If memory serves....

The MAF was only used for close-loop-control feedback to control the EGR. It had no impact on anything else. Unplugging the MAF would cause the EGR and EGR Air Flow Control Valve to park in their default position (EGR closed and EGR Air Flow Control Valve Open) - as if they weren't there.

I bought the wire harness kit to fix this but never used it. Instead I simply unplugged the MAF and plugged a Harbor Freight OBDII code reader into my port. The code reader would display the error code from the unplugged MAF 3 times and then clear the code automatically on the 4th read. The fault for this condition (MAF unplugged) only occurs once during engine start-up, so once the code was cleared automatically by the code reader you were good to go with your CEL. Any new faults during driving, if they occurred, would be displayed as normal (CEL would come on etc.). Of course, if you left the Harbor Freight code reader plugged in it would automatically clear any new faults automatically as described above. So if a real fault occurred and you wanted to keep the code from being cleard, you had to unplug the code reader before it cleared the fault. This was never a problem for me as I never had other faults (at least until right before I sold the CRD).

This code reader, by the way, was a small little device. It could be plugged directly into the port without a cable. It worked perfectly for this task.

All told - I replaced 3 EGR's and 2 EGR Air Flow Control Valves (all under warranty) before I started running the CRD with the MAF unplugged and the coder reader installed. After that, I never had another problem. I had just under 30k on the odometer before I started running it with the MAF unplugged. I believe the CRD had somewhere in the neighborhood of 80k+ when I sold it.

Thanks

So in summary the MAF was only ever there to operate the EGR.

Dont suppose you have a link for the code reader?

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2005 Jeep Liberty CRD (55 000 Miles)
GDE Eco Tune - Distributer for Southern Africa.
Running better then when she was new - Thanks to LOST

That's correct. AFAIK the MAF's sole purpose is for EGR operation. I know from experience that the CRD runs fine without the MAF plugged in. The only issue is dealing with the CEL.

I checked Harbor Freight and they don't seem to have it anymore. The brand name was "CReader". Here is a link with a picture: http://www.yotatech.com/f2/creader-obd-ii-diagnostics-code-reader-27751/. The cable detaches and you can plug the unit directly into your port. I actually just left mine plugged in all the time.

Unfortunately, it appears that model is no longer available and every other unit that I've seen comes with an attached cord.

You might want to check out Sam's CRD Noob Guide. He talks about this issue and possible solutions to include "The SEGR". The SEGR is the wiring harness mod I referred to above. I never actually implemented/installed the SEGR because I came across the CReader right before I was about to install it. The Creader was way cheaper and did nothing permanent to the vehicle.

Mass Air Flow is a new(er) way to measure oxygen in a fuel-injection system. On Gas models, the O2 is the limiting reagent (controlled by throttle flapper, usually). The MAF has a thin wire in the air stream that has very particular electrical characteristics. By taking an absolute sampling of the amount of O2 coming in the intake, the computer can (along with other sensor inputs) meter the exact amount of fuel needed for complete reaction for optimum burn, economy, power, etc. Really neat math when you look at it.

In a diesel (whose engine speed is constrained by the fuel, not the air), the MAF has no reason so report the O2 for combustion since it doesn't matter for the combustion (there's always a surplus of O2). The computer uses the amount of air to "cheat" the engine a little and do its little "EGR thing", just opening the EGR valve and slightly blocking the clean air intake with the servo-flapper just upstream of the intake manifold (the one that shatters itself and everyone has to either replace or disable).

The MAF does nothing for real engine performance, but since it's tied to emissions, throws the MIL when not reporting. GDE has (apparently) removed that logic with their tune and the SEGR just takes the computer input and pretends it's the EGR (complementary and non-interfering technologies).

