GDE fuel economy

BVCRD · **Posted:** Mon Mar 22, 2010 1:22 pm

Rixram wrote:

BVCRD wrote:

Rixram wrote:

Hiya fellas.

Quick question:
I'm looking at the GDE Tuners for my "new to me" 2006 KJ CRD (Bought it this past Saturday). The Hot and ECO tunes cost the same, but I'd like some owner feedback as to how going to the Hot tune over ECO, and whether or not there is much of a mileage hit. I need to make sure I get the best mileage possible, and am a fairly conservative driver (speed limits or close, and cruise control, usually).

If the mileage is identical for the Hot and ECO tones, I might as well go with the Hot tune, but if it sacrifices much, then it doesn't make financial sense to go hot.

Your help please? Thanks in advance.

There are other benifits to the GDE tune, but since you mainly mentioned mileage gains, doing the math, (IF) you get 3-4 more mpg, it will take you 30,000 miles before you break even on the fuel savings.

That math works in my favor. I drive 16-17K miles/year and keep vehicles usually for 4-6 years. Being this one is my first diesel, I will likely kept it at least for the 6 years, possibly more.

Then it should pay for itself. Other thing you can try is unplugging the wire harness to the aux coolant heater (viscous). It is belt driven, and it stand to reason draws some of the HP away so unplugging it could save you some fuel. The heater itself is located as you are in front of the vehicle, the pully contraption on the top-left. Look for a simple wire plug. You could also just pull the appropriate fuse. It is in the power distribution block in space R36. It is used to heat up the coolant faster as the demand in the passenger compartment requires. Since you are on the highway most of the time, I think yours would warm up quickly enough without this connected. But note, your tranny will not shift into overdrive until the engine coolant and tranny fluid are warm so this may delay that shifting process. Probably not though. Right now, it takes 1-3 miles for it to heat up sufficiently.

The viscous heater is a pump that churns a silicon gel to generate heat through friction. The heater warms the engine coolant as it passes through the pump's housing en route to the heater core. The pump is driven by the engine's serpentine accessory drive belt and engages via a standard air-conditioning compressor clutch. It turns on when the air temperature is below freezing and the engine is below its operating temperature. Once up to temperature, the pump disengages, letting the engine provide heat. But even a running diesel can cool off too much, such as when idling at a traffic light, so the heater will reengage if the coolant temperature drops.

- Dan Carney

DOC4444 · **Posted:** Mon Mar 22, 2010 7:44 pm

If you drive the same, there is no difference in MPG between the HOT and ECO tunes. However, if you tow heavy, make sure you have the new upgraded TC installed if you go with the HOT tune. (If you don't tow, you can "drive around" the shudder.)

No reason to remove the VH relay anymore. GDE resets the VH shutoff point lower so it is only on for about the first 5 minutes of cold runninng in cold weather.

DOC

Rixram · **Posted:** Mon Mar 22, 2010 8:58 pm

DOC4444 wrote:

However, if you tow heavy, make sure you have the new upgraded TC installed if you go with the HOT tune. (If you don't tow, you can "drive around" the shudder.)

DOC

TC?

Tow Controller?

Traction Control?

Thanks for the input. I do intend to eventually do towing (one of my major reasons for the CRD)

DOC4444 · **Posted:** Mon Mar 22, 2010 9:06 pm

Rixram,

TC= Torque Converter.

BTW, I work in Lincoln, RI. If you would like to try a CRD with "all the fixin's", arrange to meet me this week.

(PM me with your mobile number.)

DOC

BVCRD · **Posted:** Tue Mar 23, 2010 8:42 am

I actually did the math on the VH, and I would save around $2 a month if I umplugged it. Not worth it.

BVCRD · **Posted:** Tue Mar 23, 2010 8:43 am

DOC4444 wrote:

If you drive the same, there is no difference in MPG between the HOT and ECO tunes. However, if you tow heavy, make sure you have the new upgraded TC installed if you go with the HOT tune. (If you don't tow, you can "drive around" the shudder.)

No reason to remove the VH relay anymore. GDE resets the VH shutoff point lower so it is only on for about the first 5 minutes of cold runninng in cold weather.

DOC

That's all it's on anyway in a typical cold weather start-up.

DOC4444 · **Posted:** Tue Mar 23, 2010 8:58 am

BVCRD,

Based on my experience, I think it will be worth your trouble to drive for 10 minutes in sub-40 degree weather, pop the hood and confirm that the VH has disengaged as you think it should have. (Just make sure you look at it on cold startup so you can tell the difference between when the clutch is engaged and it is not engaged.) Even if you find your particular CRD disengages the VH this quickly, I do not think that is typical of most CRDs.

BTW, GDE has a track record of not offering "baloney" tweaks. They would not include the VH mod if their winter testing did not show that the stock VH settings result in excessive VH operation, compromising winter fuel economy.

