P0131 code with hesitation when accelerating and poor gas mileage

[cplvan]

Originally Posted by trottida

It's good that you see a positive change after changing out the thermostat; you know that you've done something right however I'm stumped as to why you are still experiencing poor fuel mileage.

What brand thermostat did you put in there? Do you know for sure the outgoing one was OEM style and the housing is OEM? I ask because your temp reading now seems high for a GEN3. This would happen when you put an OEM thermostat in an aftermarket housing (like MotoRad). It restricts the thermostat from fully opening. I don't think this would affect fuel mileage though. It would cause your cooling fan to run more often then usual.

I assume this picture is showing operating temperature; the temperature when the car is warmed up and lots of air is moving through the radiator. I'm guessing this reading is around 211 degrees Fahrenheit. Do you have a scanner? What temp reading does it show?

Back to the fuel mileage. You'd expect to see an drop in fuel mileage in the colder months; especially if you are pre-heating the car before leaving. I'm not sure what climate you are in. Low tire pressure would also contribute; have you topped them up since the cold weather arrived? What spark plugs did you have installed? You might want to pull them and see what brand/style/product number they are and note the condition of the tip (dry/wet/oily/white-ish/etc...). The wrong spark plug may affect fuel mileage. Does your exhaust smell like gas?

Anybody else have some ideas?

I went with a Stant 14279 thermostat from rock auto and it came w/ the housing. so that should be all good. I would expect a slight drop in fuel mileage during the cold months (i live in Connecticut, USA) but definitely not all the way down to 15 mpg. the tire pressure is good. Not sure what to do. any ideas?

[cplvan]

Originally Posted by trottida

It's good that you see a positive change after changing out the thermostat; you know that you've done something right however I'm stumped as to why you are still experiencing poor fuel mileage.

What brand thermostat did you put in there? Do you know for sure the outgoing one was OEM style and the housing is OEM? I ask because your temp reading now seems high for a GEN3. This would happen when you put an OEM thermostat in an aftermarket housing (like MotoRad). It restricts the thermostat from fully opening. I don't think this would affect fuel mileage though. It would cause your cooling fan to run more often then usual.

I assume this picture is showing operating temperature; the temperature when the car is warmed up and lots of air is moving through the radiator. I'm guessing this reading is around 211 degrees Fahrenheit. Do you have a scanner? What temp reading does it show?

Back to the fuel mileage. You'd expect to see an drop in fuel mileage in the colder months; especially if you are pre-heating the car before leaving. I'm not sure what climate you are in. Low tire pressure would also contribute; have you topped them up since the cold weather arrived? What spark plugs did you have installed? You might want to pull them and see what brand/style/product number they are and note the condition of the tip (dry/wet/oily/white-ish/etc...). The wrong spark plug may affect fuel mileage. Does your exhaust smell like gas?

Anybody else have some ideas?

i used the Stant 14279 thermostat and it came with the housing. so that should be all good. yes that is at normal operating temperature when I got to work i took that picture. id expect the car to have a little bit worse fuel mileage in the colder months but not 15 mpg..... tire pressure is good. Any ideas? thanks for the help

[cplvan]

I went with a Stant 14279 thermostat from rock auto and it came w/ the housing. so that should be all good. I would expect a slight drop in fuel mileage during the cold months (i live in Connecticut, USA) but definitely not all the way down to 15 mpg. the tire pressure is good. Not sure what to do. any ideas?

[Waiex191]

Have you read the sticky?
http://www.saturnfans.com/forums/sho...d.php?t=177672

I'd check for vacuum leaks if you have not already.

Originally Posted by adventureoflink

18. Intake Manifold (Gaskets).

* 2000-2002 SOHC engines: P0301 + P0507 = a nice recipe for a soured intake manifold gasket. Due to a defect from the factory (either miscalibrated robots or a bad IM gasket), these things like to leak vaccuum and set these two SES codes usually right around... NOW. These two codes, as well as spraying brake cleaner around the cyl #1 area will confirm this.

