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Jim Grant's Tech Tips
‘93 Oldsmobile Bravada,
Vascular Organ or Emission Problems
Q: I bought a ‘93 Oldsmobile Bravada last January and it sat in the
garage until I sold another car in April. Then in two weeks after driving around,
the engine light came on and the brake acted funny. The mechanic cleaned the
valve and then a month later it came on again, so another garage checked it
on a computer and said that the EKG valve had carbon on it. He told me to wait
until it happens again, then he’d fix it. I wonder if it’s safe to drive it
around? What do you think caused it?
A: The problem you
are having with your Exhaust Gas Recirculation (EGR) valve is a common complaint
with vehicles of your type. As for your EKG? It would clearly show signs of
coronary stress (accelerated heart rate) when the brake pedal in your vehicle
turns hard as a rock and doesn’t want to stop the vehicle because the EGR valve
is sticking. The EGR valve introduces (feeds) exhaust gases back to the engine
to reduce a smog forming exhaust emission. The problem is carbon deposits form
(from the exhaust gases that collect in the passage to the EGR valve. The carbon
deposits can break loose and get caught, holding the EGR valve open. The result
is a poor idle with possible stalling and a brake pedal that doesn’t seem to
stop the vehicle like it should. The power brakes on your vehicle use vacuum
created by the engine for power assist. A rough running engine doesn’t make
much vacuum, so there’s not much power assist. GM was making offerings to aid
in correcting this problem, but due to the vehicle’s age the comfort offered
is no longer there. Have your tech check to be sure that your computer has the
latest software upgrade. Believe it or not the program was modified in a manner
that allows for greater movement of the EGR valve which reduces the possibility
of carbon deposits getting caught in the valve. Lastly, cleaning the EGR valve
is the way to go. A replacement is over $200 and can still be affected by carbon
deposits.
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