Cylinder Misfire
#1
10-14-2004, 05:43 PM
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Cylinder Misfire
Just did a seafoam treatment 2 weeks ago, got rid of a hesitition problem I was having, BUT
Changed spark plugs (motorcraft) after treatment, now getting cylinder 1 misfire, plan on changing wires (motorcraft) and checking cylinder 1 plug on my day off.
Besides plug or wire what else would set off a cylinder misfire?
P.S. Erased code after it first happened in the morning when I went to work, never came back on untill next morning after sitting all night and in morning runs rough when it throws cylinder misfire, but clears after I restart it but then does the same thing the next morning.
Thinks in advanced
Changed spark plugs (motorcraft) after treatment, now getting cylinder 1 misfire, plan on changing wires (motorcraft) and checking cylinder 1 plug on my day off.
Besides plug or wire what else would set off a cylinder misfire?
P.S. Erased code after it first happened in the morning when I went to work, never came back on untill next morning after sitting all night and in morning runs rough when it throws cylinder misfire, but clears after I restart it but then does the same thing the next morning.
Thinks in advanced
#4
10-18-2004, 12:44 PM
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Homer,
Would he need to do that at 66k miles? Perhaps try spraying all around that area with injector cleaner while the engine is running to see if there are any leaks.
My guess right off the bat is that if you were having a hesitation problem it was probably a bad wire to begin with. One thing at a time though, change all the wires and that plug first and lets see if the problem goes away.
Tom
Would he need to do that at 66k miles? Perhaps try spraying all around that area with injector cleaner while the engine is running to see if there are any leaks.
My guess right off the bat is that if you were having a hesitation problem it was probably a bad wire to begin with. One thing at a time though, change all the wires and that plug first and lets see if the problem goes away.
Tom
#5
10-24-2004, 06:51 PM
my 97 was missing on cylinder 2 the other day changed plugs and wires still missing it ended up being the coil $74.00 at advance auto parts they said i could bring it back if it didnt fix the problem i just changed it in there parking lot 4 bolts make sure you dont mix up the plug wires
hope this helps
hope this helps
#7
11-01-2004, 09:48 PM
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*UPDATE*
So far I have replaced all wires w/motorcraft, coil pack, and cylinder 1 plug. The light just came back on today saying cylinder 1 misfire what else could it be, like I said before it did not come on until I changed the spark plugs. The plugs are motorcraft from autozone (686).
Just Read through another post and it had said that they were getting cylinder misfire because of bad pcv valve.
Well that is what I used to adminster the seafoam. Could this be the problem
So far I have replaced all wires w/motorcraft, coil pack, and cylinder 1 plug. The light just came back on today saying cylinder 1 misfire what else could it be, like I said before it did not come on until I changed the spark plugs. The plugs are motorcraft from autozone (686).
Just Read through another post and it had said that they were getting cylinder misfire because of bad pcv valve.
Well that is what I used to adminster the seafoam. Could this be the problem
Last edited by fordguy21; 11-01-2004 at 09:53 PM.
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#8
11-02-2004, 08:23 AM
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#10
11-03-2004, 08:26 AM
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Ok, I got your problem. This is long but it's worth the read. It's a news letter I get emailed to me each week about various occuring problems, and this mornings topic was yours exactly. This may solve your problem. Please read.
P0304 Cylinder 4 misfire detected
Now that I knew the problem, I also knew my light was flashing was because driving with a misfire can wreck the catalytic converter. The right thing to do here would be to call a tow-truck. But, I didn't. We drove home very gently. I was able to use AutoTap to monitor the live misfire counts in cylinder four and was able to find some "sweet-spots" where the misfire seemed to mostly go away. I really don't know if that was effective, but it made me feel better. A couple miles into the drive, the MIL stopped blinking and turned steady-on.
The next morning I headed straight to the garage. I'm going to go through this part quickly because I still want to tell you how the misfire detection system works.
