Vortec 8.1 hesitating on acceleration and under load

[drisley]

Funny you bring this thread up again. Because, just recently, even here in Florida, had the same issue pop up again.

So, back in 2018, what ended up happening is that I drove all the way back to Florida without actually finding out the cause. And, also, the problem disappeared. Basically, as I came down in elevation and in temperature, the problem simply vanished and I drove home without issue.

Interestingly, the following year, I was in the Smokies area climbing some pretty steep hills and the engine performed without issue. So, I figure, I'm not as high above sea level and the temps aren't as high, so engine be good.

Interestingly, though, literally just a week ago, the engine started doing this again after coming out of the mountains. And even did it here in Florida. So now, this is not about elevation and the air thickness. It could be related to temp, since it has been quite hot. But, again, when the engine was under load and at low RPMs especially, it would miss and sputter. When flat and level and driving normally, the engine is smooth as silk.

At this point, I'm about to replace my plugs and wires again. Last I did it was about 4 years ago (before the trip out west). Putting the OEM plugs from AC Delco and this time thinking about getting the UltraPower plug wires. I think plugs and wires are the most likely culprit.

After that, I'll be looking at the fuel filter (which was replaced out west), the MAF sensor (not really likely, but I cleaned that out west, too)... and perhaps the ignition modules on top of the engine.

It is an annoying issue to debug because it only duplicates the issue in certain circumstances that are difficult to replicate unless I'm out traveling. When I'm actually in a position to more easily do something about it, the engine purrs like a kitten. Go figure.

 

[TheBar]

Check the fuel pressure before spending money.

 

[Gary RV_Wizard]

Replace the fuel filter before doing anything else.

 

[Hobnob]

Unfortunately I don’t know. I bought the unit 1.5 years ago with 65k miles. I took it to a mechanic right off and ask him to check it out, make recommendations (which I’ve always followed). He’s very honest and I believe competent. Honestly, I try to educate myself through forums like this and other online resources so I can communicate with him. For all I know these wires could be original from 2003. He and other mechanics have told me that the Rv looks like it’s been well maintained through the years. I do know, outside of the auto park brake fiasco, I’ve had no engine issues to date. Since I’ve had it there’s been 3 oil and filter changes two fuel filter changes but no tune up as it’s been running great until now.

 

[drisley]

I know when I replaced my sparks and wires the first time, it made an incredible difference in how the engine ran. And I didn't even know it wasn't running well before. So, if you don't know whether it has been done, I'd just do it.

 

[Isaac-1]

After burning through 2 sets or $140 Taylor Extreme plug wires, I switched to the Brazels Ultra RV Magnum Extreme plug wires (they are pricey, but worth it) and all my spark issues went away and stayed away so far. SPWEX8100 - UltraPower 8.1L Extreme Magnum Spark Plug Wires (note they also sell a cheaper spark plug wire with a similar name)

 

[drisley]

After burning through 2 sets or $140 Taylor Extreme plug wires, I switched to the Brazels Ultra RV Magnum Extreme plug wires (they are pricey, but worth it) and all my spark issues went away and stayed away so far. SPWEX8100 - UltraPower 8.1L Extreme Magnum Spark Plug Wires (note they also sell a cheaper spark plug wire with a similar name)

Yeah, those are the ones I'm thinking of using. Expensive, but seems like they would alleviate any future issues regarding burning the wires.

 

[pfmaddox]

summit racing products are equal to or better than oem. they are designed for competition vehicles, not just for everyday driving.
how old is the coach and how many miles does it have on it.
according to workhorse service rep, the fuel pump is rated for 1000 hrs of use. my w20 model with the 8.1 engine, had the same problem, and the fuel pump finally failed at 190,000 miles.
i had misfires long before, and cured that with one new coil, and new plug wires.

 

[Mark_K5LXP]

One would have to think a misfire that severe would trip the CEL, or at a minimum set a pending code.

Mark B.
Albuquerque, NM

 

[drisley]

I've only got about 62K on mine. Nowhere near 190K. I doubt, in my case, it is fuel pump. I'll rule out other things first. Sparks, wires, and even the coils are all much easier to deal with.

I did get a P0332 code on mine at one point (if my memory serves). Think that means the knock sensor. But, only happened once and didn't repeat the whole way back. So might be totally unrelated.

 

[penman39]

Brazels Ultra RV sells some very good plug wires. My coach with the 8.1 Vortec seemed to struggle under low rpm high load conditions until I changed wires and put in new plugs at Brazel's recommended gap of .045. My coach is around 56K miles.

 

[autopros]

Good day everyone. I was reading the discussion on the 8.1 gas issue and I was wondering if anyone figure out the real cause of the problem because I am having the exact same issue plugs, wires ,fuel filter and regulator all ignition coils all new. Cleaned throttle body new MAF sensor crank and cam relearn. I even had replaced the engine ( used) thinking that would solve my problems. Since I replaced the engine and did all the work listed on the new motor it runs great but in high temperature it has that sputter on acceleration going up the hill. Test drove it in cooler weather and it runs great. PLEAS HELP

 

[udidwht]

Good day everyone. I was reading the discussion on the 8.1 gas issue and I was wondering if anyone figure out the real cause of the problem because I am having the exact same issue plugs, wires ,fuel filter and regulator all ignition coils all new. Cleaned throttle body new MAF sensor crank and cam relearn. I even had replaced the engine ( used) thinking that would solve my problems. Since I replaced the engine and did all the work listed on the new motor it runs great but in high temperature it has that sputter on acceleration going up the hill. Test drove it in cooler weather and it runs great. PLEAS HELP

Fuel pressure check before anything else.