2002 Firebird engine miss

[Tubingluvr]

I have a 2002 Pontiac Firebird with a bad engine miss.
Misfiring on Cylinder 3....I have put in new plugs and wires and checked the primary and secondary resistance on coil pack and did a compression check and everything checks out fine.

Misfire on cylinder 3 is the only code it is throwing.
I have a snap-on Fast trak graphing scanner so i can see what all the sensors are doing and everything looks fine.

I am thinking intake gasket..........what do you think?

Oh I am sorry, forgot to tell you......it has a 3800 (series 2) with 133,000 on it.
Is this engine known for intake gasket problems like the 4.3......I believe the 3.1,3.8 and 4.3 are all the same block, just different bore and stroke...right?

 

[Jhoppy]

Re: 2002 Firebird engine miss

All internal combustion engines must have spark, compression and fuel in order to run even in today?s electronic filled cars. You must check for all and find out what you are missing, to find out why you are missing. You must check spark at the end of the plug wire to find out if you are getting spark that far. If you are getting spark then a compression test on that cylinder would be in order. Then you can test for fuel/Lack of fuel or vacuum leak problems. Try spraying a little carb spray down the intake, if the engine speeds up lack of fuel is your problem. You can test for vacuum leaks externally with carb spray and you can test for vacuum leaks internally by plugging off the pcv port on the engine, plug the crankcase breather port on the engine and hook a vacuum gauge to the dip stick tube. If you see vacuum in the crankcase then intake gasket leak is likely your problem, if you see more than a couple of pounds of pressure then the engine is internally worn. If you find no dice so far then check to see if the injector is getting a signal to spray fuel, you can get a set of noid lights from the auto parts for about 20$ they are just a light bulb that check the circuit of the injector. You just unplug the injector and plug in the correct noid light, You should see it flash. You also could try and tap on the injector lightly, they can sometimes stick and that will free them, If it did put some seafoam in you gas, change your fuel filter and buy better gas. Let us know what you find.

The 4.3, and 3.8 are different blocks, the 3.4 and 3.1 are the same.

hoppy

 

[TilliamWe]

Re: 2002 Firebird engine miss

...
Is this engine known for intake gasket problems like the 4.3......I believe the 3.1,3.8 and 4.3 are all the same block, just different bore and stroke...right?

Yes, the 3800 is one of the engines affected by the intake manifold gasket issue.

No, as partially explained above those engines are NOT the same, not even close.
The 3.8 is/was Buick engine from the 1960's, that has been extensively modified. 90 degree V, and originally an even fired cranshaft.
The 4.3 is based on the small block Chevy V-8. 90 degree V, same bore/stroke as the 350 (5.7), with cylinders #3 and #4 removed.
The 2.8, 3.1, 3.4, and now the 3.5 (in Impalas) are 60 degree V-6 blocks developed in the early 1980s.

"All" GM engines got the intake manifold gaskets that were troublesome. My 1997 Mercruiser 5.7LX EFI Gen + even had them!

Are you experiencing and unexplained coolant loss? Does your engine oil have antifreeze contamination? Does your engine temperature seem too low all the time? Those are the tell tale signs of intake gasket failure.

 

[windsors03cobra]

Re: 2002 Firebird engine miss

Pretty sure this will have the crappy Delphi pencil injectors I think in the early 2000's the offshore built Delphi injectors started being implemented lots of those died and had to be replaced. I usually just replace them 1 at a time.

That badly designed/cheaply made lower intake gasket affected just about every GM V enigne design from the mid 90's till the 2000's
Loved that one I read on here the other day 2 types on engines, ones that have had the gaskets changed and ones that need the gasket changed.
I think most GM V engines are a dry intake now, the Vortecs are for sure.

 

[TilliamWe]

Re: 2002 Firebird engine miss

...
I think most GM V engines are a dry intake now, the Vortecs are for sure.

Yeah, ever since they did away with TBI on the V8s, "everything" should be "port injection" now.

I, too, liked the line about the two types of engines!

 

[Tubingluvr]

Re: 2002 Firebird engine miss

Figured it out......did some checking on the internet and found out that the coil pack can check out all right when sitting in the driveway, but will fail when under load.

So i switched the front and center coil packs around and the miss moved from cylinder 3 to cylinder 5.

Coil pack appears to be the culprit.

Thanks for all your help though.

 

[Jhoppy]

Re: 2002 Firebird engine miss

Sounds good that you figgued it out

Sorry but I hate to bust the dry intake vortec bubble but even though GM stopped running water though the intake on the newer motors, the gaskets did not get better. They are known for leaking vacuum when cold and causing cold drivability issues. They are no fun to try and find a leak on either, it is really hard to catch.

Hoppy