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Car Forum / Chrysler Cars / November 2007Diagnose engine misfire problem
This is a Town and Country 2003 van (3.8L). It ran fine then the next day when I started it, it didn't run smoothly. The car shakes a lot. Check engine line came on and I smelt gas. So, I shut down. I read the code and it has 3 codes. 1 code is random engine misfire. The 2nd code is cylinder 3 misfire and 3rd code is cylinder 4 misfire. So, I disconnect batter and replace all the spark plugs with a platinum (2 prongs) spark plug. The service manual says platinum type is the one, but the old spark plug from the car is coper type (I believe, based on the look of it). Put everything back and starts. The car no longer shakes, but the engine is not smooth. I plugin the code reader and get a check engine light is on, but no code. So I press clear on the code reader, which said it can't do that. But read again, there is no code and check engine light is off. I unplugged the wire to the spark plug of cylinder 4, and plugged it into a test spark plug. Started the engine. Sparks came out of the thing. Plugged back and I drove around a couple block to see if the problem goes away. Engine still rough, not smooth, and still no code when read. I no longer smell gas. How do I go from here for finding out what the problem is? What's the most likely cause for this? Fuel system? What would a mechanic do from here? if you used bosch spark plughs get rid of them they foul out real easy > This is a Town and Country 2003 van (3.8L). It ran fine then the next > day when I started it, it didn't run smoothly. The car shakes a lot. [quoted text clipped - 21 lines] > most likely cause for this? Fuel system? What would a mechanic do > from here? Unfortunately, I think that's what I got. However, I don't think I can return it, because I already use it. Do you think I can do that? Do you think that it's bad already that causes the current problem? > if you used bosch spark plughs get rid of them they foul out real easy man i can't tell you how many people come to my shop and they say they just did the plugs themselfs and 95 % of the time they are bosch our first question to the customers is did u use bosch plugs!second is plug wires that failed esp. on gm cars > Unfortunately, I think that's what I got. However, I don't think I > can return it, because I already use it. Do you think I can do that? > Do you think that it's bad already that causes the current problem? > > > if you used bosch spark plughs get rid of them they foul out real easy > This is a Town and Country 2003 van (3.8L). It ran fine then the next > day when I started it, it didn't run smoothly. The car shakes a lot. [quoted text clipped - 21 lines] > most likely cause for this? Fuel system? What would a mechanic do > from here? Take the vehicle out and get it hot, going about 40mph come to a coasting roll for about 20sec and then check to see what the engine fault code says. Chances are the plug wires are bad. The adaptive numerator may have to be learned in order to detect what cylinder is misfiring. and coming to a coasting stop will learn it Glenn Beasley Chrysler Tech I took the car out this morning and drive it to hot. Also, I drove it at different speed, including highway, 45mph, and slow with many stops. I have tried to coast many times, but had to use the brake eventually because I didn't have the distance, and morning traffic. However, the engine light does not come on. I'll read the code tonight. When the engine is hot, it seems to run more smoothly. However, when comes to stop, it is still not smooth, but not as rough as when started. > Take the vehicle out and get it hot, going about 40mph come to a coasting > roll for about 20sec and then check to see what the engine fault code says. [quoted text clipped - 4 lines] > Glenn Beasley > Chrysler Tech I got the check engine light on again. This time, the code is cylinder 3 misfire. How would I go about to trouble shoot this? I am thinking of measuring the resistance of the cord connecting to the spark plug. Is this the way to do it? > I got the check engine light on again. This time, the code is > cylinder 3 misfire. How would I go about to trouble shoot this? I am > thinking of measuring the resistance of the cord connecting to the > spark plug. Is this the way to do it? By disconnecting the battery you erased the learned adaptive numerator memory and all the rest your monitors. Therefore it would not show you what cylinder was misfiring. That's why you should not do a battery disconnect!! More then likely you have a plug wire that is causing the problem. you can either go out and purchase a good set of wires to see if that takes care of the problem or try switching number 3 wire with number 4 wire. If the misfire now shows number 4 cyl misfiring then you know for sure the plug wires are at fault. Glenn Beasley Chrysler Tech or since you changed plugs you could swap plugs first > > I got the check engine light on again. This time, the code is > > cylinder 3 misfire. How would I go about to trouble shoot this? I am [quoted text clipped - 12 lines] > Glenn Beasley > Chrysler Tech That's an excellent suggestion. I'll try that out. I was working for the whole weekend. The