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This makes no sense! Misfires that jump from one cylinder to the next ?


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Mr.John187
User

Jan 19, 2023, 1:47 PM

Post #1 of 6 (202 views)
This makes no sense! Misfires that jump from one cylinder to the next ? Sign In

Hey guys, I'm REALLY hoping someone here can explain this cause to me it makes absolutely no sense..
I've got a Mazda tribute 03 with 455000km on the clock.. v6 3L engine.
On Sunday night on my way home from my delivery job which was completely uneventful, using this car. Something happened which made the car start sputtering so much it actually stalled, and i believe this may have happened upon trying to start it up again, but, the belt ended up shredded a bit and the codes it was throwing was misfire on #4 and #6.

Now in a different post here i mentioned that i was having misfires on #6 on damp days but only at the beginning of the day, after a few miles the misfire would go away. That morning i didn't have that problem.

So now I'm having to get my car towed to the shop, where my mechanic says it needs and proceeds to complete a tune up, changing the spark plugs and a couple rubber boots, the belt, and maybe something else i can't remember, plus a couple things unrelated to the engine.

After completing the job he informs me that i need a new motor because cylinder 6 is having some internal damage which is causing it to misfire. I tell him about my previously existing problem but he says that it is different than what I'm referring to/explaining. He then says i could drive the car somewhat but it will idle like garbage. But while it's driving it actually drives pretty nice despite everything.

So i leave the shop and i notice that the car does run way differently than when i was having the problem before the incident (for which nobody seems to be certain of the causes BTW)

I scan the codes and there's nothing about cylinder 6 but #3 is misfiring.. but, i can't afford to NOT work since i now have to buy a new motor or a new car even though i just put thousands of dollars into this one now.
So i proceed to work and do deliveries. After a while i scan the codes occasionally erasing them to see what pops up given the weirdness of what i was getting as results. After a bit, #3 didn't show up anymore but #2 did. After a while longer it was all but #1 that were all misfiring. Then after some more time it was back to #6.

My mechanic seemed to think there might be a bent valve on #6 or something of the sort. But how would that cause misfires to STOP happening on that cylinder and starting on a different one (s) ??? I'm soooo confused and distressed... this makes no sense to me but I'm hoping someone here can make sense of it and let me know what I'm dealing with here... thank you so much in advance!!

Have a wonderful day guys!!

John


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Jan 19, 2023, 1:54 PM

Post #2 of 6 (197 views)
Re: This makes no sense! Misfires that jump from one cylinder to the next ? Sign In

With 280K miles why on earth would you sink thousands of dollars into it?

At this stage of the game you need to do a complete compression test and I wouldn't sink any more money into it until you know the condition of this engine and even then the rest of the car has to be worn out completely.



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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



Sidom
Veteran / Moderator
Sidom profile image

Jan 19, 2023, 2:19 PM

Post #3 of 6 (187 views)
Re: This makes no sense! Misfires that jump from one cylinder to the next ? Sign In

There is a lot of things that can cause multiple misfires. One misfire can actually affect other cylinders and create misfires or "ghost"misfires.
That's a lot of miles on the engine, but these days I get how expensive used cars are it's gotten crazy.
First as Desi stated you really need to do a full compression and leak down test to really see what you're working with. Then check out the other misfires to see if they are actual misfires or just false misfires created by the number six misfire.
As far as the number six misfire you can get carbon on a valve that can intermittently affect the compression on a cylinder. When it's affecting the compression there will be a misfire but when there's no compression lost in the cylinder will run fine.
But it's already stated you got to start at square One


(This post was edited by Sidom on Jan 19, 2023, 2:21 PM)


Mr.John187
User

Jan 19, 2023, 2:55 PM

Post #4 of 6 (179 views)
Re: This makes no sense! Misfires that jump from one cylinder to the next ? Sign In

To answer your question as to why i would sink thousands into it, well, it was already pretty much answered, used cars are ridiculously expensive nowadays and I'd have to have the money all at once to get one, on which i wouldn't know what was good/recently repaired and what was likely to give out in the near future. I also absolutely love this car it gave me a long run without needing any repairs for the longest time, it ran really well up untill Sunday, other than that random misfire for which i was waiting for a coil pack to replace it. I don't have the means to get an other car, and now it seems i probably don't have the choice either... so lets say the problem IS a bent valve.
I just did the brakes, the front control arms, the fuel pump, the alternator, brand new tires, i think I'm forgetting some other things but, all this was done in the last 2 years. Brakes and tires just before winter... oh battery as well..

Are you guys suggesting that the new (used) motor option is basically the wrong one here? I'm so damn lost right now


Hammer Time
Ultimate Carjunky / Moderator
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Jan 19, 2023, 3:02 PM

Post #5 of 6 (175 views)
Re: This makes no sense! Misfires that jump from one cylinder to the next ? Sign In

I totally understand the costs and issues with buying a new car but you also need to understand machines wear out and at some point there is nothing of value or reliability left and you are just throwing good money after bad.

With that many miles there is a very good chance the the cause of all these misfires is simply low compression which would be totally expected with that many miles and considered terminal for that engine.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



Sidom
Veteran / Moderator
Sidom profile image

Jan 19, 2023, 3:30 PM

Post #6 of 6 (168 views)
Re: This makes no sense! Misfires that jump from one cylinder to the next ? Sign In

First you need to find out is what is going on. What the actual problems are and what the real misfires are. A worn out engine is a conclusion, you need to find out what the problem is. A bent valve would have a constant misfire all the time. It wouldn't ever go away.
The first step would be a complete compression test. The test should be run when number 6 is misfiring. Like I said before there could be just one misfire causing false readings for other misfires. I had an Acura once with one bad coil that started a Cascade effect that set five misfires and when the bad coil was replaced all the misfires went away. But first you got to make sure the engine is mechanically sound. It wouldn't be bad to throw a hundred or so at it with plugs, wires and maybe a coil pack to get it to run right but if there is any kind of mechanical problem, with an engine with this many miles you'd be best off looking at a replacement, either an aftermarket engine or low mileage used except those can always be a gamble too.
But first things first....... Is the engine mechanically sound? A lot of local parts stores rent tools like compression gauges. YouTube has a wealth of information on how to do a compression check. I don't know if I can recommend channels here but absolutely stay away from Scotty kilmer, that guy's a hack






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