SEGR vs GDE tune and Weeks kit?

BR549 · **Joined:** Wed May 20, 2015 9:06 pm **Posts:** 4

I just bought UFO's crd which has a SEGR. Will there be any performance improvements if I add a GDE tune and weeks kit? Adding EHM today.

flash7210 · **Posted:** Mon Jun 01, 2015 12:59 pm

Dont be so quick to do the EHM.
Search the forum, there are some very good reasons for not doing it.
More important is getting rid of the EGR and if you are still concerned about oil in the intake, install a provent.
Even though you have the SEGR (I still have mine in) the GDE tune is still a good performance modification. Just let GDE know about your SEGR and SasquatchMotosports intake elbow kit.
Also, I highly recommend doing both Stage 1 and 2 EGR delete kits. (that is the intake elbow and exhaust manifold cap)

If you want to save some money, there are some DIY engine tunes available (see the CRD TECH section) that work with the intake elbow/EGR delete kits. They do not provide all the benefits of the GDE tune but they do add some more power. Of course, the DIY tunes are use-at-your-own-risk but there are lots of satisfied users.

At this point the SEGR is far beyond obsolete. The GDE and DIY tunes have pretty much eliminated any need for the SEGR. But keep it in there. Its not hurting anything. No need to mess with any wiring.

How many miles are on your CRD?

papaindigo · **Posted:** Mon Jun 01, 2015 1:31 pm

At the risk of getting flamed:
1. SEGR was an early approach to electrically trick the KJ computer system to deactivate the EGR without lighting up the CEL or throwing a code. As such it's an old but valid approach to eliminate soot in the intake which tends to clog the intake and is not good for the rocker bearings. As far as I know it provides no performance or mpg benefits.
2. GDE tune (EcoTune is fine start for a vehicle with the stock torque converter) minimized EGR function to eliminate soot in the intake PLUS provides substantial performance and mpg (in my experience ca. 10-20% better in town and on hwy) benefits.
3. EHM is IMHO not something you want to do. First off all it does is dump CCV oily vapor into the air and/or on the ground which is not good. Otherwise that oily vapor would, especially with a SEGR or GDE tune, pass relatively harmlessly thru the turbo, CAC hoses, intercooler, and intake into the combustion chambers. I will admit that oily vapor can cause a) airbox to turbo hose decay ($65 every so often but mines fine at 50k miles) and/or b) CAC hose failure (if you replace with Samcos that problem goes away). I've mentioned this before but routing CCA oily vapor to the intake dates back to the use of PCV valves beginning in 1961 so that's nothing new. Also FYI an EHM in cold climates is a know cause of rear main seal failure (end of hose freezes; crankcase pressure builds, main seal fails) which means drop transmission time.
4. Weeks101 kit - a great product (I have one but not yet installed) that removes the failure prone FCV and blocks EGR. For now you can live without this given that you have the SEGR the EGR is effectively blocked and a bad FCV can be fixed by removal of the 2 screws holding the butterfly plate in place.

If it was me I'd save my $ until I could replace the SEGR with a GDE EcoTune first and then save $ for the Weeks kit.

BR549 · **Joined:** Wed May 20, 2015 9:06 pm **Posts:** 4

Thanks for the much needed advise. This is long time LOST member UFO's 05 crd. I flew to Denver then drove it 750 miles at 75+mph home and averaged 26mph for the trip. Has 142k miles, things done are: TB/water pump job, alternator, power steering rack, Fuel head, air intake mod, and SEGR.

UFO · **Posted:** Mon Jun 01, 2015 2:01 pm

I didn't even know what the Weeks kit was until I just looked it up. One thing I would caution about that kit is the removal of the FCV. If that is gone, you could suffer a runaway with no way to shut down the engine. At least with a functioning FCV you have a chance to turn off the ignition and stop it.

pjigar · **Posted:** Mon Jun 01, 2015 8:33 pm

UFO wrote:

I didn't even know what the Weeks kit was until I just looked it up. One thing I would caution about that kit is the removal of the FCV. If that is gone, you could suffer a runaway with no way to shut down the engine. At least with a functioning FCV you have a chance to turn off the ignition and stop it.

There was some debate about this on the forum and based on my reading, FCV can NOT stop runaway diesel. I may be wrong but do your own research.

weeks101 · **Joined:** Mon Jul 30, 2012 3:29 pm **Posts:** 747

During development I reached out to Keith at Green Diesel Engineering (GDE) regarding the Flow Control Valve (FCV) to address customer concerns about overrun protection. This is what he had to say (posted with permission):

Quote:

There is no overrun protection with respect to the FCV in the software. The only overrun protection is zero fuel delivery above 4600 rpm…which does not help with a real overrun anyway in that oil is providing the combustion fuel in an overrun.

papaindigo · **Posted:** Tue Jun 02, 2015 7:48 am

Sigh - runaway/overrun has been beaten to death on the forum. As GDE and others have noted there is no runaway protection in the CRD design. Could it be added; sure just install an manually operated flapper in the intake.

