I have had my EGR blocked off. It is still plugged in. However I get a "P0400 Exhaust Gas Recirculation Flow" fault code. Now this is on a 99 XJR. From what I gathered, I shouldn't get a fault code on this model year if it's blocked off but still plugged in.

I'm pretty sure I don't have a MAP/vacuum sensor as in later years. I only have two vacuum lines, one to the bypass valve and the other to the evap. There is no third hose and no map sensor. The connector (4 wires) where the map sensor would be on the firewall is capped off from the factory.

How does the ecu know that the EGR is not functioning? Is there a way to trick the ecu into thinking the EGR is working? Can the fault codes be disabled on the AJ26 ecu?

I no longer have the coolant lines connected to the EGR (nor to the throttle body). Could this be causing the fault code?

 

I checked the wiring diagrams.

Why is it that the NAS spec AJ26S has an EGR valve shown in the wiring diagrams, but the ROW spec does not?





Anybody?

 

The ROW diagram has the notation "not used" at the same spot,
so likely ROW spec vehicles do not have EGR, or were not expected
to have EGR.

The ECU may infer that there is a problem with EGR flow by monitoring
mixture expecting that mixture will go lean/rich at least momentarily
shortly after operating the EGR valve via the stepper motor.

edit:

Maybe it's possible to reflash the ECU with a ROW image?

But be aware that the EVAP is also NAS specific.

 

That's because the rest of the world knows that putting the exhaust back through the induction system is a really bad idea!


Apparently so does much of the US, judging by the amount of " how to delete EGR valve" videos on Utube.

 

Am puzzled as well, as the p0400 code is based on the intake vacuum measurements, and as you do not have the map sensor, it just doesn't make any sense. I know that the 2000my US cars do have a MAP sensor (ROW does not, only from 2001). Just out of interest, does you odbii reader give a reading for the map sensor?

 

Disabling EGR requires not only a plugging a valve. It also requires a complete reflash (and that's not a DTC related issue).
EGR is used not only for NOx reduction, but it also helps to low down a temp. in a combustion chamer. So, if an EGR is plugged there's a risk of detonation under cruising conditions in a high temps.

 

There's no map sensor showing. I'm using the Autoenginuity.


So the cars without EGR from the factory are more at risk for detonation? It seems odd Jaguar would build cars with and without EGR for the same model. Under cruising conditions there isn't much boost and the compression is lower on supercharged cars so I don't see why there would by high temps.

The question still remains how the ecu is seeing a blocked EGR when there's no MAP sensor.

 

Cars w/o EGR uses different fuel/spark tables.
High temps may be caused by high ambient temp and a heat soak.
It monitors a EGR functionality by monitoring MAF and HO2S sensors.

 

I don't mean to hijack the thread, but succinctly why would you want to "delete" EGR from an X308 (or in my case X300)?

Is there evidence of increased performance or fuel efficiency?

.

 

Have your tried cleaning the valve/connector or swapping for a known Egr valve? Make sure the valve worked 100% before blocking off. Otherwise Moscowleaper is most likely correct.

Al_roethlisberger,
EGR is typically only active during part load or cruse conditions and de-activates during full load/full throttle conditions. Not only does it offer lower combustion temps and emissions as Moscowleaper mentioned but helps increases part load fuel economy (i have read 0-3 mpg in some cases) by allowing more timing advance. Too much EGR will impede flame propagation in the cylinder. In the V8 SC cars our cams have zero overlap (-5 degrees to be exact) so under all conditions our cars experience internal EGR from exhaust back pressure. There is alot more too how EGR works but that's another thread or google search!

Removing the valve would not lead to better performance or efficiency just a cleaner top end. if making a custom tune it could simplify things alot.

 

My 02 kept throwing the P0400 code, and the fix was to unblock the EGR valve. That is all.

 

Keeping the EGR is not really an option due to my mods.


It is clean, but that wouldn't be an issue since the lower housing is removed and not attached to the intake elbow. I just have the valve itself plugged in.

It worked fine before I blocked it off. I did take it apart at first so perhaps it got damaged.