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EHM- Is it obsolete?
http://www.lostjeeps.com/forum/phpBB3/viewtopic.php?f=5&t=60649		 Page 1 of 1
Author:  outriderCRD [ Thu May 12, 2011 3:37 pm ]
Post subject:  EHM- Is it obsolete?
I don't lurk here that much any more because I can't have too many expensive hobbies at the same time. :mrgreen: I have seen some pictures with what looks like the EHM, but instead of a vinyl tube, it looks like an electrical conduit box with a valve and filled with steel or copper wool. Is this a new version of the EHM? I've had my CRD for three years and it still pretty much bone stock. :banghead: With diesel prices going up, and since I have a lot of free time now, I'm gonna do every mod possible to squeeze out more MPGs.
Author:  papaindigo [ Thu May 12, 2011 4:17 pm ]
Post subject:  Re: EHM- Is it obsolete?
IMHO the most direct way to get more mpgs is the GDE EcoTune. In my case 18-19 in town went to 21-22 and 28 on hwy went to 32 or better if I'm careful. In warmer areas or in the warmer months in colder areas unplugging the relay to disable the viscous heater also helps. I have less confirmed data on this but my personal experience suggests in town 22 is now 24 but I doubt that I'll see any hwy mpg improvement as the viscous heater generally runs only early in the engine warm up cycle. Other items - clean your MAP sensor and keep it clean; good and clean air filter (I like Amsoil others have different opinions); correct engine oil (diesel spec Mobile 1, Shell or Amsoil); ATF+4 transmission fluid only; don't waste time and fuel warming up the engine (crank up, idle long enough to build oil pressure like 15 seconds, drive off but not too hard until temp guage at least shows signs of life); make sure your hoses to and from intercooler are intact (replace with Samco or at least new stock OEM if not); make sure the air box to turbo hose is intact down where it connects to the turbo (don't look feel, if not replace with OEM); if your engine temp guage at operating temp is below dead vertical or no more that 1 tick to the left you need a tstat replacement or perhaps you have a miscalibrated temp guage (dealer has to flash to fix) but the point is a cold engine due to a failed open or opening too soon tstat is an inefficient engine.

Some of this is obvious and some less so. Best I can do in haste and others may have more/better/different ideas.

PS I have no opinion on whether or not the EHM is or isn't obsolete but with the EcoTune I don't feel I need it. It doesn't directly improve mpg but rather indirectly may help by keeping certain things like the MAP from gumming up. The canister things with steel wool or other designs appear to be an EHM that captures the drips of oil for later disposal rather than dumping it on the road.
Author:  racertracer [ Thu May 12, 2011 10:07 pm ]
Post subject:  Re: EHM- Is it obsolete?
Early on I ran the jeep with the elephant hose modification and it id help to an extent but the smell did it in, I had to get rid of it because the mrs just couldn't deal with the fumes.

I have been running with the hot tune for about 30,000 miles and I find no oil residue in my CAC hoses anymore.

I found a few drops in and around the hose leading from the round black puck on top of the motor to the turbo, my MAP sensor is clean as a whistle and the MPG went up to 24 - 27.

Before the Hot tune I had oil residue everywhere, my map sensor was clogged and the Jeep ran like crap with excessive rattle and smoke.

The tune made it better and I now have the diesel I never knew existed.
Author:  flash7210 [ Fri May 13, 2011 7:44 am ]
Post subject:  Re: EHM- Is it obsolete?
The EHM is a great mod for preventing other problems.
It will help keep your intake/turbo hoses from deteriorating and help keep your MAP sensor clean.
It will not help with MPG.

