Bad misfire!! Need help!!!

ICEE

Member
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03 Protege5 / 90 Miata
Hey everyone.

so my 2003 P5 has a pretty bad misfire i know i was throwing the p0300 code along with many others. i finally got around to replacing the upstream O2 sensor but i feel like i took too long. the car was drive-able for a while but it sputters badly at idle it sputters really bad when i put my foot down on the gas. after i replaced the upstream it started smoking from the pre-cat area which i thought was weird. although the car now sputters less, it still does it at idle from time to time and almost everytime i put my foot down on the gas.

im thinking of changing the Coil packs, the down stream, and if it doesnt get better, the MAF then the pre cat it self. if none if this fixes it im honestly done with the car be cause ive dumped a lot of money into it already with just repairs. do you guys have any tips on what i should change/ look at? or any order i should change these parts in ? because , for example, i dont want to change all these parts just to find out that the pre cat was the problem and i could have changed that to start with.

Also does anyone have experience with or know about the quality of the Evan Fischer Front Catalytic Converter because it seems pretty cheap and usually cats are more expensive than that. i just dont want to pass up a product that will work beaus its cheap. if i could save money on this it would be great.

http://www.carparts.com/details/Maz...gclid=CJO2nZjqt9ACFYJahgodCDcD8w&gclsrc=aw.ds

any help would be greatly appreciated! thanks in advance!
 
Changing the catalytic converter will do nothing for your misfire, rough running condition. When is the last time the plugs were done, are they the right plugs? What are all of the codes you have? How many kms do you have on the car?

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thanks for the reply and ok i wont look into the cat then. i changed the plugs about 6 months ago. i believe they are the right plugs. they are NKGs and i also have NKG plug wires.

the codes as of now are:

P0300 Multipul misfire detected
P0037 HO2S-12 (bank 1 Sensor 2) Heater Circuit Low input (Im guessing this is the 2nd o2 sensor after the pre cat)
P2009 Variable tumble control solenoid valve circuit input low ( no idea what this is)
P0090 PRC solenoid Valve circuit malfunction
P0660 Variable inertia charging system circuit malfunction

the car has 175000 miles on it now
 
02 sensors will seldom cause a misfire, especially one that occurs when the engine is cold.

Replace the coils, plug wires, and plugs (tune up). Use standard NGK V-power plugs.

If the misfire persists, look into the EGR and vacuum leaks.

You can also unplug the fuel injectors one at a time and see if the misfire is limited to one or two cylinders.
 
P2009, P0090, P0660 these are all the solenoids that mount on your intake manifold.

P2009, VTCS (variable tumble control system)
Opens and closes flaps in the intake for swirling the intake air for cold start emissions.
This will require replacement of the VTCS solenoid.

P0090 PRC (Fuel pressure regulator control)
Sends intake vacuum to the fuel pressure regulator to adjust or steady fuel pressure to the injectors.
This will require replacement of the FPRC solenoid.

P0660 VICS (variable inertial charge system) opens and closes the flap for high RPM air flow through the short large diameter runners in the intake manifold opens at 4600RPM.
This will require replacement of the VICS solenoid.



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035a094cec1d1b6b7793a81925d007d5.jpg


Check the wiring to these solenoids the ones circled here are the VICS and VTCS I believe the VTCS is on the left and VICS is on the right.

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The FPR solenoid is also in this picture to the right side partially underneath the two black hoses with a blue vacuum line attached to it.

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hey everyone!
I really appreciate all the replies and the info. sorry ive been a bit busy and i haven't had a chance to reply.

just an update, the car drive better now the sputtering is much elss and it doesnt bog out when i put my foot down on the accelerator anymore. i think the ECU needed a little time to adjust to an O2 sensor that actually worked (hand). ive been looking for a replacment for my VTCS VICS and PRC but when looking i can only seem to find a "Protege5 Vacuum Switching Valve"

Link: http://www.partsgeek.com/ss/?ssq=solenoid&make=mazda&year=2003&model=Protege5

this seems to be the prc solenoid. am i correct on that?

Also does anyone know a website or store i should check that might have a VTCS and VICS replacement?

Thanks again!
 
The vacuum switching valve you found is exactly what you need. The FPR solenoid, VICS solenoid, and VTCS solenoid are all the same part, just make sure that you connect the vacuum lines up how they came off.

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If you look at the picture the oval piece under where the electrical plug connects is a miniature air filter, it should be removable and might go into a different nipple of the solenoid if the vacuum lines are configured differently.

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WOW! ok i feel dumb now that i look at it i see what you mean. that really helps! i just have to save the money to get them cause they are like pretty expensive if you buy all three. im going to see if i can test them. maybe i don't have to buy all three
 
Check resistance across the two terminals with a ohmmeter if you have one, if they are too expensive replace just the FPR solenoid, as it is likely causing your concerns. VTCS is for warm-up emissions, and VICS is for high RPM air flow (switches the manifold to larger runners at 4600RPM. Neither of which are needed for the engine to run. Control of the fuel pressure however is likely causing your concerns.

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thanks. i will definitely try to test it if i cant get my hands on an ohmmeter ill just replace that one first. also, when i got the CEL read by autozone, it said that my egr is probably the cause of the issue. do you think i should change this as well of just go with the solenoids first and see what happens.
 
cool beans. ill do thank and post an update as soon as its done. i really appreciate the help!
 
so i finally got around to getting the parts and putting them in the car.
i replace

the prc solenoid
the pvc valve and gromet
spark plugs
spark plug wires
ignition coils
downstream o2
and valve cover gasket (just cause)

i reset the codes and drove the car for 40 miles and the cel didnt come back on. the car still was ideling funny tho as if the missfire was still occuring (it definitely felt like it)
after a while the rough idle started smoothing itself out a bit but it still wasnt the way it was before. when i slowed to a complete stop it would still rumble

after driving it some more i stopped to get gas, once i got back in and started to drive away i noticed it ..... the dam CEL was back.
at this point im not sure what else to do besides the EGR and MAF but those are pricy.

anyone have any ideas what i should do next?
 
A lot of people have had a lot of problems with their EGR valves.
Most people just take them apart and clean them. It's become an annual event for many.
The valve gets fouled up and sticks.
There is a "Canadian" version available which has coolant lines attached to it and those who have installed it haven't had problems with it again.
 
There is a lot of causes for a random misfire so its kind of a crap shoot..... But the EGR is a common culprit.

 
You should have started with cleaning the EGR; spray some MAF cleaner on the MAF for good measure. And check your intake tube for tears if you have the stock intake.
 
Thanks everyone.
It's funny, because the print out they gave me for my CEL at advanced auto parts said that the likely issue is my egr. Considering the one they sell is 100 bucks I thought they were kind of trying to sell me something ( stupid me ) and also I forgot to mention that about 7-8 months back I actually cleaned my egr valve and maf. Considering the time frame, it might be time to clean it again. If the problem continues after cleaning, would it be wise to just replace it or should I test other things like my maf first. I know my friends mazda 3 had maf issues so maybe I should look at trying to clean that again as well?


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