Dan

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2005 Silver CRD Limited
245/75R16 GoodYear Duratracs
Fumoto drain | ProVent CCV Filter
Stanadyne FM100 filter | Cummins fuel pump
GDE Eco | SEGR | BoulderBars | FrankenLift | Frankenskids

I would add a word of caution of leaving a code scanner plugged in all the time. There have been plenty of reports of the transmission doing very stupid things randomly at highway speeds with code scanners plugged in.
I know there are a lot of folks out there concerned about cutting the wire harness and putting in the SEGR module. Very good concern too as if some stupid does it wrong, it will cause problems. (Absolutely NO crimp splicing allowed! Don’t even think about it. Solder and heat shrink ONLY!)
However, on the bright side, there are now way too many to count that have done the SEGR box successfully and are still working perfectly years after the fact. Only a very tiny few have had issues and from what I have seen could have been avoided.
If in doubt, ask someone here or find someone that can solder for you and do it right the first time. Before you start, look the information over here FIRST and be comfortable with what has to be done to install the SEGR box. My proto-type box is still working just fine in Phoenix under-the-hood heat years later and with well over 100K miles on it.

Agreed. We purchased our 2005 with about 29k miles on it. Spent $900 on EGR and airflow valve at 30k miles. Installed the SEGR and in-tank fuel pump at that time and now have 130k miles of flawless operation. I love this rig.

Starting to get a little torque steer now, so it looks like I'll be out a hundred to replace the lower control arms and their sorry bushings. No worries. ; ' )

Mark
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2005 Liberty CRD
2004.5 Cummins 5.9L TD, F1s, NV5600 6-speed in a '93 GMC Suburban

Thanks guys - Can we still get SEGRS kits? I live in RSA which is always a pain for delivery of these things...

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2005 Jeep Liberty CRD (55 000 Miles)
GDE Eco Tune - Distributer for Southern Africa.
Running better then when she was new - Thanks to LOST

If one is able to unplug the EGR at the valve itself will it dissable it without throwing a code?

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2006 Liberty CRD 275K, JBA 2.5 with Fox Shocks, GDE Turbo Kit, GDE TCM Tune, Suncoast TC, OEM fuel filter housing converted to fit Caterpillar Fuel Filter 1R-0749, OEM themostat housing modified to accept Hemi 203 F thermostat.

I don't think so... part of the SEGR was a healthy sized resistor to draw enough current to convince the ECM that the EGR was working. Lacking that or something like it, the ECM would likely sense this and throw a code.

Mark
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2005 Liberty CRD
2004.5 Cummins 5.9L TD, F1s, NV5600 6-speed in a '93 GMC Suburban

If the EGR feed line is removed and capped will this through any codes?

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2006 Liberty CRD 275K, JBA 2.5 with Fox Shocks, GDE Turbo Kit, GDE TCM Tune, Suncoast TC, OEM fuel filter housing converted to fit Caterpillar Fuel Filter 1R-0749, OEM themostat housing modified to accept Hemi 203 F thermostat.

With a factory computer, yes, plus a CEL. With the GDE load... dunno, but I've had my SEGR a lot longer than my GDE tune

Sarge, the whole purpose of the SEGR is to basically allow the EGR to be disconnected AND have the computer think it isn't. There's LOTS of details if you read the whole thread

Dan

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2005 Silver CRD Limited
245/75R16 GoodYear Duratracs
Fumoto drain | ProVent CCV Filter
Stanadyne FM100 filter | Cummins fuel pump
GDE Eco | SEGR | BoulderBars | FrankenLift | Frankenskids

I would also be concerned that when the AFR kicked in, restricting fresh air, the plugged EGR would then give the engine no good alternative and starve the engine?

The EGR doesn't operate alone, rather the combination of EGR and AFR working together accomplish the diversion of intake to include some percentage of exhaust in the incoming air stream.

Like the previous poster said, either SEGR or GDM tune addresses the whole system and gives you good operation with no codes.

The ORM gives you decent (but not perfect) operation, but with codes.

Mark

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2005 Liberty CRD
2004.5 Cummins 5.9L TD, F1s, NV5600 6-speed in a '93 GMC Suburban