Stumbling

[mitmaks]

So my mx-3 is at it again. It has been hesitant for a bit and on the way to work it was just bad. Pulled codes:
16, 17 and 24.
All of ignition components have been replaced, fuel filter ~30K miles ago, O2 sensors have been replaced as well.
Btw where is EGR valve at? I was trying to locate it but engine compartment is so crowded with crap, couldn't find it.

[MrMazda92]

EGR will be on the passenger side, behind/below the intake manifold.

[mitmaks]

checked fuel pressure it's good,
checked both injector rail resistance and it's good,
checked spark plugs and they're good
I'm out of ideas what to do next.
I did fill up with premium and some techron fuel injector cleaner, maybe that's causing it?

[MrMazda92]

That's a handful of codes alright.
Check the O2 sensors, maybe carefully clean your VAF, and if you haven't done it lately set your TPS just to be safe.

As far as hesitation goes, I'm assuming you mean under light-average throttle pressure? I'd look at TPS first.
Running premium fuel shouldn't cause any issues, aside from added cost. It's only really harmful to go lower on octane, not higher.

Oh yeah, check your plug wires while you're at it... I haven't experienced distributor issues at all in my time with MX-3s, but I know others mention this quite often with hesitation under throttle.

What RPMs, speeds, gears are you having issues in? That'll help narrow it down as well...

[mitmaks]

It happens at random times. During acceleration, or from take off, feels like car is cutting out.
I did change o2 sensors (Denso), new NGK wires, disty cap/rotor
TPS was set and I've cleaned throttle body and changed water thermosensor as well.
Unless my disty is going out?
Seems to be doing it while it's cold/wet out

[MrMazda92]

Ahh, my mistake, I didn't read the first post as thoroughly as I should have.
Try testing your VAF, there's a guide for it somewhere on here... If it's sending a bad signal, it could cause your A/F ratio to be screwy, and then your O2 sensor code would be explained.

Do you have an extra VAF to test?

[mitmaks]

Don't have extra VAF.
I did unplug battery last night and reset ECU. It was running fine today on the way to work and back home.

[mx3_ryder]

You may be getting moisture in your distributor? The seal could be bad, happened to me and had same symptoms. Try taking the cap off when it is wet outside or early in the morning before the sun comes out. I always noticed it in the mornings on my car, not so much in the afternoon or when it was really hot out. Also the points on the cap could be corroded as well and may need to be cleaned up.

[MrMazda92]

Well if it keeps up try swapping disty/VAFs. I could mail you a good JE50 to test if you end up needing it.

[mitmaks]

I've put some Heet into gas, perhaps there's some water in gas, never know.
Problem still persists. When I'm going uphill/under a load, check engine light will go on and if I reduce throttle it will go off.
I also put WD40 inside disty cap just in case there's moisture coming through.

[Daninski]

You mentioned EGR, you have to remove the battery shelf to get at it. Follow the 1" pipe coming off your exhaust manifold to find it. Some people go at it from under the car. Try Seafoaming your engine and if it runs better afterwards your EGR could be plugging up.

[crazycanadian]

You mentioned EGR, you have to remove the battery shelf to get at it. Follow the 1" pipe coming off your exhaust manifold to find it. Some people go at it from under the car. Try Seafoaming your engine and if it runs better afterwards your EGR could be plugging up.

Plugged EGR's don't cause missing/stumbling problems... Stuck open ones do though... As a test you'd plug the EGR valve port and see if the problem went away..

[Daninski]

I stand corrected,,,,like you said. Thanks. Even if you replaced parts some times the parts you install could be bad right from the get go or fail shortly after. Not much help I know.

[mitmaks]

Is there EGR block off plate that I can buy somewhere? Would it cause me to fail emissions if I deleted EGR?

[crazycanadian]

Is there EGR block off plate that I can buy somewhere? Would it cause me to fail emissions if I deleted EGR?

not sure... Yes it can cause you to fail emissions...

Its pretty hard and labor intensive to try and block off the egr valve... For now just pull the vacuum line off and plug it... Try that and see if your problem continues...