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Discussion Starter #1
Ok I’m at a loss with this one and looking for some help.

So I had the Fj apart and installed a upgraded radiator, transmission cooler, replaced all the water hoses, and thermostat and housing. Put it all back together and pressure washed the underside and engine compartment throughly.

Now here is the problem. Fuel mileage dropped 4 to 5 mpg. I have been monitoring the system via odb2 for several days. No codes!! The A/f ratio seems to be very rich under modest acceleration and the exhausts temps seem to confirm this as well. TPS is within specs, MAF is within specs. O2 sensors seem to be in spec as well.

Anyone got any ideas?




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Yikes, that’s a huge drop! Following for my own benefit.

What got wet when you pressure washed the engine bay?


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This same issue happened to me years ago on a ford F350. Performed normal maintenance, flushing the radiator and replacing the thermostat. It was a week of troubling shooting before I discovered that I installed a thermostat with the wrong temperature range. The engine would never reach optimum operating temp and the ECM kept the fuel mixture rich.
 

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Discussion Starter #4
Yikes, that’s a huge drop! Following for my own benefit.

What got wet when you pressure washed the engine bay?


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Pretty much everything, but it set for a couple of days before I started it back up, and it started up fine. Seems to run fine ie no skips of mis firing, just crappie mpg compared to before.


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This same issue happened to me years ago on a ford F350. Performed normal maintenance, flushing the radiator and replacing the thermostat. It was a week of troubling shooting before I discovered that I installed a thermostat with the wrong temperature range. The engine would never reach optimum operating temp and the ECM kept the fuel mixture rich.


Engine temps are at 185 to 190. Isn’t that about right?


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Possibly just water in the MAF sensor or MAF sensor connectors which is erroneously indicating to the ECU that there is more air entering the engine than actually is, and the ECU is commanding excess fuel.

Remove the MAF and clean it carefully, and de-mate the MAF connector and blow out both halves with clean, dry comoressed air.

Also, de-mate the connectors at all four of the exhaust gas sensors and blow out the connectors with compressed air.

But, much more info is needed to perform any kind of useful diagnostics.

1. What year model?
2. Original or aftermarket air cleaner system?
3. Have you verified that the engine air filter(s) are not water saturated?
4. How many miles on the odometer?
5. Have any or all of the exhaust gas sensors been replaced?

NEVER, EVER PRESSURE WASH THE ENGINE CMOARTMENT OR ANY PART OF THE WIRING HARNESS WITH A HIGH PRESSURE WASH SYSTEM

All the electrical connectors are “sealed”, but a 2,000 PSI pressure-washer will force water (or worse, detergent solution) past the seals, where it will stay and immediately cause false readings from sensors, or it will sit there for weeks or months, slowly causing corrosion
 

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Discussion Starter #7
Possibly just water in the MAF sensor or MAF sensor connectors which iis indicating to the ECU that there is more air entering the engine than actually is, and the ECU is commanding excess fuel.

Remove the MAF and clean it carefully, and de-mate the MAF connector and blow out both halves with clean, dry comoressed air.

Also, de-mate the connectors at all four of the exhaust gas sensors and blow out the connectors with compressed air.

But, much more info is needed to perform any kind of useful diagnostics.

1. What year model?
2. Original or aftermarket air cleaner system?
3. Have you verified that the engine air filter(s) are not water saturated?
4. How many miles on the odometer?
5. Have any or all of the exhaust gas sensors been replaced?

NEVER, EVER PRESSURE WASH THE ENGINE CMOARTMENT OR ANY PART OF THE WIRING HARNESS WITH A HIGH PRESSURE WASH SYSTEM

All the electrical connectors are “sealed”, but a 2,000 PSI pressure-washer will force water (or worse, detergent solution) past the seals, where it will stay and immediately cause false readings from sensors, or it will sit there for weeks or months, slowly causing corrosion


MAF was the first thing I checked and cleaned, no moisture in the connector. I haven’t checked the o2 sensors connects but I will tomorrow.



