3.4L v6 Power Problems - Fourth Generation Pontiac Firebird (1993 - 2002) - Firebird Nation

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3.4L v6 Power Problems

power issues misfire

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4 replies to this topic

#1 WeLiVeR

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  • Engine: 3.4 V6
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Posted 2 weeks ago

Initially when I got it, 8 or so months ago it ran great; had plenty of power, everything was steady. Maybe for the last 3 months, it's been having issues accelerating, and misfires/chugs in 4/5th gear. 
In the early gears it runs great, until the engine gets up to normal temperature seems like.
If you ease the accelerator down, it runs great, but if it goes more than maybe 1/4th down it chugs/misfires again. When this is happening if the accelerator gets passed the 3/4th spot, it quits misfiring but has no power and won't go passed 3k rpm.
 
I've been learning as I go, trying my best to diagnose the issue. I've changed the fuel filter, all 6 spark plugs/wires, and O2 sensors(None of this helped the actual issue but did improve how the car ran in general.)
 
Originally I thought it may of been electrical, but there is a strong gasoline smell inside the cab, so I believe fuel is too rich. Car did idle rough but changing o2 sensors fixed that. 
 
Almost at my wits end here, running out of ideas. 

Edit: Car has 136k miles, driven regularly by last owner.

Car idle:(little worse today than yesterday)

Edited by WeLiVeR, 2 weeks ago.


#2 JOE68

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Posted 2 weeks ago

your converter may be getting plugged.   pull the o2 sensor before the cat and drive it.



#3 ZumpTA

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Posted 2 weeks ago

I was thinking converter too, but I also question the coils.  At idle, it sounds like it's missing to me.  When a plug wire came off a plug on my LT1, the sound at idle was the same as in the video and the symptoms were very similar tho not as extreme due to all the extra torque the v8 has.


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#4 WeLiVeR

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Posted A week ago

Thanks for the suggestions, might take it to a muffler shop and have it looked at. Had surgery yesterday so wont be able to mess with it any for a little while.

#5 Papa Tango

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Posted A week ago

Dakota, Check your fuel pressure at the fuel rail. Are you getting any codes? Low fuel pressure will not throw a code. Electrical and ignition issues usually give you a code. The fuel smell could be from a cracked rubber hose. There are a couple of transition hoses, above the rear axle and under the driver's seat area where the fuel and vent lines run. Also off the fuel tank and the charcoal canister. If you replace one, replace them all and save yourself headaches later. Good luck, Pete





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