Hesitation when accelerating from a dead stop

[TobyP]

Just a little update: so far so good.
I took the hose off the engine side of the PCV system and filled it up with about half a can of sea foam last night (the hose from the block to catch can is about 2 feet long) while the engine was nice and hot & let it sit overnight. It runs better today than it ever has & seems to have quite a bit more pep! Hopefully this is the fix. I did empty the catch can, it has about a teaspoon of off brown, almost creamy looking oil in it. I am guessing it's from sucking all the sludge out that has built up in the PCV passages/ orifices.
Yes, before anyone brings it up, I am well aware the seafoam & barrymans are eventually draining into the crank /oil. I want this to happen to continue to clean any deposits in the engine & she will get a fresh oil change this weekend along with an engine flush. I feel like, from the staining I saw inside the engine when replacing the gaskets, they used conventional oil in it. I run full synthetic, so it will eventually get it all cleaned out.

Random question though: what kind of MPG are y'all getting in your 4.2's? I'm getting an average of 14.5. I'm not sure if that's normal for these engines, but it seems pretty bad..

 

[Beacon]

14.7 here. Practically no highway driving. And I usually leave winter tires on all year long

 

[TobyP]

14.7 here. Practically no highway driving. And I usually leave winter tires on all year long

Oof, so mine is probably about normal then. I do highway / freeway driving. I do have a slight lead foot though 😁

 

[brad_]

Oof, so mine is probably about normal then. I do highway / freeway driving. I do have a slight lead foot though 😁

I drive my TB with a very light foot and I'm getting about 12mpg rn in Massachusetts... I'm jealous

 

[Mooseman]

Here's mine:

 

[TobyP]

Time for an update, I really believe the PCV system being clogged was the culprit. I have run a can of berrymans and a can of seafoam, about 1/4 of a can every few days, while whenengine was hot at the end of the day and let it sit and eat over night. I changed the oil this weekend since it had 2 cans of cleaner in it, it was not very dark, granted it only had about 1000 miles on this oil. It is running better and smoother today than it ever has. Hopefully this can help somebody out who is having the same issues!

 

[mrrsm]

I would not make a habit of using any of Berryman's Powerful Solvents in Long Duration, Closed Engine Solvent Soaks TOO often, as the Front and Rear PTFE (Poly-Tetra-Fluoro-Ethylene) TEFLON Crankshaft Oil Seals fitted inside the Front Timing Cover and Rear Engine Block Cover may succumb to the Strong Vapors and Concentrated Liquid by softening them to the point of having 'seal sag' ...which can result in Oil Leaks.

Polytetrafluoroethylene - Wikipedia

en.wikipedia.org

https://coatingcenterinc.com/assets/files/ptfe-msds-sep18.pdf

https://www.labtex.co.uk/wp-content/uploads/2019/10/PTFE-labware-white-paper.pdf

 

[TobyP]

I would not make a habit of using any of Berryman's Powerful Solvents in Long Duration, Closed Engine Solvent Soaks TOO often, as the Front and Rear PTFE (Poly-Tetra-Fluoro-Ethylene) TEFLON Crankshaft Oil Seals fitted inside the Front Timing Cover and Rear Engine Block Cover may succumb to the Strong Vapors and Concentrated Liquid by softening them to the point of having 'seal sag' ...which can result in Oil Leaks.

Polytetrafluoroethylene - Wikipedia

en.wikipedia.org

https://coatingcenterinc.com/assets/files/ptfe-msds-sep18.pdf

https://www.labtex.co.uk/wp-content/uploads/2019/10/PTFE-labware-white-paper.pdf

Thanks for the info / advice. I rarely run any sort of cleaners in the crank case for this very reason. Who knows what they'll do to any gaskets or seals. This was just to get the PCV system cleaned out, definitely not a long term or frequent occurrence. That's why I did such an early oil change as well, I didn't want that stuff just hanging around in there. Full synthetic oil does enough cleaning on its own to remove normal buildup IMO.

 

[TobyP]

Here's mine:

I love this app! I don't know why I never thought of looking for an app to do this sooner.
Turns out I'm actually averaging about 16.2. I was going off the average MPG on the DIC. Apparently the TB isn't accurate at all. My Yukon is spot on with the MPG display. Live and learn!

 

[TobyP]

Hi all,
I thought I would give another update. The hesitation is still there, very minimally, and very rarely presents itself.
I ordered a new tune from PCMForLess and installed it this weekend, I was tired of the lackluster shifting of the stock TB. Holy cow has it brought the TB to life. I ordered the 91 octane tune with a stage 2 shift package. The throttle response is so much better, and seems to have taken away all the hesitation it had, it even idles complete smooth (I thought it idled smooth before). My guess would be there was some sort of factory tune glitch or just flat out bad tuning. It has only been a couple days, but hopefully this solves all the issues.
Anyone thinking about a tune, I strongly recommend them, well worth the small investment for sure, even just for the performance gains and better drivability.

 

[mrrsm]

Don't Forget... @limequat ...as many Folks here also like HIS Tune as well. :>)

 

[brad_]

Hi all,
I thought I would give another update. The hesitation is still there, very minimally, and very rarely presents itself.
I ordered a new tune from PCMForLess and installed it this weekend, I was tired of the lackluster shifting of the stock TB. Holy cow has it brought the TB to life. I ordered the 91 octane tune with a stage 2 shift package. The throttle response is so much better, and seems to have taken away all the hesitation it had, it even idles complete smooth (I thought it idled smooth before). My guess would be there was some sort of factory tune glitch or just flat out bad tuning. It has only been a couple days, but hopefully this solves all the issues.
Anyone thinking about a tune, I strongly recommend them, well worth the small investment for sure, even just for the performance gains and better drivability.

Please let me know how your MPG changes! I was curious about the 91 octane tune

 

[TobyP]

Please let me know how your MPG changes! I was curious about the 91 octane tune

Definitely! I'm curious as well. I'm averaging mid 16's now. Hopefully this bumps it up a bit.

 

[TobyP]

Please let me know how your MPG changes! I was curious about the 91 octane tune

Okay, here are my MPG's after about 2 weeks with the new PCM / tune. I have gained about an average of 1 mpg. I most definitely do not have a light foot, this is a combination of a little weekend city driving, most highway / freeway commuting (average of 50mph, 80mph).

The blue line is where I installed the PCM, everything above that line is the new MPG.