1. 2012
2. TRD intake
3. Filter does not appear to be saturated and MAF reads within specs at idle and at 2,500 rpm per specs.
4 137,000 miles
5. I haven’t replaced any of the exhaust sensors but they appear to be reading voltages within factory specs.

That’s what’s getting me, sensors seem to be reading a rich condition, high exhaust temps seem to confirm this (along with the poor mpg) but it’s like the computer is not adjusting accordingly.

TPS sensor is within specs as well....



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MAF was the first thing I checked and cleaned, no moisture in the connector. I haven’t checked the o2 sensors connects but I will tomorrow.

1. 2012
2. TRD intake
3. Filter does not appear to be saturated and MAF reads within specs at idle and at 2,500 rpm per specs.
4 137,000 miles
5. I haven’t replaced any of the exhaust sensors but they appear to be reading voltages within factory specs.

That’s what’s getting me, sensors seem to be reading a rich condition, high exhaust temps seem to confirm this (along with the poor mpg) but it’s like the computer is not adjusting accordingly.

TPS sensor is within specs as well.... Sent from my iPhone using Tapatalk
How and where are you reading "exhaust gas temps"? The 1GR-FE has no true exhaust gas temperature sensors, only the electrical heater temperatures in the exhaust gas sensors.

At 137K miles, ALL four of your exhaust gas sensors (2 air/fuel, 2 O2) are well past their design life, and are very likely not providing accurate data to the ECU. They air/fuel sensors typically function correctly for 85 to maybe slightly over 100K miles, but are very unlikely to be accurate at 137K miles. It's not just output voltage that's critical, but linearity and response time.

A rich mixture typically LOWERS exhaust gas temperature, while a lean mixture RAISES exhaust gas temp.

Regardless of what else you might find, replace the air/fuel sensors ASAP, using ONLY the OEM Denso sensors.
 

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Discussion Starter #9
How and where are you reading "exhaust gas temps"? The 1GR-FE has no true exhaust gas temperature sensors, only the electrical heater temperatures in the exhaust gas sensors.

At 137K miles, ALL four of your exhaust gas sensors (2 air/fuel, 2 O2) are well past their design life, and are very likely not providing accurate data to the ECU. They air/fuel sensors typically function correctly for 85 to maybe slightly over 100K miles, but are very unlikely to be accurate at 137K miles. It's not just output voltage that's critical, but linearity and response time.

A rich mixture typically LOWERS exhaust gas temperature, while a lean mixture RAISES exhaust gas temp.

Regardless of what else you might find, replace the air/fuel sensors ASAP, using ONLY the OEM Denso sensors.


Yeah the o2 sensors was my original suspect until I plotted them together and watched how they reacted voltage wise. I already had them in my cart to order and then second guessed it after looking at the readings from the computer.

Exhaust temps where pulled via odb2 scan from the exhaust sensors.

It was my understanding that running rich could raise or lower temps depending on the fuel and wasn’t always one way or the other.

At the same time I’m also the dump a$& that thought it would be a good idea to take the pressure washer to the engine bay, smh. Lesson learned.




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Maybe check that the post-MAF intake coupling didn't get slightly bumped off (or cracked) from the pressure washer. Maybe some of the air going past the MAF isn't making it to the engine. The ECU is going to trust the MAF but, if not all of that air is getting there, it would run rich.
 

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Maybe check that the post-MAF intake coupling didn't get slightly bumped off (or cracked) from the pressure washer. Maybe some of the air going past the MAF isn't making it to the engine. The ECU is going to trust the MAF but, if not all of that air is getting there, it would run rich.
No, not the case.
If some intake air is bypassing the MAF, the MAF will report LESS air than is actually passing through the engine, and the ECU will supply only enough fuel to match the reported amount of air. Since more air than reported by the MAF is actually passing through, the resulting fuel mixture will be LEAN.
 