I hooked AutoTap back up (the PC version this time, I keep an old laptop in the garage for just such an occasion). I configured the screen to show real-time misfire counts on all cylinders. Cylinder four definitely showed up as the culprit. Now I need to decide if it's an ignition or fuel problem (I ruled out a compression problem on purely on the basis of thinking positive). I swapped spark plugs and plug wires and coils with a different cylinder. With each swap AutoTap still showed #4 as the problem. That confirmed it wasn't a spark problem.
The next day I paid to have the car hooked up to a professional fuel-injection cleaning system. Magically, all my problems were solved (funny how money can do that). No more misfires, and the tech tells me he sees a lot of this. The pintle-valve in the injector gets clogged with varnish from fuel deposits. As preventative maintenance, he recommended using an injector cleaner additive each time I change the oil. Sounds like good advice. I should add that when I brought in the car I told the mechanic about the ignition system tests I had done. He agreed that he didn't need to do any further diagnosis and hooked it up to the cleaning system. I suspect that saved me close to an hour of shop time.
Happy days…for about three weeks. Then the problem reoccurs. AutoTap confirms it's the same cylinder. I do a little research and decide to change out the fuel injector. Those professional cleanings aren't terribly cheap and I don't want to do this once a month. I pick up a new fuel injector and o-rings for under $100.
I definitely underestimated how much work it was to change an injector on this car. There was a LOT of stuff in the way. Quite a few hours later, my new injector is in and everything's buttoned back up (no parts left, the measure of success in my garage). I start the car. Seems like its running smoothly. Check AutoTap for misfires - cylinder four is looking good. I pull up the DTC page of AutoTap and click the magic (and very satisfying) "Clear DTCs" button and the light turns off. I use my Palm a few times over the next few days to check for Pending DTC's and watch cylinder four. Success!
This was a pretty involved project on this car. A professional tech could have done it faster than me, but there's no way they could have gotten it done in less than three hours, not including any diagnostic work. I never did check what the repair charge would have been, but I suspect I saved a few hundred dollars on this one.
Now - How it works. Here's what I find amazing about the OBDII misfire detection system. Not only did it tell me about a misfire, but it pinpointed exactly which cylinder had the problem. That's a huge timesaver! How? Read on!
The computer monitors crankshaft position. It needs to know this for a number of reasons so this sensor is nothing new. What's clever is that it uses this sensor to measure how much the crankshaft accelerates every time a cylinder fires. So if a cylinder isn't pulling its weight, the computer can tell which one was supposed to be firing at that time and reports that info back through the OBDII port. That it can do this at any RPM and load impresses the heck out of me.
If the computer detects enough misfires in a cycle, it turns on the light. It even does some clever things to detect if it's just a bumpy road causing the crankshaft to accelerate erratically. There are some other types of misfire detection systems, but I understand that this method is the most common. The system is also quite sensitive. It can detect a misfire long before you'll feel it as a drivability problem. Slight misfires can cause a Pending DTC (remember that email?). If they re-occur it turns on the light. Severe misfires cause the light to flash because it could mean that unburned fuel is getting to the catalytic converter (damaging it very quickly). Any misfire means your car is polluting.
That's it for this week's (long) email. I'm getting lots of great suggestions for more topics. Next week I'll share a reader's story of how to diagnose a bad coolant temperature sensor.
P0304 Cylinder 4 misfire detected
Now that I knew the problem, I also knew my light was flashing was because driving with a misfire can wreck the catalytic converter. The right thing to do here would be to call a tow-truck. But, I didn't. We drove home very gently. I was able to use AutoTap to monitor the live misfire counts in cylinder four and was able to find some "sweet-spots" where the misfire seemed to mostly go away. I really don't know if that was effective, but it made me feel better. A couple miles into the drive, the MIL stopped blinking and turned steady-on.
The next morning I headed straight to the garage. I'm going to go through this part quickly because I still want to tell you how the misfire detection system works.
I hooked AutoTap back up (the PC version this time, I keep an old laptop in the garage for just such an occasion). I configured the screen to show real-time misfire counts on all cylinders. Cylinder four definitely showed up as the culprit. Now I need to decide if it's an ignition or fuel problem (I ruled out a compression problem on purely on the basis of thinking positive). I swapped spark plugs and plug wires and coils with a different cylinder. With each swap AutoTap still showed #4 as the problem. That confirmed it wasn't a spark problem.
