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Car Forum / Chrysler Cars / November 2007300M misfire code P0302 -> no coil codes, no injector codes?
Just today my '00 300M started running rough. Most noticable at idle - like a cylinder not firing. Engine light came on. After parking it for a while, and starting it, it idles rough, but no engine light. Engine light only comes on if I drive it a little. Codes displayed on odometer are P1684 and P0302. The 1684 is a battery disconnect code (it has the original battery, which hasn't been disconnected for years - if ever, so perhaps this is an indication of a weak battery - although it turns the engine over just fine when cold). The 1684 code is said to not be responsible for the check-engine light. The P0302 code (if I'm right) indicates misfire in cylinder 2. This website: http://www.aa1car.com/library/copign.htm says that I should also expect to see either a coil code that corresponds to the same cylinder (P0351 to P0358) or a code that indicates an open or shorted injector in that cylinder (P0201 to P0208). I don't see any of those codes. Just 1684 and 0302. Might this set of conditions represent just a bad plug then? (orginal plugs). Car is exactly 8 years old tommorrow - bought it new back on Nov 1, 1999. Comments? Answers? Recommendations for aftermarket plug brand (I might as well start there) ? Have never taken off a coil pack before - any special tools, or is it self-evident? Which one is cylinder 2? > Just today my '00 300M started running rough. Most noticable at idle > - like a cylinder not firing. [quoted text clipped - 39 lines] > > Which one is cylinder 2? Start with replacing the plugs if you gonna take a pot shot at it. If it didn't take care of it the next thing you can do is swap coils from one cylinder to another to see if the misfire switches, if it does...replace the effected coil. you don't specify what engine, number 2 cyl on the 3.2/3.5 is on the drivers side front. the 2.7 is on the passenger side front. Glenn Beasley Chrysler Tech >>Just today my '00 300M started running rough. Most noticable at idle >>- like a cylinder not firing. [quoted text clipped - 37 lines] >>Have never taken off a coil pack before - any special tools, or is it >>self-evident? Coil screw heads will either be torx #25 or #27 depending on engine. They can be frozen and difficult to remove without stripping the heads. Get torx bit straight and fully seated. Penetrating oil soak ahead of time wouldn't hurt. Also try good tap directly on head of the screw with a hammer to help break them loose before trying to remove. >>Which one is cylinder 2? > [quoted text clipped - 6 lines] > Glenn Beasley > Chrysler Tech Glenn - Every piece of documentation I have says #1 cyl. is front passenger side for all three engines (3.2, 3.5, 2.7) and therefore #2 is front drive's side. Can you check your documentation and post back? Bill Putney (To reply by e-mail, replace the last letter of the alphabet in my address with the letter 'x') > >>Just today my '00 300M started running rough. Most noticable at idle > >>- like a cylinder not firing. [quoted text clipped - 62 lines] > (To reply by e-mail, replace the last letter of the alphabet in my > address with the letter 'x') Your correct, I was thinking of the transverse set up as in a Sebring Convertible 2.7 which would put the #2 plug at the passenger side front. Must be an old age thing setting in > > Codes displayed on odometer are P1684 and P0302. > Start with replacing the plugs if you gonna take a pot shot at > it. If it didn't take care of it the next thing you can do is > swap coils from one cylinder to another to see if the misfire > switches, if it does...replace the effected coil. The coils came off easy, and so did the plugs. I started by putting a new plug into #2 (front driver side). Original plug was dirty (8 years, 72k miles). Replacement was exact same kind (champion). I didn't gap the new plug (do you still gap plugs these days?). That didn't work - it still idled rough. I then replaced plug #1 (front passenger side) and swapped the coils between 1 and 2. (original plug 1 looked to be in the same shape as #2). That didn't work - it still idled rough. Codes still say 1684 and 0302 (still indicating the problem is with cylinder 2). > you don't specify what engine, 3.5L So at this point, how does the computer know that the problem is cylinder 2? What other sensor could tell the computer that #2 is the problem? If it was the injector, then why no injector codes? Regarding the battery - I did have to get a replacement ignition key and fob to replace a stolen one (about 2 weeks ago). The dealer reprogrammed the car to accept the new key and fob and reject the stolen ones. Would that have required disconnecting the battery? >>>Codes displayed on odometer are P1684 and P0302. > [quoted text clipped - 35 lines] > accept the new key and fob and reject the stolen ones. Would that > have required disconnecting the battery? Did you reset the codes? Bill Putney (To reply by e-mail, replace the last letter of the alphabet in my address with the letter 'x') > Did you reset the codes? No - how do you do that? PS: Cylinder 2 is front driver side, with front meaning closest to the front of the car - yes? > Did you reset the codes? Hypothetically, let's say my problem is a bad #2 coil. Say