DOC

BVCRD · **Posted:** Tue Mar 23, 2010 9:48 am

DOC4444 wrote:

BVCRD,

Based on my experience, I think it will be worth your trouble to drive for 10 minutes in sub-40 degree weather, pop the hood and confirm that the VH has disengaged as you think it should have. (Just make sure you look at it on cold startup so you can tell the difference between when the clutch is engaged and it is not engaged.) Even if you find your particular CRD disengages the VH this quickly, I do not think that is typical of most CRDs.

BTW, GDE has a track record of not offering "baloney" tweaks. They would not include the VH mod if their winter testing did not show that the stock VH settings result in excessive VH operation, compromising winter fuel economy.

DOC

I have. It turns off when coolant temps reach a certain level. We have to run about 1 1/2 miles until we reach the city limits, then another 2 miles until we reach a 65 mph speed zone. By then, we are up to temp and it has turned off. So, it is only on for those 5 minutes in the morning for us, and for about 5 minutes or even less when we come home because the ambient temp has gone up over the course of the day. You agree that there is no need for it to be on IF the operating temp has been reached wouldn't you? So, figure an average MPG gain of 3, for 6 miles a day, times the 18 days we drive to work. Fuel here is $2.89 right now. Now granted, my CRD spends it's nights tucked nicel away in a 45* heated garage. I'm sure that plays some role in the time that it take to get up to operating temps aka VH shutdown. Feel free to do your own math. I would save $2 a month. I loose that much change in the sofa. There are other benefits to a GDE tune. This one fails in my opinion however.

kapalczynski · **Posted:** Tue Mar 23, 2010 11:53 am

DOC4444 wrote:

Kap,

Please make your thermostat change the last move you make after GDE HOT, etc. This will be much more helpful to many of us who believe higher coolant temps will help mileage. However, the OEM unit appears to be a "two-stage" which makes it all a bit more complicated.

I expect you should see 4-5 MPG improvement with a GDE tune alone.

DOC

Unfortunately my current thermostat is bad, but I will run the same bad thermostat for a fair comparison of the GDE to stock tune. Then the 192* and see the difference. Unfortunately I do not have a spare ECU so I won't be able to compare 192/stock to 192/GDE.

kapalczynski · **Posted:** Tue Mar 23, 2010 12:10 pm

BVCRD wrote:

kapalczynski wrote:

LibertyCRD wrote:

Finally got the CRD out on the Interstate to see just how high I can get the MPG to go. Check this out:

Previous '05 CRD Sport - bone stock. Bought new in May '05. Not even a Provent or EHM...BONE stock. Grabber AT2 tires. 23-24 MPG on my normal driving routine. 26 MPG on the Interstate.

Current '05 CRD Limited - EHM, GDE HOT tune, Grabber AT2 tires. So far 19-21 MPG on my normal driving routine. 26 MPG on the Interstate with A/C off, windows up, cruise set at 70, sunny and 50s outside.

It appears that my mileage isn't improved significantly over a stock CRD. Everything else is awesome....but the mileage hasn't improved much. And I truthfully drive more conservatively now than I did 5 years ago. Age does that to us. I may be seeing 10% improvement at very best if you account for cold weather lately...but I won't know for certain until after the weather has been warm for a while.

All these numbers are hand calculated. EVIC is 2-4 MPG too high with each tank.

Just curious, where are you sitting on your coolant temp gauge after engine is warmed up and you are moving at a constant speed with torque converter locked?

Engine Temp is significant to economy. I live in Colorado Springs, CO where it is routinely 20F* - 40F* outside on my commute (winter) and have been around 20-22mpg to work and back at ~55-65mph mostly highway with cleaned MAP sensor and a brand new intercooler (replaced due to leak). My coolant gauge is usually 154F* according to scanner (roughly 3/8 on the gauge) so I KNOW my thermostat is bad. I am replacing thermostat/waterpump/timing belt next weekend and also getting GDE hot tune so curious to see where I end up.

Keith at GDE recommended I try a 192* thermostat for efficiency when I get my housing design complete.

After waterpump/timing belt replacement and GDE tune, I think I will run the bad thermostat (probably opening at 140-150*), then the 180*, the 192* and post all the temp numbers according to the scangauge and the tank economy results with different thermostat on each tank.

If you can hook up a scan gauge for actual numbers it would be cool to see where exactly you are at, but you can guestimate with the gauge.

The painted in needle is where I am usually at:

Thx GDE for image -

So, according to your gauge, the stock setting is around 196*. I can only imagine that as cold as you are running now, with the engine in a constant state of trying to warm itself, you would save a load on fuel costs by getting the thing heated up.

Stock properly working thermostat starts opening 80* C (176* F), so factory operating temp is probably around 180*-190*. mine is RUNNING at 154* warmed up.

so just the thermostat change should help economy alot. Thats why I will run GDE tune a tank or 2 prior to thermostat change to be fair on comparison. Though running that cold there may not be any difference in MPG between tunes since it is much more inefficient.

kapalczynski · **Posted:** Tue Mar 23, 2010 12:13 pm

LibertyCRD wrote:

According to that picture...mine runs at 176 when it's a warm day....and just barely below 176 when it's in the 40s and 50s outside.