[cplvan]

So on my way home from work today. It started hesitating again and the temperature was back to a little above 1/4 again. The only thing I did was add coolant because I thought it was low. When I got home I drained some coolant because maybe I added to much. So hopefully the hesitation goes away now that I’ve taken away some coolant? Very weird

[trottida]

How many miles on your SL SOHC? How long have you had it and what was the mileage when acquired?

Check for vacuum leaks as I mentioned this morning and Waiex mentioned this afternoon. Check both the vacuum lines and the intake manifold gasket.

Something is off with the coolant temperature situation reading too high and now too low after you replaced the thermostat. You've already replaced the ECTS so look at the ECTS connector again and answer these questions...

• Has it been replaced before (shows evidence of wires from the harness being cut and spliced)?
• If replaced have the wires been soldered and shrink tubed correctly?
• Do they have crimp connectors which are a known point of failure on this circuit?
• Looking at the connector pins does it look like there is coolant residue or dirt present?

Loss of power will also happen with a clogged pre-cat attached to your exhaust manifold or a clogged catalytic converter. If you run the car too rich for an extended period these components get clogged with carbon deposits.

How does the exhaust smell? Any unburnt fuel smells?


.

[cplvan]

So just before I was about to come on here and say my problem was all fixed. i was driving home yesterday and my temp gage went back to in between 1/4 and 1/2 (see picture) and my fuel mileage is back to being very bad. I can get an exact number tomorrow when I calculate it. the hesitation when accelerating isnt nearly as bad but it stated to come back once and that was it. it seemed like replacing the thermostat fixed the hesitation and the fuel mileage eventually went back to normal but then the problem came back. could the stant thermostat already be failing??? any ideas?

[cplvan]

1.jpg

[Waiex191]

Check out my post:
http://www.saturnfans.com/forums/sho...&postcount=128

I think you said the ECT connector was good, but did you inspect it closely? Mine stopped working a day after after I changed my ECT and I took a closer look.

[cplvan]

Waiex191 i did and it was not corroded like that at all. ill double check but no green or any other rust was present. i think the ECTS was probably fine t o be honest because it was not cracked or anything but I still replaced it because of what was said about it failing eventually.

i dont know if i wasnt to just throw a new connector on there just because if i think its working properly. is there anyway to test it with a voltmeter?

[trottida]

Originally Posted by cplvan

Attachment 64666

This is exactly where I would expect it to be in a GEN3 like yours at operating temperature. It'll sit there continuously while your moving at a good speed.
Your earlier picture seemed high and that is why I asked if you could take a reading using a scanner with live data capabilities. I though maybe your gauge calibration was off.

My last post had a bunch of questions that haven't been answered.

[TomM96]

Given the misfire code (initially), I'd check all the spark plugs, and verify
that they are the conventional style (Not fine-wire platinum). On both
my '97 and 2000, I've discovered small flakes of carbon across the gap, causing shorts.
This is rare, and generally accompanies other issues... but if there are
fuel consumption issues, it is helpful to cover all the bases, and do fundamental blocking/tackling on the basics.
...
There ought not be misfires just months after new plugs+wires; possibly
the 'spark' is weak, or the IgCtl Module is out of sorts. The appearance of each plug will reflect the conditions within that cylinder.
* *

You - cplvan - remarked that you added coolant, AND the engine temperature is varying. That may indicate "bad coolant" issues, which
may be affecting the head gasket composition.

Have you removed the coolant from the block, and FLUSHED out the
block yet??

The original factory coolant was the pink-colored 'DexCool', which was
found to be very good in many vehicles. However, in Saturn cars, the Dexcool, after some years (and, notably, If the coolant level is allowed
to decline) becomes ACIDIC, and dissolves some of the head gasket material.
Soooo, a good practice is to remove the thermostat, fully drain the
coolant, monitoring its color (green or pink... or green becoming pink
while draining).

