The story of multiple codes on my Mazda today

Status
Not open for further replies.
Joined
Feb 15, 2016
Messages
4,757
Location
GA
The good thing is I fixed it as of right now; I’ll check on it again tomorrow...

So out of nowhere today, while I went to a shopping center about 20 miles away of my place of living, the car started to act strangely; sudden vibration of engine; at first I thought about someone messed my car while I was away but nothing unusual I noticed; meanwhile the sky opened, rain; I moved inside the car and I’ve noticed the engine light was on; I have the OBD scanner but it was at my home 20 miles away; the car was experiencing vibration and was shaking significantly and while it runs right at low speeds, once you reach up to speed it sounds much better; on my way home via interstate I've noticed inconsistency of the check light, while flashing one time, others time is solid; on my way back I stopped to the Advance and they scanned it for the codes; there were three codes P0304, P0171, P2274 so that 4th cylinder was misfiring; from that point I was suggested to step by step elimination process; and that’s what I did;

I swap the coils between the spark plug and no improvement; I want back to the Advance while they were still open, this was at 7:30pm and I got me Denso spark plugs; I replaced them; then there was a change, the car went back to normal; however I found of traces

So tomorrow I’ll watch for the check engine light, and I hope I’ll go back to work in my Mazda; I need my Mazda not gave up on me also if anyone knows more about spark plugs I wanted to see your opinion and what do you say the condition my engine in Mazda
 
I hope you can see it, this was a last minute change on Sunday!
 
I think i noticed an oil spot or two, like spread at the the cylinder head only on 4th while others were clean; I’ve noticed also there was oil on 2nd and 4th spark plug on the outside indicating leak of the valve cover ring

And yes spark plugs have about 60k miles if not more
 
Last edited:
Originally Posted By: Chris142
Look for a vacuum leak


This... and then check fuel pressure if you know for certain there is no vacuum or crankcase/pcv leak.

Lean mixture code diagnosis will lead to the cause of the problem. The misfire is the effect.
 
Originally Posted By: Seventh
Originally Posted By: Chris142
Look for a vacuum leak


This... and then check fuel pressure if you know for certain there is no vacuum or crankcase/pcv leak.

Lean mixture code diagnosis will lead to the cause of the problem. The misfire is the effect.


So how do I check for vacuum and what would be symptoms of a leak in general please
 
What are your short and long term fuel trims at idle and at 2500rpm?

Generally speaking, lean conditions that are worst at idle but get better at 2500 rpm are vacuum leaks. If the lean condition is ok at idle but worsens at high rpm, most likely have a fuel issue.

Inadequate fueling can cause misfires. If you are not able to perform an injector balance test try swapping injectors with cyl 4.
 
Originally Posted By: miden851
Originally Posted By: Seventh
Originally Posted By: Chris142
Look for a vacuum leak


This... and then check fuel pressure if you know for certain there is no vacuum or crankcase/pcv leak.

Lean mixture code diagnosis will lead to the cause of the problem. The misfire is the effect.


So how do I check for vacuum and what would be symptoms of a leak in general please


The symptoms are your lean codes, misfires, and your engine runs poorly. You already know that.

Your air fuel mixture is wonky. Too much air and/or not enough fuel. Your air mass meter calculates the amount of air being sucked into the engine so the computer knows how much fuel to inject in order to keep the air fuel ratio stoich.

If your engine is sucking in air (vacuum leak) that is not being accounted for by the air mass meter, the computer doesn't know how to keep the air fuel ratio stoich, the 02 sensor complains, computer adds fuel, once it adds a certain amount it sets codes and or starts misfiring if it can't add enough.

So you're looking for intake hoses/boots that are torn, clamps loose, vacuum lines loose, crank case hoses/connectors leaking or torn, etc. This is best accomplished with a smoke machine. Pump smoke into the intake and it will leak out at your problem areas.

Basically check all the rubber things and their associated clamps first.

Could also be a bad air mass meter or fuel delivery problem but check the basics first.
 
I ran that car this morning for about 15min, no check engine light it works just fine; should I still be concerned, or maybe not, I don’t know; the car is 10 years and but still just fine car when cranked up or driven.

The spark plugs have antisizure lubricant last time I had replaced them; they look pretty worn out with carbon build up on them; no oil on them specifically.

My scan tool is 10 year old and it doesn’t have live update nor live scanning for a possible problems so I cannot confirm fuel trims up or down; prior to my problem, I drove car hard on interstate yesterday, 4-5000 rpms frequently, also used cheap gas on QT in our area in latest weeks; in addition I changed the fuel pump like a month ago and I put 2000 miles on it; my fuel efficiency is good 22-24 everyday; now that I’m changed the pump and spark plugs car feels livelier than before.

Also no hissing sound in engine bay
 
With engine warmed up and running, try spraying carb cleaner around different parts of the engine. In a really bad case you might see it being sucked in, but probably not. What you are really looking for is a change in engine idle. If that happens when you spray a certain spot, you have a vacuum leak there.
 
This morning engine behaved normal; I went to work then to lunch no problems; on my way back it started to shake and sure enough the light was on; for a moment flashing then for a moment stayed on; it reaped this cycle several times then went to normal again, no check engine light; I did not have my OBD tool to scan either right them; then this evening on my way home it was normal again; once got home I went to some of my night classes and issue was back; now I’m here at my home the car drove just fine;

Btw I never changed PVC on the car or any of the hoses

Thanks for all your support and sticking here with me on this one y’all great People!!!

Im just trying to do symple stuff first, the one i can do before I ask for a professional help...
 
Wait a minute, if it is an iridium plug why would it be worn out so fast? It doesn't make sense.
Also if it is a bad MAP or dirty MAF sensor it wouldn't be just cyl 4 misfire but all 4 of them. I suspect it is vacuum leak around cyl 4 (i.e. if it is used as EGR port or if PCV hose go into only cyl 4).

Was any of the plug loose? Did you lose any coolant (i.e. bad head gasket -> lose coolant or compression issue)?
 
Status
Not open for further replies.
Back
Top