2005 Crescendo with CAT diesel performance issues

[RockinAB]

Hi all
Was just wondering if any of you have had any issues with studder or slow go. There are only 23k miles on it and it is serviced regularly. I have tried additives, cleaning the jets and new air filter. It doesn't do it all the time, but it is happening more and more... I need it to go when I push the accelerator. It used to go every time. Please help!

[robquin]

Hi. I own the 2006 Crescendo and a few years back I had the exact same problem. I had the two gas filters replaced and that solves the problem. Any slight blockage to diesel will cause the stuttering and RV will also slow down and lose power.

[Frutza]

Look it up on Cat forms, the C7 runs great, if you take good care of it, It likes good clean oil to protect the Heui system, It may cost a little more, but its cheap insurance, I had used various good quality oils and filters, but in talking to Cat mechanics I have gone to using Cat oil and filters, not much different in price than using other stuff, I also change my oil ao or before 7500 miles. look up adept ape videos, very informative, hears one,https://www.youtube.com/watch?v=MzUojErZRyU

But like was said start with fuel filters, both of them, also if its has sat for a long time it could have algae in the tank.
Oh, I think mine runs great, I can take off from a light and keep right with traffic

[mhhorowi]

If it's not the filters, it could also be the dreaded fuel injector issue. We've had to replace all of our fuel injectors. If the Heui pump fails, it sends metal into the fuel injectors and then they are lost too. An expensive problem that is mitigated with very clean oil.

[jamador1010]

I have 04 with a C7 330 with updated software to 350. So, I would start with process of elimination. I believe you are sucking air through fuel. 1) check to be sure your fuel filter (s) do not have a double gasket left by old filter. 2) If you have a hand pump on fuel filter housing replace and install new gasket, look inside mount to make sure there are no hairline cracks. 3) check all fuel lines for loose connections and chaffing. 4) the fuel return on back of head take it off and run carb cleaner through it and blow out repeatedly. 5) make sure all pre-charge hoses do not have a pin hole and or broken or loose clamp. I truly don't believe you have a Huei pump issue. I would strongly consider running the overhead, it's easy and, it can make a big difference. Takes half the day though! Following!!!

[mhhorowi]

I have 04 with a C7 330 with updated software to 350. So, I would start with process of elimination. I believe you are sucking air through fuel. 1) check to be sure your fuel filter (s) do not have a double gasket left by oiled filter. 2) If you have a hand pump on fuel filter housing replace and install new gasket, look inside mount to make sure there are no hairline cracks. 3) check all fuel lines for loose connections and chaffing. 4) the fuel return on back of head take it off and run carb cleaner through it and blow out repeatedly. 5) make sure all pre-charge hoses do not have a pin hole and or broken or loose clamp. I truly don't believe you have a Huei pump issue. I would strongly consider running the overhead, it's easy and, it can make a big difference. Takes half the day though! Following!!!

We also have an 04 C7 330. How do you like the upgrade?

[jamador1010]

Honestly, I was after lower end torque as I dingy tow a 1500 Chevy Silverado and travel to Colorado Springs / Kremmling frequently. I did loose 1/10 on my MPG but I'm okay with that. Additionally, I have free access to software so all I have in it was my time. You would be surprised on how much difference just running the overhead makes without updating software....

[jamador1010]

Also, keep in mind to check your engine fan bearings annually, some have grease and some have sealed bearing. Mine has been issue free and I wash out radiator as well, but this was one of the biggest issues with Cat!

[mhhorowi]

It's nice to have free access :). We tow a CR-V; so, it's not much of an issue for us. We just did a trip from Southern Arizona to see Mount Rushmore and Devils tower and of course went through Colorado. We averaged 8.2 mpg as I was pretty good at keeping the RPM's in a reasonable range. It's not always easy when you need to climb those mountains. We just went over 50K miles but we also had to have all the Injectors replaced and a Heui pump due to a failure. I inquired about the software upgrade but declined when I found out the cost. Time for an oil change :)

[Big Shasta]

Don't mean to hijack your thread but this is similar. We just picked up our 06 GS crescendo 8356 and drove it home 6 hours. looks like I got ~7 MPG Previous owner said he got 10 consistently going 70 on the highway (was he exaggerating?). I wasn't towing but I did run the generator since it was stupid hot in florida. My wife was following and she said every so often and randomly there would be a puff of smoke out the exhaust. Any ideas. Should I throw some fuel cleaner in it, not sure how long it's been sitting but it only has about 20K miles on it. Dealership just changed the oils. Power seemed fine, but I don't know what to expect. It got up to speed just fine and I set the cruise at 70 on the interstate.

