04 Roadrek 190 11-12MPG

[Kon]

Hi and thanks everyone,
Our Chevy 6.0 V8 is currently getting around 11-12 MPG so far.
Haven'treally taken it anywhere with long stretches of highways, so these avg aretaken from 75% hwy/ 25% city driving.

Any tips or mods to help me improve?

70k miles so far.

only recent work is a new fan clutch and coolant.
Plus oil change.
Thanks for everyone's input!

 

[rowiebowie]

I think my mileage is fairly typical ('2011 3500 6.0L) at a little over 14 mpg on the dash computer, which is optimistic by at least 5%. I drive pretty fast. The speed limit at 60 & under and only about 5mph under when the limit is higher. No 55-60 mph to try and boost mpg.

Funny thing is I used to get a full mpg more (around 15) until I changed tires from Firestone Transforce to Michelin Defender LTX M/S's. This was the only change and the result was an immediate drop of 1 full mpg. I didn't think tires could have such an effect, but that was the only change that occurred.

 

[markopolo-ClassB]

It might have the 4.10 rear end so mpg will be less than the 3.73.

The RPO codes should be on a sticker on or around a door. You can enter the codes and find out a lot about your van. See here -> https://www.classbforum.com/forums/f5/gm-rpo-code-lookup-and-decoder-1748.html

 

[RAA357]

We have a 2007 RT210 Versatile, 6.0 liter V8, 6 speed transmission. I have a ScanGauge II installed and monitor the Current MPG and Ave MPG along with a few other options.
At 65 MPH we get 16.1 MPG with the cruise control on. 11-13 in the city with a light foot. I have verified these figures with manual calculations.

I run Mobil 1 full synthetic 5W/30 motor oil, Full synthetic rear end oil. High volume air filter. I use Marvel Mystery Oil with every fill up which helps clean the fuel system.
If i stop using MMO my MPG drops @ .5 MPG, with a 31 gallon fuel tank that equates to @15 miles.

One thing a lot of people overlook is cleaning the MAF (Mass Air Flow) Sensor which is located just before the Air filter intake. I clean my MAF twice a year with CRC MAF Spray cleaner. This is a 3 minute job.

We have 30765 miles on the 210 and plan on putting many more miles on it.

 

[themexicandoctor]

We have a 2007 RT210 Versatile, 6.0 liter V8, 6 speed transmission. I have a ScanGauge II installed and monitor the Current MPG and Ave MPG along with a few other options.
At 65 MPH we get 16.1 MPG with the cruise control on. 11-13 in the city with a light foot. I have verified these figures with manual calculations.

I run Mobil 1 full synthetic 5W/30 motor oil, Full synthetic rear end oil. High volume air filter. I use Marvel Mystery Oil with every fill up which helps clean the fuel system.
If i stop using MMO my MPG drops @ .5 MPG, with a 31 gallon fuel tank that equates to @15 miles.

One thing a lot of people overlook is cleaning the MAF (Mass Air Flow) Sensor which is located just before the Air filter intake. I clean my MAF twice a year with CRC MAF Spray cleaner. This is a 3 minute job.

We have 30765 miles on the 210 and plan on putting many more miles on it.

Great idea, I have a 2005 190 on a 2004 Chassis.

I wonder if I have a MAF Sensor?

 

[booster]

I would caution anyone who gets into very fine detail mileage keeping to be sure the odometer is correct and also that if you use a scanguage that the odometer correction in that has been compensated to correct. Our Chevy was between 2 and 3 percent off to high side on the odometer so we though we were getting better mileage than we were. Scangauge normally is matched to the odometer so that was off also.


In Minnesota we used to have a few 10 mile "odometer check" stretches of road that were nice for checking with signs every 1/10 mile, but I think all are gone except maybe one. We now try to check on about a 50 mile stretch of freeway against the mile markers, which aren't nearly as accurate. You need to look at every in the last 10 miles of the test and average how far you are off.



Scanguage says you can use a GPS to setup the speedometer settings, which we found OK for speed but not for mileage.


If there is a shop around that specializes in gauges they might have a calibrated speedometer dyno so you could get actually tested.

