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sprinkles08, ASE Certified Technician
Category: Car
Satisfied Customers: 22519
Experience:  ASE Master and Advanced level certified. Factory trained with 15 years dealership experience
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Cadillac Eldorado: I removed the throttle bogy from the intake

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I removed the throttle bogy from the intake manifold on my '93 Eldorado with the 4.9L engine. When looking into the intake bores, there is a "tube" centered in each bore. the one in the rear bore is open and clear, while the tube in the front bore appears to be filled with what looks like carbon/oily gunk with only a very small hole down the center. Should this tube be clear/open or is it's ID restricted for a reason? I do not want to try cleaning the tube if it's supposed to be restricted. I sprayed throttle body/intake cleaner into the bores and wiped the sides of the bores clean.

Hello and welcome to JustAnswer!


I believe what you are seeing is the EGR passage. The EGR valve is mounted on the right side of the intake and allows exhaust to flow back through the intake tract to cool combustion temperatures, reducing NOx and slightly raising fuel mileage.


It's common for EGR passages to become restricted because of the carbon flowing back through them, plus the temperature of the exhaust coming in will cause blowby gases and oil in the intake to gel up a bit on and in the tube.


If you aren't having any performance issues and aren't setting an EGR code it probably isn't to the point of being an issue yet. If it does set a code or it's just something you want to clean up before it becomes a problem then you can clean the passages with some carb cleaner, in many cases the valve would have to be removed and something pushed through the tube along with the carb cleaner to get it all out.

Customer: replied 3 years ago.

The Service Engine light came on and my local service center checked the error code, which pointed to a bad EGR valve. I removed the throttle body to facilitate replacing the EGR valve. The rear tube appears clear but the front is clogged. I will try to clean the front tube as best I can. Thank you for your answer, it was very helpful.

If you're setting an EGR code then the restricted tube may very well have something to do with it. In that case I'd probably go ahead and clean up the tube.
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