poor than poor - GDE??

dr5chrome · **Posted:** Thu Mar 05, 2015 10:15 pm

Hello again –

I have had the GDE in for 3wks or so.. ALL the belts changed.. fuel additive input..
The engine runs great – Tons of power - no running issues I can tell.
Though I have not as-yet, taken a road trip to determine hwy-mileage, and not a chance to see what the mileage was before the GDE [just purchased this jeep], I was able to determine my street only mileage – basic trips to the store and errands.

Ive determined this well running jeep CRD gets a whopping 13mi to the gal. :shock:

This is exceptionally poor. My 6cyl 98 Cherokee got 20mpg on the street & 25~26 on the hwy.

Do you think there is something wrong why it is sucking so much fuel??
The point of all this effort, this Jeep & diesel & GDE was to improve my mileage over my Cherokee

Opinions would be appreciated.

dw

tjkj2002 · **Posted:** Thu Mar 05, 2015 10:19 pm

With the current temps and combined with only short trips never allowing the engine and drivetrain to fully warm up 13mpg maybe what your only going to get.

Don't feel bad I only get 5mpg's during the winter if I'm lucky.

RockyMountainYote · **Joined:** Sun Oct 20, 2013 8:32 pm **Posts:** 77

I think there may be something up due to the elevation. I have GDE tunes in 1 vehicle. the other is stock. The stock one makes it up the mountain in overdrive with no issue. The GDE tuned one cannot make it up the mountain in overdrive, it starts to overheat (with cruise control on too) and lose speed. The engine cracked in a non-stressed area of the block. I wrote it off as a possible casting flaw, but my roomate's CRD engine just took a dump too. It had an Eco tune as well. Coincidence? not sure. Definitely not happy. Oh, and my fuel economy has been better in the stock CRD vs the GDE one, but that may be due to the fact I actually tried to get good MPG my last trip across the country in the stocker

dr5chrome · **Posted:** Fri Mar 06, 2015 1:54 am

...everyone 'bloated' about the GDE tune. Did I waste 700$?

according to their web -

"Welcome to Green Diesel Engineering, your new home for the best in diesel powertrain tuning! GDE provides engine and transmission control unit re-programming that produces large percentage gains in fuel economy and power while maintaining a smoke-free exhaust and respect to all component limitations. Tuning has many benefits to prolonged engine life including cleaner oil, lower exhaust temps, and eliminating intake soot."

...how would you explain less power over the stock tune??
How can this tune potentially damage the engine when they state otherwise??

dw

RockyMountainYote wrote:

I think there may be something up due to the elevation. I have GDE tunes in 1 vehicle. the other is stock. The stock one makes it up the mountain in overdrive with no issue. The GDE tuned one cannot make it up the mountain in overdrive, it starts to overheat (with cruise control on too) and lose speed. The engine cracked in a non-stressed area of the block. I wrote it off as a possible casting flaw, but my roomate's CRD engine just took a dump too. It had an Eco tune as well. Coincidence? not sure. Definitely not happy. Oh, and my fuel economy has been better in the stock CRD vs the GDE one.

flman · **Posted:** Fri Mar 06, 2015 7:41 am

dr5chrome wrote:

...everyone 'bloated' about the GDE tune. Did I waste 700$?

according to their web -

"Welcome to Green Diesel Engineering, your new home for the best in diesel powertrain tuning! GDE provides engine and transmission control unit re-programming that produces large percentage gains in fuel economy and power while maintaining a smoke-free exhaust and respect to all component limitations. Tuning has many benefits to prolonged engine life including cleaner oil, lower exhaust temps, and eliminating intake soot."

...how would you explain less power over the stock tune??
How can this tune potentially damage the engine when they state otherwise??

dw
:POPCORN:

RockyMountainYote wrote:

I think there may be something up due to the elevation. I have GDE tunes in 1 vehicle. the other is stock. The stock one makes it up the mountain in overdrive with no issue. The GDE tuned one cannot make it up the mountain in overdrive, it starts to overheat (with cruise control on too) and lose speed. The engine cracked in a non-stressed area of the block. I wrote it off as a possible casting flaw, but my roomate's CRD engine just took a dump too. It had an Eco tune as well. Coincidence? not sure. Definitely not happy. Oh, and my fuel economy has been better in the stock CRD vs the GDE one.