The engine is a Cat C7 but we were told it was a 300, 330 and a 350 by different folks. How can I tell?

[Frutza]

Exaggerating, I get 7.9 and not at 70, I usually run 62-68
Contact freightliner with your Vin # they are all the same engine with different programming, but I think Gulfsteam used the 350 in that year.
A puff of smoke can be normal if the engine was coasting and then coming into power, but check your air cleaner

[mhhorowi]

Agree on the exaggeration.

[jamador1010]

I believe because of engine fan direct drive, I have never gotten over 7.3 and this is running the overhead, change air filter every two years and perform full PM services at every 5000 miles reguardless. I also add Lucas to my oil and I drive between 62/65 on cruise as much as possible. Unless you're software has been updated, you have a 330.

[jamador1010]

Also, were you running engine brake, if so, that's most likely the puffs she was seeing.

[Big Shasta]

I believe because of engine fan direct drive, I have never gotten over 7.3 and this is running the overhead, change air filter every two years and perform full PM services at every 5000 miles reguardless. I also add Lucas to my oil and I drive between 62/65 on cruise as much as possible. Unless you're software has been updated, you have a 330.
Thanks

Also, were you running engine brake, if so, that's most likely the puffs she was seeing.

That could have been it. Although I turned it off a lot. Sometimes you just want to coast.

I do recall one time I was on the phone with her driving straight and level didn't brake, didn't let off the gas and she said "There goes a puff".

I have no idea how long the fuel has been sitting. I added lucas fuel cleaner figured it couldn't hurt.

https://images.homedepot-static.com/productImages/13e308a7-f8a2-4e60-b4e4-02266dce4c22/svn/lucas-oil-maintenance-fluids-10003-64_1000.jpg

Sorry I hijacked this topic.

[jamador1010]

Make sure not to fuel stack, run as close to empty as you can before refueling. You may want to try Howes lubricant and a bottle of FPPF together to clean tank and injectors.

[vmcjr1]

Hi I had the same issue on my 05 crescendo with the cat c7 350 horse. Slowed down ,no power spider and lots of smoke.
THERE IS A WIRE CONECTOR UNDER THE ENGINE CLOSET THE TRANSMISSION IS LIKE A BLACK ROUND TWIST KIND CONECTOR. IT WAS LOOSE BUT CONECTE ENOUGH ,THAT WAS CREATING THE ISSUES. I JUST TIGHTEN IT AND PUT A BIT OF SILICON. TO MAKE SURE VIBRATION WON'T MAKE IT LIKE AGAIN. AND PROBLEM SOLVED. ALSO MAKE SURE YOU WASH AND CLEAN YOUR RADIATOR BECAUSE IT GET FULL OF STUFF FROM THE ROAD AND THE OIL AND CLUFS IT UP A BIT AND THAT CAUSES A BIT OF OVER HEATING.
USE ANY KING OF DEGREASER TO HELP.

[clepp]

I know it's an old thread, but if someone searches for this problem, they might find my experience helpful if nothing else works.

We had a similar issue with stuttering and no power. It got worse over time until it was every time you stepped on the pedal it would not move faster than a crawl. I did all the regular diagnosing and found nothing. Then I did an ohms test on the throttle pedal position sensor (under the throttle pedal) and found it was bad. We changed it out (it was a total nightmare to do. Have to have someone underneath the coach to hold the nuts with a wrench). Freightliner in Edmonton did not sell just the module so we had to buy a whole pedal assembly. Once replaced everything was back to normal and has been working perfectly ever since.