that's what's causing the 0302 code. So I swap coil #2 with coil #1. But I don't reset the codes. So I start the car, car idles rough, and the check engine light goes on. I then do another read of the codes. Because I didn't reset the codes, I guess I'll still see 0302. But if cylinder #1 now has the bad coil, shouldn't I now see code 0301 ??? BTW, is there any way to reset the codes other than disconnecting the battery? >> Did you reset the codes? > [quoted text clipped - 12 lines] > Because I didn't reset the codes, I guess I'll still see 0302. But if > cylinder #1 now has the bad coil, shouldn't I now see code 0301 ??? Yes, but it may not set a code for cyl#1 right away. You may have to run it for a while for the code to set. > BTW, is there any way to reset the codes other than disconnecting the > battery? Yes, it can be done with a scan tool or some code readers. The easiest way to reset the codes is to diconnect the battery for a minute or two. I would suggest you leave the coils were they are now, replace all the spark plugs, clear the codes and take it for a ride and see if the check engine light comes on again. >>Did you reset the codes? > [quoted text clipped - 12 lines] > Because I didn't reset the codes, I guess I'll still see 0302. But if > cylinder #1 now has the bad coil, shouldn't I now see code 0301 ??? That's what I'm thinking. But also, if you reset the codes and you get no code later, but it still runs rough that would mean something different than resetting and getting the code for only cylinder 1. Not sure what exactly, but it would mean something. If code for cyl. 2 comes back, that would be instructive too. Right now you don't know if it would come back or if you're just seeing the old code. I think we both suspect that cyl. 2 code will come back. > BTW, is there any way to reset the codes other than disconnecting the > battery? Pull Fuse N in the Power Distribution Center for 15 minutes to reset the PCM. Bill Putney (To reply by e-mail, replace the last letter of the alphabet in my address with the letter 'x') > > Because I didn't reset the codes, I guess I'll still see 0302. > > But if cylinder #1 now has the bad coil, shouldn't I now see [quoted text clipped - 4 lines] > something different than resetting and getting the code for only > cylinder 1. Resetting and getting no codes, and still running like a cylinder isin't functioning doesn't make sense, given the earlier code 0302. Do plugged injectors result in an injector code? Or does only an electrically-inoperative injector result in an injector code? > > BTW, is there any way to reset the codes other than > > disconnecting the battery? > > Pull Fuse N in the Power Distribution Center for 15 minutes to > reset the PCM. Some references to the "Power Distribution Center" say it's located under the hood near the battery. I have no such item (that I can see) near the battery. I do have a "Fuse and relay center" on the driver's side, in front of the rad overflow tank. The fuses and relays are identified by name only - no numbers or letters. The relay center behind the dashboard panel on the driver's side are labelled with numbers - but I don't see anything referring to the PCM. So basically - where is the Fuse N you're talking about? >>>Because I didn't reset the codes, I guess I'll still see 0302. >>>But if cylinder #1 now has the bad coil, shouldn't I now see [quoted text clipped - 21 lines] > Some references to the "Power Distribution Center" say it's located > under the hood near the battery. Please tell me what references say that so I'll know to avoid them. :) > I have no such item (that I can see) near the battery. > > I do have a "Fuse and relay center" on the driver's side, in front of > the rad overflow tank. The fuses and relays are identified by name > only - no numbers or letters... Yep that's it. > So basically - where is the Fuse N you're talking about? Here's a figure from the FSM that I have labeled the fuses on: http://images22.fotki.com/v810/photos/4/42816/1994050/PDC1999labeled-vi.jpg Bill Putney (To reply by e-mail, replace the last letter of the alphabet in my address with the letter 'x') go out and buy some good plugs replace them all !do not use bosch plugs ngk has some good ones at a very affordable price swapping coils is a good thing like glenn stated but if you don't have a scan tool that shows misfires then it is a waste of time. in your case it will still run rough . accell products now sell super coils at a very affordable cost 30 to 50 dollars new or a salvage yard.throwing cheaper parts at since you don't have a scantool if you have a 2.7 engine it could be the signs of a timing chain jumping time but that will usually show a cam senser code too if you want for good measure go to a dealer and get a couple cans of combustion chamber cleaner and follow the instrutions to a tee this chemical is the best I found for cleaning carbon off the valves which can also set the misfire code if all checks out good after this then a compression test of the engine is in order > > > Because I didn't reset the codes, I guess I'll still see 0302. > > > But if cylinder #1 now has the bad coil, shouldn't I now see [quoted text clipped - 31 lines] > > So basically - where is the Fuse N you're talking about? >> > Codes displayed on odometer are P1684 and P0302. > [quoted text clipped - 