Workhorse Hesitation with Load

[HoboTWD]

I have a 2004 Winnebago Suncruiser with 42k miles. This motorhome has run with no issues until two months ago. I live in rural Tennessee use the motorhome as my work apartment in the city I drive the motorhome on average 160 miles per week. I drive mountainous roads and started noticing hesitation and loss of power on inclines.

I first thought a tune-up was in order and so to the motorhome dealer we went for a tune-up. We replaced wiring and spark plugs. At first the motorhome ran like a champ quick response no hesitation we thought bravo--but no. A few weeks after it started hesitating on inclines with a loss of power--back to the dealer--no fault codes. The thought process was the catalytic converters needed to be replaced. I took the motorhome to a muffler shop I chose only by online reviews with a 4.5 star rating with over 200 reviews. I could have fallen over when they told me they could install new catalytic converters but they would not solve my problems. The muffler shop suggested I go to a mechanic they thought could help me--who suggested adding Chevron Techron fuel additive to the fuel. Bravo!! Ran like a champ for about 75 miles---Then no Bravo! Same situation.

Dealer suggested running the fuel to empty and then adding the fuel additive with 93 Octane fuel and see if that would fix the problem. The first 50 miles were rough, I thought all this for nothing and then as if magic the engine started running smoothly, great acceleration, no hesitation, she was running like a champ. I even called the dealer and said problem solved--but NO. Today (the next day) I started on my voyage to work and I do believe the champ is hung over and is running worse than it ever has.

I am determined not discouraged--but I have to figure out the issue and get it fixed. When I search the internet this problem is apparently common and the message boards and forums go for a while but then stop without ever concluding what fixed the issue. I promise to finish this thread to the end with the solution to my hesitation and loss of power to maybe help my fellow RV'er. The dealer has suggested before this to replace the coils which would cost around $1k but they are not sure this will fix my problem. I would gladly pay that if I knew my hesitation and loss of power would be gone for ever. However, they agree it is a gamble. I am all about starting with the cheaper solutions and working toward the granddaddy of expenses when we are shooting in the dark. I think we have ruled out the fuel or bad gas theory. Here are my thoughts and trust me I am not a mechanic and I am looking for--no actually begging for a deeper understanding and suggestions than mine.

I have changed the fuel filter and that did not help. Does the Suncruiser have more than one fuel filter?

These are my thoughts please offer yours:

1) Check fuel pressure
2) Check and clean HAF sensor

Sorry for the length of this post if you are still reading you are either really bored or you have been in my situation and know my frustration.
Thank you in advance for your input.

My Best,

SB

[Morich]

Well, I am sorta semi-bored but I can tell you a story while we wait!
I would not go for the big money on the converter as that is a pretty open shut case if they think very far. But there are tons of other things that can cause a problem of your sort. Are you into the years that got into fuel injectors or not quite on your engine? Don't see a mention of what engine.

[emiddleb]

Back in the day I had an RV with the W24 chassis and 8.1 engine. Many owners had issues (myself included) with power loss and hesitation which was caused by the spark plug wires getting burned and shorting. The issue was poor airflow over the engine causing wires to get too hot. Some manufacturers retrofitted various air dams in the front to increase the air flow over the engine. Some owners resolved the issue by swapping for high-temp spark plug wires. You said you replaced them once, things ran fine for a while and then problem came back. I'd take a look at them to see if they might have failed again. Just a thought...

[345 desoto]

In the old days, sounds like it would have been a bad coil. Worked fine, until it heated up, then it would short out internally...FWIW.

[HoboTWD]

Originally Posted by Morich

Well, I am sorta semi-bored but I can tell you a story while we wait!
I would not go for the big money on the converter as that is a pretty open shut case if they think very far. But there are tons of other things that can cause a problem of your sort. Are you into the years that got into fuel injectors or not quite on your engine? Don't see a mention of what engine.

Sorry about that--it would helpful.

Workhorse 8.1 W22

[HoboTWD]

Thank you we are looking into changing to high temp wires--easy enough

Sid

[Morich]

Also don't miss reading the current posting on hesitation/missing due to wiring chewed by rodents! Things that we notice at slower speeds can run close enough to normal to miss them at higher RPM.
But it can also be a real nightmare to get things fixed at times. My story that I skipped telling is that my 2014 Focus is now back to a different Ford dealer for repairs of a "fail to crank" issue. Two trips to change things under recall for the TCM but the third time they decided my battery was bad???? So we have it at another dealer who has called twice to say it is fixed but I insist they keep it overnight and try it again and it fails to crank!
Small things can be hard to figure with lots more sensors on newer vehicles. They can change the TCM all day if that's what the codes show but I think they will have to look deeper. Starts/runs fine ---if I want to go out and start it every few hours!

[Bo Walker]

A mechanic said 7mm spark plug wires come from the factory now. But he said it will not run as well as with 8mm spark plug wires. I think I got the 8mm from Car Quest. I had trouble with the pickup coil in the distributor also. I think it's called a pickup coil. That's a pretty easy fix as well.

[CWfrmTx]

We have a 2008 itasca 8.1 that was having the same issues. Initial mechanic did not identify a burned wire on the back plug. We replaced the wires with solid core from from Brazels https://www.brazelsrv.com/SPW8100-Ul...ark-Plug-Wires

and included heat shields. Make sure that you have the heat shields or they will quickly burn which is what it sounds like has happened to you.

[tjwoody]

Actually, this could be coming from an entirely different place - sensors. Bad or dirty oxygen or airflow sensors can cause hesitation and loss of power.

