EGR idle help

[Wilb]

Hi, I am new here.

I have been trying to solve Idle problems with my '02 Protege ES (2.0). First the car had an erratic idle 500rpm-1800rpm, then it would not idle at all...stalls as soon as my foot is not on accelerator. So...I put in new plugs, pcv valve...no change. I took out, and cleaned the egr valve, and cleaned the throttle plate, and all the problems disappeared---it ran beautifully (1200rpm on cold startup, 800rpm idle when warm, no fluctuation, no stalls...ran perfect.... For about 50-100kms...Then the bad idle returned. revs to about 4000rpm for a few seconds then starts bouncing between 1500 and 2000.

I thought I didnt clean the egr well enough so I took it out again, and took more time, cleaned it up good... now on startup it goes to 3000-4000rpm for about 10 seconds then drops and bounces between 1500 and 2000 rpm...constantly surging. Its driving me crazy...Is it possible that I didnt tighten the egr valve enough when I put it back on and now the gasket is messed up so i am not getting a good seal?? Thats all I can think of.... I really don't want to take out the egr again, but I think I must have been on the right track because it ran so good for a couple days... Any thoughts or suggestions would be greatly appreciated.

 

[Wilb]

Ok... a couple things to add:

I unplugged the EGR while it was surging at idle....nothing changed.
I unplugged the IAC while it was surging at idle....nothing changed.
I pinched off a line to the IAC and still nothing changed.
Does this tell anyone anything? Could cleaning the EGR loosen up carbon in the system and cause a problem somewhere else (such as the IAC)?

 

[Wilb]

Alright... I took out the egr again. It looks clean. Valve springs back easily.
Removed the IAC. It looks clean as well.

"If you have an idle (in park) that is high and cycles up and down, that could be a lack of coolant flowing thru the hoses to the throttlebody. I had that problem and when I removed the hoses there was no coolant in them. Put it all back together and made sure there was coolant in those hoses, and no more high idle."

I found this^^...If this was my problem, how would I solve it? Other than that I think it could be a vacuum leak?? There is no CEL so that should rule out O2 sensors--correct?
I know I am just kind of asking myself these questions....but if anyone has any comments at all....please give me some more/other ideas.

 

[Wilb]

I put the Egr, and Iac back in. Idle was still the same, so I took it for a drive and ran it hard (5000-6000rpm) for 5-10 mins...and...the idle went back to completely normal. runs great again. Not sure what that means or how long it will last but its good for now. Thanks for all your input!!

 

[_rgk]

If the coolant line was plugged, you would either replace the little coolant hoses going to the throttle body, or run a stiff wire brush through them. Avoid putting your lips on the hose.

I see you are in Canada. Have you ever replaced the EGR valve? If so, you should replace it with a "Canadian" part. No, it wasn't made in Canada - rather it's a special mod to the part that routes coolant through it to help it avoid rusting up. Mazda has replaced a TSB about this issue, and it's been covered on this board.

Take a look here for more info: http://www.mazdas247.com/forum/showthread.php?123732861-Canadian-EGR-valve-exposed

Seeing as how this problem started for you as the weather has gotten bitterly cold, it's entirely possible that the EGR valve is your sole problem.