Diagnosing multiple misfires in a computer controlled car

[Kern Dog]

I decided to look at a few YouTube videos about misfires.
One guy spoke about using a digital multimeter to check for power to each coil pack and to each injector. THAT would possibly pinpoint the issue.
He did a compression test as well but disabled the fuel pump relay to do it.
If someone here has mentioned this already. please forgive my oversight. I sometimes get lost in all the responses.

 

[toolmanmike]

The misfire does not change from dead cold to operating temperature. It didn't feel that bad under a load but the power was down. The code reader isn't a real expensive one. I bought it about 10 years ago for around $100.

If it doesn't change from first start to operating temp it probably isn't fuel related. The mixture is rich at start up and leans out with time and temp. It sounds electrical/ computer related.

 

[Budnicks]

View attachment 1614346

 

[Kern Dog]

This is what resonates with me:

Again....

There is no clatter. You can hear something but not clatter. I have run solid lifter camshafts in the red car and hydraulics. I am no expert but I've heard valve clatter before.

 

[DeltaV]

It still posts the same 3 codes

The MIL shows Cyl 1 misfire, Cyl 3 misfire and random misfire.

I'm curious, what are the actual code "numbers"?

 

[68 Sport Satellite]

@Kern Dog
the honda service manual is only one source of info. Manufactures don't always cover everything that occurs real world. I've found better outcomes by using information from both the service manual as well as forums for the car in question. I've owned 6 Hondas over the years, the most recent being a 2019 Honda Civic Si 6 speed manual. At only 20K miles 6 separate digital idiot lights appeared, no loss of car function. Forums said one of the electrical harnesses to blame due to heat. Took to dealer under warranty. Dealer mechanic had awesome attitude and welcomed all my input (rare). He consulted service manual and his own knowledge and found no solution. He then consulted an internal online Honda mechanic forum and several agreed it was the turbo harness gone bad due to heat. He replaced it and all was good.

Please read some info at this CRV owners forum where they mention valve adjustment not always making noise on these motors and exhaust valves are known to tighten with time in a silent fashion, then combine it with the service manual info and then make an educated decision on approach. Usually works for me (most of the time).
Valve adjustment

 

[eldubb440]

file the points and inspect your cap, maybe change out the condenser....... oh, wait

 

[Kern Dog]

I'm curious, what are the actual code "numbers"?

The codes are 0300, 0301 and 0303.

 

[DeltaV]

P0300 Random Misfire
P0301 No. 1 Cylinder Misfire
P0303 No. 3 Cylinder Misfire

For posterity

 

[68 Sport Satellite]

Misfire??

 

[DeltaV]

$80 retail for ONE

Armed robbery! Were they pointing a gun at you?

I checked around and saw four (4) NGK coils for $180.

Is there a short rubber tube that runs between the coil pack and the spark plug? Did one come with the new coil you purchased?

 

[charge70]

Valves that have tight lash are not noisy,just the opposite they are quieter.You can bounce this back and forth all you want.You could have had them adjusted by now and eliminated that as the possible problem Just my thought on this. And it won't cost anything orther than maybe a cover gasket and your time.Any tight ones will most likely be the exhaust and they probably won't have zero lash.

 

[toolmanmike]

Valves that have tight lash are not noisy,just the opposite they are quieter.You can bounce this back and forth all you want.You could have had them adjusted by now and eliminated that as the possible problem Just my thought on this.

But it ran good sat for a month and now has random misfires. Did the valves loose adjustment sitting outside next to his garage? Something changed while it sat.

 

[charge70]

He said previous that he felt it didn't have the power it should before it was parked.And it's due for an adjustment by milage.

 

[toolmanmike]

He said previous that he felt it didn't have the power it should before it was parked.And it's due for an adjustment by milage.

Ah news to me. That info must be buried in the 6 pages of guesses. It is due for a valve adjustment and it needed a set of plugs.

 

[Kern Dog]

Ooof.
The man at NAPA did give me the Military discount so my price was $68 each. I only bought one because in error, I only noticed one DTC instead of three.

Later at home I noticed the upper right hand corner showed this:

What? Now it is showing eight??
I cleared them, started the car and waited. The 300, 301 and 303 codes came back.
With the exorbitant cost of the new coil packs, I went junkyarding to see what I could find.
Now… I usually LOVE that. Strolling around looking for treasures. Lately I’ve been looking for spare parts for my 2007 Dodge truck. The self serve yards separate cars and trucks so I just go to the truck section and look for the Dodges.
Today? I learned that they put ALL IMPORTS into one big section and nothing is organized. You’ll find Hondas next to the 20 other import brands, minivans next to sedans, SUVs next to mini trucks and…. All these imports look the same to me! Almost every vehicle there had front end damage of some sort, missing the grilles or hoods where the EMBLEMS to identify them are visible. I had to walk every inch of each yard. (4 in total)
Add to that my ignorant mindset that their online inventory list was accurate which it WAS NOT. Vehicles on their list are not always still there. I trusted the list and stupidly carried my toolbox loaded with heavy tools that I didn’t need because the model of cars I needed weren’t there.
PLUS…. The yards looked like Beirut 1989 where bombs went off scattering parts everywhere….

THIS was the neatest yard. The first three were four times as bad.

 

[Kern Dog]

In the 4th yard, I found three Hondas with the 2.4. I took nuts and bolts from all 3. I don’t have many metric fasteners here so when I lose something, I have to leave to find some.
I got 8 coil packs, here are some of them:

They have a rubber seal under the coil and one at the end where they snap into the spark plug.
These are plastic. I’m going to try these to see if they help.
If there are damaged wires, the two vehicles that gave up these coil packs had no rodent damage visible so maybe a sub- harness may be needed.
Here is what I mean by rodent damage in this car:

I know, it looks terrible.
Maybe I need to put ammonia near the Honda? I heard the rats hate the smell.

 

[toolmanmike]

In the 4th yard, I found three Hondas with the 2.4. I took nuts and bolts from all 3. I don’t have many metric fasteners here so when I lose something, I have to leave to find some.
I got 8 coil packs, here are some of them:

View attachment 1614781
They have a rubber seal under the coil and one at the end where they snap into the spark plug.
These are plastic. I’m going to try these to see if they help.
If there are damaged wires, the two vehicles that gave up these coil packs had no rodent damage visible so maybe a sub- harness may be needed.
Here is what I mean by rodent damage in this car:

View attachment 1614782

View attachment 1614783

View attachment 1614784

View attachment 1614785

I know, it looks terrible.
Maybe I need to put ammonia near the Honda? I heard the rats hate the smell.

Imagine how your wiring harness could look.

 

[Kern Dog]

Please read some info at this CRV owners forum where they mention valve adjustment
Valve adjustment

Thanks, Dwayne.
I’ll check that once I’m in for the night. I have trouble reading some stuff on the phone, I prefer the bigger screen of the computer.

 

[Kern Dog]

I put in four used coil packs…

The staff marks the parts for warranty purposes.

NO change.
Spark plugs didn’t change anything.
Fresh gas made no difference.
Coil packs made no change. At least there is a 30 day exchange on them. I could use the $108 credit for some other treasures.
I’m narrowing down the possibilities…
Valve adjustment, chewed wires or what???
Stay tuned.