9 lines] > (champion). I didn't gap the new plug (do you still gap plugs these > days?). Yes. Plugs still get gapped unless they are platinum tipped. > That didn't work - it still idled rough. It may help if you replace all the plugs at that mileage. > I then replaced plug #1 (front passenger side) and swapped the coils > between 1 and 2. (original plug 1 looked to be in the same shape as [quoted text clipped - 12 lines] > cylinder 2? What other sensor could tell the computer that #2 is the > problem? If it was the injector, then why no injector codes? When the coil fires for cyl #2 the PCM expects to see a jump in cranshaft speed when cyl #2 fires. It reads crankshaft speed via the crank sensor. If cyl #2 doesn't fire the PCM sees no increase in crank speed and sets a code. It takes more than a single misfire to set a code. If it was an electrical problem with the injector the PCM would be able to pick that up and set a code. If it was a mechanical problem, such as a plugged injector, the PCM would not be able to sense that. > Regarding the battery - > > I did have to get a replacement ignition key and fob to replace a > stolen one (about 2 weeks ago). The dealer reprogrammed the car to > accept the new key and fob and reject the stolen ones. Would that > have required disconnecting the battery? > > > Codes displayed on odometer are P1684 and P0302. > [quoted text clipped - 35 lines] > accept the new key and fob and reject the stolen ones. Would that > have required disconnecting the battery? The fault code should have gone to the other cylinder if the coil was bad, you wouldn't have to reset the codes, it would have automatically set a hard fault code for the other cylinder if it were the coil. Your gonna have to go back to basics, compression? fuel (injector). The injector pintel could be bad or the injector is stopped up, this would not set a fault code unless the injector circuit was at fault. If you have the time, swap injectors. Glenn >>>>Codes displayed on odometer are P1684 and P0302. >> [quoted text clipped - 44 lines] > > Glenn I was suggesting resetting the codes first to maker sure cyl. 2 was not still having a problem that would set a code. Bill Putney (To reply by e-mail, replace the last letter of the alphabet in my address with the letter 'x') >>>>>Codes displayed on odometer are P1684 and P0302. >>> [quoted text clipped - 51 lines] >(To reply by e-mail, replace the last letter of the alphabet in my >address with the letter 'x') That would work if you were just clearing the codes using a scan tool. Clearing the codes by interrupting the power supply to the PCM will result in misfire monitoring being disabled. No misfire can be detected until the vehicle is driven under specific conditions to allow the PCM re-learn the baseline variance between cylinders. (am I the only one to correctly edit their posts around here?) > That would work if you were just clearing the codes using a scan > tool. Clearing the codes by interrupting the power supply to the > PCM will result in misfire monitoring being disabled. No misfire > can be detected until the vehicle is driven under specific > conditions to allow the PCM re-learn the baseline variance between > cylinders. Jesus christ. Ok, that would explain a few things. Will this OBD II tool work for my '00 300M ? http://www.redflagdeals.com/deals/main.php/alldeals/comments/princess_auto_obd_i i_code_reader_4999 >(am I the only one to correctly edit their posts around here?) > [quoted text clipped - 12 lines] > >http://www.redflagdeals.com/deals/main.php/alldeals/comments/princess_auto_obd_i i_code_reader_4999 They say it will read and clear codes. If it does what they say it'll do, and that's all you want to do, then yes. >>I was suggesting resetting the codes first to maker sure cyl. 2 was not >>still having a problem that would set a code. [quoted text clipped - 8 lines] > detected until the vehicle is driven under specific conditions to > allow the PCM re-learn the baseline variance between cylinders. So the new baseline that it learns will include any anomaly, such as any cylinders that are missing. That being the new baseline, it will think any missing (the new baseline of "variance between cylindrs") is normal operation and will never set a code (until reset again under new conditions)? Bill Putney (To reply by e-mail, replace the last letter of the alphabet in my address with the letter 'x') >>>I was suggesting resetting the codes first to maker sure cyl. 2 was not >>>still having a problem that would set a code. [quoted text clipped - 18 lines] >(To reply by e-mail, replace the last letter of the alphabet in my >address with the letter 'x') No. The baseline is learned during a hard (fuel shutoff) decel condition, which takes a misfire out of the equation. Sometimes it takes a few of these, and sometimes it needs to be driven a few miles after it's learned before misfire detection is re-enabled. Without a good scan tool that can tell you if misfire detection is enabled, you don't know if the fault didn't set because the misfire's gone or the PCM's not looking. >>>>I was suggesting resetting the codes first to maker sure cyl. 2 was not >>>>still having a problem that would set a code. [quoted text clipped - 26 lines] > don't know if the fault didn't set because the misfire's gone or the > PCM's not looking. I