[glend]

I have decided to go ahead and bypass or shutdown my EGR, as I feel that this has been causing my rather lumpy idle of late, which is very annoying at crawl speed.

It is well known that pre-2005 models can disable EGR with the blocking of the small vacuum line as covered in other posts here (or though CRDJON's small can approach). For years 2005 onward, the EGR is electroncially controlled via sensors, and the MAF plays a key role.

The easiest approach is to simply unplug the MAF on the top of the airbox, but this generates a CEL and code (usually a P0102).

The Liberty Owners in the US have developed the messy SEGR kit to splice into the wiring loom and spoof the EGR signals to keep it closed and to eliminate CELs and codes.

Green Diesel Engineering (GDE) has developed an ECU flash that minimises (or mostly eliminates) EGR activity (and of course they must tell you that this should not be used on the road in the USA - which their buyers generally ignore).

I have been involved in email discussions with GDE about software differences in USA and Export models. They have confirmed that Export software is different, and there are things that they will change in software flash eventually delivered to Australia or European markets. GDE ECU flash availability in Australia is probably at least six months off, if/when they find a local distributor to handle ECU swaps and burns.

So last night I went ahead and unplugged the MAF and did some testing. First time it was unplugged (prior to starting up) it did not generate a code or CEL, and I must admit I got excited about finding that out. Subsequent starts did generate a P0102 and a CEL. These are easily cleared with my scanner but annoying none the less. I am assuming that some sensor state was not cleared through the first unplugged start but was altered later. The MAF can supposedly be unplugged after the start up without generating a CEL or code (but that will get real old very quickly if you have to pop the bonnet each time you want to start the vehicle).

Performance wise my previous lumpy idle and shudder crawl has disappeared with EGR no longer opening (and idle is where it was heavily used). Getting moving off the line is much crisper and the engine seems to respond better at small throttle adjustments. Idle RPM has dropped slightly but it is very smooth now. I haven't done Cmohr's "headlight smoke test" yet but it is obvious in performance that it is not dumping hot gases and soot into my intake tract. I can still generate smoke out the back (through overfueling by standing on the go peddle).

I'll carry my scanner in the car from now on, but probably only clear it before trips (where you might want to know if a new CEL comes on, (and why)).

I'd appreciate SAKJ getting back to me on how he managed to disable the CEL and code on his late model CRD.

I've duct taped up the MAF plug and socket, but will reinstall it for Jeep service (especially because I am still under warranty).

Here is a question: If my EGR was causing my idle and crawl performance problems should I go ahead and plug it back in to try and get it to fail - so that I can get it replaced under warranty, or just leave it disabled? I have about six months of warranty left.

BTW shutdown is not noticably different, although I don't seem to hear the FCV closing now.

Anticipated benefits (in addition to driveability and performance ) are increase fuel economy and generally cooler running temperatures, elimination of further soot buildup in the intake body, cleaner Boost Control Sensor, cleaner oil, etc.

I'll come back to this thread when I get some reasonable fuel economy data.