I am going with what TJKJ said, short trips in an ice cold diesel is not going to net you any good MPG. Not sure what kind of problems Rocky is having, but I never had a tuning related issue with either of mine, and no one in the forum has had one, other then blaming the tune on some other engine failure.

dirtmover · **Posted:** Fri Mar 06, 2015 9:03 am

dr5chrome wrote:

Ive determined this well running jeep CRD gets a whopping 13mi to the gal. :shock:

This is exceptionally poor. My 6cyl 98 Cherokee got 20mpg on the street & 25~26 on the hwy.

Depending on your driving style and usage this may be normal for this time of year. Look on the bright side, without GDE you'd probably be closer to 11 :shock:

.

gmctd · **Posted:** Fri Mar 06, 2015 9:54 am

Correct - low to really low ambients can result in reduced fuel economy
- low temp air is dense air - dense air is more difficult to pump\compress, which results in more power lost to overhead
- tailpipe emission would appear normal as engine is actually burning the excess fuel to maintain function
- can also result in incomplete combustion with less BTU per injected volume = reduced power = more fuel consumed per volume of work
- tailpipe emission ranging from white vapors, where fuel did not reach combustion temperature, to gray to black haze, where fuel reached combustion temperature but flame went out are also normal during winter climes

This is where it would be better to have a steel air filter case with temperature-controlled valved ducting over to an exhaust pipe stove, such that intake air would be preheated in winter ambients, resulting in reduced pumping effort and improved fuel economy

DOC4444 · **Posted:** Fri Mar 06, 2015 10:23 am

There are a myriad of things that lower mileage on KJ CRDs that need to be addressed, one by one. Search the site. You never checked your mileage BEFORE adding a tune and you want to jump to blaming GDE? (It's not the tune.)

DOC

thermorex · **Posted:** Fri Mar 06, 2015 10:51 am

You may have a bad thermostat? What's the temperature on the gauge when you drive? As pretty much everyone said, cold weather is a very big impediment in mileage. The lowest I get with my Crd, was 19mpg on -10f. Summer I get a combined of 25-ish (22 city and 30 highway with constant speed at 70-ish mph).

Tips to improve mileage on Crd:

- If you drive less than 5 miles, stick with the Cherokee, seriously. Gas is cheaper, engine warms up faster.
- disconnect the relay for viscous heater, so it will take some load from your engine. I drive the jeep this way and I don't mind it at all. Theoretically your cabin air won't get as warm right away, I haven't seen a huge difference.
- try upgrading the viscous fan to an electric. There is a kit I use with ffdynamics fan 3600 cfm that comes with a shroud for Crd (around 300 bucks, it is worth especially in the winter as you won't move blistering cold air towards the engine all the time, but it gives you also couple mpg in the summer). If you don't tow heavy weights regularly, you'll have no issues no matter how warm is outside, that fan cools very well.
- make sure thermostat is working properly and it would reach the half way mark on the gauge. If it doesn't, the thermostat is stuck partially opened and it causes the engine to run cool.
- check your calipers. Liberty calipers are known to drag. Front calipers especially. They have a rubber boot in the guiding pin, one per caliper, that gets swollen and prevents the caliper to decompress so you drive "with brakes on". Its purpose is to muffle the noises the caliper does when it moves with the rotor when you brake. Take the rubber boot out, grease the pin with purple ceramic grease and you're set. Also rear caliper piston can get dirty, it's a plastic composite and can create dragging. You won't necessarily see the jeep pulling left or right, the only way to see it is comparing with a non-dragging wheel, id advise in just removing the rubber boot as is a recipe to "disaster".
- check your axle ujoints, they can get rusty and don't move easy. Inspect them every 3000miles and lube as necessary (same for Cherokee btw, this is from the maintenance manual)
- wheel bearings, same thing, they can drag also, although not as likely unless the bearing is shot.
- check tire pressure. I recommend going with at least 38psi, up to 40-45 if you don't have offroad tires (offroad tires are very rough if you go over 40psi).

