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"#1 cylinder misfire" is not adequate information!
Was the misfire caused by the spark plug, the fuel injector, the spark plug wire, the coil, or what? If the vehicle is going to watch the engine parameters, it should be capable of telling exactly what went wrong.
I get a CEL every now and then in my Dodge truck. I don't even bother to check the code any more, because it tells me nothing, and the light goes out on its own. The truck runs just fine.
I got a CEL on my PT Cruiser a few times. It took 3 new gas caps to eliminate the problem. The last one I bought at NAPA. The ones I bought at O'Reilley's were no good.
It's perfectly fine information. What you don't understand is that it's not actually seeing a misfire.. It's sensing speed changes of the crankshaft and diagnosing it as a misfire based on which cylinder should have been firing at that time.
Codes are not to tell you what is wrong, they're to tell you what is being seen.. It's up to you to apply diagnostic skills to determine the problem.
Could they make it so that it would point you to an exact part? Sure, you're then adding more sensors to detect each of these things, which are more parts to fail.
Engine codes don’t help me much because I can’t fix them. I have a persistent lean condition (I think P0171) that nobody seems to be able to trace.
Yeah these codes can often be useless and a huge hassle. My 1997 Mustang had a check engine light on that threw the code "running rich in bank 2". NO ONE could get this light to go off. I drove with it like this for about 8 years. I then moved to a state where emissions inspections were required so I had to try again to get this resolved. Once again, no luck. One mechanic even suggested the computer was going bad because he could not locate any other cause. I had to beat the system to get it to pass inspection by disconnecting the battery to reset the CEL, then drive enough just to get the car in a ready conditon for the test, and hope the light didnt come back on before I got to the shop. Fun times.
About 3 years ago another mechanic pulled the code and said it was some simple sensor, replaced it, and the light has been off ever since. Madness.
I say pop the hood and have a look around. A solid engine light usually points to an emissions problem whereas a blinking light is something more serious and you need to have it fixed quickly.
What year is the car? You may have a emission hose that is cracked and leaking air.
We have a 02 JeeP Wrangler and the light comes on now and again. I took it to Autozone, they put it on the code reader and a few codes came up pointing us to the evap system and or gas cap. The clerk thought it could be something to do with the fuel pump do hickey on top of the gas tank, we went in to look up the part and guess what the JeeP doesn't even have what he was talking about. Moral of the story is Don't believe everything they tell you"
Once before I did find a cracked hose and another time I replaced the fuel cap.
You will need to get the repair done and get that light to go off when it comes time for your inspection sticker. That is how it works in MAss.
"#1 cylinder misfire" is not adequate information!
Was the misfire caused by the spark plug, the fuel injector, the spark plug wire, the coil, or what? If the vehicle is going to watch the engine parameters, it should be capable of telling exactly what went wrong..
The information given is perfect adequate to begin diagnosis.
What you are asking is impossible because the car does not have individual sensors for each component to be able to tell exactly what part failed. Some of the sensors on the car do, but in the case of a misfire, the car can only sense that the cylinder is not contributing 100% of available power and generates a code it cannot pinpoint the exact cause because such component do not exist. There isn't a spark plug with wires on it to tell if it's firing. There isn't a cylinder compression checker to tell the computer that the head gasket popped. What you are asking way too much for a system that has practical design limitations.
Whether the cause is a spark plug, coil, fuel injector, or popped head gasket is up to the troubleshooter to determine by running down the same checklist of causes that have been around since the early days of carbs.
With that said, you are onto something in the way the OBD2 codes can be a little misleading as to the true cause.
The codes in an OBD2 system are pretty much standard. Let me use a recent example here. Infiniti G35 comes up with a P0455 code. The code scanner read LARGE EVAP LEAK, and the EVAP readiness monitor would not complete at all. Not a whole lot of information to go by there other than knowing you have a vacuum leak.
Now, here's where troubleshooting the code for the model car comes into play. The G35 Factory Service Manual is posted on the internet, and inside it it lists what sensors are affected by what codes. Code P0455 according to the Infiniti FSM is a EVAP canister purge valve solenoid. It's located under the rear bumper, is a $50 solenoid and takes two seconds to replace. This was all outlined in the FSM here on page 460 here http://www.nicoclub.com/FSM/G35/Seda...5_Sedan/ec.pdf
The problem with that if you notice is the troubleshoot procedure is pretty complex and points to two arbitrary sensors on the car. Meanwhile, all my code reader said was "Large EVAP LEAK P0455". Now, if you didn't have a copy of the Infiniti FSM, it might be pretty difficult to have traced down the failing vent canister sensor.
So no, OBD2 is not perfect in the information it conveys, but it is a tool that does help to narrow down the cause. How easily it is to find such cause depends entirely on the skillset of the troubleshooter.
Last edited by BostonMike7; 04-17-2015 at 12:48 PM..
Yeah these codes can often be useless and a huge hassle. My 1997 Mustang had a check engine light on that threw the code "running rich in bank 2". NO ONE could get this light to go off. I drove with it like this for about 8 years. I then moved to a state where emissions inspections were required so I had to try again to get this resolved. Once again, no luck. One mechanic even suggested the computer was going bad because he could not locate any other cause. I had to beat the system to get it to pass inspection by disconnecting the battery to reset the CEL, then drive enough just to get the car in a ready conditon for the test, and hope the light didnt come back on before I got to the shop. Fun times.
About 3 years ago another mechanic pulled the code and said it was some simple sensor, replaced it, and the light has been off ever since. Madness.
O2 sensor most likely. At least, that's where my mind goes. Lots of possibilities, and that's where the troubleshooting ability comes into play.
But, regardless.. You can't do that today.. Most states that inspect actually check to see that the vehicle has made it through its internal diagnostic procedures on each system and passed before they will allow the car to pass inspection. I happen to live in SC where there is no state inspection.. Since about 1994 or so.. And honestly.. You rarely see a vehicle where you say "That thing shouldn't be on the road".. A few where you see colored plastic over the taillight, but.. You know, that's the #1 way that the cops stop crackmobiles.
I know on my Colorado, it takes about a week before the entire diagnostic procedure has run and the computer comes back with an "All Clear" after either the computer has been cleared or battery power has been lost.
I know on my Colorado, it takes about a week before the entire diagnostic procedure has run and the computer comes back with an "All Clear" after either the computer has been cleared or battery power has been lost.
If's funny how each car is different. If I clear the codes and reset the monitors on my Infiniti, I can start the engine, drive for 20 mins and all the monitors will reset and i'm good to go.
Other car's I've worked on take days to reset the monitors and be good to go for a state inspection test.
It's the EVAP testing that takes so long on my Colorado.. Most of the tests are clear in.. 2 minutes of driving with the vehicle at operating temperature.
The Catalyst system test.. Seems to take a day or 2 (I'm guessing 3 to 4 drive cycles).. The evap system.. At least 5 days, sometimes longer.. I think it might require burning an entire tank of fuel or something (I'm guessing here) to trigger the test as 'passed' vs 'In Progress'.
Will all the modern technology going into cars nowaday's, you'd think they would do away with this outdated "cel" and instead have the cars computer read out exactly is the issue at hand rather than a check engine light coming on and you not knowing the reason for it unless you actually hook up a code reader to it.
If my car can tell me how much air pressure is in each tire, then manufacturers can surely make it so that it reads out the codes to me whenever an issue occurs rather than a CEL lighting up for what can be a number of reasons.
My car does that. I'd have to look at the owners manual but I know there is a combination of button pushes that will elicit a display of the code(s) on the main screen.
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