Then, fill the block with purified water (distilled, de-ionized, or Reverse Osmosis), run engine without thermostat for 5 minutes, and drain
coolant, monitoring color. If the color is other than pale green, repeat
with another 5-minute flush with purified water, and drain again.
Then, install thermostat, add 1 full gallon of (fresh-New) green prestone antifreeze, and top off with Purified water.

That would require 2gal + 2gal + 1gal == 5 gallons purified water = $5.
Better practice involves addition of an ounce/tablespoon/shotglass
of electric dishwasher detergent to the initial flushing mixture (suggested
in the OEM/Helm Factory Service Manual.

After you top off reservoir with purified water ... add 2 GM 'Cooling
System Tablets' for aluminum block engines, available at Cadilac &/or
Chevy dealerships for ~$5-$7. After running the engine for an hour or
two, may need add a little more water to just below level of horizontal
seam in plastic reservoir.
* *
After which, resume troubleshooting.

[cplvan]

Originally Posted by trottida

How many miles on your SL SOHC? How long have you had it and what was the mileage when acquired?

Check for vacuum leaks as I mentioned this morning and Waiex mentioned this afternoon. Check both the vacuum lines and the intake manifold gasket.

Something is off with the coolant temperature situation reading too high and now too low after you replaced the thermostat. You've already replaced the ECTS so look at the ECTS connector again and answer these questions...

• Has it been replaced before (shows evidence of wires from the harness being cut and spliced)?
• If replaced have the wires been soldered and shrink tubed correctly?
• Do they have crimp connectors which are a known point of failure on this circuit?
• Looking at the connector pins does it look like there is coolant residue or dirt present?

Loss of power will also happen with a clogged pre-cat attached to your exhaust manifold or a clogged catalytic converter. If you run the car too rich for an extended period these components get clogged with carbon deposits.

How does the exhaust smell? Any unburnt fuel smells?


.

I had it for about 6 months so far and but over 10k miles on it. There’s about 75k miles on it right now. I’m not totally sure how to check for vacuum leaks.

No it doesn’t look like the connector has been replaced before and there no coolant residue or dirt on the connector pins.

It does feel like there is a bit of a loss of power. The exhaust smells fine. No unburnt fuel smells.

[cplvan]

Originally Posted by TomM96

Given the misfire code (initially), I'd check all the spark plugs, and verify
that they are the conventional style (Not fine-wire platinum). On both
my '97 and 2000, I've discovered small flakes of carbon across the gap, causing shorts.
This is rare, and generally accompanies other issues... but if there are
fuel consumption issues, it is helpful to cover all the bases, and do fundamental blocking/tackling on the basics.
...
There ought not be misfires just months after new plugs+wires; possibly
the 'spark' is weak, or the IgCtl Module is out of sorts. The appearance of each plug will reflect the conditions within that cylinder.
* *

You - cplvan - remarked that you added coolant, AND the engine temperature is varying. That may indicate "bad coolant" issues, which
may be affecting the head gasket composition.

Have you removed the coolant from the block, and FLUSHED out the
block yet??

The original factory coolant was the pink-colored 'DexCool', which was
found to be very good in many vehicles. However, in Saturn cars, the Dexcool, after some years (and, notably, If the coolant level is allowed
to decline) becomes ACIDIC, and dissolves some of the head gasket material.
Soooo, a good practice is to remove the thermostat, fully drain the
coolant, monitoring its color (green or pink... or green becoming pink
while draining).

Then, fill the block with purified water (distilled, de-ionized, or Reverse Osmosis), run engine without thermostat for 5 minutes, and drain
coolant, monitoring color. If the color is other than pale green, repeat
with another 5-minute flush with purified water, and drain again.
Then, install thermostat, add 1 full gallon of (fresh-New) green prestone antifreeze, and top off with Purified water.

That would require 2gal + 2gal + 1gal == 5 gallons purified water = $5.
Better practice involves addition of an ounce/tablespoon/shotglass
of electric dishwasher detergent to the initial flushing mixture (suggested
in the OEM/Helm Factory Service Manual.