Sounds like your thermostat is good, that is where most people that have changed their thermostat out have been sitting.

DOC4444 · **Posted:** Tue Mar 23, 2010 2:17 pm

BVDCRD,

Very interesting. So there is at least some variability, vehicle to vehicle. Leaving ours in an heated garage would not make a difference. Our VH used to run after an hour long highway run @ 45 degree ambient.

DOC

BVCRD · **Posted:** Tue Mar 23, 2010 2:23 pm

DOC4444 wrote:

BVDCRD,

Very interesting. So there is at least some varibility, vehicle to vehicle. Leaving ours in an heated garage would not make a difference. Our VH used to run after an hour long highway run @ 45 degree ambient.

DOC

I looked it up yesterday, and it's supposed (key word) to shut off when the coolant gets up to temp. If it was running non-stop, then it would save me a little over $8 a month. That would more than pay for one of my $5 Walmart prescriptions. Might be worth doing if indeed yours was a runaway. Like I said yesterday, the controls on the AC/heater switches turn it off and on. If you could wear a heavy coat until the engine heats up, and then turn on the cabin heat, this would be another way of by-passing it. So basically, if your cabin heat is turned off, no VH will turn on. It is the passenger compartment heat supply that turns it on, along with the ECM. At least that's what the shop manual says.

The viscous heater is a pump that churns a silicon gel to generate heat through friction. The heater warms the engine coolant as it passes through the pump's housing en route to the heater core. The pump is driven by the engine's serpentine accessory drive belt and engages via a standard air-conditioning compressor clutch. It turns on when the air temperature is below freezing and the engine is below its operating temperature. Once up to temperature, the pump disengages, letting the engine provide heat. But even a running diesel can cool off too much, such as when idling at a traffic light, so the heater will reengage if the coolant temperature drops.

- Dan

BVCRD · **Posted:** Tue Mar 23, 2010 2:42 pm

DOC4444 wrote:

BVDCRD,

Very interesting. So there is at least some varibility, vehicle to vehicle. Leaving ours in an heated garage would not make a difference. Our VH used to run after an hour long highway run @ 45 degree ambient.

DOC

Did you have the heater turned on at the time?

DOC4444 · **Posted:** Tue Mar 23, 2010 2:48 pm

Yes and not just one time.

DOC

BVCRD · **Posted:** Tue Mar 23, 2010 2:54 pm

DOC4444 wrote:

Yes and not just one time.

DOC

That would have kept it on as long as there was demand for passenger heat.

Rixram · **Posted:** Tue Mar 23, 2010 4:10 pm

BVCRD wrote:

DOC4444 wrote:

Yes and not just one time.

DOC

That would have kept it on as long as there was demand for passenger heat.

With the GDE tune, will the VH turn off once operating temp is achieved?

BVCRD · **Posted:** Tue Mar 23, 2010 8:18 pm

It will with the stock tune. I don't know what the GDE perameters are, where it's a timed event or when temp is reached.

Rixram · **Posted:** Wed Mar 24, 2010 9:52 am

GreenDieselEngineering wrote:

The viscous heater is not timed and will turn on based on engine rpm, ambient temp and coolant temp. The second two are the most important factors. A stock CRD has the following settings to have the VH on: ambient temp below 53.6 F and coolant temp below 161.6 F. With the tune the new limits are: ambient temp below 44.6 F and coolant temp below 131 F.

The fuel economy gain is minimal if the thermostat is working properly and the vehicle is not idling for a ling time or running at very light loads. However, with an old thermostat it is possible to have the stabilized coolant temps in the winter in the range of 155 F to 160 F and in this case the VH will stay on indefinitely. This is where the new settings will have a greater impact on the fuel economy.

The largest driver for improved fuel economy with the tune is the optimized combustion parameters (injection timing, boost and pilot injection quantity). Hopefully this will clarify the VH changes.

Green Diesel Engineering (GDE):
Regarding the thermostat (please excuse me, but this is my first diesel, although I've drooled over the notion of getting one for a decade), I've always understood that diesels run warmer than gassers. For example, in my old Ram 2500, the OEM t-stat was 190 or 195 degrees (IIRC) for my gasser, while the diesel ran 215 degrees. (5.9L V-8 gasser versus 5.9L I-6 Cummins TD)

It appears that the CRD Liberty runs significantly cooler. What is the engine t-stat factory spec, Is there an aftermarket t-stat that you'd recommend for the CRD. Or am I still thinking gasser when I assume that this would benefit the CRD?

BVCRD:

BVCRD wrote:

DOC4444 wrote:

Yes and not just one time.
DOC

That would have kept it on as long as there was demand for passenger heat.

It appears to me that DOCs answer was actually to the inquiry of whether or not he'd ever popped the hood to verify the activity state of the VH.

BVCRD · **Posted:** Wed Mar 24, 2010 10:04 am

The VH will turn on as passenger demand calls for heat too.

GDE fuel economy

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