Idle Issues: Sudden "blip" drop in RPM and Stuttering

[sonick]

Just started happening this weekend, when I come to a stop, the idle usually is rock solid however for some reason it would randomly 'blip' and drop RPM suddenly for a moment but go back to normal. This would also cause the engine/car to shake, kind of like a 'cough'. I can feel it happening while accelerating as well, it would stutter slightly.

Any suggestion where to start?

• The idle doesn't seem as rough as a faulty EGR valve would cause.
• Plugs replaced very recently
• Air intake boot shows cracking on the outside, but a leak would again seem to cause a rougher idle than just a sudden random 'blip'
• Coils/wires could be due for replacement

Video:

 

[esnave09]

I would definitely check the coils first. They tend to fail randomly, although when mine did it was a continuous shaking and sputtering. Is your CEL on?

 

[Fresco]

• Air intake boot shows cracking on the outside, but a leak would again seem to cause a rougher idle than just a sudden random 'blip'

start here, when the engine warms up the rubber becomes soft and when you accelerate you literally pull the crack open ever so slightly.

 

[sonick]

Thanks for the replies.

And no, haven't gotten a CEL.

 

[zoom zoom sp20]

Coils/wires and you don't need a CEL for that to happen

 

[Inside]

Coils?

Sorry, dumb question -- my car has been doing a similar thing I think.

 

[sonick]

ok so it did end up throwing a code when I was poking around the engine bay earlier today.

Just cutting together a video of the idle issue now and sourcing an ODB2 reader.

 

[Jordysoso]

Coil packs. Should be the parts on top of the valve cover with two bolts in each, one wire going to cylinder 3 from one cool pack and one wire from cylinder 4 coil pack to cylinder 1. Just replace coil packs, spark plugs, and the two wires. When you replace them, use dielectric grease on the end of the boots of both the wires and coil packs.

 

[sonick]

Here is a video of the idle issue. It happens more frequently when hot and with AC on. It still happens on occasion with A/C off, but not as frequently:

 

[esnave09]

Coils/wires and you don't need a CEL for that to happen

Mine had a CEL for the coil pack. Cylinder 2 misfire.

But like Fresco said, check on that intake boot. That seems like it would be at least part of the problem, with surges of air going into the engine and messing with fuel mixtures and thus engine speeds.

 

[zoom zoom sp20]

Mine had a CEL for the coil pack. Cylinder 2 misfire.

But like Fresco said, check on that intake boot. That seems like it would be at least part of the problem, with surges of air going into the engine and messing with fuel mixtures and thus engine speeds.

My SP20 had bad coils and I did not get a CEL

 

[pcb]

I had a huge crack in my intake snorkel (tube) but had no noticeable driveability issues or MIL.
When I replaced my tube, my fuel trim jumped to 23 (it's not supposed to move by more than 10)

http://www.mazdas247.com/forum/showthread.php?123828382-Check-Your-Intake-Tube-!!!

Seafoam helps cure hiccups too.

http://www.seafoamsales.com/

 

[sonick]

Ah, couldn't borrow a code reader locally so just bit the bullet and ordered new intake hose, coils and wires.

 

[Ubel Knubel]

mine does the same thing. threw a code today, gonna check it out here in a bit.

 

[sonick]

Just an update, I installed air intake boot, new coils and new wires and it seems to have fixed it; not sure which. I am thinking either coils or wires, coz my intake boot was not that bad; there were small cracks on the outside but nothing through to the inside.

Low end drivability seems much smoother as well with less surging.

 

[zoom zoom sp20]

Great

 

[Jezis]

Anyone ever have this relate to a p0455 code?

 

[mp5build2013]

I have had that problem on the car since i got it. i have replaced EVERYTHING you mentioned .. and some. the problem eased up after a while and the rpms do not drop as much but they still do. when i am driving and the car shifts, it holds the rpms for about a second then it drops again. i cant get the problem to go away, as a metter of fact you can say i made it worse.. somewhere down the line i messed with something and my idle is now at 550 rmps instead of the 7-8 it should be at.
so if you got it to ease down a bit... id leave it like that lol

but if i was to take a guess at it...MAF

 

[Jezis]

My cat rattles when I start. Any possibility with that? I get that they can rattle when they get old, but if there is a leak, could it relate?

 

[kosteniuks17]

I would recommend changing your spark plugs. My car ran a lot better after new spark plugs, new packs, and wires. Of course later i did the egr valve too but my stock one was really clean so idk that was it. But after that it got it didnt drop rpm anymore like it used too at idle. Also maybe through some seafoam in it before you change the plugs.