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Help in Diagnosing problem with '07 Malibu

7K views 19 replies 4 participants last post by  heights 222 
#1 · (Edited)
Hi, My 2007 Malibu LS 2.2L struggles to run when engine is cold. In the winter I always warm the car up before leaving but lately even after I do that it still struggles to run but once its completely warmed up it runs alot better but it will struggle to accelerate to gain speed and/or trying to pass another vehicle and going up hills. It also has a non-working fuel gauge.
Its like it can't get enough air or gas or something. Once I turn the key I can hear the fuel pump working and once i start the car it idles fine, in fact its so smooth and quiet its hard to tell if its even running :)

I took the car to Auto Zone and they put the scan tool on and it threw a code about the fuel sending unit. It apparently has a "bad electrical connection at the fuel level sending unit, probable cause failed fuel level sending unit."

I took the car to a mechanic a few weeks back and they did a quick scan on it and all that was found was that it needed a tune up so I had them do that. They replaced the spark plugs, coil boot(?) etc... which really didn't help much as its still struggling to run.

The car has just over 100,00 miles on it

So now this brings me to this forum in hopes to find possibilities i could try. I'm totally at a loss. Anyone with any ideas?

I think I'm going to invest into a scan tool :D

Thanks!
 
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#2 ·
Check the catalytic convertor.

Also see if you have an EGR which can cause similar issues.

O2 sensors replaced anytime recently? They're usually good for about 100K miles.

Do you keep getting gas from the same place? You might be getting water in the fuel or some other garbage and need to change your fuel filter.

When was the last time you checked the air filter? Clogged AF can do what you say.

So many things to check - some easy, some not so. Come back and tell us more...
 
#4 ·
Wow thanks for the list! That should help alot. Thats quite a bit of stuff but like engines these days there could be a million things it could be :(

To answer your questions: No I get my gas where ever I'm at at the time. i keep it on full most of the time because of the gauge not working.
I just changed the air filter about a month ago when I had my oil change. I get regular oil changes and they keep an eye on my filter, wipers, lights etc...


I have a question for you, Would a non working fuel gauge and sending unit if bad would cause the engine not getting enough gas through the system? I am about to replace that soon as I was suspecting that is the problem, Am I right? plus it would be awesome to have a working gauge again and stop worrying about running out of gas!

Thanks a bunch for your help with this I certainly appreciate this alot!
 
#6 ·
The only way that I can think of where a non-functioning or intermittent fuel gauge and/or sender would cause any kind of driveability issue would be if the fuel pump wiring or connector has also been damaged or compromised in some way. They are separate systems (sensing vs supply) that merge at the tank.
 
#9 ·
Well, I'm not sure. These Ecotech engines are complicated to say the least IMO but its a nice smooth quiet engine, that i do like :)
But I'm not really having the issues with hard starting and stalling at all. It's idling smooth but just alot of resistance getting up to speed and going uphills is a battle. I just try to hold steady and be patient lol!

Thanks for your help, much appreciated.
 
#11 ·
Runs smooth but lacks power - hmmm, still sounds like a cat. Instead of paying a bunch of $$$ for a pump try this free diagnosis first: drop the exhaust ahead of the cat and then drive the car. (Of course, support the pipe so it doesn't drag...) If it's loud but the power comes back, it's the cat. If it's loud and still drags its butt, it isn't the cat.

On my V6 I have 3 cats. One at the header on each bank, then one after they join together. So if one or both of the header cats were to clog I couldn't perform the test above on them. I hope yours isn't similar but it's possible. I had a '90 Toyota 1.6L and the cat was right at the header. We're 20 years further down the road and it wouldn't surprise me if most or all gas cars had cats that close so they'll light off quickly.
 
#12 ·
Well the Cat did cross my mind but when I hear of the rotten egg smell I don't smell anything like that or any kind of smell. There is no odor. Not even a gas smell. So in my mind its prob not the cat. But before we install the new fuel pump we will take a closer look at the cat just in case. Tho I really want my gauge working again.
 
#14 ·
Moved from General Discussion area ...

Not sure why your thread couldn't be found. I just now moved it.
 
#16 ·
The rotten egg smell (sulphur dioxide) is the result of a cat that's working, usually a new replacement. If it has failed or is plugged or severely restricted it probably won't have any smell at all. Mine doesn't and it works perfectly.
 
#19 ·
That's great news! I hope it wasn't too expensive. Did you do any or all of the work? How long did it take? What did you or they do to confirm the cause?

Boy, are we just full of questions? ;)
 
#20 ·
Hi Driven, Yes they were kinda expensive, but it helped that I got a good deal on the parts and labor. I got both fixed for just under $ 1000.00. It took all together about 1/2 to 3/4 a day to get them both done. I am happy that I got the power in my car back and improved gas mileage!! :D

I was just hoping so bad that it wasn't the cat as I knew it would be expensive. I wanted to be in complete denial! lol
but oh well whats done is done and I am happy the painful experience is overwith. :eek:
Thanks again to you and the others for helping me get through this.
 
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