I can tell you one thing for sure, don't regret getting gde tune, that's the best thing you did for your Crd. I have never seen the oil so clean in any Diesel engine that I had. That is a great tune that would help your engine last longer. I am sure you have other issues that are causing this poor mileage, not the tune. Fix those and you'll be a happy owner.

dr5chrome · **Posted:** Fri Mar 06, 2015 1:32 pm

Thanks all for the suggestions.. :!:

I can tell you that this jeep does run very cool, even if its been running a while. I thought this was normal. Of the 4 sections on the temp gauge I have never seen the temp go higher than the middle of the "1st section". It also can take 4~5 miles before I get any heat from the heater. Is changing the thermostat difficult?? would you say it was sticking or not working?? Do I have to take off 1/2 the engine to get at it? This engine does run very cool.

- what function does the viscous heater have to the engine?
All of the drive shafts + U-joints have surface rust and the u-joints have no lube nipple - I think they are the 'non-lube' type

This jeep has gone through every engine maintenance I could think to do - It actually run very well! No obvious smoke or other signs of running poorly.

It has the 5v plug's, which GDE says is better than the 7v. Does the cooler 5v cause less MPG?

..unfortunately I no longer have the Cherokee

dw

thermorex wrote:

You may have a bad thermostat? What's the temperature on the gauge when you drive? As pretty much everyone said, cold weather is a very big impediment in mileage. The lowest I get with my Crd, was 19mpg on -10f. Summer I get a combined of 25-ish (22 city and 30 highway with constant speed at 70-ish mph).
Tips to improve mileage on Crd:

- If you drive less than 5 miles, stick with the Cherokee, seriously. Gas is cheaper, engine warms up faster.
- disconnect the relay for viscous heater, so it will take some load from your engine. I drive the jeep this way and I don't mind it at all. Theoretically your cabin air won't get as warm right away, I haven't seen a huge difference.
- try upgrading the viscous fan to an electric. There is a kit I use with ffdynamics fan 3600 cfm that comes with a shroud for Crd (around 300 bucks, it is worth especially in the winter as you won't move blistering cold air towards the engine all the time, but it gives you also couple mpg in the summer). If you don't tow heavy weights regularly, you'll have no issues no matter how warm is outside, that fan cools very well.
- make sure thermostat is working properly and it would reach the half way mark on the gauge. If it doesn't, the thermostat is stuck partially opened and it causes the engine to run cool.
- check your calipers. Liberty calipers are known to drag. Front calipers especially. They have a rubber boot in the guiding pin, one per caliper, that gets swollen and prevents the caliper to decompress so you drive "with brakes on". Its purpose is to muffle the noises the caliper does when it moves with the rotor when you brake. Take the rubber boot out, grease the pin with purple ceramic grease and you're set. Also rear caliper piston can get dirty, it's a plastic composite and can create dragging. You won't necessarily see the jeep pulling left or right, the only way to see it is comparing with a non-dragging wheel, id advise in just removing the rubber boot as is a recipe to "disaster".
- check your axle ujoints, they can get rusty and don't move easy. Inspect them every 3000miles and lube as necessary (same for Cherokee btw, this is from the maintenance manual)
- wheel bearings, same thing, they can drag also, although not as likely unless the bearing is shot.
- check tire pressure. I recommend going with at least 38psi, up to 40-45 if you don't have offroad tires (offroad tires are very rough if you go over 40psi).

I can tell you one thing for sure, don't regret getting gde tune, that's the best thing you did for your Crd. I have never seen the oil so clean in any Diesel engine that I had. That is a great tune that would help your engine last longer. I am sure you have other issues that are causing this poor mileage, not the tune. Fix those and you'll be a happy owner.

Mountainman · **Posted:** Fri Mar 06, 2015 1:41 pm

I've seen a dramatic difference in power between CRDs. I'm guessing either the owners neglected to clean the MAP sensor, the rockers are really worn, or the timing isn't quite as good as it should be (no key-ways on the cams, so easy to be off enough to matter). Oh, and then there's a possible issue with the turbo causing less boost. Or a combination of those and other factors. And, mechanical fan, bad thermostat...