cylinder 3 is inside, which means I have to take the wiper rack out. I'll try to get that done as soon as possible. Thanks. > or since you changed plugs you could swap plugs first > That's an excellent suggestion. I'll try that out. I was working for > the whole weekend. The cylinder 3 is inside, which means I have to > take the wiper rack out. I'll try to get that done as soon as > possible. Thanks. > > > or since you changed plugs you could swap plugs first You don't need to take the wiper module out to access plugs and wires on this vehicle. Just swap the plug wires and you will more then likely see the misfire went to the other cylinder. DO NOT disconnect the battery Glenn Thanks for the suggestion. I have swapped the wire, same problem. The same thing happens when I swap the spark plug. The cylinder 3 still misfire. I also put in a brand new Mopar ignition coil. The problem still persist. I notice that after running for a while, when the temperature stabilized for awhile, the misfire appears to be gone. I even brought to a local shop. They asked me to replace the ignition coil, the spark plug, and the wires, and air filter, and gas filter. I thought to myself, I can do all that. The point is that they must know which is the bad one, and replace/fix that, not just replacing everything. From the test, the wires appear to be good, same for the spark plug. I can't imagine the ignition coil is bad, given it's brand new. So, these mechanics doesn't know what they're doing, or they're trying to fool me. I took the car back. Now, I want to give it a last shot before bringing it to another autoshop. I want to go by the book. I have the diagnostics book from the manufacturer. It appears that other problems could be gas related. Some of the steps (about 18) asks me to check the pressure of gas, which means I have to access to the fuel rail (do I?). The diagnostic book doesn't say this, but I imagine that swapping the fuel injectors would give me some indication too, is that a correct assumption? I already bought the pressure gauge. The question is do I have to to take out the upper manifold to do this? How about the lower manifold? Taking out the lower manifold is very tedious. I have to drain coolant. It (the book) asks me to replace the gasket everytime I do this. Sure, I can replace it, but for diagnostics? Also, if the fuel injector is the culprit, then do I have to take out both manifolds? Please help. > > > or since you changed plugs you could swap plugs first > [quoted text clipped - 3 lines] > > Glenn > Thanks for the suggestion. > [quoted text clipped - 45 lines] > > > > Glenn First of all, are you the same person I replied to a month ago or are you just replying to this thread? what engine? Fuel pressure wont cause a cyl misfire on one cylinder!! Go back to basics......you have to have fuel pressure, I assume you do because the vehicle runs and you aren't getting a multiple cylinder misfire. assuming that you have spark on all cylinders because you aren't getting a primary ign fault code. the next step before throwing any other parts at this would be to check compression on the effected cylinder. If I were to bet I would say you have low compression. Glenn Thank you for the reply. Please see inline comment below. > First of all, are you the same person I replied to a month ago or are you > just replying to this thread? Yes, it's the same me. > what engine? Fuel pressure wont cause a cyl > misfire on one cylinder!! Go back to basics......you have to have fuel > pressure, I assume you do because the vehicle runs and you aren't getting a > multiple cylinder misfire. assuming that you have spark on all cylinders The first time I got the problem, use the OBD to read, I got multiple engine misfired, cylinder 3 misfire, cylinder 4 misfire. Now, I got cylinder 3 misfire. > because you aren't getting a primary ign fault code. the next step before > throwing any other parts at this would be to check compression on the > effected cylinder. If I were to bet I would say you have low compression. > > Glenn I'll check the compression on the cylinder 3. But first, I have to learn how to do that. Below is for your reference of the steps the diagnostic book said. It applies to all P030x misfire problems. 1) Visual check: worn serpentine belt, binding A/C compressor, P/S pump (I just replaced this a while back, wonder if the rebuilt part is bad, not problem with steering power though), water pump. Misalignment water pump, P/S pump, A/C compressor pulleys. Corroded PCM power and circuits. Improper CKP, CMP, MAP and TP Sensor mounting. Poor connector for CKP sensor, fuel injector, ignition coil, etc. Vacuum leaks. Restricted Air induction system or exhaust system. 2) Ign off, disc ign coil connector, disc the fuel injector connector, ignition on, engine not running, use test light probe A142 ASD relay output circuit at the ign coil connector and fuel injector connector. I can see the ign coil connector and probe that. I think with just cylinder 3 problem, it can't be this. I don't know how to probe the injector connector as yet. I wonder if I have to take out the manifold(s) to get to that. 3) Ign off, disc. ign wire from spark plug. Disc fuel injector connector of the cylinder being tested. Install a spark tester on the ign wire. Crank engine, observe the tester. 