If you want to get better MPG, you have to change the flow rate and duration of fuel into the cylinders.
Only two ways to do that: 1. change your right foot, 2. get a special ECM tune
Author:  chrismc [ Fri May 13, 2011 9:30 am ]
Post subject:  Re: EHM- Is it obsolete?
There's a lot of mis-information here. The EHM has little to do with fuel economy, it only keeps oil residue from getting into the air intake system and fouling the hoses and MAP sensor. The Hot (or Eco) Tune has nothing to do with oil residue in the intake system, or with oil residue fouling the MAP sensor. The GDE tunes WILL minimize the EGR system functionality, which keeps SOOT from fouling the MAP sensor. The MAP sensor gets fouled from both oil and soot, and the combo of both is by far the worst. If you have the EHM and a GDE tune, you'll keep both nasty elements away from the sensor. As previously mentioned, the only way to keep fuel economy in check is by reducing fuel (via the ECM or your right foot). Keeping the MAP sensor clean (oil- and soot-free) will help the ECM make the best calculations for fuel usage, (helping fuel economy), but won't make nearly as much of a dent in fuel usage as a GDE (or driver's foot) tune.
Author:  warp2diesel [ Fri May 13, 2011 9:44 am ]
Post subject:  Re: EHM- Is it obsolete?
Last year between Evansville, IN and Oswego, IL I got 34MPG with my Inmotil Stage II tune. Due to the rout and all the Revenue Enhancement Law Enforcement Officers, I had to watch my right foot, hence more MPG. The next week I was on I 94 in Michigan and only got 24MPG because I drove like the natives in Michigan drive to comply with the local customs.
Mods that increase MPG include going to narrower tires that can hold more pressure and opening up the exhaust at the choke point that includes the stock muffler and the stupid 2 1/8" ID rear cat flange. I ran all the tests with a pressure gauge tapped into the pipe between the CAT and Turbo before and after and posted them. Extra oxygen allows all the fuel to burn and puts more power to the rear wheels, regulate the power with your foot and you will get more MPG. SIMPLE
Author:  chrismc [ Fri May 13, 2011 9:57 am ]
Post subject:  Re: EHM- Is it obsolete?
warp2diesel wrote:
Mods that increase MPG include going to narrower tires that can hold more pressure and opening up the exhaust at the choke point that includes the stock muffler and the stupid 2 1/8" ID rear cat flange. I ran all the tests with a pressure gauge tapped into the pipe between the CAT and Turbo before and after and posted them. Extra oxygen allows all the fuel to burn and puts more power to the rear wheels, regulate the power with your foot and you will get more MPG. SIMPLE


Warp- I missed that post and I'd be curious to see those numbers (I'll search for it). I had always heard that the CRD had a relatively open exhaust and that upgrades didn't help much unless you had an upgraded turbo that moved more air. I'm not sure that a more open exhaust will get significantly more air into the cylinder for combustion on a positively-pressurized turbo engine like it would on a naturally-aspirated engine, but it will definitely help keep exhaust temps down (especially while towing). Lower EGT=cooler engine=better mpg.
Author:  warp2diesel [ Fri May 13, 2011 6:23 pm ]
Post subject:  Re: EHM- Is it obsolete?
chrismc wrote:
warp2diesel wrote:
Mods that increase MPG include going to narrower tires that can hold more pressure and opening up the exhaust at the choke point that includes the stock muffler and the stupid 2 1/8" ID rear cat flange. I ran all the tests with a pressure gauge tapped into the pipe between the CAT and Turbo before and after and posted them. Extra oxygen allows all the fuel to burn and puts more power to the rear wheels, regulate the power with your foot and you will get more MPG. SIMPLE


Warp- I missed that post and I'd be curious to see those numbers (I'll search for it). I had always heard that the CRD had a relatively open exhaust and that upgrades didn't help much unless you had an upgraded turbo that moved more air. I'm not sure that a more open exhaust will get significantly more air into the cylinder for combustion on a positively-pressurized turbo engine like it would on a naturally-aspirated engine, but it will definitely help keep exhaust temps down (especially while towing). Lower EGT=cooler engine=better mpg.


A brief summery; I got as high as 5 PSI back pressure with the stock system when towing a trailer. After I opened up the system the back pressure dropped to 0.0PSI. I removed the gauge and put it back on the shelf in the garage. My boost pressure climes much faster and I can get 20 PSI boost measured at the manifold after it droops going through the intercooler.
Conclusion, removing the CAT is a waste of time and is illegal, replacing the crap stock muffler with a straight through 2 1/2" and opening up the 2 1/8" choke point on the back of the CAT is all you need with any tune that the 2.8L can handle.
Author:  RAF 3829 [ Sat May 14, 2011 9:09 am ]
Post subject:  Re: EHM- Is it obsolete?
Got the GDE ECO tune last year & have been running the EHM for several years now. It's staying the way it is, don't plan on putting it back to stock.
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