripple” that can cause some wild issues. I used a nice OBD2 tool and observed the voltage output, it fluctuates a lot between 14.3 to 14.9 volts.
Is this normal for an alternator?

If the charging system is of the ” normal type ” and not a “smart charging system” yes the reading are normal.
there are YT videos explaining a “smart charging system”

As to the surging issue:
Might take a look at this,
https://www.2carpros.com/articles/engine-surges
This will give some areas to check.

[Michael Lambert]

I have another picture of my sisters alternator readings off her dodge ram 2013 3.6l

The one that is far more spiked is mine. Hers is consistent, mine is wild. I’ve changed spark plugs. Crankshaft sensor, camsensor, throttle body, transmission TCC solenoid, fluid, filter

Alternator slightly whines and seens to be a bit erratic, those fluctuations could be felt when those injectors are firing off thousands of times per minute no?

[Michael Lambert]

Alright here’s an update.

That is the rpm flick, it’s been doing this for nearly 2 years and as of the past year it’s been turning into a surge when under load. I have seemed to fend off the surging via cleaning map, pvc, temp sensors. But the flick is still there.

I have changed oil, filter
Tranny fluid, filter (80c its right lvl)
Crank sensor
Map sensor
New battery
New tcc solenoid
New front axle disconnect (it started clunking around same time rpm flick began, had to get new)
Differential and transfer case fluids changed
New throttle body with TPS

I mean I’m not sure what else to change here. I’ve been shotgunning this car by guessing and spending, 2 garages couldn’t figure it out either.

Found my steering fluid was extremely low, causing steering to make noise when turning left, the location of this steering fluid is ridiculous.

[Michael Lambert]

Update

Changed torque converter and the surge disappeared, this slight rpm flick may be chewing the variable lockup in the torque converter. New tach gage and rpm fluctuation is still there at idle.

[Author]

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