4) Ign off, remove spark plug, visual check spark plugs. 5) Release the fuel system pressure. Install fuel gauge to fuel rail, start engine and observe the gauge reading. (334 KPa +/- 34 KPa) 6) Release the fuel system pressure. Install fuel pressure gauge, start engine until max pressure. Ign off, use clamp to pinch the rubber fuel line between the fuel pressure gauge and the engine. Monitor the pressure gauge for > 5 minutes. Replace the leaking fuel injector(s) if pressure is below spec (400KPa +/- 34 KPa) 7) Release the fuel system pressure. Ign off, connect fuel pressure gauge to fuel rail. Start engine until max pressure. Ign on, engine off, use DRBIII actuate the fuel injector for cylinder misfired. Check for drop in pressure. 8) Check: engine vacuum, engine valve timing, engine compression, engine exhaust system, engine PCV system, torque converter stall speed, power brake booster, fuel contamination, cam lobes, cylinder leakage test, valve springs. These are a lot of checks. I don't know how to do most of them. 9) Ign off, disc the fuel injector connector, ign on, engine not running. Use DRBIII erase DTC. Use 12 V test light connected to 12 volts, probe the injector control circuit. Use DRBIII actuate the fuel injector. If test light blink/flicker, replace the fuel injector. 10) Ign off, disc fuel injector connector, disc PCM harness connectors. Check injector control circuit for open, short. 11) Ign off, release fuel pressure, raise vehicle, disconnect the fuel pressure line at the fuel pump module, install fuel line adapter fuel pressure gauge between fuel supply line and the fuel pump module. Ign on, engine not running, use DRBIII actuate the ASD fuel system test, observer pressure gauge. Is within 400KPa +/- 34 KPa? Repair fuel supply as needed. 12) Ign off, release fuel press., remove fuel pump module, check fuel inlet strainer for plugged. Replaced if so. 13) Ign off, measure resistance of ign wire. Is it below 10K ohms? Replace if above 14) Ign off, disc ign coil harness connector. Remove the fuel pump relay or ASD relay. Use 12 v test light connected to 12 volts. Probe the ignition coil control circuit. Crank the engine for 5 seconds while observing th test light. If light brightly blink, replace the ignition coil. 15) Ign off, disc ign coil narness connector. Disc the PCM harness connectors. Check the coil control circuit for open, short to ground, short to voltage. Repair as needed. 16) Inspect wire, repair as needed. Replace and program the PCM. > Thank you for the reply. Please see inline comment below. > [quoted text clipped - 101 lines] > > 16) Inspect wire, repair as needed. Replace and program the PCM. You have pulled this test from a Chrysler Diagnostic Manual and without the DRB it is useless. Perform a compression test on the effected cylinder(s) The only way fuel pressure would affect one cylinder would be a stopped up/inop injector. Glenn Compression test will be my 1st priority this evening. Just to think ahead, what would I do next if the compression test fails? Succeeds? > You have pulled this test from a Chrysler Diagnostic Manual and without the > DRB it is useless. Perform a compression test on the effected cylinder(s) > The only way fuel pressure would affect one cylinder would be a stopped > up/inop injector. > > Glenn The passed weekend was hectic for me. I had to work in the weekend. A few errands turned up. A loss of a family member. I couldn't get this done, other than got my self a real compression test kit (I thought I had one, but it's a fuel pressure meter). If I have time tonight, I'll do that (besides changing the oil on the other car). I have a few questions though. The factory service manual said to test while hot. This means, I probably needs to take the wiper module off, right? Because I'll get burnt taking out the spark plugs with little space. Is there a better way to do this? The more important question is that every guide I read, it says if the pressure is low, "squirt" a tea spoon of engine oil into the spark plug and test again. What does "squirt" mean? Like spray with some kind of pressurized bottle, or with a hand lever? I called advance auto parts, and they don't know what I am talking about. I don't think "squirt" means just pour the liquid in. What do DIYers use for this and where do I get it? Thanks. >If I have time tonight, I'll do that (besides changing the oil on the >other car). I have a few questions though. The factory service >manual said to test while hot. This means, I probably needs to take >the wiper module off, right? Because I'll get burnt taking out the >spark plugs with little space. Is there a better way to do this? I would do the test on a cold engine just so I didn't burn myself. While you might be a more accurate number on a warm engine in the big picture you are more concerned about differences between the cylinders than the actual number. Make sure you disable the ignition system and block the throttle open to run the test. Keep the battery charged up so that the engine is spinning at the same speed for each cylinders test. >The more important question is that every guide I read, it says if the >pressure is low, "squirt" a tea spoon