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No, not the case.
If some intake air is bypassing the MAF, the MAF will report LESS air than is actually passing through the engine, and the ECU will supply only enough fuel to match the reported amount of air. Since more air than reported by the MAF is actually passing through, the resulting fuel mixture will be LEAN.


He said check after the MAF but with the TRD intake it would be pretty obvious if that was the case.

Did you get a T-stat that’s a higher temp than OEM? It was mentioned before but maybe she’s just not getting to normal operation temps with the upgraded radiator. Was the coolant system “burped” properly? If not it can cause a false reading in coolant temp.


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Discussion Starter #13
He said check after the MAF but with the TRD intake it would be pretty obvious if that was the case.

Did you get a T-stat that’s a higher temp than OEM? It was mentioned before but maybe she’s just not getting to normal operation temps with the upgraded radiator. Was the coolant system “burped” properly? If not it can cause a false reading in coolant temp.


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It’s a 180 degree thermostat and I did “burp” the system when filling. Temp seem to indicate it is operational.


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He said check after the MAF but with the TRD intake it would be pretty obvious if that was the case.

Did you get a T-stat that’s a higher temp than OEM? It was mentioned before but maybe she’s just not getting to normal operation temps with the upgraded radiator. Was the coolant system “burped” properly? If not it can cause a false reading in coolant temp. Sent from my iPhone using Tapatalk
Regardless of the "size" of the radiator, the thermostat will regulate the coolant temperature very close to the thermostat's temperature rating.

Normal coolant temperature for the 1GR-FE is 185-195F, and the OP reported that his new thermostat is maintaining the coolant temperature right where it should be.
 

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Regardless of the "size" of the radiator, the thermostat will regulate the coolant temperature very close to the thermostat's temperature rating.



Normal coolant temperature for the 1GR-FE is 185-195F, and the OP reported that his new thermostat is maintaining the coolant temperature is right where it should be.


I was eluding more towards the system being burped properly after the install of the new radiator, not that the radiator itself was the cause of the operating temp being lower.


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There is a vacuum-modulated fuel-pressure regulator in the fuel rail towards th rear of the intake manifold.

Check that your pressure washing didn’t disconnect or damage the vacuum line.

Also, if the diaphragm in the regulator developes a pinhole, it can dribble raw fuel into the intake manifold.
 

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Discussion Starter #17
There is a vacuum-modulated fuel-pressure regulator in the fuel rail towards th rear of the intake manifold.

Check that your pressure washing didn’t disconnect or damage the vacuum line.

Also, if the diaphragm in the regulator developes a pinhole, it can dribble raw fuel into the intake manifold.


I checked that line today and pulled and cleaned the throttle body. It was in good shape. I will have to look up the test procedures for the pressure regulator.

O2 sensors should be here Tuesday so I can get them replaced as well.

Thanks for the help while I try to sort this out.


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cory3122,

I can feel your frustration. This may be a long shot but if I were in your shoes I would disconnect the the negative battery cable, wait 30 minutes, then reconnect it. Perhaps something in your system will re-set itself. Most likely won't be beneficial but why not try anyway.
 

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G'Day Cory,
long shot...but switch back the OE tune...see what happens....cant see that the Raptor tune would affect it, but good to get based line ...and work up from there.
dats all i got.
Good luck,
Cheers
Baz
:blueblob:
 

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G'Day Cory,
long shot...but switch back the OE tune...see what happens....cant see that the Raptor tune would affect it, but good to get based line ...and work up from there.
dats all i got.
Good luck,
Cheers
Baz
:blueblob:
Raptor tune??

There was no mention anywhere in this thread about ECU reprogramming, just new radiator, thermostat, transmission cooler, etc.

And then the high-pressure water-blast cleaning of the engine bay.

Is this engine running a non-stock tune?
 
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