Help with Misfire problems/ p0421

[ChaoSki]

So last year, car would studder a bit at times while sitting on the light or upon acceleration. Worst thing is that it's random. Happened once every month or so.

Fast forward to this year, cold temps kicked in and now it's escalating.

Few months back car would get a check engine light blinking and had no power. Upon pulling over/scan the codes, I got the following:
P0421 warm up catalyst below threshold bank 1
P0300 random/multiple cylinder misfire detected
P0660 intake manifold tunning control ckt open bank 1

Clear the codes, car is fine.

week or 2 go by, same thing. I used to be able to shut off the car, restart it and CEL would just be on (not blinking). That has now ended as of this week. I need to clear the code in order to stop the blinking.

Clearly, it's getting bad....and I know....I've been negligent.

So I've been doing some reserach and the whole P0421 code sounds SCARY.

I just checked to make sure the spark plugs are not lose. I did notice that Cylinder 3 bottom of the coil boot was broke, but it still clips in just fine (the rubber thing on the bottom of it was broke).

Worst thing about all this is right now car is fine. No cel, runs great......

I was thinking about with either startign off by unscrewing the bottom O2 Sensor and plugging it (letting it hang) or get one of these?Auto Dynasty - Universal O2 Sensor Spacer Adapter Isolator Extender
https://www.amazon.com/dp/ (commissions earned)

 

[MrGiggles]

P0421 is nothing to worry about.. It just means your pre-cat is not working, you can fool the 02 with the non-fouler mod, but the part you linked will most likely work fine as well.

Start with ignition components. Go with NGK standard plugs and replace both coils.

 

[ChaoSki]

P0421 is nothing to worry about.. It just means your pre-cat is not working, you can fool the 02 with the non-fouler mod, but the part you linked will most likely work fine as well.

Start with ignition components. Go with NGK standard plugs and replace both coils.

Thanks for reply. I think I will just get the part in the link (no drilling etc).

Since P0660 was the first code to appear before P0421 arrived. I did little research and found below.

http://www.mazdas247.com/forum/show...es-that-mean&p=6045163&viewfull=1#post6045163

I just put a mutimeter to VICS Valve and I'm not getting any reading at all.

I started the car, revved it and watched the intake actuator control arm and it didn't move at all?

Should I order VICS valve? Is this a common issue?

 

[Jackie chan]

Vics only opens at high rpm. Are all vacuum lines connected and free of holes. I last threw a p0660 when the vac line slipped off the bottom of the actuator. You might also want to try swapping vics and vtcs solenoids before you go buying one. Worst case scenario, you lose vtcs function. Which in my opinion is a good thing.

 

[ChaoSki]

Hmm good idea, I will do that.

Based on the troubleshooting guilds I've seen on VICS, it should engage the actuator for 5 seconds upon start up. Mine doesn't move. No continuity either.

 

[hornsfan10609]

Thanks for reply. I think I will just get the part in the link (no drilling etc).

Since P0660 was the first code to appear before P0421 arrived. I did little research and found below.

http://www.mazdas247.com/forum/show...es-that-mean&p=6045163&viewfull=1#post6045163

I just put a mutimeter to VICS Valve and I'm not getting any reading at all.

I started the car, revved it and watched the intake actuator control arm and it didn't move at all?

Should I order VICS valve? Is this a common issue?

You just need the solenoid on the intake, it is very common for them to fail over time.

 

[ChaoSki]

You just need the solenoid on the intake, it is very common for them to fail over time.

They do look different color but same shape size. I will swap them.

Ordered new plugs and wires. And the o2 extender thingy.

Hope it solves it, will keep you guys posted.

 

[smetzger]

The P0300 is most likely a coil pack.

 

[cartracer12]

It could either be VTCS or VICS depending on the code, they are both intake manifold tuning valves. VICS will likely not throw a check engine light as it is not an emissions component. On a cold day look under the hood and have someone start the car VTCS should activate causing the actuator where the intake manifold meets the cylinder head to move. If it does the VTCS is working. Have somone rev the car up (over 4600rpm) the VICS should move the actuator closer to the firewall.

Sent from my XT1032 using Tapatalk

 

[cartracer12]

If either fails to move I would recommend replacing both solenoids from their tray on the top of the intake manifold as if one fails the other is likely to follow suite soon after.

Sent from my XT1032 using Tapatalk

 

[The_big_dill]

P0660 is the vics solenoid, have seen it happened on every protege my friends have owned. Its the one with the white connector. This code doesn't trigger the light as it is not emissions related. If you want to have a quick check, swap the white and green connectors, if its indeed the solenoid, then you will get another code.

P0300 is either your coil packs or EGR. If coils don't fix it, replace the EGR.

 

[Fastandloud]

I finally passed my smog yesterday after a long time trying to figure out how to fix this p0421 code. I did the non fouler method. I watched the video on YouTube but what the video failed to mention was that you use both of the non foulers not just one. Bore the one closet to sensor I believe to half a inch so the sensor can still sniff then put the other one unaltered to the end that attaches to cat. Then reset computer and drive it a while about 150 miles. I was so happy when this worked. Took me a month and half to pass my smog due to my alternator going out and trying other methods to clean the catalytic convertor with cataclean and a another cleaner that did not work for me. Good luck I hope you get that fixed up!