 

[RAA357]

2004 Chevrolet Express 3500s have a MAF, it is in a housing that you can remove and clean or just replace. Looked up the cost of of new MAF for your 2004 and they are averaging $62.00. My MAF plugs into the housing and it is a simple removal.

 

[RAA357]

I had the speedometer checked and calibrated when i had new tires put on last year,
it was off just slightly. The Scangauge figures and my calculations are very close.

 

[booster]

I had the speedometer checked and calibrated when i had new tires put on last year,
it was off just slightly. The Scangauge figures and my calculations are very close.

Who did you have do the calibration of the speedo, odometer? The test is pretty common, but I am pretty sure it takes a tuner or factory flash tool to change the PCM. Did a tire shop have the tools or did you have to go to the Chevy dealer?

 

[RAA357]

I have connections with several major race teams and one of them did the calibration for me. Their cars have to be dead nuts on with the instrumentation.

 

[booster]

I have connections with several major race teams and one of them did the calibration for me. Their cars have to be dead nuts on with the instrumentation.

That would certainly explain it as they would not only have the dyno but would also have the tuner.


I just looked at my HPTuner that I used to reprogram the shift points and lockup parameters on our 07 190P to get rid of overheating issues and to get rid of the irritating early downshifts on rolling hills. There are actually two parameters related to vehicle speed and engine speed/cluster. One setting inputs the trans shift points and lockup and the other inputs the engine controls and cluster. I didn't address the speedo error with ours when I did the trans programming as I didn't want anything that would influence a direct comparison of the trans changes. By the time we did the trans changes, we had also changed to larger tires, so our speed error changed from the 2-3% high to 2-3% low. Now with the trans changes settled in, and new tires probably in the spring, I will do the speedo changes at that point to get closer. You can never be perfect unless you adjust it regularly for tire wear, which would be a bit over the top, I think, so I will set it at mid tire wear. Our Scangauge has always been set to actual checked miles, so it doesn't match the odometer, but is accurate and conforms to the odometer if I add in the error to the odometer.

 

[Asphalt Addict]

2008 PW 6.0. Averaging 15-16mpg than it went to 11-12. I replaced the upstream oxygen senors, there are 2, and milage increased. They control fuel mixture by measuring the air-fuel ratio in the exhaust. Have them tested by a qualified mechanic you trust.
Good luck,

 

[Kon]

Cool
Thanks for the tips

 

[Mr Perkins]

2008 PW 6.0. Averaging 15-16mpg than it went to 11-12. I replaced the upstream oxygen senors, there are 2, and milage increased. They control fuel mixture by measuring the air-fuel ratio in the exhaust. Have them tested by a qualified mechanic you trust.
Good luck,

Any clue why replacing the O2 sensors would help? I checked the performance using a real-time scan tool of the O2 sensors and long-term and short-term fuel trim and they looked good. I replaced the MAF.

Thanks, Rob

 

[booster]

Any clue why replacing the O2 sensors would help? I checked the performance using a real-time scan tool of the O2 sensors and long-term and short-term fuel trim and they looked good. I replaced the MAF.

Thanks, Rob

The ones I have seen fail do normally drift the voltage off of what it should be when they are at the right mixture, but they can also give a good voltage when they are at the wrong mixture. Long term trim is allowed to be quite wide in most cars now so they can cover the alcohol content variations in the gas, I think. On the program for a later model they actually adjust the targeted AF ratio for alcohol content. If it determines the heat content is 10% alcohol, they set the base stoich mixture at 13.9 AFR, if I remember correctly.



I think the only real way to tell for sure is with a dedicated tester for the sensors. Most mechanics just replace them if there is a question and it does often improve mileage.

 

[Asphalt Addict]

Any clue why replacing the O2 sensors would help? I checked the performance using a real-time scan tool of the O2 sensors and long-term and short-term fuel trim and they looked good. I replaced the MAF.

Thanks, Rob

The mechanic I used actually diagnosed over the phone. I took it in and he used a scanner to confirm. They were not that expensive and he changed them for $40 plus the O2