I recently got 2003 mazdaspeed protege w/ a front mount intercooler and cold air intake and when I first turn on the car the idle is bad for the first 20 seconds then goes back to normal however this happen sometimes, but not constisantly. I thought it was a vaccum leak, but I'm not sure. If anyone has an idea of what it could be let me know. Thanks

P.S. The check engine is not on or at least yet

 

removed VTCS maybe? That's make it run like crap when it's expecting the flaps to open, but they're not there. That's my guess if it's only during startup.

 

I experience this exact bad idle for 20 seconds on my car (using the Mazdaspeed Protege ECU and basically the same turbo setup). I know it's exactly 20 seconds because the NGK wideband counts down from 20 as it warms up, and right after it hits 1 *bam* the idle improves. I figured it was an issue with high current draw of the wideband while it's heater circuit is on.. times 3 because I'm running three oxygen sensors.

And yes, I do have removed VTCS. When I ran the MP3 ecu pre-turbo, I still had VTCS in and it was fine. I removed VTCS about a month before I turboed the car (the solenoid is still plugged in so that I don't get a CEL), running with the Protege5 ecu, and it ran perfectly.

Because the issue appeared progressively, I'm going to guess that it is the EGR valve gunked up yet again (cleaning it with the harsh chemicals we all do significantly reduces the timespan between required cleanings). Does anyone know if the EGR valve is open for a set number of seconds after cold startup, because it seriously is precisely 20 seconds, every time.

 

To be honest, an EGR valve is NEVER suppose to open at idle, because then you would be runing rich causing a rough idle (you probably already know this). But one thing for sure that if those events are happening with the EGR valve the check engine light would turn on due to the fact that check engine light is usually emisson related.

 

^^ I see. I had a couple other theories, I guess it'll be trial and error to get it fixed. I'll definitely report back if I find any more info on it now that I know someone has the issue.

 

There a mazda dealership next to my house and when I get chance I'll see what they have to say.

 

could be the IAC too. I know I've never cleaned mine (as I don't have a security torx set) and I'm over 91k miles so that's probably gunked up.

I'm going to clean it and the EGR with a dremel (with rough brush attachment) on Friday