Serious drop in gas mileage.

[J33Pfan]

i own the $100 unit
https://www.amazon.com/OTC-3208-Enh...coding=UTF8&psc=1&refRID=DV3TVBGEX192F3JDMPM3


if you spray starter fluid around the hoses & intake parts you can find an vacuum leak. just dont be in a hurry and dont set the car on fire.

 

[PunkChachi]

I had a few minutes so I figured I would check out the brakes, bought synthetic grease and new pins/rubber bushing. I jacked it up and spun the wheel to see if there was a difference before and after. I didn't notice much if any of a difference after I changed them. That being said, it was rather hard to pull out the old pins. The grease looked like it may have hardened up some and based on the color I think I used multipurpose grease last time I did it. So cleaned them out and hoping for the best just filled it up and gonna see how gas mileage is.

Also It was hard to start again, starter/battery were fine it just seemed like it wasn't getting any gas. Had to push the pedal down before it revved to life. Could that just be due to me cleaning the throttle body and using a little too much cleaner?

OH! The internet taught me a fun fact! If you put your key in and move it to the accessory position (2nd position) three times and leaving it in the accessory position on the third time, right where your odometer is it will display all engine codes and then read "done" when it is finished! Love people that add these little things.

 

[HoosierJeeper]

For sure, mine doesn't start easy if there's a TB cleaner in it. I wouldn't worry.

 

[sota]

* if you can do your own work, take out your Fuel Injectors and sent them to a guy on Ebay to be rebuilt. you should have them back 2 - 3 days.

are you running different tires?

did you lift it?

winter fuels here on the East Coast are terrible for gas mileage. What octane are you using?
oh and did you install additional skid plates? (inside joke from a different thread)

I don't know about ebay vendors for that, but I can recommend a company called Fuel Injector Clinic. I, and many of the Neon crowd, have used them for work, and bought their injectors. No complaints. Best part was getting the flow numbers for each injector. I sent in 8 for the Neon and took the 4 that best balanced out for the car. Also got an injector that was in bad shape back in working order (clogged.)

Just my $0.02

 

[sota]

I use Seafoam. Depending on the vehicle I either see some white smoke or I smog out the entire county.

 

[J33Pfan]

I don't know about ebay vendors for that, but I can recommend a company called Fuel Injector Clinic. I, and many of the Neon crowd, have used them for work, and bought their injectors. No complaints. Best part was getting the flow numbers for each injector. I sent in 8 for the Neon and took the 4 that best balanced out for the car. Also got an injector that was in bad shape back in working order (clogged.)

Just my $0.02

ive used a guy a few times already. Awesome service!

its not just cleaning or guess cleaned. They measure the output before & after. give you a print out so you can see what the problem was. replace screens & o-rings etc. its a rebuild not a wash. $10 - $12 each

 

[uss2defiant]

mopar combustion chamber cleaner

 

[PunkChachi]

Here is the freeze frame from when the code was given.

DTC for which Freeze Frame was Stored------P0300
Fuel System 1 Status---------------------------Open Loop
Fuel System 2 Status---------------------------Open Loop
Calculated LOAD Value-------------------------52.94 %
Engine Coolant Temp---------------------------222.80 °F
Short Term Fuel Trim - Bank 1----------------0.00 %
Long Term Fuel Trim - Bank 1-----------------0.00 %
Short Term Fuel Trim - Bank 2----------------0.00 %
Long Term Fuel Trim - Bank 2-----------------3.13 %
Intake Manifold Absolute Pressure------------21.91 inHg
Engine RPM-------------------------------------175.25 rpm
Vehicle Speed Sensor--------------------------0.00 mph
Ignition Timing Advance #1 Cylinder---------(-1.00 °)
Intake Air Temperature------------------------141.80 °F
Absolute Throttle Position----------------------14.51 %

The only thing I saw (based off my knowledge of absolutely nothing) was the LTFT B2 wasn't 0.0% like the rest. With that said when I was sitting at idle and hooked up the scanner and viewed live data, all the Fuel Trims were within 2-3% of 0 except LTFT B2 which stayed at 7% and would only change if I hit the gas. But just sitting there idling it was a solid 7 the whole time. Is that a problem?

 

[renegade 04]

I think you could have a intake manifold leak, the pressure should be around 9 or 10 inhg.

 

[PunkChachi]

Could it be a bad MAP? I bought one just incase, it was only like $34 so figured, might as well.

 

[tjkj2002]

Here is the freeze frame from when the code was given.

