• When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.

Diagnosing multiple misfires in a computer controlled car

Kern Dog

Kern Dog

Life is full of turns. Build your car to handle.
FBBO Gold Member
Local time
4:54 AM
Joined
Apr 13, 2012
Messages
35,601
Reaction score
125,446
Location
Granite Bay CA
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
 
When I had a misfire (only under acceleration), the plugs were only 20,000 miles old, so I changed the coil pack. No fix. Then changed plug wires. No fix. Turned out to be the Bosch platinum plugs that I used. After that I went back with OEM plugs. Plugs are probably the cheapest and easiest things to start with anyway.
 
Might want to change the fuel filter.
Not saying its the problem.
A good diagnostic tool can show you almost everything MAP sensor every temperature etc...
 
Have you ever had the valve lash checked/adjusted? Might be a tight valve that may cause the misfire.
 
If you change the filter you can take a sample of the fuel.
You may be correct - water in the gas.
If that's the case just try adding some Heet or other fuel additive and keep driving it.
Burn as much as you can then get fresh fuel in it.
 
Kern Dog said:
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
Click to expand...
It sounds like you need a Honda Tech or you can just keep throwing parts at it until something sticks. (or doesn't)
 
I agree, start with new plugs. NGK.
old plugs stress coil packs.
 
And pick up the trash in your yard.
It's probably what is attracting the rats. :poke:
 
How is the battery ? All the electronics in new vehicles put a drain on battery. Had similar problems with 2015 jgc , new battery took care of it.
 
check the air filter while you're at it......it won't be you issue, but mice can live in the box and jam it up
 
Pump fuel separates when it sits for more than a week. It's called Phase Separation. Moisture from the atmosphere, water in the underground fuel tanks blesses us with water in the fuel and leads to rough running. Even some of your "Top Tier" fuel stations can have junk fuel with too high of an ethanol concentration leaving you with rough running. And as mentioned above, battery issues, rodents chewing on wiring and plumbing adds to the fun.
 
Check fuel pressure
New OEM plugs
Test fire injectors
Move injectors around to see if misfire follows the injectors
 
Many years ago my dad had a new 03 300C w5.7. One day my bro and I were visiting him and he told us his less than year old car was running bad. Checked it out, DTC lit up on the dash and yes running rough. Popped the hood while it was running for a look see, looked fine. Took the Hemi engine cover off while running still and found Bugs Bunny actively chewing on wires. Had to replace the engine harness. Still ran bad. Turns out that the chewed wires took out some of the injector drivers in the PCM. Was able to get that part done under warranty by playing dumb. Dad used to like throwing his food trash just past the parking area, into the lemon grove. The landscaping around his house was like a jungle. Suggested not throwing the garbage out like that, clear out the jungle and park his car in the shop. He said mind your own bees wax. Checked his car again a month or so later, wires getting chewed again. Was able to fix the wires with parts of the old harness. Told him what I found and he started parking his car in the shop at least. Vermin, 4 legged, just need food/shelter/water to hang out. Eliminate at least two and the problem will go away. This also applies to the two legged ones. If Mary's or any other cars get parked outside, leave the hood up. Rodents don't like being exposed where they can get picked off. After dad passed, we did a massive landscape elimination. No more hiding places. And no more food garbage in the grove.
 
Computer controlled car....

1. Re-boot operating system
2. Clear cookies and browser history
3. Clear cache
4. Check plugged in
5. Call 1-800-IBM SUCKS for further assistance. (Press 1 for English)

You're :welcome:
 
Usually when you see the random misfire code, P0300, and specific cylinder misfires accompanying that, I suspect a vacuum leak. Usually vacuum leaks produce a lean condition code, but not always, as it really depends on the leak and duration of the issue. It takes many good 'trips' before the computer sees it as an ongoing issue. A trip is defined as getting to operating temperature and driving for a set amount of time. If these conditions are met, then the computer can see the condition is still present and it will elevate the code to pending. After another trip or 2 with the same conditions being met, it will move the code to active. Hard codes, like a misfire, don't need as much scrutiny to go active and turn on the MIL, as they can damage the cats quickly. I agree, look for vacuum leaks and swap injectors around to see if the misfire follows them, or easier is to watch your dataflow and monitor O2 front and rear sensors to see if it's going lean and staying there. Good luck.
 
You can check the injectors with a stethoscope. Listen for the clicking.
 
You must log in or register to reply here.

Similar threads

Huicho417
Help. Engine shakes badly at idle.
2
Replies
21
Views
1K
Huicho417
Huicho417
V
79 dodge 440 misfiring on cylinders 7&8
Replies
16
Views
1K
RemCharger
RemCharger
P
engine stalled
Replies
2
Views
271
paul1969cars
P
Hubert
Cold starting Issues
Replies
4
Views
470
Hubert
Hubert
P
1969 roadrunner tank vent line
Replies
4
Views
385
paul1969cars
P
Auto Transport Service
Back
Top