Hi Folks,

When is the EGR open (ie-recirculating max exhaust gas) and when is it closed (ie- NOT recirculating any exhaust gas)? Mean under what condtitions?

Best

Dylan

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'04 Liberty(Cherokee) stock.

On the CRD, the computer has it set for the most EGR flow of any vehicle I have ever seen. Pretty much, about the only time that the thing is closed is when you are at almost full throttle. Accelerating away from a light (not racing, but not granny-driving either) closes the EGR, it is closed while accelerating up an on-ramp... Any steady-state cruise or light-demand condition, feel confident that the EGR has probably been commanded open. Yes, it is open just about all the time.

The nanny-system in the computer cross-checks the airflow of the EGR and EGR operation against the drop in flow over the MAF, in concert with the secondary air pressure sensor mounted in the airbox. The ultimate function of that second MAP sensor is unknown to me, but it needs to be there.

Unplugging the MAF sensor prevents the computer from knowing the incoming air volume and whether the EGR is working or not, so the computer uses a default number for fuel map calculations and leaves the EGR valve closed. In many cases, this default number actually increases the performance and the mileage, and the benefits of NOT having EGR are a reduction in soot-coking of the oil and removal of abrasive non-burnable filth from the intake and combustion chambers.

Why would you be concerned about when it is in use? The best answer is an SEGR device or a GDE tune to eliminate this filth feed from your engine.

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Proud supporting vendor of LOST Jeeps
TRAVELING CRD TECH. I come to you!
Need help? Just ask! I've taken it apart more than most.
Email jeep [at] maincomputer [dot] com - BOARD MESSAGING IS BROKEN
Over 225 CRDs currently driving with my valves, timing belt, rockers, or ARP Studs.
Bad noises = REALLY bad things.

It's an 04 in South Africa. I don't recall what year KJ billwill has but he is also in South Africa. I mention this only because IIRC earlier KJ CRDs have an EGR that operates differently than the 05 and 06, but I don't recall if that includes the 04. On those earlier models one can disable be EGR by unplugging a vacuum line; inserting a plug like a small bolt; and then plugging the vacuum line in. This is invisible and in contrast to unplugging the MAF does not throw a CEL on the dash. I don't recall the details but I know they are around here somewhere.

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Sold to LOST member my 05 Ltd, GDE Stg II turbo + TCM tune, SunCoast TC w. Transgo kit, Steiger window regulators, Samcos, Fumoto valve, 2nd gen filter head with Lub. Spec. bleeder, Hayden clutch & 11 blade fan, inverted spare, P-1 battery, BF Goodrich Long Trail TAs, Etecno1 glow plugs, timing belt at 50K miles/8 yrs

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OOPS! Good Catch, Papaindigo - I completely missed his location when typing my reply.

Yeah, do what he said. Much easier!

_________________
Proud supporting vendor of LOST Jeeps
TRAVELING CRD TECH. I come to you!
Need help? Just ask! I've taken it apart more than most.
Email jeep [at] maincomputer [dot] com - BOARD MESSAGING IS BROKEN
Over 225 CRDs currently driving with my valves, timing belt, rockers, or ARP Studs.
Bad noises = REALLY bad things.

Thanks guys. I was asking out of interest. There are no sensors on my inlet hose from the airbox. I have blocked the vacuum at the EGR solenoid. Lol I accidentally left the CCV hose off at the airbox and this made a lot of smoke in the engine bay. I might leave it like this but with the ehm. Is it normal for smoke to come out there. It wasn't just vapor. It looks like exhaust smoke.

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'04 Liberty(Cherokee) stock.