would think then that you would still need to reset so you can see what does eventually come back as far as codes. Otherwise you don't know if the codes is old (obsolete news or not. Bill Putney (To reply by e-mail, replace the last letter of the alphabet in my address with the letter 'x') >>>>>I was suggesting resetting the codes first to maker sure cyl. 2 was not >>>>>still having a problem that would set a code. [quoted text clipped - 34 lines] >(To reply by e-mail, replace the last letter of the alphabet in my >address with the letter 'x') Which is the point of my original reply in this thread. There is a difference between clearing codes using a scan tool or code reader, and resetting the PCM by disconnecting the battery. Clearing codes won't disable misfire monitoring by resetting the baseline value learned by the PCM. Disconnecting the battery will. >>I would think then that you would still need to reset so you can see >>what does eventually come back as far as codes. Otherwise you don't [quoted text clipped - 9 lines] > won't disable misfire monitoring by resetting the baseline value > learned by the PCM. Disconnecting the battery will. Got it. Bill Putney (To reply by e-mail, replace the last letter of the alphabet in my address with the letter 'x') > I was suggesting resetting the codes first to maker sure cyl. 2 was not > still having a problem that would set a code. Also, if its a plugged injector or mechanically failed injector (not an electrical fault) it may take its own sweet time about setting the code because its doing its misfire detection by crankshaft speed variation routine, and it has to detect that consistently before it will set the code. You might even need to drive around the block after clearing the codes before it will decide that yeah, its a real fault and it had better set the code. If the code stays with the same cylinder, I'd check compression and the injector. >> I was suggesting resetting the codes first to maker sure cyl. 2 was >> not still having a problem that would set a code. [quoted text clipped - 9 lines] > If the code stays with the same cylinder, I'd check compression and the > injector. Well - according to Dr. Bllsht, it will never happen anyway because the PCM will be learning the baseline from the present conditions. If the present conditions are with a steady cylinder miss, that will become the new baseline. So it will think the miss is the baseline and will not set a code for any current anomalies. Bill Putney (To reply by e-mail, replace the last letter of the alphabet in my address with the letter 'x') >>> I was suggesting resetting the codes first to maker sure cyl. 2 was >>> not still having a problem that would set a code. [quoted text clipped - 19 lines] >(To reply by e-mail, replace the last letter of the alphabet in my >address with the letter 'x') That's not what I said. See my other reply. 8 years on the original battery? Replace the battery since it is on borrowed time. A bad battery with low operating voltage can mess up the sensor readings and computer controls. I'd see how it runs after that before trying anything else. Bob > Just today my '00 300M started running rough. Most noticable at idle > - like a cylinder not firing. [quoted text clipped - 39 lines] > > Which one is cylinder 2? To re-cap a little, my '00 300M abruptly started to run rough 2 days ago, obviously one cylinder wasn't working. I was seeing code P0302 on the odometer, indicating cylinder #2. I replaced the (original) plugs in both cyliners 1 and 2, but that didn't solve the problem. I swapped coils 1 and 2, started the engine a few times, but the problem was still there. I was expecting (hoping) to see code 0301 but it didn't show. Today, I drove the car about a mile, parked it, and then read the codes. Only then did it show both 0302 and 0301. I disconnected the negative cable from the firewall - I tried a few times but ultimately it had to be disconnected for between 30 to 45 minutes for the codes to clear. I drove the car for a few miles, but it wasn't enough for the engine light to come on, or for any codes to appear. I did a resistance check on the suspect coil and another (presumably good) coil and found that on the suspect coil there was a measurable resistance (less than 200 ohms) between the high-tension terminal and each of the primary (low-voltage) terminals. The "good" coil had no such resistance. I then bought a new coil at a dealership ($81 plus tax) and tested it. It also did not show any resistance between the high-tension terminal and the 2 low-voltage terminals. I installed the new coil and the other "good" coil and started the engine. It ran and idled smoothly. So the secondary (high-voltage) winding of the transformer had developed a short to the primary (low voltage) winding. The low-voltage winding measured about 1 ohm, but I wasn't able to measure the secondary winding because I couldn't figure out where to measure the opposite end of the coil (is it connected to the metal body of the transformer?). I can see why it didn't generate a coil fault because the primary winding didn't fail (ie it didn't open up). Well, that was a relatively easy fix, not requiring any expensive tools, or any servicing at the dealership. > To re-cap a little, my '00 300M abruptly started to run rough 2 days > ago, obviously one cylinder