The next day I paid to have the car hooked up to a professional fuel-injection cleaning system. Magically, all my problems were solved (funny how money can do that). No more misfires, and the tech tells me he sees a lot of this. The pintle-valve in the injector gets clogged with varnish from fuel deposits. As preventative maintenance, he recommended using an injector cleaner additive each time I change the oil. Sounds like good advice. I should add that when I brought in the car I told the mechanic about the ignition system tests I had done. He agreed that he didn't need to do any further diagnosis and hooked it up to the cleaning system. I suspect that saved me close to an hour of shop time.
Happy days…for about three weeks. Then the problem reoccurs. AutoTap confirms it's the same cylinder. I do a little research and decide to change out the fuel injector. Those professional cleanings aren't terribly cheap and I don't want to do this once a month. I pick up a new fuel injector and o-rings for under $100.
I definitely underestimated how much work it was to change an injector on this car. There was a LOT of stuff in the way. Quite a few hours later, my new injector is in and everything's buttoned back up (no parts left, the measure of success in my garage). I start the car. Seems like its running smoothly. Check AutoTap for misfires - cylinder four is looking good. I pull up the DTC page of AutoTap and click the magic (and very satisfying) "Clear DTCs" button and the light turns off. I use my Palm a few times over the next few days to check for Pending DTC's and watch cylinder four. Success!
This was a pretty involved project on this car. A professional tech could have done it faster than me, but there's no way they could have gotten it done in less than three hours, not including any diagnostic work. I never did check what the repair charge would have been, but I suspect I saved a few hundred dollars on this one.
Now - How it works. Here's what I find amazing about the OBDII misfire detection system. Not only did it tell me about a misfire, but it pinpointed exactly which cylinder had the problem. That's a huge timesaver! How? Read on!
The computer monitors crankshaft position. It needs to know this for a number of reasons so this sensor is nothing new. What's clever is that it uses this sensor to measure how much the crankshaft accelerates every time a cylinder fires. So if a cylinder isn't pulling its weight, the computer can tell which one was supposed to be firing at that time and reports that info back through the OBDII port. That it can do this at any RPM and load impresses the heck out of me.
If the computer detects enough misfires in a cycle, it turns on the light. It even does some clever things to detect if it's just a bumpy road causing the crankshaft to accelerate erratically. There are some other types of misfire detection systems, but I understand that this method is the most common. The system is also quite sensitive. It can detect a misfire long before you'll feel it as a drivability problem. Slight misfires can cause a Pending DTC (remember that email?). If they re-occur it turns on the light. Severe misfires cause the light to flash because it could mean that unburned fuel is getting to the catalytic converter (damaging it very quickly). Any misfire means your car is polluting.
That's it for this week's (long) email. I'm getting lots of great suggestions for more topics. Next week I'll share a reader's story of how to diagnose a bad coolant temperature sensor.
#11
11-03-2004, 09:42 PM
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#14
11-10-2004, 07:42 PM
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I got out my dads mechaics stesoscope and I stuck it on the injector but it sounded like the other injectors, not sure if I am doing it right.
I went by a local mechaic that I have used before. He told me to take the spark plug out so I did abd to bring it to him so he could see if there were any oil or un burned oil on it. He said there were no oil or gas on the plug which was good. He told me to switch wires from the cylinder beside it and to erase the code to see the code follews the wire.
If it still comes up with cylinder one again, then he said he'll put on a pulse tester to test the injector. Then we will go from there
We shall see. I'll keep posted
I went by a local mechaic that I have used before. He told me to take the spark plug out so I did abd to bring it to him so he could see if there were any oil or un burned oil on it. He said there were no oil or gas on the plug which was good. He told me to switch wires from the cylinder beside it and to erase the code to see the code follews the wire.
If it still comes up with cylinder one again, then he said he'll put on a pulse tester to test the injector. Then we will go from there
We shall see. I'll keep posted