of engine oil into the spark [quoted text clipped - 3 lines] >think "squirt" means just pour the liquid in. What do DIYers use for >this and where do I get it? Thanks. Just get the oil in there. You can squirt it in using an oil can if you have one available and are able to get it in there. I usually use a piece of clear hose and a funnel... Stick the end of the hose in the sparkplug hole then pour a little oil in the funnel. You want to give it a little crank to distribute the oil before you test again. Basically you have a big empty hole and you just need to get some oil in there. In case you aren't aware... You put the oil in and test again if you have low compression to test the rings. Oil will help seal worn leaky rings so the numbers go up. If the numbers don't go up with the oil then you have a valve problem or a really big problem with the rings. Steve B. Thank you Steve. That was helpful. Reading your post, I feel like listening to my older brother in a good way. The results are in. The compression test passed. Here they are: Cylinder:Pressure (PSI) 1 : 192 3 : 195 5 : 200 2 : 190 4 : 190 6 : 180 The trouble cylinder 3 has 195, which is within 2.5% of the highest cylinder 5 of 200, and the cylinder 6, with the lowest pressure has 180, which is within 10% of the highest. This is cold engine test. So, what could be the culprit here? Is it the bad fuel injector? If that is the case, do I just remove the upper manifold (not the lower manifold) to replace this? Thanks all. > >If I have time tonight, I'll do that (besides changing the oil on the > >other car). I have a few questions though. The factory service [quoted text clipped - 34 lines] > > Steve B. I plan on order a fuel injector from partstrain.com: http://www2.partstrain.com/v5/products.php?N=4294964613+1589+4294967162+5657 I'll do that as soon as I figure out the exact item to order. Right now, the same SKU# SIFJ478 is used for both Original Equipment # 4861238AA and Original Equipment # 4861238AB, which is confusing. I need advice on these "Standard" made injectors. Are they good? How do "Standard" auto parts compared to OEM parts? Is "Standard" just "standard", or it's actually a trade name? Also, please tell me if anything else I can test before change this because I don't want to change it to find out it's not the one causing the problem. My previous question about "should I take out both the upper and lower intake manifold to replace the injector" did not get any answer. Any help here? Thanks. I am so disappointed right now. Just feel disgusting some how in my stomach. I am sorry for saying this. I just replace 3 fuel injectors, for cylinders 1, 3, and 5. Same problem! The replace and hope method just doesn't cut it. There has to be a way to test these things the right way. This is a very funky problem. I took it to an auto service center. They have been looking into it for 3 hours, and haven't figured it out. They have changed the sparks and wires. Also test pressure again and they said there's signal in the fuel injector electric wire. I'll update if they find anything, or any news on this. I am sorry for the last post. It was a moment of frustration. I didn't mean to aim that at anyone. You're all been very nice and helpful. The mechanics gave up on this. I'll go to the dealer next. > This is a very funky problem. I took it to an auto service center. > They have been looking into it for 3 hours, and haven't figured it [quoted text clipped - 5 lines] > didn't mean to aim that at anyone. You're all been very nice and > helpful. So, I took it to a Chrysler dealer. Initially, they asked for $100 to look at the engine problem. Later, ask $250 to open it up and look inside. They still can't find out the problem. They suggested to open more (cylinder head, or something like that) for $400 or replace the engine for $3600 (with 3 years warranty). They also mentioned of the cost of rebuilding would be $2500 with 1 year warranty. That's after 4 days of looking into it. I paid them $250 and took the car home. I took it to a mechanic that I know, couple hundred miles away. He said the knock appears to come from a cam that developed a hole in it (due to some manufacture defects). He replaced the engine. He said he opened it up and it was the problem. The car runs fine now. I wonder if that problem can be fixed or replaced locally to lower the cost instead of replacing the whole engine. Anyone familiar with this mind to share? why not just replace the cam and lifters??? > So, I took it to a Chrysler dealer. Initially, they asked for $100 to > look at the engine problem. Later, ask $250 to open it up and look [quoted text clipped - 13 lines] > replaced locally to lower the cost instead of replacing the whole > engine. Anyone familiar with this mind to share? > This is a Town and Country 2003 van (3.8L). It ran fine then the next > day when I started it, it didn't run smoothly. The car shakes a lot. [quoted text clipped - 21 lines] > most likely cause for this? Fuel system? What would a mechanic do > from here? I have a 98 caravan with the 2.4l 4cyl. I was getting a random misfire and I put di-electric grease in both ends of the sparkplug wires and that stopped the misfire. |
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