DTC for which Freeze Frame was Stored------P0300
Fuel System 1 Status---------------------------Open Loop
Fuel System 2 Status---------------------------Open Loop
Calculated LOAD Value-------------------------52.94 %
Engine Coolant Temp---------------------------222.80 °F
Short Term Fuel Trim - Bank 1----------------0.00 %
Long Term Fuel Trim - Bank 1-----------------0.00 %
Short Term Fuel Trim - Bank 2----------------0.00 %
Long Term Fuel Trim - Bank 2-----------------3.13 %
Intake Manifold Absolute Pressure------------21.91 inHg
Engine RPM-------------------------------------175.25 rpm
Vehicle Speed Sensor--------------------------0.00 mph
Ignition Timing Advance #1 Cylinder---------(-1.00 °)
Intake Air Temperature------------------------141.80 °F
Absolute Throttle Position----------------------14.51 %

The only thing I saw (based off my knowledge of absolutely nothing) was the LTFT B2 wasn't 0.0% like the rest. With that said when I was sitting at idle and hooked up the scanner and viewed live data, all the Fuel Trims were within 2-3% of 0 except LTFT B2 which stayed at 7% and would only change if I hit the gas. But just sitting there idling it was a solid 7 the whole time. Is that a problem?

In bold are all issues if your idling.

 

[PunkChachi]

Thanks for highlighting what was wrong but I don't know what that means. Here is data from a min ago when I was just sitting and letting it idle after I drove.

Fuel System 1 Status---------------------------Closed Loop
Fuel System 2 Status---------------------------Closed Loop
Calculated LOAD Value-------------------------19.2 %
Engine Coolant Temp---------------------------210 °F
Short Term Fuel Trim - Bank 1----------------(-5.5 %)
Long Term Fuel Trim - Bank 1-----------------0.00 %
Short Term Fuel Trim - Bank 2----------------(-2.3 %)
Long Term Fuel Trim - Bank 2-----------------4.7 %
Intake Manifold Absolute Pressure------------10.6 inHg
Engine RPM-------------------------------------175.25 rpm
Vehicle Speed Sensor--------------------------0.00 mph
Spark Adv---------(5.5 °)
Intake Air Temperature------------------------102 °F
Absolute Throttle Position----------------------14.5 %

Is this better, the check engine light went away, I didn't reset it.
Based off this does it point anyone in the direction why my Jeep is sucking at life?

 

[Royy]

175 rpm at idle is extremely low. Mine is around 550 rpm.

The 7% LTFT value you mentioned, that's a little bit high, but nothing extreme.
However, the short term fuel trims definitely look off to me. The short term fuel trim values constantly change (on my scanner I see them refresh multiple times every second). So seeing both of them at exactly 0.00% in the freeze frame data... I'm not sure what would cause this. With a vacuum leak (like an intake manifold leak) I'd expect to see very high fuel trim values, because the computer would try to compensate for the extra air entering the system.
In the second set of data it looks a lot better.

I don't know much about the rest of the data, so I'll leave that to others.

 

[tjkj2002]

175 rpm at idle is extremely low. Mine is around 550 rpm.

The 7% LTFT value you mentioned, that's a little bit high, but nothing extreme.
However, the short term fuel trims definitely look off to me. The short term fuel trim values constantly change (on my scanner I see them refresh multiple times every second). So seeing both of them at exactly 0.00% in the freeze frame data... I'm not sure what would cause this. With a vacuum leak (like an intake manifold leak) I'd expect to see very high fuel trim values, because the computer would try to compensate for the extra air entering the system.
In the second set of data it looks a lot better.

I don't know much about the rest of the data, so I'll leave that to others.

As long as the STFT and LTFT's don't ad up to 25%(+/-) your fine.At 6200' elevation my short term fuel trims never see anywhere close to 0%,I'm always +10% and my LTFT's are always +5%.

 

[renegade 04]

You may need to look at getting a new IAC motor, as your idle is way to low.

 

[Royy]

As long as the STFT and LTFT's don't ad up to 25%(+/-) your fine.At 6200' elevation my short term fuel trims never see anywhere close to 0%,I'm always +10% and my LTFT's are always +5%.

To my knowledge occasionally seeing values of 8-10% is normal, but always...? I'm at over 7000 feet elevation here, and my STFTs are under +5% for like 99% of the time.

 

[LibertyTC]

IDK but...how the heck can the jeep even idle @ 175rpm without stalling?
PunkChachi what were the running conditions when code set? (park) idle or in drive?
What does your rpm gauge read in park/drive for instance ?
Troy you bolded the Throttle position sensor, should the OP consider a new one at this point and an IAC?

 

[J33Pfan]

was the car really at 175 RPMs or is the sensor not working?

 

[PunkChachi]

The first set of numbers I posted were from when the code was kicked out. When I started up the jeep. The second set of numbers are from a normal idle with no check engine light. The top set of numbers is not how my Jeep normally runs, it doesn't idle at 175 rpms.

 

[PunkChachi]

I started looking into some of the the numbers. My TPS % isn't right, so I turned the car off and put the key in the ignition. TPS % read 13.7% (14.1% when idling or coasting down the road). I slowly depressed the pedal until it was grounded and TPS% only went up to 77.3%. Could this be a reason for my bad gas mileage? If so is it just the sensor I need to replace or do I have to do something else?