Slight hesitation/ stumble on acceleration when RPM between 10,000-15,000...

[Beamercub]

When this happens, in the past the remedy has been coil replacement..  All 3 times coil packs were replaced under warranty.  Second time around the spark plugs were replaced.  Couple things, with the weather change I have noticed the car starting ( turning over ) very slow - 2 year old battery..  I also recently got gas at a gas station I don't go to - could it be bad gas?   I was thinking of pro-actively replacing the battery and I added a bottle of HEET to the tank..   Problem seemed to be less frequent with the addition of HEET.  Hooked it up to code reader and no codes are being reported.  

I remember a tech telling me once that the common issue with the 3.6R is cylinder 5 ( coil )..   Due to it's location and exposure..   I haven't tackled the coils myself to date...     Anyone else have a similar issue>?  

[ammcinnis]

Reality check: Please edit the thread title.

[Beamercub]

What might you suggest?  

Reality check?  Seriously?

[ronemus]

Unless VERY heavily modified, your engine would resemble a large grenade at 10,000 rpm, much less 15,000!

Edited November 17 by ronemus

[MoleMan]

On 11/15/2023 at 6:10 PM, ronemus said:

Unless VERY heavily modifier, tour engine would resemble a large grenade at 10,000 rpm, much less 15,000!

Second that

In all reality the Red bottle Iso-Heet is ok for both a water remover and I injector cleaner the yellow is jiat a water remover and will do nothing.  Fill up next time at a brand name station using supreme and add a bottle of Techron and see what happens.  The winter blend will make the car run like crap for a month or so before a constant cold temp stays.

With me I rarely drive my 3.6 so I put 91 octane ethanol free fuel in and it runs like a champ.  

If you have no codes it's not the coil packs.  They should run a code if they are bad.  Same with a bad plug.  OEM coil packs are not cheap at all. I would not just throw parts at the car.

Try the Chevron premium and Techron method and go for a long highway drive and see what happens.

[Beamercub]

Yikes, those RPM's do seem a bit HIGH.  

I really appreciate the advice!  I hadn't thought about a winter blend of fuel being an issue..  It does seem that this issue appears around this time of year...   I am religious about getting gas from the same place, I was in a pinch..  Another reason, why I could never have an all electric car..  I would suffer from range anxiety.  I just went out and OBD said no codes.  I'm going to go back to my trusted gas station ( getting 93 this time ) and I will try a bottle of Techron.

Another thing I noticed, I'm getting about 3mpg less with this past fill-up.

I'm also going to replace the battery.  It has been getting down to 35f at night around here and when I start the car in the morning it's cranking very slow..  Better to be pro-active, eh?

I'll circle back in a couple days..

 

 

 

[waldguy]

7 hours ago, Beamercub said:

At 10K rpms, you should be going for jet fuel only, high octane

As for the battery, two years old isn't much.  Get it load tested before replacing.