Carbon in EGR passage

[Ken Cunningham]

I removed my doghouse to install the power plate and saw a big 'stalagmite' of carbon coming out of the egr passage. It looked like a big black olive!! I broke it off and then cleaned out the passage as best I could under the circumstances. Now I regret that I only drilled a 3/8" hole in the plate (as per the instructions) rather than filing out the plate to the hole size in the gasket. Am I in for more problems down the line? BTW, I just passed Calif. coastal smog with flying colors, so I assume that I still have full egr function.

 

[Jimn8or]

If you passed Cal emisions, I'd assume that the EGR was at least partialy functioning as well. If you pull the doghouse off again, I used a sharp small regular screwdriver to break off all that crud, all the while playing 'surgeon' with suction provided by my vacuum with a 3/8" fuel line duct-taped to the crevice tool to grab all the little pieces as they broke off. Several times I had to pull the hose out of the egr passage and shake the lodged deposits out of the hose...then go back in for more. Not fun, not worth a tenth, not seen, but not the way it was meant to be either, so I did it.
Jim

 

[dpok69]

I just installed a power plate today. But i did not take the dog house off completely, and slid the power plate in. I did not check to see if there was carbon build up. On the other hand, i installed the power plate without drilling the hole for the EGR. Does the crud thats in there have an effect on me still?

 

[Ken Cunningham]

Jimn8or: The vacuum sounds like a good idea...I just brushed out the gunk towards the front and let it fall. Some pieces inevitably did get into the intake, but nothing large. My thought was that I was seeing the end of the egr trail, and if the end looked that bad, what must the rest of the passage from the egr valve look like? I could dig down with a probe, but I could never dig all the way to the valve, could I?

dpok69: I know what you mean by sliding the plate in. I left the coolant lines and the throttle linkage attached, too. But I had enough access to pull the doghouse up and to one side to get a fairly good look. I could never have just slid my plate into position, though. The egr carbon would have prevented the plate from settling into position. If you did not drill out your plate, then you do not need to be concerned about any carbon build up. But then you do not have a passage for exhaust gasses to enter the intake stream anymore either. I could never pass my bi-annual smog test without egr function.

 

[gofstbuick]

In Oceanside, there isn't a EGR functional test. The test procedure relies on the measurement of NOx emissions to determine if the EGR is functioning properly. So the EGR passages may still be plugged. Try this, manually lift the EGR valve with your finger with the engine at idle. Does the engine stumble? If so, then your EGR passages are clear.

 

[dpok69]

Thank god i only have emissions once a year. When it comes for emmissions time, i will just slide the power plate out, and then go.

Do we lose HP when we use the EGR?

 

[gofstbuick]

Technically, no, you won't lose HP when the EGR is functioning properly. Here are some reasons for "no": the EGR only functions during light cruise in 3rd and 4th gear and does not operate during full throttle or in open loop. Additionally, the effects of recirculating some spent exhaust gasses through the combustion process will reduce peak combustion temps, NOx and some detonation. Here is a reasons for "yes": if the engine is equipped with an aftermarket EGR (which flows are not calibrated like the factory unit) and the flow is excessive, it could put out too much combustion (remember, the spent exhaust gas does not fire) or the flow is less than factory and the engine detonates more that normal and thus the computer pulls the timing back (cuz the engine is knocking)