Cylinder misfire help

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Old 08-27-09, 08:19 PM
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Cylinder misfire help

Ive got a 97 Monte Carlo 3.4L engine. Check engine light started coming on last week. Had the code read and it was cylinder 2 misfire. Checked the plug and wire, everything looked ok. Swapped plug wire with cylinder 4. Code still reads cylinder 2 misfire. Swapped the spark plug with cylinder 4. Still reads cylinder 2 misfire. So taht pretty much leaves the coil pack as being bad right? Aside from something internally wrong which I doubt. There are 2 cylinders on each coil. 2 and 5 are together. Can just one side of the coil be going bad since I am not having trouble with cylinder 5 at all? Thanks
 
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Old 08-27-09, 09:50 PM
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Missfire

Is it a throttle body or port injection, also consider running a compression test. It helps to know you still have a good engine to start with.
Bill
 
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Old 08-28-09, 08:57 AM
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I am not sure if its throttle body but I believe it is. I have no way of doing a compression check. Vehicle runs ok at speed. Just hesitant at excelleration. I have no reason to think that the cylinder itself has a problem.
 
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Old 08-28-09, 09:31 AM
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Misfire diagnosis

You indicated that the car has a repeated code for a cylinder misfire at position 2 despite attempts to move the miss by moving components. That a situation exists at cylinder 2 that still is problematic. A port injected motor could have an injector that is cylinder specific based on an injector problem as well as a cylinder mechanical problem. You as the owner have to be proactive in the diagnostic process as none of us can see or touch the car. That makes a compression test etc your test, not ours. Automobile diagnosis and repair is a thing that requires hands on procedures and as I stated your it in this situation. A single cylinder misfire in a V-8 will delete 1/8 of the power available at the time of occurance so a hesitation would be a possibility.
Bill
 
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Old 08-28-09, 11:09 AM
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the guys at the monte carlo forum have no issues helping me with my questions. So thats where I will be going Bill. The whole point of the forum is for guys that know to help guys that dont. Ive worked very little on my monte in the 10 years I have had it so I dont know much about it. I am aware that the problem is my problem. Never said it wasnt. Never asked you to do anything for me. I suspect you wouldnt know if I did.

Thanks to the others that answered to help me and not being like Bill is.
 
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Old 08-28-09, 11:27 AM
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Was gonna say swap coil packs..but it appears you only have one coil? (going by what Autozone says...not familiar with the car.) Seems like you are saying you have 3...I imagine they are identical?
 
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Old 08-28-09, 03:38 PM
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Gunguy,

thanks for the help. As a gun guy myself, I have to like your name.

I do have 3 coils. The coil in question controls cylinders 2 and 5. No problems on cylinder 5 though.

I did a resistance check on the fuel injector for cylinder 2 and it reads the same as the other two I can easily access. 13.6 ohms.

Coil pack swap seems to be the next step. Thanks for your help
 
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Old 08-28-09, 03:48 PM
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Back to basics for a moment.....

Air, Fuel and Fire....

AIR ...as TIJOE has mentioned, a compression test should be done to ensure the engine is capable of performing properly.....

Fuel...Just because there is pressure at the rail , means nothing if it doesnt get into the combustion chamber to be burned. The lack of a "200" series Trouble code pretty much (But not entirely) eliminates the electrical feed and driver circuits to the injectors....A 3400 engine for 1997 SHOULD be sequentially injected PORT...Not a T-Body...

Fire...You have swapped plugs, and wires.....from offending cylinder to other positions with no change.....You have 3 individual coils mounted to your Module.....Which are a BEAR to remove, even with the engine ICE COLD..... If you suspect only half of a coil is working...which is possible....Try swapping the wires around on the pack....and only the Pack.....Remove the #5 wire and put it on the #2 Tower...and vice versa with #2.....Now see if your misfire moves.....
 
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Old 08-28-09, 04:09 PM
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i could be your injector is scored or just dirty causing the fuel being sprayed into the cylinder to stream.

if partially clogged then it would missfire during a load or increased rpm, but run fine at idol.


with what i have encountered with fuel injection is there is usually problems with fuel and ignition (fire) and not so much with air, but that`s just what i`ve encountered.

we had a diesel truck with a bad injector and it sounded like the connecting rod had broken in half.
 
