2007 Saturn Aura XE, 16MPG , opinions

[TroubleFree]

Hello,

I was offered a 2007 aura xe for $1k. I took it, the paint and interior are absolutely pristine. Single owner, and the clear coat looks factory.

It does have have one issue though. It's throwing codes P0171 and P0174

Do you think it could just be the MAF sensor? Where is the best place to start diagnosing it.

It's got a 115k miles on it. The transmission seems "ok", sometimes when going into reverse it gives me a little thud and every now than it a slight thud when accelerating after a turn, do you think that could be because the fluid is migrating to one side and its low? (I know its a sealed transmission but just curious why it only happens when turning).

Thanks for any input.

Again, these thuds are almost completely unnoticeable. I'm literally half the time wondering if its a road or if I'm hearing things, but it does happen ever so often.

Right now my fuel economy at 16mpg is not so great though, and do you think those lean fuel bank codes could be knocking a few off?

Thanks for the help guys, for $1k its a great car, I still have my new car but this is a little project for me to play with.

[imaddicted2u]

P0171 SATURN - Fuel Trim System Lean Bank 1
P0174 SATURN - Fuel Trim System Lean Bank 2
Possible Causes
Intake air leaks
Faulty front heated oxygen sensor
Ignition misfiring
Faulty fuel injectors
Exhaust gas leaks
Incorrect fuel pressure
Lack of fuel
Faulty Mass Air Flow (MAF) sensor
Incorrect Positive Crankcase Ventilation (PCV) hose connection
Tech Notes
If the P0171 is combined with the P0174 code, it's very likely that the problem is caused by an intake leak. If there are no intake leaks, the next step is to replace the air filter and clean the air flow meter. If the problem persists the front oxygen (O2) sensor may need to be replaced.
The P0174 code could also be caused may be caused by one or more of the following: debris on MAF sensor causing an incorrect reading, improper oil level, low or high fuel pressure or Engine Control Temperature (ECT) Sensor reading inaccurate.

There is a factory service bulletin for the following Saturn models:
2000-2008 Saturn Factory Service Bulletin OBDII Code P0174
https://www.autocodes.com/pdfview.ph...06-04-030F.pdf

[imaddicted2u]

As far as the thud goes, fluid doesn't migrate from one side to the other. The fluid engages clutches and bands to mechanically connect the transmission to the engine.
If you want to check the fluid level 3:44 of this video shows where the check plug is and what to look for (do not take the plug out with the engine off...you will have fluid everywhere) Engine must be running to check it.
https://www.youtube.com/watch?v=ZmucpIRGjDw&t=156s
Could be a myriad of reasons for the thud, CV joints, worn front end parts/bushings, motor/transmission mounts, strut bearings, I'm sure there could be more.

[imaddicted2u]

For the codes, check for vacuum lines off or broken as well.

[TroubleFree]

So basically I should strongly assume its an intake leak.

Besides buying a smoke machine are there any other ways to tell if I have an intake leak?

Thank you, I was heading down the path that something was wrong with the fuel injectors.

I still will clean the MAF, probably needs it anyway.

[imaddicted2u]

Originally Posted by TroubleFree

So basically I should strongly assume its an intake leak.

Besides buying a smoke machine are there any other ways to tell if I have an intake leak?

Thank you, I was heading down the path that something was wrong with the fuel injectors.

I still will clean the MAF, probably needs it anyway.

Try this...spray carburetor cleaner (I've used water too) around intake manifold and throttle body mating gaskets and vacuum hoses and fittings, listen for an obvious change in engine RPM.

[TroubleFree]

This won't create a big combustion in the engine will it? I will try to spray a bit and see if I get anything. The filter was just replaced before I got it, I wonder if maybe just the MAF is all dirty. Then again its throwing both codes not just the one.

[imaddicted2u]

Originally Posted by TroubleFree

This won't create a big combustion in the engine will it? I will try to spray a bit and see if I get anything. The filter was just replaced before I got it, I wonder if maybe just the MAF is all dirty. Then again its throwing both codes not just the one.

Could be the MAF. Try cleaning it first, see if it cures the problem.
Carb cleaner sucked in through a leak won't huts anything. It just seals the leak and richens up the mixture for a few moments, the engine speed changes because the air/fuel ratio is changed. The engine computer will adjust things to bring it all back in line. There is a risk of it igniting in the air if there is a spark but I've never had a problem. If it's safety worries you, use water. I had an intake leak on my old SL1. I found it by pouring water over the gasket area. You could hear it gurgling and the engine speed dropped until the water was sucked through. I replaced the intake gasket and all returned to normal.

[imaddicted2u]

You didn't say which engine you have. Since your codes are for bank1 and bank2, I'm assuming you have the V6, 3.5L. Can you confirm?
I came across this video, top 5 reasons for P0171 and P0174
https://www.youtube.com/watch?v=7v1eAzipqfY

[TroubleFree]

Yes its the 3.5L 4 speed

[imaddicted2u]

Things with common impact on both banks,
MAF
Throttle body and/or gasket
Vacuum lines to:
Brake booster-Vacuum line-diaphragm could leak internally
EVAP purge-stuck open or vacuum lines
Crankcase ventilation
Vacuum leak around MAP sensor
Fuel pressure
Fuel injectors
Here's a video of using carb cleaner to check for vacuum leak on a car.
https://www.youtube.com/watch?v=9CPqbaSgcok

[TroubleFree]

I am beginning to think its the intake manifold gasket

I am losing some coolant, not much but a bit.

[imaddicted2u]

There are two sets of gaskets on the intake. The upper plenum and the lower intake gaskets. A leak in the upper would pull in air, a leak in the lower would pull water. So the upper intake plenum gasket would be more likely to cause your lean codes. The lower could cause a water leak.
A common 3.5 coolant leak point is the crossover gasket. My 3.5 was losing a little coolant but only when the engine was off on the coldest days of winter. I re-torqued the bolts and the leak stopped and I didn't need to change the gasket.