Problems with 1999 Pontiac Grand Am GT 3.4L V6

Roshambobobo
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Joined: Thu Oct 09, 2014 4:06 am

Problems with 1999 Pontiac Grand Am GT 3.4L V6

Unread post by Roshambobobo » Thu Oct 09, 2014 6:11 am

Hi, I just replaced the engine in my Grand Am a few days ago, and am currently running into some issues. The first day I got it running, everything was fine. I didn't run into a single problem. But the second day, it started acting funny. At first, the only issue was that every so often while accelerating even slightly, the engine would sputter just a little, as if it was running out of gas, and then it would be fine for a while.

Then today, I went to drive it again, and it was absolutely fine for a while, no sputtering whatsoever. It eventually started sputtering again, and started happening more and more often. It started sputtering even when I was idling or decelerating. The sputtering wasn't very intense at all though, it was really light and was only for a second.

Then as I'm turning into the grocery store, my engine just starts making this really low and loud rumbling, and it accelerates extremely slow. It sounds like my entire exhaust just fell off at the engine. When I parked and opened my hood, I was blasted with exhaust fumes. I checked at my muffler, and there's barely anything coming out of it. Also, besides the loud rumbling, there's something else that just sounds off about the engine, but I'm not sure how to describe it. I would venture to say it sounds like what I would assume is one or more of the pistons not firing.

Additional information:
The car itself is a '99. The new engine in it is the same as the previous (3.4L), but the new one is an '03.

My car had been sitting in my garage on jack stands without the engine in it for the last 7 months.

Also, after the rumbling started, my car overheard fairly quickly.

After some research, my best guess is that the fuel injectors are clogged, but I want better opinions on the problem before I go tearing this engine apart.

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carriedi
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Re: Problems with 1999 Pontiac Grand Am GT 3.4L V6

Unread post by carriedi » Thu Oct 09, 2014 11:29 am

you might want to pull out your O2 sensor and try starting it up and see how much exhaust you have coming out the O2 sensor hole. you might have a plugged exhaust. taking the O2 sensor out will allow the exhaust to vent and the cars. computer will default the O2 to 4.5v. you might get a code for the O2 but the car will run ok without the signal.
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Roshambobobo
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Joined: Thu Oct 09, 2014 4:06 am

Re: Problems with 1999 Pontiac Grand Am GT 3.4L V6

Unread post by Roshambobobo » Thu Oct 09, 2014 11:38 am

Okay, thank you. I'll go try that now and see what happens.

Roshambobobo
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Joined: Thu Oct 09, 2014 4:06 am

Re: Problems with 1999 Pontiac Grand Am GT 3.4L V6

Unread post by Roshambobobo » Thu Oct 09, 2014 1:06 pm

Okay, so it's hell trying to get a wrench down there to remove the sensor. A buddy of mine came over with a code reader and I'm getting code P0300, and that's it. It doesn't give any specific piston, it just says one or multiple misfires.

Okay, update. I was looking around underneath my car and bumped the exhaust crawling out.. It moved just a little too much. The plate that bolts onto the engine is still bolted on, but the weld broke on the pipe and it's just barely hanging off of it, which explains the low rumbling. Could this also explain the misfiring?

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carriedi
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Re: Problems with 1999 Pontiac Grand Am GT 3.4L V6

Unread post by carriedi » Fri Oct 10, 2014 9:25 pm

I have had a few 3.1 and 3.4 engines that have had poor injector performance. running a good injector cleaner or doing a motorvac has cleared up the condition. the engine usually have over a hundred thousand miles on them but the drivers don't notice a misfire during normal driving. However, the check engine light has come on, the code stored is P0300 and they can't pass the smog check.

A loose or open exhaust usually won't cause a misfire condition but will affect your fuel trims depending where the exhaust leak is. If you scanned for codes did you look at fuel trims and other parts of the data stream?
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Re: Problems with 2003 Pontiac Grand Am GT 3.4L V6

Unread post by guest » Sun Mar 26, 2017 4:44 am

Hey my name is Ryan i have a 2003 Pontiac grand am gt 3.4 liter sfi a couple days ago i went to town i turned my car off went in to store come back out and my car wouldn't start after several hours for some unknown reason I checked my fuses and replaced the crank fuse my car started but the fuse didn't look blowed well the same problem happen again so i changed the fuse again well next day my car wouldn't start at all it just turns over what could be the problem please someone give me a answer and thanks for your time and advice

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carriedi
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Re: Problems with 1999 Pontiac Grand Am GT 3.4L V6

Unread post by carriedi » Sat Apr 01, 2017 8:15 pm

you're going to have to check for the basics to find out what is missing. spark, correct fuel pressure, injector pulse. Depending on the tools you have, it might be hard to check these things yourself. Security light could show you if there is a problem with starting.

does the starter crank the engine over and the engine not start?

does the starter crank the engine over?

does the engine start but dies right away?
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