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Old 08-28-09, 09:13 PM
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printer man,

just as a lets see what happens kind of thing, I put in two bottles of fuel cleaner and ran out on the hwy for about 30 minutes. Seems to be less hesitation but there is some still there. Might be a badly dirty injector. I will go ahead and run it another day or so and see if it gets even better. Might just have cleaned up all the injectors and it feels like its running better??


Unclediesel,


I wish the 2 and 5 switch was as easy as it sounds. I have to take the intake, etc off to get to the #5 spark plug wire. #2 is right there in the front. Im just going to have to swap the coil packs and see what happens. Problem with that is one of the screws on the coil pack will not budge and Im rounding off the bolt head.

Actually, removing the coil packs on my car is quite easy. two screws each and they lift right off. Well except the one I need to remove has screw issues. May have to use an extractor.



Thanks for everyones ideas and help
 
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Old 08-28-09, 09:22 PM
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I wish the 2 and 5 switch was as easy as it sounds. I have to take the intake, etc off to get to the #5 spark plug wire. #2 is right there in the front. Im just going to have to swap the coil packs and see what happens. Problem with that is one of the screws on the coil pack will not budge and Im rounding off the bolt head.


Nope...Just swap the wires at the pack...Leave the plug wires where they are...

Each coil has a pair...1/4, 2/5. 3/6 ......I want you to do this.....1/4, 5/2 , 3/6.
 
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Old 08-29-09, 10:25 AM
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OK Uncle D, I will give that a shot and see what happens. Thanks
 
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Old 08-29-09, 01:06 PM
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Uncle D, swapped the spark plug wires at the coil for 2 and 5. Drove it half an hour. The check engine light flashed on at least one occasion then went back steady. I think that means a new code has come up when it flashes. Anyway, still reading cylinder #2 misfire. Never had anything show up with 5. So Im not sure what to do now. Guy at NAPA told me that it would have nothing to do with compression at all.
 
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Old 08-29-09, 01:42 PM
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Fixed a Corsica last year as a project car for sister's bf's daughter. Had a misfire and this was the cause (the one on the right). I actually salvaged it with a good cleaning:

 
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Old 08-29-09, 03:08 PM
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wow. Thanks for the info and pic. How did you get it cleaned so well?
 
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Old 08-29-09, 03:47 PM
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Tow guy beat me to it.......

Guy at NAPA told me that it would have nothing to do with compression at all.

Sansert... Very likely, and hopefully the NAPA guy is correct.....

BUT

Someone who is in the trade should NEVER make a remark like that....


You have a MISFIRE... which simply translates to "No Explosion In the Combustion Chamber" .... AIR , FUEL,AND FIRE.... Any of those three individually, or any combination of them, CAN AND WILL cause a misfire..... As a kid , I remember an old CAT IN THE HAT scenario..."The way to find a missing something. is to find out where it is not"...Until you can rule out , with absolute certainty, the offending peice of the puzzle, You have no Business "Dissmissing It". You have pretty much ruled out FIRE, and a compression test is easier than removing a fuel rail......
 
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Old 08-29-09, 07:09 PM
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your going to have to take the injector out to clean it.

most of the time those additives won`t cut it.

especially if it`s corroision or a chunk of rust.

if it was running better then the others were getting
dirty/clogged as well.

if they have high mileson them you may want to put all
new ones in. it could help your fuel mileage as well.
 
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Old 08-29-09, 10:57 PM
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I pulled the injector out. I see no build up or corrosion at all. Unless there is corrosion inside where I cant see it
 
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Old 08-30-09, 11:41 AM
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swapped the injectors from 2 and 4 around. Now getting a code 300 which is a multiple misfire reading. Do I swap them back and see if I am back to just code 302 cylinder 2 misfire?
 
