IAC valve question

[c4racer]

I am getting an idle problem and figure the first thing to do is remove and clean up both IACV and the EGR valve.

The service manual shows that the IAC valve is held on with a single bolt.

I have a 2003 Protege5 with the 2.0L motor.

Seems to me it is held on with 4 phillips screws?

It is the thingy on the top side of the throttle body, correct?

 

[slavrenz]

Yeah, the service manual only shows 1 bolt, but it is supposed to represent all 4 bolts. I would actually buy some of the torx bits that hold the little black solenoid on as well, so that you can thoroughly clean it. But first focus on the EGR valve.

 

[c4racer]

Yeah, the service manual only shows 1 bolt, but it is supposed to represent all 4 bolts. I would actually buy some of the torx bits that hold the little black solenoid on as well, so that you can thoroughly clean it. But first focus on the EGR valve.

OK - that's what I figured. Of course the EGR valve is harder to get to. Dammit - I should have done all this when the motor was out of the car. Kicking myself. I just dropped in a sub 40K mile Japanese take-out replacement because the 120K mile original motor blew a head gasket, and it seemed a better idea all around to swap the motor.

Of course all of the external stuff is from the original motor, and it was sitting around not getting used for about 10 weeks while the car was down.

When the motor first fired up it had some idle issues - then it cleared up for 50 miles or so, then started up again. Seems to idle at a lower RPM than it should which has me thinking IACV. The car just passed smog with nearly zero HC, but it was running perfectly then and now the idle quality is not as good. Also just threw a CEL which I don't think a dirty IACV will cause. I will read the codes today.

That EGR valve looks painful to get to.... (sad1)

 

[Boston5761]

OK - that's what I figured. Of course the EGR valve is harder to get to. Dammit - I should have done all this when the motor was out of the car. Kicking myself. I just dropped in a sub 40K mile Japanese take-out replacement because the 120K mile original motor blew a head gasket, and it seemed a better idea all around to swap the motor.

Of course all of the external stuff is from the original motor, and it was sitting around not getting used for about 10 weeks while the car was down.

When the motor first fired up it had some idle issues - then it cleared up for 50 miles or so, then started up again. Seems to idle at a lower RPM than it should which has me thinking IACV. The car just passed smog with nearly zero HC, but it was running perfectly then and now the idle quality is not as good. Also just threw a CEL which I don't think a dirty IACV will cause. I will read the codes today.

That EGR valve looks painful to get to.... (sad1)

EGR cleaning didn't help me, try the easiest things first.

 

[justanothermp5]

egr is freakin easy to get to, only hard part is gettin the pipe off

 

[Boston5761]

egr is freakin easy to get to, only hard part is gettin the pipe off

I say getting it back in place all without the gasket falling off is the hardest part

 

[c4racer]

hmm. Code was 0304 which is cylinder #4 misfire. Can that be caused by an erratic idle due to EGR or IACV? Or could I be barking up the wrong tree there? Plugs are new. Wires are new. Coils are originals - planning to replace them anyway.

Which cyl is #4? Furthest on the drivers side?

 

[Boston5761]

Def replace coil packs

 

[c4racer]

well - I got the EGR valve off. That is a bit of a PITA. Should be real fun to get back on with the gasket in place. I have it soaking in brake cleaner. Did not seem sticky or corroded or anything like that.

On the IACV why in the hell did Mazda use phillips screws to fasten this thing? Should be torx or hex. Phillips cannot hold enough torque to keep from stripping them. So the only way this is gonna come off would be to remove the TB and grind off the heads and then replace the bolts with something better. I cannot get a single one to budge and they are already starting to strip. So I ended up removing the solenoid part of the IACV and sprayed a bunh of brake cleaner into it. Maybe I shoulda used carb cleaner. Oops. Well - it should all evaporate before I start it so maybe doesn't matter. Hopefully that is sufficient to clean it.

Then again - these two could be just fine and the issue might just be the coil-pack.

 

[justanothermp5]

if that doesn't fix it then it could be a vac leak..im havin a problem with my car too
whenever i let off the gas and push in the clutch it stays at 1.5k rpm's for a while and then it goes to normal idle...
im not sure what it is but im thinkin a vac leak somewhere

 

[c4racer]

Got it all back together. That EGR is a serious PITA project. Ended up installing it from underneath the car, but even so those bolts are very hard to get to with that motor mount right below them.

Here is one tip - don't use brake cleaner into the intake... I normally use carb/choke cleaner but spaced it since I had the brake cleaner out. And even after a couple hours to evaporate the motor barely started, and then barely ran for 20-30 seconds until that cleared out. At first I thought I must have forgotten something important, but after a while it ran normally.

So that helped the idle get better. But it is not 100%. It still has an occasional drop like a miss. So combined with the 0304 misfire code that has me thinking it could be coil packs. But the IAC / EGR valves were contributing to poor idle because it is a lot better after cleaning them. Also it may take a few miles for the ECM to get everything working right again since it was reset. But even so it feels like something is still not quite right. I will replace coils and look for vacuum leaks. I installed a few new lines when the motor was replaced, but everything else looked OK. The RPM is not pulsing up and down like you would normally see with a vacuum leak so I don't think that is it. Although you never know - I've been fooled before so I never rule anything out.

 

[c4racer]

OK - I found a smoking gun, and I don't like the thought of what it could mean... Spark plug on the drivers side was hammered to half the normal gap. I re-gapped it and the miss at idle went away. Still doesn't idle totally smooth however, but the motor was cold and the ECM had just been reset so maybe there is hope. But not sure it matters because a hammered spark plug means what, the piston hit it? That can't be good. I may need to invoke the warrantee on this Japan take-out motor and get another one. Crap. I really don't want to do that motor swap again....

 

[LinuxRacr]

Any dates to how the idle is now?

 

[hornsfan10609]

It may just have the wrong plugs on it, some people have issues with long reach plugs hitting the piston. Is it an FS-DE or FS-ZE?

 

[Kazaba]

I've just aquired a 2001 323 SP20 Manual that has the same problem - when you push the clutch in, take your foot off the gas, the throttle hangs at around 1500 for about 5 seconds, then dramatically drops down to ~800. The impact if you are just trying to slow down with the cluch out, is that the car lurches to a slower pace as the throttle drop drags the speed down.
There is also quite a 'wheeze' when you turn the engine off.
Did you manage to track your idle problem to a vac leak? I haven't been able to spot one.
I'm considering taking off the EGR and cleaning it, my first attempt failed due to really awkward positioning of the bolts, so it might be a mechanic trip if that is the issue...
Any shared experiences would be greatly appreciated