Diagnosing multiple misfires in a computer controlled car

[Triplegreen500]

I would expect the engine management software to be able to detect out of range signals and throw a code for the MAF and O2 sensors. The EPA probably requires it.

The MAP/MAF/O2 can still be "in range"...just not at the right place for conditions. THAT, will not throw a code.

For instance - the O2 says ratio is 12:1. Range is 10:1-16:1. 12:1 is "in range"...but the car may actually be running at 14:1, and the computer will be basing adjustments on the wrong base value.

Same for MAF. It could show a certain airflow rate (usually related to barometric pressure, and throttle opening)...but while "in range", it could be off one, or five, percentage points - again, causing calculations to be based on incorrect baseline data.

Now, there ARE codes for "O2 stuck rich", "O2 stuck lean" (i.e. no voltage/signal change at all), and there are "out of range" faults for just about any sensor...but being within range, and just at the wrong spot? Won't throw a code.

 

[Triplegreen500]

It is quite telling how the term "Check Engine Light" is so commonly used....that started with General Motors. I still sometimes say it.
My 2007 Dodge truck manual refers to it as an MIL, "Malfunction Indicator Light" which feels clunky and odd to say.
My code reader also has MIL on the display so maybe that is the actual industry term for it?
Dang you, GM....your terminology has infected our language!

Yes, MIL is the correct industry term for it. Mainly because now, it encompasses engine management, emissions controls, and transmission management.

"Check engine light" is the colloquial term, because most times the light itself is shaped like an engine block. Or, because, as you said, GM put the actual words "CHECK ENGINE" on their dash for a while.

 

[eldubb440]

my Durango was running like a top with 210K

I assume they were original

 

[DeltaV]

One is Autolite and the other is Champion?

 

[Triplegreen500]

No...the new one has a center electrode, the old one does not.

 

[DeltaV]

No...the new one has a center electrode, the old one does not.

Ok, I misinterpreted "they" to be both of them. Yeah, obviously, the one in the foreground is brandy new. It's been another one of those days!

 

[Triplegreen500]

That's ok. I had to look twice myself.

That's one hell of a gap on the old plug!!

 

[charge70]

Please forgive me if this topic is deemed inappropriate for the forum...
The wife and I have a 2003 Honda CRV that we have had since it was new. We keep it to haul our dogs to the vet and out to play. It has been great and required very few repairs in the 20 years, 130,000 miles.
The problem....Yesterday it was running rough and it lit up the engine light. My code reader showed a DTC of cylinder 3 misfire.
It has sat since New Years eve with the same gas in it since before Christmas.
Today I pulled the coil pack from #3 and swapped it with #1.
Then the code read cyl # 1 misfire. Score...that must mean the coil pack is bad so I bought ONE....$80 retail for ONE.
Back home, I swapped the new coil plug into #1 and started it up. Now I got a code for cyl #3 misfire again. The spark plug for cyl 3 looked okay but I don't recall when I changed the spark plugs. Maybe I should just put in a new set. A closer look at the code reader showed THREE codes....cyl 1 misfire, cyl 3 misfire and random misfire. It does feel like it is missing a bit but not 2 cylinders. Maybe they are intermittent?
I swapped coil packs all around but keep getting the same 3 codes.
I wanted to pull some gas from the tank to get a look at it....cloudy means water in the fuel. The system is sealed but we have had a lot of rain lately and the Honda sits outside most of the time. I went out to drive it to use up some gas but the damned thing barely used any fuel. You'd expect a misfire or two would really cut down on the fuel economy but that wasn't the case. It is down on power though and I can feel the engine lagging.
The fuel filler neck must have some baffle in it because I couldn't get the fuel hose to go in very far. I guess I'll have to just run the gas out and then pour in fresh gas to see if the problem is fuel related. The air filter is fairly new and still clean.
We have mice and rats crawling around this rural area so I looked at the wiring underhood. Nothing looked bad from what I could see but it has happened before. I had to solder in wires for the transmission solenoids a few years ago.
Before I take it to a shop....do you have any ideas on what else I should look for to fix this thing? It seems like I'm forgetting something.
Thanks

Kern,most likely the valve adjustment will fix it.Hondas are very sensitive to having the correct lash and the lash service should be done every 100K.If it's something you're gonna try yourself,The car needs to be stone cold,let it sit overnite,that way you get an accurate adjustment.Good Luck.