The elevation thing doesn't hold water with a turbo diesel (unless the turbo isn't working right, since they cram enough air in to make it a non issue).

Like others have said, it's probably short trips, plus a bad stock thermostat (even a good one is running way too cold especially in CO with a stock fan over cooling it further), and maybe a dirty MAP also.

Pull that mech fan in the winter and you'll get a couple MPGs. And a block heater an hour or so before you run it.

And viscous heater X2

Mountainman · **Posted:** Fri Mar 06, 2015 1:47 pm

nope on the 5v's. And, that low temp is most of your problem. Put an inline stat in today and you'll have a big difference, and you won't freeze to death!

Changing the stock stat will help a lot, but it's a waste of $$ because it still won't be warm enough. Buy one of Turbodieselfreaks stats and have a permanent solution, or do an inline. Inline is easy, stock thermostat is a pain and it still runs cool. Viscous heater sucks mpgs, and warms the engine up faster.

Mountainman · **Posted:** Fri Mar 06, 2015 1:52 pm

Oh, one more thing. Dragging brakes also hit your MPG, and they are common on these rigs.

If you never tow or don't pull major grades slowly, you'll probably be able to keep the mech fan off permanently, like some others have. Not certain if the big grades on the highway near Denver will be ok in summer with no mechanical fan, but it would be easy to test. Drive them only where you can get off the road, and if temp climbs past the half way mark, pull off immediately and let it idle, or even better, do a u turn and coast down hill. You definitely don't need that fan in the winter.

dr5chrome · **Posted:** Fri Mar 06, 2015 2:03 pm

mountain - Where do I buy the Turbodieselfreaks stats ?? Is it easy to install? ..or is an inline better?

thanks! dw

Mountainman wrote:

nope on the 5v's. And, that low temp is most of your problem. Put an inline stat in today and you'll have a big difference, and you won't freeze to death!

Changing the stock stat will help a lot, but it's a waste of $$ because it still won't be warm enough. Buy one of Turbodieselfreaks stats and have a permanent solution, or do an inline. Inline is easy, stock thermostat is a pain and it still runs cool. Viscous heater sucks mpgs, and warms the engine up faster.

Mountainman · **Posted:** Fri Mar 06, 2015 2:24 pm

Well, it's a long story. TURBO-DIESEL-FREAK is the guy on here who sells a completely re-engineered thermostat housing that holds a "normal" stat like all older autos have. It runs about $480 shipped, but the stock one's run about $150 or more, and only last something like 30k miles. So, after 100k miles, the TDF stat is a no brainer, plus it may save your engine, and will save you gas in the meantime. So, maybe a break even over stock stat at 60k miles or so, and then money in the bank after that. He's out of stock now, and you'll probably have to wait a couple months to get one, so just spend $15 on an inline stat, stick it in the upper hose, and you'll be good for now. If you never tow heavy, the inline may be fine for the long term, but I have been towing heavy, and I have bad head gasket right before my TDF stat arrives (it's in the mail as we speak). The inline with a bad stock stat doesn't circulate fluid as well as the TDF will allow, so it's possible that the inline could cause hot spots. Probably not even an issue when you're not towing in winter.

Anytime! :JEEPIN:

Mountainman · **Posted:** Fri Mar 06, 2015 2:29 pm

not bad to install, especially if you delete the viscous heater like I did, but that was a project. Check out the inline thermostat thread, and the one about TDF's stat.

dr5chrome · **Posted:** Fri Mar 06, 2015 2:35 pm

..wow

, 480.. Seems like an inline might not be safe either. Id rather not risk it.
I will be towing a trailer but it is only a small 13.5'.

dw

Mountainman wrote:

Well, it's a long story. TURBO-DIESEL-FREAK is the guy on here who sells a completely re-engineered thermostat housing that holds a "normal" stat like all older autos have. It runs about $480 shipped, but the stock one's run about $150 or more, and only last something like 30k miles. So, after 100k miles, the TDF stat is a no brainer, plus it may save your engine, and will save you gas in the meantime. So, maybe a break even over stock stat at 60k miles or so, and then money in the bank after that. He's out of stock now, and you'll probably have to wait a couple months to get one, so just spend $15 on an inline stat, stick it in the upper hose, and you'll be good for now. If you never tow heavy, the inline may be fine for the long term, but I have been towing heavy, and I have bad head gasket right before my TDF stat arrives (it's in the mail as we speak). The inline with a bad stock stat doesn't circulate fluid as well as the TDF will allow, so it's possible that the inline could cause hot spots. Probably not even an issue when you're not towing in winter.

Anytime! :JEEPIN:

flman · **Posted:** Fri Mar 06, 2015 2:37 pm

gmctd wrote:

Correct - low to really low ambients can result in reduced fuel economy
- low temp air is dense air - dense air is more difficult to pump\compress, which results in more power lost to overhead
- tailpipe emission would appear normal as engine is actually burning the excess fuel to maintain function
- can also result in incomplete combustion with less BTU per injected volume = reduced power = more fuel consumed per volume of work
- tailpipe emission ranging from white vapors, where fuel did not reach combustion temperature, to gray to black haze, where fuel reached combustion temperature but flame went out are also normal during winter climes

This is where it would be better to have a steel air filter case with temperature-controlled valved ducting over to an exhaust pipe stove, such that intake air would be preheated in winter ambients, resulting in reduced pumping effort and improved fuel economy

Not to mention that all the fluids in the drive-train are like honey until they warm up.

Mountainman · **Posted:** Fri Mar 06, 2015 2:48 pm

flman wrote:

gmctd wrote:

Correct - low to really low ambients can result in reduced fuel economy
- low temp air is dense air - dense air is more difficult to pump\compress, which results in more power lost to overhead
- tailpipe emission would appear normal as engine is actually burning the excess fuel to maintain function
- can also result in incomplete combustion with less BTU per injected volume = reduced power = more fuel consumed per volume of work
- tailpipe emission ranging from white vapors, where fuel did not reach combustion temperature, to gray to black haze, where fuel reached combustion temperature but flame went out are also normal during winter climes

This is where it would be better to have a steel air filter case with temperature-controlled valved ducting over to an exhaust pipe stove, such that intake air would be preheated in winter ambients, resulting in reduced pumping effort and improved fuel economy

Not to mention that all the fluids in the drive-train are like honey until they warm up.

Hmm, I hadn't thought about that. Sure could make an attached garage a big MPG boost (on short trips more so), especially for a diesel

papaindigo · **Posted:** Fri Mar 06, 2015 3:29 pm

Just to kind of list things that an hit mpg in one place and assuming your new ride has already had a DOCUMENTED timing belt job done, may have been mentioned in the list but I did not notice.
1. winter fuel - I've seen mention of a 10% mpg hit or more especially without using a winter fuel treatment like the appropriate PowerService.
2. bad thermostat and yours is bad - I've personally seen at least a 10%+ mpg hit
3. dragging front brakes - another 10-20% mpg hit. Easy to check - with cold Jeep on level or slight slope does it roll easily? After a brief drive with essentially no brake use are the wheels/rotor really hot, be careful when checking.
4. viscous heater until engine is warm might cost 1mpg.
5. cold weather and short drives (e.g. anything under say 15 miles even with a functional tstat) - I've seen a hit of 3-4mpg
6. cold drive train fluids - for example tranny won't shift into higher gears at all unless tranny fluid is above a set temp.
That's not to mention tire pressure, wind, and terrain.

I'm assuming your mpg is based on hand calculation and a GPS correction of odometer reading as the EVIC is notorious for being off but usually on the high side and odometer can be +-5% with stock tires and still meet spec.

Personally I would avoid the inline tstat option but it's ok for short term use.

If you haven't done anything about the tstat by the end of March you can have my used OEM (14k miles) for the cost of shipping. Stoutdog gets the TDF one and I get Kap's from stoutdog.

poor than poor - GDE??

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