Hesitation/studder when on gas soft or hard

nathanh · June 7, 2019

Hi guys. I have 14 Silverado double cab with 5.3. Just about to turn over 200k. Have been running E85 for a while now with no issues.

Yesterday I noticed my truck struggling a bit once I got on interstate after work. One could call this hesitation or studdering. Almost feels like a lot of shifting but it’s not just a change in rpm. When I was on the pedal, light or a lot, the truck seemed like it was misfiring so I pulled off and looked into fluids a bit and everything was good there.

Went home after doing this and noticed that I had to be over 15mph to notice/feel the truck not seem like it was at full power when on the pedal.

here is video of me on cruise at 60 with flat terrain.

No codes are being issued but cyl 6 did have misfire in it. Was not able to get a live scanner.. so then I changed coil packs on 6 and 4. After doing this I read truck again and then it said mis fire on 1 and 5. So I’m not sure if I believe those readings. Any idea why misfire reading is jumping around like this?

Went ahead and cleaned throttle body and MAF. We will see if that helps. Some other folks have mentioned fuel pumps?? How can I check to see if it is this as there is no longer a fuel rail for me to check psi coming from pump.

I have new plugs waiting to go in and also have new wires in the mail.

Looking for some some other ideas to check out before going to a shop.

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On another note, I have a severe shake going on at 75 mph +. Just put a hair bigger tires on and level and it seemed to increase. Did 4wheel alignment and that didn’t help. This was prevalent on old tires 18 and new tires 20.

I noticed that the drive shaft has been under coated (supposed to do that?)and I am seeing some rust specs that Are starting to form. Could this be the culprit?

Paintor · June 7, 2019

At that mileage, I’d get a tranny fluid flush.

Torque convertor builds up gunk in it throwing it out of balance and supposedly this fixes it.

Slvijoe · June 21, 2019

Do you have a Catch Can on it. ????

You got great mileage out of her, just wondering.

nathanh · July 18, 2019

There is no catch can on there currently-have been considering throwing one on there just have not yet.

UPDATE: Ended up getting really bad slipping to the point where the tranny wouldn't even engage. No reverse either .

Took it to the dealer (other than having to wait 2.5 weeks to get on lift) and had a new tranny installed in 2 days. Lucky for me I had extended warranty and they covered this for me . I only had to pay $600 for upgrade to GM reman vs 3rd party and some extra things for the $4,200 job!