Dreaded Misfire P0300

[ShadowsPapa]

Obviously needs to be a software update. Which they've already tried once

What makes you say that? A wild guess?
Why would it be software? If yours is up to date, then how could it be software if no one else is experiencing the exact same symptoms under the same conditions.

What if it's a sensor going goofy when it gets hot?
Coolant in the normal range doesn't speak to other parts, say, O2 sensors just for example.
Have you tried using some software, perhaps AlfaOBD or JSCAN for a true diagnosis?

Sponsored

 

[Gonenuckinfutz]

Maybe because I can just pull over shut down the vehicle restart it and it'll carry on with no issues? It's probably not the right way to think about it but just my thoughts... Been trying to do a little bit more reading since I posted. And someone mentioned to me about it possibly being an oil pressure issue? Everyone has their thoughts I guess. Calling it a dry fire? Not sure if that makes sense? That there's not enough oil pressure once you restart the vehicle? I don't know it just gets frustrating have something can disappear for so long and then all of a sudden show up again. You spend all this money on these vehicles and they don't even know how to fix them.

 

[Gonenuckinfutz]

So at the end of the day they're saying it's software... An update to the powertrain control module. It says rapid response transmittal 22-231 must be performed 22 MY JT. I just hope this solves the problem finally but time will tell

 

[Gvsukids]

Anyone using a throttle booster and getting these codes?

So at the end of the day they're saying it's software... An update to the powertrain control module. It says rapid response transmittal 22-231 must be performed 22 MY JT. I just hope this solves the problem finally but time will tell

Has it?

 

[ShadowsPapa]

Why would a so-called "throttle booster" matter since they don't really change anything except remap the signal from the pedal?

 

[Weldit]

Sorry for the long post.
Our first 3+ hour highway road trip after purchasing this ‘22 model in October, (22k miles), about 2 hours in it started missing pulling hills like it’s starving for fuel and eventually lit the check engine light. It had a half tank, but I fueled up anyway just to eliminate a possible fuel pickup issue. The miss got worse, not better, so I pulled over, shut it off and waited a few minutes. Started it up and it ran smooth so continued on our trip, but babied it some so it wouldn’t mis-fire. Eventually It would only slightly misfire when running it pretty hard.
We made it home ok and was going to take it in but the check engine light went off so assume any codes have cleared. Is this assumption correct? I don’t have a code reader and it’s still under warranty.
Currently doesn’t miss except when it’s completely warmed up and under pretty hard acceleration, like 1/2 throttle (guessing). And it’s sort of an intermittent stumble.
I just had 2 separate surgeries so haven’t had time to take it in and we have other vehicles, but definitely want to get it diagnosed and fixed before the warranty runs out.

 

[Hootbro]

Sorry for the long post.
Our first 3+ hour highway road trip after purchasing this ‘22 model in October, (22k miles), about 2 hours in it started missing pulling hills like it’s starving for fuel and eventually lit the check engine light. It had a half tank, but I fueled up anyway just to eliminate a possible fuel pickup issue. The miss got worse, not better, so I pulled over, shut it off and waited a few minutes. Started it up and it ran smooth so continued on our trip, but babied it some so it wouldn’t mis-fire. Eventually It would only slightly misfire when running it pretty hard.
We made it home ok and was going to take it in but the check engine light went off so assume any codes have cleared. Is this assumption correct? I don’t have a code reader and it’s still under warranty.
Currently doesn’t miss except when it’s completely warmed up and under pretty hard acceleration, like 1/2 throttle (guessing). And it’s sort of an intermittent stumble.
I just had 2 separate surgeries so haven’t had time to take it in and we have other vehicles, but definitely want to get it diagnosed and fixed before the warranty runs out.

Since you mentioned being on a road trip, I would not rule out a tank of bad fuel, possibly water contamination.

 

[ShadowsPapa]

Since you mentioned being on a road trip, I would not rule out a tank of bad fuel, possibly water contamination.

True, but then he mentioned this as well.......