Runaways are caused by an oversupply of burnable fuel usually from a source outside the normal fuel delivery system. A not uncommon source in the past around oil patch type sites was excess atmospheric hydrocarbons. It is possible for the CRD turbo to fail in such a manner as to dump oil into the CAC>intercooler>intake and cause a runaway although I suspect that would be the least of your problems. If the turbo fails in this manner it almost immediately pumps all the oil out of the engine and #1 and/or #2 piston rods will likely leave the block in short order. The one and only, to the best of my knowledge, brief CRD runaway mentioned on the forum IIRC was right after reinstallation of an intercooler that was full of oil but which had not been cleaned. As I recall the problem was relatively brief but scarey.

weeks101 · **Joined:** Mon Jul 30, 2012 3:29 pm **Posts:** 747

papaindigo wrote:

The one and only, to the best of my knowledge, brief CRD runaway mentioned on the forum IIRC was right after reinstallation of an intercooler that was full of oil but which had not been cleaned.

This is the only one I know of as well, and it had an unmodified FCV in place.

BR549 · **Joined:** Wed May 20, 2015 9:06 pm **Posts:** 4

So I guess my final question is when I do get the GDE should I leave the SEGR in place or does it matter?

flash7210 · **Posted:** Tue Jun 02, 2015 10:46 am

BR549 wrote:

So I guess my final question is when I do get the GDE should I leave the SEGR in place or does it matter?

I say leave it in. Its not hurting anything.
If you completely remove it, you will have to undo all its wiring.

papaindigo · **Posted:** Tue Jun 02, 2015 10:54 am

flash7210 is correct leaving it in does not harm but then I don't like leaving useless stuff installed so I'd remove it. That said you may want to ask the forum or see what you can dig up on the SEGR (maybe geordi remembers) but I have a vague memory of a plug that was part of the kit or some such that allowed easy reversal for inspections.

geordi · **Posted:** Tue Jun 02, 2015 11:03 am

The runaway question is a moot point for exactly the reasons Papaindigo stated. The computer cannot detect runaway conditions because it is outside the scope of the programming. The turbo failures that people have had - have usually resulted in the oil passing into the exhaust and not the intake anyway, but the engine will *quickly* grenade and stop without oil within it. There is a "bypass" plug that returns the wiring to stock, but I'd just leave it alone and pretend it isn't there. - more on that later.

Unless you are operating your diesel in a fuel-enriched air environment (and you'd know if you were) then you have very little to worry about with this particular situation. The FCV exists SOLELY as a means of forcing even more EGR flow into the engine, controlled by the nanny system in the computer. If the computer doesn't think the drop in airflow across the MAF is sufficient, then it commands the FCV to close at least partially, and choke the fresh air and increase the suction from the EGR behind that flap. If the drop in MAF flow STILL isn't sufficient to satisfy the computer, then it throws the "insufficient flow" EGR code. Basically: "Waaaaaaaahhhhh, I can't fill the engine with my own already-burned super-abrasive garbage! The spotted tree hippo of Northern Elbonia will suffer because the engine is producing CARBON, and I'm not programmed to know that carbon is the basis for all living things!"

Yeah. The elbow kit is a fabulous upgrade that solves this problem completely, and I think you will find a significant increase in mileage as it does seem that UFO's EGR valve is not fully sealed closed. This is not unusual - I do not believe they maintain a solid closure against the boost pressure, and that allows leakage and reduced economy. How much boost leaks varies from vehicle to vehicle, but ALL of the ones that I have installed so far, the owners have commented that they can definitely feel the increase in performance immediately. Perhaps it is a bit of butt-dyno effect, but mileage numbers don't lie. If by some chance you did have the EGR idiot light, the Yeti or GDE tunes can eliminate that code from the computer's memory entirely, and there are other major benefits. GDE is very finely engineered and offers performance benefits, while the Yeti tune is nearly free. It is a trade-off.

UFO · **Posted:** Tue Jun 02, 2015 1:41 pm

flash7210 wrote:

BR549 wrote:

So I guess my final question is when I do get the GDE should I leave the SEGR in place or does it matter?

I say leave it in. Its not hurting anything.
If you completely remove it, you will have to undo all its wiring.

No you don't, just install the bypass plug. These were supplied with all SEGR kits for just this reason.

UFO · **Posted:** Tue Jun 02, 2015 1:53 pm

I apologize if the subject of run-away has been beaten down; I do not remember taking part in that discussion. However, there are several points in this thread I want to address. First of all, I did not claim the ECU could detect runaway and shut it down. What I said was the ignition could be switched off to stop it - it might already be too late, but because the FCV is controlled by the ignition switch, it can cut off the air necessary to sustain runaway. I admit I don't know if it really does, but the SEGR will allow the FCV to operate normally when the Jeep is shifted to N or P. And the FCV is used to shut the engine down smoothly. If it is properly controlled, it can stop a runaway.

thermorex · **Posted:** Tue Jun 02, 2015 5:34 pm

The problem is that the FCV doesn't close for more than couple seconds. Not enough to stop the runaway.

Now, if one modifies to cut air on a cable, like chokes, eliminating the plastic weak engagement teeth (gears), that would be definitely a good runaway prevention.

WWDiesel · **Posted:** Tue Jun 02, 2015 6:41 pm

Look into the DIY tunes, they are super and save yourself a chunk of money to spend on other things. There are lot of very satisfied CRD owners running them currently and have nothing but praise for the results. :wink:

SEGR vs GDE tune and Weeks kit?

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