battle for mileage, 2007 Century, 14L EGR Series 60

I bought my Century in July 2012. It's just been one little battle after another. I will keep this to mileage issues I have dealt with. I will be adding posts to this and trying to break it up to get it all together. hopefully in chronological order. You'll be amazed all all the things that will add up to bad mileage.

The spec's for my truck:
2007 Freightliner Century.
DD Series 60 14L EGR
13 speed transmission
3.42 differentials
LP 22.5 tires.

I turn about 1400 RPM at 66-67 mph. This is my cruising speed of 1400-1425 RPM. When I am pulling BIG hills, I will get it up to about 1600 RPM. Normally, just by getting out of OD and staying in Direct.

My first quarter IFTA was 6.7 MPG. So I KNOW I can get the mileage. After Sept 2012, I have never seen an average close to that.

July - Had a delta-p trouble code set in the truck.

Aug - Replaced kingpins. 3 axle Alignment too. $2600

Sept - Stopped in at Pacific Truck in Kent WA. They were who I bought the truck from. They also are the west coast Detroit engine company. As such, I was making sure that the computer was set exactly the way I wanted it. In this case, I wanted them to turn the engine brake on during cruise. Yop, it did exactly what I wanted it to do. While there though, we found an exhaust manifold leak. I was also showing a VNT and delta - P sensor trouble code. On the house.

Took the exh man to my local guy who does all my engine work. He also tested my Charge air cooler for leaks. None found. He did the repair and installed a block heater. pretty much needed for there Minnesota winters. $1100.

October - Took a trip out to the mountains. It was bad. 4.0-4.3 mpg. I talked to the mechanic who did my exhaust manifold. He was top notch in helping me out. I used spray cleaner and was able to see that now I was having an intake leak at the boots between the turbo and charge air cooler. I used RTV to seal them up on the road until I got home and could get a new set of boots. NOTE: blue colored boots are for the cool side of the charge air cooler. Red are for the hot side between the CAC and Turbo.

November - Had a delta - P sensor code set. Was able to get it repaired. $360. CAC was tested by Interstate Detroit in the Twin Cities.

December - Went to east coast for loads. While there, got together with Rebel 127 and had him tune my ECM. We met on Thursday. He drove over 100 miles to meet up with me and tune my truck. In the couple hours we worked together, he really made my truck come alive.

We agreed to meet in Greencastle PA the following Monday and he'd get to run my truck on their dyno. You'd have to talk to Rebel127 why he chose that dyno, but both he and the folks at Antrim Diesel are top notch. In the end, I got a very nice tune. Rebel127 got some great data for his work too.

View attachment power gains.pdf View attachment dyno_run.pdf

I struggled as I was not seeing any really significant mileage increases. If anything, as time was going by, this was getting worse.

January - I continued looking for ANYTHING that would cause my fuel mileage issues. I noticed I had a major kink in the line from the DAVCO fuel filter to the fuel pump on the air compressor. When I took the line off, you could see there was more than a 50% restriction in the line. I replaced it with a line about 6 inches longer to increase my radius. Another design issue with Freightliner. I also removed the 90 degree elbow on the inlet side of the DAVCO as it was causing a restriction also. About $40 for the fuel line.



I also took the truck to my engine mechanic to have the overhead ran. We found most of the intakes all under 0.003" clearance. Really smoothed out the idle on the truck. $400 parts and labor.

February /March - Still having mileage issues and not getting headway. Not much done for mileage. Focusing on other maintenance issues.

April - Fuel mileage REALLY tanked again. Just like October. I was able to test the CAC / intake boots in the parking lot with spray cleaner again. The boots were all good. But boy was the CAC bad. Cost to replace. $850. I replaced it myself with some extra help to lift it in and out. Glad I had the help too. Significant improvements on the mileage....for a bit. But it still seemed something was not right.



At the start of the month, my engine gages started to act up. By this I mean, they'd work, then they wouldn't. like the truck just turned off. I pulled the dash apart looking for stuff that was bad. Nothing. Made sure ALL the connectors were good. Talked with rebel127. Thought was to unplug the ABS controller under the 5th wheel. If it brought the gages back, it was likely the ABS controller. Has something to do with the data link and how the different systems communicate. Didn't fix anything.

I drove the truck and was constantly looking for what could be the issue. The dash was TOTALLY unreliable to use. An intermittent electrical issue is VERY draining, emotionally and if you don't know what you are doing, financially. I wasn't afraid to tackle this. Especially with Rebel127 and a couple other folks to help me out with random phone calls.

Last week, I finally bit the bullet and took the truck into a local Freightliner dealer. Seems that the Freightliner diagnostic software would not recognize the truck. The truck was masking it from the computer. What was noticed is that there was a "missing qualcomm controller" error message. Since I DON'T have one of those stupid machines, we ripped out the entire harness that was a parasite to the system. The dash came back to life and the computer began to recognize the truck.......long enough to back it out of the shop and go down the road. Dang.....