 

[DeltaV]

@Kern Dog should trade it in for a scat pack shaker Challenger; manual transmission if possible. A used one of course since new ones are unaffordable.

 

[alsant]

My head is spinning from all this , buy the Scat Pack like DeltaV said !

 

[QuickBpBp]

I didn't read all the responses but my wife's 2500 Hemi Ram did this years ago.. Engine light came on under load and there were 2 coils bad and were arching from the coil packs. Found them cheaper than the dealership $175 for a pair of OE Mopar ones off e-bay. After I replaced them no more arching there but turned on multiple mis-fires anyway.. So I waited for the darkness of night to check again and found two of the SIXTEEN plug wires were arching to the valve covers. I guess the bad coils took care of the path of least resistance so it then showed up in the wires. I replaced all 16 wires with an OE Mopar wire set carefully as it's like spaghetti junction under the hood with them. It fired right up and never had an issue again... Good luck as I hate ANYTHING electrical.

 

[Kern Dog]

@Kern Dog should trade it in for a scat pack shaker Challenger; manual transmission if possible. A used one of course since new ones are unaffordable.

She already drives this:

2015 R/T with the basic 5.7 and automatic. She does not know how to drive a manual trans.
Besides....The mini SUV works well for hauling the woofers:

 

[Kern Dog]

Kern,most likely the valve adjustment will fix it.Hondas are very sensitive to having the correct lash and the lash service should be done every 100K.If it's something you're gonna try yourself,The car needs to be stone cold,let it sit overnite,that way you get an accurate adjustment.Good Luck.

If this is the reason. I'd be pretty surprised. It has never ran real smooth....4 cylinder engines often seem to vibrate a bit compared to the stock V8s I've owned. I'm not arguing, it just isn't something that I thought of. There is no valvetrain noise that I can tell. I will check into this if the ignition isn't the issue.

 

[eldubb440]

in the 90s I bought wrecked Hondas, fixed them, and sold them

also owned a few drivers, put my Mom in one, put a gf in another one.....

the reason was simple........ they never needed anything mechanical that didn't break in the wreck; they just run.

I cannot ever remember doing anything more complicated than a timing belt

Honda's are good for ever, with just basic maintenance

 

[66 Sat]

What about the Throttle Body.
Easy to take it off and clean it. My son's Mazda had a low rough idle and low speed miss.
Took off the Throttle Body last weekend, cleaned it up and reinstalled, now idles smoothly at 750rpm.

 

[eldubb440]

how does the computer detect a misfire?

does it detect the actual "misfire"?....... no matter the cause?

or does it just detect lack of continuity in the coil or injector circuit?

if you run out of gas, no misfires are recordred

if you lose compression, creating a dead hole....... does that record a misfire? even though the injector and coil are still firing?...... I don't think so

 

[RemCharger]

how does the computer detect a misfire?

does it detect the actual "misfire"?....... no matter the cause?

or does it just detect lack of continuity in the coil or injector circuit?

if you run out of gas, no misfires are recordred

if you lose compression, creating a dead hole....... does that record a misfire? even though the injector and coil are still firing?...... I don't think so

It's actually pretty neat, the computer watches the power pulses in a wave form from the crank sensor. Kind of like a heart beat. And it knows which beat is which cylinder. That wave slows down, and there's your dead cylinder.
They were actually doing that way back as a cylinder performance test with the old sun equipment

 

[RemCharger]

Back then it would kill a cylinder and measure rpm loss

 

[68 Sport Satellite]

That era CRV has this happen around this mileage. If the valves were never adjusted, it is a likely suspect. Hondas like that need a valve adjustment after 90K miles or so. Before the misfires, did you notice the engine power not feeling as strong over the last year? If so, that's often the valves from what I've heard. On some Honda forums I've ready that with multiple cylinder misfires people have swapped plugs, wires, coil packs and things got better but didn't last. Adjusted valves and that solved it, but only sometimes. Other times it was too late, the damage was done.

 

[Kern Dog]

This Honda has never made much power. It always felt weak compared to everything else I've owned. A friend also had one that felt about the same so I don't think this one is a bad egg, just an overall underpowered vehicle. 2.4 liter 4 cylinder in an AWD compact "crossover" that surely weighs at least 3000 lbs?
It actually is Mary's car, not mine but I do most of the driving when we are together.
My experience has been that valve lash loosens over time and clatter increases. This engine sounds the same as always.
Am I wrong on that?

****EDIT****

3455 lbs for our model with a 2.4 L 4 cylinder?