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98 Camaro misfire


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TheOrangeSkittle
New User

Mar 19, 2016, 3:34 PM

Post #1 of 10 (943 views)
  post locked   98 Camaro misfire  

Hello my first time posting here, my 98 camaro v6 3,8l had a check engine light so took it to autozone and scan tool said it had bad egr valve bad o2 sensor and a misfire, got new egr valve and the only code that shows up is the misfire on cylinder 4, o2 sensor code went away with egr valve. Have put a new set of coil packs on, new spark plugs, checked for vacuum leaks and nothing has changed, car will shake while idling but the engine sounds normal to me, doesnt backfire accelerates fine, a mechanic next door came over and he looked at it and felt the engine while running and said it feels like it has a slight misfire but he cant tell what it would be, took it to dealership and they said they have no idea either as fuel pressure and compression is also okay, the only thing they found was front tires need aligned slighty but cant see why it would misfire. So With all of that tried would anyone here know why it would do this? the guy at the dealership said theyd have to tear down the engine to find out for sure. The car has 200,000 miles on it and I got it like that, it sounds fine on road has 0 problems with power it accelerates fine but shakes alot when accelerating sometimes, it doesnt while decelerating though. I think maybe 02 could still be bad enough to make misfire but not show up as it failing on codes? not sure if that could happen though. any help is much appreciated! thanks


Discretesignals
Ultimate Carjunky / Moderator
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Mar 19, 2016, 4:50 PM

Post #2 of 10 (936 views)
  post locked   Re: 98 Camaro misfire  

O2 sensor shouldn't cause a single cylinder misfire. I don't agree with tearing the engine down to determine what is causing your misfire unless they determined it was some type of mechanical problem causing it.

Someone needs to do some testing to figure out what is causing the misfire on 4. I think you should try a different shop that specializes in drive-ability issues.





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(This post was edited by Discretesignals on Mar 19, 2016, 4:51 PM)


Tom Greenleaf
Ultimate Carjunky / Moderator
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Mar 20, 2016, 3:09 AM

Post #3 of 10 (925 views)
  post locked   Re: 98 Camaro misfire  

200K known? Open book exam IMO. What can pick on ONE cylinder by miles/wear and show good compression? First what were the pressure results both dry and wet of the compression test. I wouldn't fake it but rather have real results not just cylinder cranking forces measured if so.
Enough miles I'm leaning towards plain mechanical if you are convinced of no vacuum or other faults have been found. Things like a lobe in cam worn, weak valve spring especially exhaust.
If dealer had all the plugs out what comments were made on how they looked?
If you don't have results it needs to be done.
IDK - they suggested a complete teardown and I also disagree. You should be able to pin this down without going that far and if so for that much work why even put that engine back in?
Some ramblings: I would first because I have them check temp of exhaust manifold while idling on #4 and one that doesn't misfire proves it. Should read about 400-450F and it wont unless it's been firing we know it doesn't but may with a load on it sitting still and if so go onward to removing a valve cover checking plug, valve spring and measure even crudely the lift of camshaft from just there,


T



kev2
Veteran
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Mar 20, 2016, 7:03 AM

Post #4 of 10 (918 views)
  post locked   Re: 98 Camaro misfire  

always post ALL the codes for us to consider a outcome. Definitions from autozone et al are aimed (skewed) to sell PARTS !
before you tear into it there are some tests to be completed, questions answered .
I agree 100% with colleague a different shop is suggested.


TheOrangeSkittle
New User

Mar 20, 2016, 8:07 PM

Post #5 of 10 (901 views)
  post locked   Re: 98 Camaro misfire  

p0304, that was the code I think, autozone and the dealer got the same one.


TheOrangeSkittle
New User

Mar 20, 2016, 8:13 PM

Post #6 of 10 (900 views)
  post locked   Re: 98 Camaro misfire  

They didnt really give results to any of it so its really debatable if they did it or not, all they said was all the compression and hoses and pretty much every minor problem that could be it isnt it. It has an lt1 engine btw.


Tom Greenleaf
Ultimate Carjunky / Moderator
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Mar 21, 2016, 2:25 AM

Post #7 of 10 (889 views)
  post locked   Re: 98 Camaro misfire  

? No results! Another shop needed. This has 200K and doesn't fire on one cylinder so all they've told you is tear it all apart is a cop out to me.
You might think what do you expect at the miles how an engine should be or could be and have no results of any testing in hand so doubt much was done also.
I'm done with this stuff for the most part but still do some. As already said and more you can tell tons by the look of a spark plug and you know which one or actually a simple temp test or vacuum reading tell more then you can tell a lot more removing just a valve cover on mechanical for valvetrain. If shop and or the tech(s) have a scope (wish I did for the years of working meaning the thing you can use to look thru now on a screen even capture a pic of what its seeing) don't need that much just a credible check, view or test none of which has happened IMO.
Think: The term "teardown" to me means take it all apart which is a total dismantle! So great - you measure bearing, piston, cylinder wall wear that all can be pretty well known without going that far and if you did and found it worn then what? Put it all back together? I can't see the value in that on that engine and can't say from here with your info if it's still minor or plain beginning of a worn out engine - they aren't helping you help me anyway.
I need to re-read what you first said if I missed anything that would be another clue. Clearly I'm focused on the miles and have known many plain wear out, sludge out long before that much and others still behave and test like 1/2 of that from exceptional care and always some luck. Is 300K in the cards? Yes or no still but how much $$ do you want to put in it vs another whole car if your specific want for this exact one or what? All considered need someone to do some real checking which I haven't seen yet and back to another shop if this is all you have to make decisions on from those that say they did anything,


T



kev2
Veteran
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Mar 21, 2016, 7:07 AM

Post #8 of 10 (879 views)
  post locked   Re: 98 Camaro misfire  

you need a professional technician to assist you - a misfire should NOT be a mystery.
You need to decide which engine - A 3.8L a LT1 or maybe a LS1 but should know a v6 or v8 at least?


TheOrangeSkittle
New User

Mar 24, 2016, 4:14 PM

Post #9 of 10 (850 views)
  post locked   Re: 98 Camaro misfire  

Hello so this is an update on the matter for anyone else with similar problem. Dealer said car had nothing wrong with it on the outside so engine teardown was necessary, local mechanic said the same thing pretty much, neighbor specializes in gm motors and said it is misfiring but its almost unoticeable and he thinks its the fuel injector as its the most common problem with that year of camaros in his shop but I dont really feel like taking the engine apart to fix it as its most likely something like a burnt valve, valve spring bad etc..

Thank you for all the help! but I think im just gunna sell the car as I dont like it enough to take the engine apart and fool around with it anymore.


(This post was edited by TheOrangeSkittle on Mar 24, 2016, 4:20 PM)


Discretesignals
Ultimate Carjunky / Moderator
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Mar 24, 2016, 4:22 PM

Post #10 of 10 (843 views)
  post locked   Re: 98 Camaro misfire  

Thank you for the follow up. Too bad they couldn't isolate your problem. Good luck on your next vehicle purchase and be sure to have your mechanic or reputable repair shop check it over before you buy it, so you know what your getting yourself into. Closed as OP is getting rid of vehicle. Can be reopened upon request by the OP.





Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.






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