I am headed to Chicagoland from MN and as I am cruising down I-80, the truck starts to falter. I also noticed that I had no A/C. Like someone is clicking the key on and off. Rebel127 got a phone call. NOW we are getting serious here folks. 500 miles from home with a truck acting like that was NOT a pleasant experience. I was able to get the truck to Iowa80 truckstop and Rebel called me back. While I was waiting for Rebel to call me back though, I started to look at ALL my grounds etc and the harness from the ECM to the firewall. There's a solenoid right under the Coolant overflow tank and I took those connectors off too and wire brushed them. I also put in A/C system Dye to test for a leak.

NOTE: DO NOT REMOVE THE ECM CONNECTORS WITHOUT FIRST DISCONNECTING THE BATTERY NEGATIVE TERMINALS FIRST. You have now been warned.

I also removed both of the ECM connectors and put them back on to make sure the connections were good.

Did I mention how much of a help Rebel was during this?

He did some calling on my behalf and the recommendation was to check the harness from the ECM to the firewall. The one I just went over not 5 minutes earlier. He also informed me that the A/C system is also part of that same wiring harness. It might be causing it to not work too.

I HAD GAGES and AC. I grabbed the harness and pulled. I HAD NO GAGES and AC. I grabbed the harness and pushed. I HAD GAGES and AC.

Guess what's bad? I called the Davenport Freightliner parts house. Not a stocking item. Called the local FRTLR parts guy back home. Same stuff. Order it.

Thursday I got home and put the truck in the shop and started to rip the wiring harness out of the truck. In the past couple days, I also found an actual A/C system leak, so I replaced THAT hose as well.

There were 3 worn spots on the ECM/Firewall harness. All of them are at the places where there are direct and hard bends in the wiring harness. It would seem that this is a KNOWN issue with 2004 to 2007 Century / Columbia trucks. It's the same part folks. You can NOT repair these either. They are data links NOT electrical wire. As such they are twisted to control signal interference. Same with the insulation. Put a butt connector in this wire, you are changing the resistance. And that computer signal is EXTREMELY SENSITIVE to changes. That same change in the signal could change a "reading" that the computer is seeing and cause you major power/economy issues. Cost - $680.

This part of the harness is more towards the ECM on the engine. It's directly around the clamp holder directly under the intake, but above the ECM. It makes another 90 degree bend here. Directly below it is where the third worn area is. It makes and 90 degree bend and goes to the ECM at that point.


This is impossible to see IN the truck. It's located back above the starter where the harness is in a clamp and makes a SHARP almost 120 degree bend. This bend scared me the most. Those BIG white wires are battery cables that run to the starter. one is positive and one negative. They are also pressed against the harness carrier (no better way to describe it.) If those wires had also worn through, it would have created a fire hazard is my guess.
View attachment 46695

All three of those wear areas are DIRECTLY as sharp bends.

All told, I have over $4500 just is chasing this fuel mileage issue. Today, on the trip home, the same trip after my CAC was installed a couple weeks ago, I showed 7.3 - 7.5 mpg, today I showed 8.5 - 8.7 mpg. Prior to BOTH of those repairs, I was seeing 5.4-5.7 mpg on that same route. I am not saying that's what I am getting, I am just saying that is the changes I was seeing on my econometer. My guess to this is that the data links were feeding dirty signals to the ECM and that was causing it to not give an accurate performance to the truck.

I'll keep this updated with future mileage as it comes together. I track my mileage by the week and follow it closely.

 

I started yesterday about 4 PM and changed the A/C line first. I then put it into vacuum and pulled it down to a 29" vacuum. After 4 hours, it was down to 28" of vacuum. I'd say the A/C was fixed.

At 9:30 PM, I had my wife come and get me. I was debating if I wanted to repair or replace. I was tired and decided to go home.

I woke up Friday Morning with a new breath of air. I have the crimping tool for Anderson PowerPole connectors. luckily, this works too on uninsulated butt connectors too. Along with RTV, some heat shrink, you can make a weather proof repair that works very well. It's like putting a hydraulic connector on your electrical wire.

I went back to the shop thinking I would do that repair to the 6 bad wires I KNEW about. But when I opened up ALL of the harness, there were over 2 dozen spots that needed to be replaced or repaired.

The new harness went in.

I worked on it today from 9:30 AM till 2 PM and took an hour for lunch with the guys at the shop. About 6 hours labor for me to replace the entire harness.

Couple of tips:

ALWAYS buy 11" black zip ties for wiring projects. I used about 2 dozen of these putting it back together. For frame bundles, get the 24" or longer heavy duty rated for 120 lb or more. I used about 18 of these. I have a zip tie about every 6" as this is where snow and ice WILL collect during the winter. There is a single wire that runs ALL the way back to the air dryer in this harness.

Take your time and if you have to, take PICTURES of ALL connections before you tear things apart.

I should note also:

In March, I used KillEm Biocide in my fuel for the first time. It was a result of the fuel filter looking like this. It plugged my filter completely in about 300 miles.

 

07 Century, 774K miles on it. I bought it with 708K miles on it in July 2012.

It's pretty much been running ok but bad mileage. On Monday was the first time ever that I had a falter in the engine. Like someone just turned the key off and back on.

 

Bought a set of steer tires too. and there was some other work. I'd have to pull the work order. I think it was an oil change too.