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OT: 2002 Chevy Impala 3.8 L misfire

E

eremoao

Member
You guys have always had all the answers before, so how about this one. Wifes 2002 Impala is pulling a 303 code, which is #3 cyl. misfire. Changed plugs and wires, still have the misfire. Pulled codes again, got a 303 and 108, which was the MAP sensor, so changed that, still have the misfire. I did pull the wire and check for spark, there is blue spark. Where do I go next. Coil pack for #3 and #6, or cat conv.? Or is there something else I need to look at.Hopefully the cyl. isn"t dead.
 
Can you switch the coil pack with one of the others just to make sure the coil is really good. If you got the compression gage would go ahead and check compression. my 2c. good luck
 
There are two types of 3800 engines from 1995 on, those with blown intake manifold gaskets and those that will have blown intake manifold gaskets.


http://townhall-talk.edmunds.com/direct/view/.f24da35
 
LMAO!! I think I used pretty much those exact words after the last time my dad and I changed LIM gaskets on a 3800. Between the 2 of us, we have each had 2 3800 cars, and 3 of those 4 cars have had the LIM gaskets replaced. I need to get the Deathcool out of the Grand Prix I have now before it starts leaking too.
 
An easy check would be to spray some choke cleaner around the edges of the intake manifold with it idling to see if it makes a difference. The next thing to check would be compression on all cylinders. You might have a faulty injector there, but I would bet it's a vacuum leak.
Good Luck and God Bless
 
A misfire is a change in the speed of the crankshaft relative to camshaft speed on that cylinder. When enough of a change occurs and the rate is above a predetermined level then a code is stored. That said it is either spark, fuel or mechanical. As stated run compression on all cylinders to get a baseline and rule out mechanical issues like a burned valve. then you can concentrate on air/fuel as it pertains to that cylinder. Intake gasket "etc." Gerard
 
(quoted from post at 18:44:46 05/18/12) You guys have always had all the answers before, so how about this one. Wifes 2002 Impala is pulling a 303 code, which is #3 cyl. misfire. Changed plugs and wires, still have the misfire. Pulled codes again, got a 303 and 108, which was the MAP sensor, so changed that, still have the misfire. I did pull the wire and check for spark, there is blue spark. Where do I go next. Coil pack for #3 and #6, or cat conv.? Or is there something else I need to look at.Hopefully the cyl. isn"t dead.
Click to expand...

If you are positive you have good spark and swamped wires plugs and coil pack and the miss did not move with them check injector pulse... If its a bad injector are its not being commanded to pulse you can here the difference between it and one that is working,,, A noid light would confirm it fast...

I had one a week ago just like it,,, a PCM fixed it....
 
New coil pack fixed it. Had me confused since there was only a misfire on #3 and not #6. I would have thought that if the coil went bad, it would not fire on either of the cyl. on that coil, but I was wrong. Thanks for the help.
 
(quoted from post at 01:23:02 05/20/12) New coil pack fixed it. Had me confused since there was only a misfire on #3 and not #6. I would have thought that if the coil went bad, it would not fire on either of the cyl. on that coil, but I was wrong. Thanks for the help.
Click to expand...

Then you had weak spark on that cylinder,, goes to show ya color is not a good indicator...
 
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