wasn't working. [quoted text clipped - 23 lines] > each of the primary (low-voltage) terminals. The "good" coil had no > such resistance. Just a little correction of your terminology: What you observed was "*low* resistance" (or high conductivity) between the secondary and primary. > I then bought a new coil at a dealership ($81 plus tax) and tested > it. It also did not show any resistance between the high-tension > terminal and the 2 low-voltage terminals. Again, you would say it didn't show any conduction... (or you could say it showed high, or "infinite", resistance...). Saying it "did not show any resistance..." technically means it was shorted, which I know you weren't meaning to say. > I installed the new coil and the other "good" coil and started the > engine. It ran and idled smoothly. Way to go! Sometimes an educated guess pays off. Reminds me of when I was in Navy electronics school over 35 years ago. They taught us troubleshooting methods. The book said to start where you have good signal, and move forward in the circuit with your troubleshooting equipment until you loose the signal. The point at which you lose it is where the problem is. So for one of our tests, they had these radios in the lab specially built for training purposes that they would put a bad part in, and we would have to find the bad part using the troubelshooting techniques we were taught. On a hunch, instead of starting at the front end and working my way to where the signal was lost, I sarted at the bad output end and worked my way backwards until the signal was good. Just so happens the bad part was very near the output end of things. So I finished the test in record time. Should have gotten a real high score, right? No! They gave me a failing grade because I worked my way backwards instead of the way we were taught. They didn't want people thinking outside the box. LOL! Anyway - glad you got it fixed. Bill Putney (To reply by e-mail, replace the last letter of the alphabet in my address with the letter 'x') > I can see why it didn't generate a coil fault because the primary > winding didn't fail (ie it didn't open up). Interesting! I still would have suspected that it would set a coil code in that case, because the computers (I'm pretty sure) look at more than just the primary resistance. They look at the current rise time, and that should have been way off. But then, I'm thinking first-gen 3.5, and maybe they deleted the rise time measurement when they added more sophisticated misfire detection by looking at the crank speed vairation. > Well, that was a relatively easy fix, not requiring any expensive > tools, or any servicing at the dealership. Bravo! And much better than having try to diagnose a fuel injector problem. > > Well, that was a relatively easy fix, not requiring any expensive > > tools, or any servicing at the dealership. > > Bravo! And much better than having try to diagnose a fuel injector > problem. I called a non-Chrysler service garage (Canadian Tire) and asked specifically about fuel injector issues, and whether they test or clean them. Answer was that there's basically only one place in town that tests injectors (and everyone, maybe even the dealers too, send injectors there for testing), and that plugged injectors are VERY rare. Based on that, I refocused on the coils. > To re-cap a little, my '00 300M abruptly started to run rough 2 days > ago, obviously one cylinder wasn't working. [quoted text clipped - 23 lines] > each of the primary (low-voltage) terminals. The "good" coil had no > such resistance. Your lucky. My last failed coil failed by arcing internally, the problem wasn't visible with a DVM. Ted > Your lucky. My last failed coil failed by arcing internally, the problem > wasn't visible with a DVM. > > Ted Wouldn't any of the old 'ignition analyzers' that used to be popular show the reduced high voltage? Then again, those old analyzers are probably getting hard to find. I had a GLH-Turbo years ago, and had a misfire problem. Two dealers couldn't find it. One wanted to 'shotgun' the problem at my expense. At least he was honest and told me it was a shotgun fix. NEITHER dealer even was close to the problem. The car had about 80K on it so it was way out of warrantee. One day the car was missing and backfiring so bad I brought it home and went in the house to get stuff to look. Came out, it was fine. The only thing that made sense was the engine warmed up. So I tried to cool it down with cold water on the radiator. Still was fine. So, I got to thinking. It was foggy and damp that day. So I took the hose and fine misted in front of the air intake around the headlight. The car really started misfiring. Stopping the mist didn't stop the misfire. I almost went into a panic. I took a hair dryer and blew hot dry air at the light. The problem cleared up in seconds. I thought it was something in the throttle body, so I disconnected the air hose and tried it there. That didn't affect the problem. Turned out they had placed a circuit board in the air tube right behind the headlight. The board was encased in epoxy with one transistor sticking out and corroded. Guess what? That transistor fired the coil! I was going to try to fix it, but I picked up a complete board and duct assembly at the junkyard for less than $50. |
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