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Old 08-30-09, 11:54 AM
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how about buying just the one new injector #2 if that`s the bad one and see what happens.

how many miles are on them?(the injectors)

if you need to replace one you should do them all if you have the time and money.

if you keep getting that code after replacement,you may need to un-hook the battery and then re-hook it to reset the codes.
that used to be something you had to do sometimes years ago when they first came out, or as someone told me to one time.

is the injector fireing at all on that cylinder?
maybe the plug to it is bad and it`s not geeting a signal from the computer to fire.
 
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Old 08-30-09, 12:39 PM
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Printerman, I swapped the 2 injectors back to their original spots and now I am just back to the code 302 cylinder misfire. No more multiple misfire code. So that tells me that #2 injector is bad but there may possibly be a problem with the coil pack or plug wire. I know the plug is good. Looks like a new injector for cylinder 2 and we will see what happens. I think there may be multiple problems with that cylinder but maybe not.

I had an injector replaced years ago on it but the others are all original and the car has 113K miles on it. The front three would be easy to change. The back 3 injectors require a lot more work. Plugs might be original too. I think that the number 2 injector is working based upon the fact that the car isnt running THAT bad. no rough idle. Just a stumble sometimes when I get on the gas.
 
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Old 08-30-09, 01:46 PM
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A code 300 is a none descript engine misfire determined by crankshaft speed fluctuation, any code 301, 302, 303 are cylinder specific codes recognizable at the ecu. Acode 300 is usually a misfire with less than 200 occurances.
 
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Old 08-30-09, 01:50 PM
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TiJoe


I still think that the injector in cylinder 2 is bad. Moving it created a multiple misfire situation. Leaving it where it was creates a cylinder specific situation. Vehicle ran worse with the suspected injector somewhere else as well. Would you agree with that?
 
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Old 08-30-09, 02:03 PM
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There is little doubt about it, depending on the milage on the vehicle I would probably recommend replacing all of them as the same particulate has passed through all of them. If not at least you will know where to look when another becomes a problem.
Bill
 
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Old 08-30-09, 07:28 PM
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now Im back to being confused. Cleared the last 302 code and GF took it out to her sisters. It came back with another code 300. No code 302. So maybe it isnt the injector? Maybe the coil pack is failing. Anyway, going to get the new injector and see what happens. Seems worse now and when its cooler. Getting tired if messing with it
 
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Old 08-30-09, 08:26 PM
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If I read your post you said the plugs are original, if so they need to be replaced, a visual inspection will not tell if they are good or not the only way to tell for sure is to run the engine on an oscilloscope with some one who knows how to read it. I know the factory recommends 80-100K miles but they don't have to buy the fuel. yes it sounds like you need a injector but I agree with the other posts at that mileage you should replace all injectors they will have microscopic amounts of wear that will affect the spray pattern after that high of mileage. And yes I know many go much more mileage than that. Last if you are going to keep working on this vehicle invest in a compression Gage. they are not that expensive and will give you a great deal of info about your engine. Most of the time a lot of head scratching can be avoided by running a compression test before throwing parts at a vehicle.

Murphy was an optimist.
 
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Old 08-31-09, 05:19 PM
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Well guys, good news. Got the @$#%!&^* problem fixed. Changed all 3 coil packs, and that just about eliminated all stumbling and power loss. Coil pack running cylinders 5 and 2 looked like it had gotten hot. Kind of bulged on the inside but not a lot. Changed the front 3 plug wires and plugs and it runs great. I will get the back 3 wires and plugs after it has cooled down. Have to remove the intake to get to those. At this point, never messed with the injectors again.


Thanks for everybodys help and suggestions.
 
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Old 08-31-09, 06:38 PM
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glad to hear it.

as everyone might agree, it`s hard to trouble shoot engine problems
without hearing it run, or visual inspection in person,
 
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Old 08-31-09, 07:21 PM
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In my line of work, I deal with tech support people on the phone alot and I wouldnt want their job for any amount of money. It would drive me nuts not being able to get my hands or eyes on something. Thanks again for your help!
 
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Old 09-01-09, 07:31 AM
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Amen. Had to talk my sister through replacing a ceiling fan speed pull-chain switch last night. Nearly lost what's left of my mind.
 
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