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.
First I am thinking lets change the fuel filter just incase debris and or sludge made its way to the filter. Cheap enough easy enough.
2) Check fuel pressure
3) Check and clean HAF sensor
4) Purchase a OBDii scanner to see if there are codes during operation that might lead me to a solution
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.