Egr #2

Have blanked off the EGR Valve.
Its still in place and connected though.
First two drives the car was perfect - smooth and more responsive I thought to accelerator pedal.

But started the car today for work and the engine Check Light has come on.
No problems with engine - still smooth and performing normally.

I would have thought with the EGR still connected and from the ECU's point of view, still working. Why would the engine Check light have lit up? It never lit up when the EGR valve was misbehaving and causing a lumpy erratic idle, so why would it light now that its been bypassed and the engine is working beautifully?

Is it a partial or a complete blanking plate that you have fitted?
If the ECU detects a complete blockage it will throw up an error.

Quote:

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Originally Posted by Cecu

Is it a partial or a complete blanking plate that you have fitted?
If the ECU detects a complete blockage it will throw up an error.

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Yes - its a complete blank.
But check light doesn't always come on. Each time the car is driven, it may be on or it may be off. Whichever way it is when the car is started is the way it remains for the entire drive - ie: the check light never comes on partway through a drive, or if its decided to be on, it never extinguishes until next time the car is started.
Its on about 40% of the time and off about 60% of the time.

So you say if its fully blocked it will throw the error. Does that imply that if one of the two passages through the EGR was still open to either inlet manifold or exhaust manifold that it might stop throwing up the engine check light???
OR,
Does the behaviour described suggest the EGR is only checked by the ECU on startup and then decides if its faulty or not and doesn't keep checking it. If so, there may be some way to trick it electrically that its always okay when it does its check?

I was thinking the same regarding the check (it might only check at startup)
I believe the check is performed by pressure (i could be wrong though)

I had similar experience with a different car (Pajero turbo diesel)
with a full blanking plate, a lot of people reported engine check light on, in some cases the car even enters a "limp mode" with reduced power.

One of the workarounds is to have a partially blocked blanking plate, essentially it's the same plate but with a hole drilled in the middle (about 4mm in diameter). This tricks the computer into thinking everything is OK as there is still enough pressure during the engine check, and it also still allows most of the soot from the recirculated emissions to be blocked.

I then take the blanking plate out once a year to give it a clean.

hope this helps
Cecu

The proper thing to do is to have the ECU reflashed so it doesn't try to open the valve.