Currently doesn’t miss except when it’s completely warmed up and under pretty hard acceleration, like 1/2 throttle (guessing). And it’s sort of an intermittent stumble.

Not that it rules out any fuel issues, but there's still something amiss (bad bad pun)
IMO, can't hurt to try a fuel "conditioner", something to clean, and to "absorb" and residual water.

Would be really nice to toss AlfaOBD or similar against it and force a stumble or misfire and catch some real-time stats, even a freeze frame. Under load could be fuel - but also could be looking at two issues - the prior misfire, and the current "stumble".
Really hard to tell without some diagnostics.

If it can be demonstrated, duplicated, would be nice to get someone to go for a ride and show the "stumble". (especially with some warranty). Once it's talked about and they make a note of it in a work order, he's safer as far as warranty, at least from my observations.

Still, a fuel system additive might not be a bad thing to try.

 

[Weldit]

Since you mentioned being on a road trip, I would not rule out a tank of bad fuel, possibly water contamination.

Possibly, but have run a few tanks of fuel through it and still has an intermittent miss under hard acceleration, and when it first started doing it I was a half tank into a full top off at a station I use all the time. I will dump a bottle of Heat in the tank though and see if that helps. Couldn’t hurt, though there’s already more alcohol in the fuel than I would like.

Depending on cost I may put a new fuel filter on it.

Thanks for the suggestions.

 

[Hootbro]

Depending on cost I may put a new fuel filter on it.

There is no serviceable fuel filter on the gas engine. Just a strainer on the fuel pump pickup in the tank.

 

[Weldit]

True, but then he mentioned this as well.......



Not that it rules out any fuel issues, but there's still something amiss (bad bad pun)
IMO, can't hurt to try a fuel "conditioner", something to clean, and to "absorb" and residual water.

Would be really nice to toss AlfaOBD or similar against it and force a stumble or misfire and catch some real-time stats, even a freeze frame. Under load could be fuel - but also could be looking at two issues - the prior misfire, and the current "stumble".
Really hard to tell without some diagnostics.

If it can be demonstrated, duplicated, would be nice to get someone to go for a ride and show the "stumble". (especially with some warranty). Once it's talked about and they make a note of it in a work order, he's safer as far as warranty, at least from my observations.

Still, a fuel system additive might not be a bad thing to try.

I do have a diagnostic fuel pressure guage I could put on it and watch while reproducing the miss. (If I can find it)

 

[Weldit]

There is no serviceable fuel filter on the gas engine. Just a strainer on the fuel pump pickup in the tank.

Lol why? Are they trying to sell injectors? Lol

 

[Hootbro]

Lol why? Are they trying to sell injectors? Lol

That has been the industry wide trend for a few years now to do away with external serviceable fuel filters on gas engines. No clue on the reasoning.

 

[ShadowsPapa]

I haven't seen a need for one for years. I did change the filter on my SX4 a couple of years ago "just because" but it had 10 years and 35,000 miles on it and was clean from the normal perspective. It did have black from the incorrect type of fuel hose I hung the in-tank pump from but that was my bad, not the vehicle, tank, or fuel vendor's problem. (I failed to use a fully submersible hose when I made the adaptation to hang a fuel pump in the tank. Dummy me failed to realize that although the inside of the hose was fuel proof or resistant, the outside didn't have to be so it rotted outside-in over the years)
I've just not had any fuel issues that a filter would help, and the filters or strainers in the tanks these days are at least as good as many proper "gas filters" of the past.
New tank materials mean you don't get flaking rust in the tank, underground tanks at stations mean you don't have the constant temperature changes that go along with condensation and storage tank issues.
Having witnessed years of changes, one thing I have noticed in recent years - you don't have the same severity or even frequency of fuel issues you used to have where a filter would do any good. We used to stock pretty much every style and type of filter made for any vehicle, and you'd see crud come out of the filter as you changed 'em - just not seeing that today.
The inside of my 82's tank is as clean as it was years ago when I put it into service.
Besides, I want the bad stuff caught before it gets to a pump that costs so much money.

Sponsored