[delhawk]

I have to vote for the spark plug wires. Had them replaced at least 3 times before we went with high temperature racing engine wires. My mechanic replaced at no labor cost. I’ve probably gone at least 50,000 miles with no further performance problems. We have a 2000 P30 chassis with a 454/7.4 engine. One of the reasons for damaged wires was an exhaust manifold leak cause by a couple of broken bolts. I’m told a fairly common issue with these big lock GM/Workhorse engines. Hope you get the problem solved, cheaper rather than later.

2000 Winnebago Brave 33V pushing 200,000 miles.

[Chitter]

I have a 2005 Adventurer with the Workhorse engine and I had the same problem. It was running fine but I started losing power on the inclines. Well, it turned out to be the air filter. Now the air filter that was in there was not that old and it looked fine, but when I changed it problem gone. I use genuine workhorse air filters and usually keep two or three on hand. It seems like every 3000 miles or so it’s about due.
Hope this helps.

Joe

[rvbud]

Though you might have changed the fuel filter once, you might want to try again. If there's junk in the fuel tank that gets picked up because you used additives for cleaning, you might just have another dirty filter. With a dirty filter at higher revs, engine will lean out and you'll loose power. I made the fatal mistake of not changing our fuel filter for 5 years....now, I carry an extra and change at least yearly after start up following a couple of months non-use
. I also agree with the mentions on the spark plug wiring; heat is the culprit quite often...high temp wires with asbestos heat shielding over the plug terminal in addition to reinstalling the stock heat shielding at each plug (pain that it was) solved our 454 problems in an EFI P30.

[jbrattain]

Started having the same problem with my 2002 Sightseer 30B with the 8.1 liter Chevy a couple of years ago. My mechanic would replace the plug wires with good quality wires, but two of them would start failing under a load on the next trip or so. Changed to ACCEL ceramic plug wires from Summit Racing and it solved the problem. I keep a spare set in the camper. They are a bit pricey, but not much more than AC-Delco wires, and well worth it for the peace of mind.

[HappiHenri]

I have a 2005 with the W22 Workhorse chassis. Has been running well, though a few years ago I had a few problems. Hooked up my OBD meter and was told that I had a mis-fire on plug 8. So I replaced the ignition coil - easy job and the OE part is available on Amazon. Fixed the problem temporarily - but then it started mis-firing again. So I looked instead to the small wiring harness which feeds each of the coils. Ordered new one (again on Amazon) and replaced it - and no problems since. Those wiring harnesses (1 for each bank) have a small connector which plugs into each of the individual coils. They were coated with a grease - which kept out moisture in order to ensure a good electrical connection. But over time that grease dried out and hardened, and apparently did not allow for a good electrical connection. When that happens the coil is not necessarily being activated properly - hence, my misfire.

In replacing this wiring harness I made sure to clean up all the coil connections. Then I smeared a good silicon dielectric clear grease right on the plug ends and in the coil socket to help preserve the electrical connection. Now runs like a champ.

Some other learnings -
1> Get an ODB meter! Not that much $$ and they will tell you of any fault codes which may be generated. In diagnosing your problem this should have been the 1st step.

2> This 8.1 l engine is known for running very hot, so Winnebago added a 2 1/2" duct on each side of the engine to direct fresh air to the rear spark plugs. As others have mentioned sometimes the OE spark plug wires can actually burn out and should be replaced with good Hi-Temp silicon wires. So make sure your cooling ducts are in place and aimed correctly.

Parts links for the Workhorse 8.1l engine -

Ignition Coil - <$30/each - (8 used) https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

Spark Plug Wire Set - https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

Spark Plug Set - https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

Ignition Coil Harness (2 required) - https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

[jbrattain]

My mechanic installed the OEM AC silicon spark plug wires with the OEM heat shields. Two of the AC silicon boots were "cooked" in just a few hundred miles.

After doing a little research, I also learned about the hot spots on certain Winnebago Chevy engines. So that's when I had the ACCEL ceramic boot wires installed. That was about two years and several thousand miles ago, and I haven't had any more problems.

[HoboTWD]

As promised I want to follow up with my workhorse Hesitation with Load and if it was fixed or not. The best news is yes Larry at Larry's Auto Clinic diagnosed and repaired the issue. WOW and it only took about five hours. Larry is a gift!

The issue was the coils. The coils on my Workhorse were producing 9 to 10KV and were after market coils replaced prior to my purchase. The Workhorse requires 11.7 to 13.2KV to operate properly. Larry and is mechanic Justin replaced all coils with AC Delco # 12558693 and the motorhome has never ran this good. It is an unbelievable difference and something that should have been easily tested by the numerous repair shops we tried before Larry's Auto Clinic in Myrtle Beach SC.

My biggest lesion of this challenge is to use ONLY original replacement parts no substitutions. I will only purchase the original equipment from here on out. When I dealer says "oh its the same thing just cheaper..." always say no I want the original replacement parts. This was a simple repair for a shop that knows their trade!! I have returned two other times to have Larry make other repairs and I am completely satisfied. Thanks Mike for the referral and Thanks to Larry what a blessing!

Larry is a warrior--he has devoted his life, knowledge, skill, and love to help others. I am honored and privileged to know Larry and had the opportunity to work with him.

[Cataska]

If it its a chevy always use AC Delco ask me how i know,well no don't i don't have that much time.

[USAlimey]

While my baby only has 49K miles she's getting old - this thread has been VERY helpful.

I will now plan on replacing these items during my next tune:

AC-Delco Coil
AC-Delco Plugs
EXTREME heat cables
Replace Exhaust Manifold Bolts and seals

Sincerely

Paul