Rough idle after spark plug change

JJL0325

Member
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2002 Mazda Protege5
Hey guys, new member and new owner of a well used 2002 Protege5, manual tranny. My car was running fine but I thought it seemed to have a very VERY slight stumble from 4500rpm-redline so I went ahead and changed the plugs with the exact same ones that were already in it, Denso PK20TT. It started right up, almost zero hesitation, almost like it was a brand new car. I then made a short 7 mile trip, then came back home. Next time I started it it had a bouncy idle, almost stalls out. I am only noticing a problem at idle. ANy ideas? Thanks
 
yeah, EGR valves in proteges are notorious for this. So two things to check...the EGR valve/solenoid...and the gap of the new spark plugs (improper gapping is often only noticeable at idle)...

the EGR valve is located underneath the throttle body, looks like a 3-4 inch metal tube like thing...with a lead from the engine harness going in, as well as a connection from a tube running form the exhaust manifold...if you are having trouble finding it, locate the tube on the driver side of the exhaust manifold, sort of pointing towards the air intake (you'll have to remove the plastic intake piece leading to the filter to see this) that makes a bend and travels over the gear box back towards the fire wall. You'll also have to remove the rest of the intake tubing to get to the valve itself.

They get stuck open, causing idling problems, occasional missing, and poor gas mileage, once the engine is heated up. There are how-to's on here in order to clean it yourself...or can be replaced for around $80 iirc.
 
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