After you top off reservoir with purified water ... add 2 GM 'Cooling
System Tablets' for aluminum block engines, available at Cadilac &/or
Chevy dealerships for ~$5-$7. After running the engine for an hour or
two, may need add a little more water to just below level of horizontal
seam in plastic reservoir.
* *
After which, resume troubleshooting.

The coolant seems fine. It’s orange gm coolant not pink or green. Also I just changed the oil two days ago and it doesn’t look like there’s any signs of water in the oil from a leaky head gasket. Do you think this is still necessary?

[Waiex191]

Originally Posted by cplvan

I’m not totally sure how to check for vacuum leaks.

Check this out. It's easy.
https://youtu.be/9CPqbaSgcok

The coolant seems fine. It’s orange gm coolant not pink or green. Also I just changed the oil two days ago and it doesn’t look like there’s any signs of water in the oil from a leaky head gasket. Do you think this is still necessary?

This would have nothing to do with your current issue. Not a bad thing to change coolant, especially if you don't know how old it is. I won't get into the green vs orange wars here.

[PrestonIII]

On engines with a Mass Airflow Meter, a vacuum leak causes problems because THAT air doesn't go through the meter and doesn't get computed in the calculations used to inject fuel into the engine.

But on engines without the MAF sensor ( this is called speed density type), there's no actual measurement of the air getting into the engine. The air volume is calculated based on Air Temperature, Vacuum, and RPM. So, a vacuum leak doesn't have the impact on this type of engine control as the Mass Airflow type. Thus, unless you have a MASSIVE vacuum leak (which you'd hear), I seriously doubt that a vacuum leak is the problem.

I think your problems are more likely an O2 sensor failure (Bank 1 sensor 1)(sensor 2 wont cause running issues), or a plugged up catalytic convertor.

PLUS, the Engine Coolant Temperature Sensor, ECT, plays a major roll in the calculations that the Saturn computer does. Thus a bad ECT can cause ALL KINDS OF PROBLEMS. The thermostat isn't as important yet, because the engine will run 'Ok' with the thermostat open. I believe that reason that the ECT impacts the Saturn so much is because the engine is so small. So the problem appears more intense on this small engine.

So, the first thing to do is the ECT replacement. It's cheap.

Next step, remove the O2 sensor and see if the engine runs better with the hole open, thus less back pressure. If it runs better, it's likely a plugged up catalytic convertor.

Otherwise, replace the O2 sensor and go from there. Fuel pressure could be an issue as well.

And of course, while you're polking around under the hood, tighten up the vacuum hoses, clean the port under the MAP sensor, clean the throttle body, and verify that the hose to the fuel pressure regulator is intact and correct. You might even check the ports under the EGR valve, and the valve itself. These items will make the engine run smoother and idle with less vibration. But they wont necessarily cause drivability issues like you mention.

Preston

[trottida]

I'm going to call the ECTS, ECTS connector and thermostat as all being good based on your actions and responses. The last gauge reading is what I would expect and the only thing additional you can do is take a live reading to confirm the temp is approximately 193. Your root cause has been resolved with the exception of a possible vacuum leak. Waiex191 has got you covered with the video. Let us know if this is confirmed and subsequently fixed.

With all that said I think now you are looking at the problems caused by the previous owner (and yourself since ownership) running the engine too rich for an extended amount of time (because of failed thermostat). As mentioned it creates a lot of carbon deposits within the throttle body, EGR valve, engine, exhaust manifold, air injection system, pre-cat, oxygen sensor and catalytic converter. You need to clean this up to restore air and exhaust flow.

Everything but the catalytic converter, oxygen sensor and possibly the EGR valve (if pintle movement can't be restored) involves just labour. I'd start with throttle body, egr and the air injection system manifold tube. As mentioned you can also temporarily remove the O2 sensor and take a test drive to see if there is a downstream exhaust restriction (plugged catalytic converter). As you work through this methodically you will determine what is causing the power loss.