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Just another poor mileage tread..


jmvb

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1998 Explorer XLT
My 98 XLT V6 SOHC is running well, more or less, the idle is not so smooth, but no rough neither... I think that it could be better

RPM about 700

I have 31x10.50R15 tires

With the new tires, the speedmeter have an 10% error, checked with GPS

50 MPH in dashboard, actual 55... I guess that in the odometer is the same thing

I did a few things trying to improve my mileage

- New thermostat, the truck reach service temp fast
- New o2 sensors (ebay chinese ones) no check engine light, but I don't know if there are some unread codes
- Upper intake manifold gasket
- PCV valve cleaning
- Acceleration body cleaning
- IAC valve cleaning
- Mass air flow sensor cleaning


In city the best average is 11 MPG, driving like a granny

I live in a small town, so short trips.

In high way, at 60MPH with crusier control, the average is 16MPG

Poor, uh?
 


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koda2000

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Jose,
You don't say how many miles you have, but O2 sensors (upstream) are due to be changed around 100,000-120,000 miles. They make a big difference to MPG and don't set the CEL because they may be reporting w/in an acceptable range to the PCM. The O2 sensors after the cats have no bearing on fuel trim. They just monitor cat efficiency.

Your idle is high for a SOHC. If you can believe the tachometer, it should be around 500-550 RPM. You report a slightly rough idle. That can be due to leaking intake manifold O-rings (quite common on the Job 1 SOHC engine).

Good idea to clean the MAF sensor, also the throttle body and the IAC. There is a small screw that stops the throttle body plate from closing all the way (if it closes to far it will stick closed) but it is possible to turn that screw a little to raise/lower to idle. There's a spec for how far open the throttle plate should be at idle (so many thousands of an inch) which should not be exceeded, but I've increased the idle on my '97 Sport SOHC a little bit as I felt it was too low. It's been adjusted that way for 2 years now w/out any issues.

Usually (unless someone has turned up the T/B plate stop screw, higher than spec idle is due to a vacuum leak somewhere. The intake manifold O-rings are a common source of air leaks, especially when the engine is cold.

Other things that can effect fuel trim are the coolant temp sensor and the input air charge temp sensor (sometimes the air charge temp sensor is part of the MAF sensor, sometimes it's a separate sensor in the area of the MAF). I'm not an advocate of throwing parts at a problem without proper diagnosis, just trying to give you some ideas. Do you believe you've checked/fixed all the vacuum lines after the fire?
 




Machine090767

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2014 Explorer XLT
I get around 17-18 on my 2007, so 16 mpg isn't really bad at all.
 




jmvb

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Phil

Thanks for you kind reply.

My XLT have 175.000 miles

I changed all o2 sensor, less than 100 miles ago
About the idle, it always been high
When the truck star cold, it is about 1000RPM, after a couple of blocks it drops to 700

I saw the 700 RPM when I took the explorer to the annual test.
BTW, the exhaust gases are fine for the local regulations, no smokes at all

at 2500 RPM
HC = 9PPM
CO% = 0.14

At idle
HC = 26PPM
CO% = 0.07

Also, I changed (myself) the upper intake manifold orings last week.
I checked all vacuum hoses as far I can. The one where the PCV valve is plugged, I was unable to follow down between the engine and the firewall.

After fire, the power booster vacuum hose was damaged, and also the EGR and the AC ones... all was changed.

If I put the XLT into a scanner, it could give me clues about the poor mileage and the vacuum leaks?
 




koda2000

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Phil

Thanks for you kind reply.

My XLT have 175.000 miles

I changed all o2 sensor, less than 100 miles ago
About the idle, it always been high
When the truck star cold, it is about 1000RPM, after a couple of blocks it drops to 700

I saw the 700 RPM when I took the explorer to the annual test.
BTW, the exhaust gases are fine for the local regulations, no smokes at all

at 2500 RPM
HC = 9PPM
CO% = 0.14

At idle
HC = 26PPM
CO% = 0.07

Also, I changed (myself) the upper intake manifold orings last week.
I checked all vacuum hoses as far I can. The one where the PCV valve is plugged, I was unable to follow down between the engine and the firewall.

After fire, the power booster vacuum hose was damaged, and also the EGR and the AC ones... all was changed.

If I put the XLT into a scanner, it could give me clues about the poor mileage and the vacuum leaks?
IDK, couldn't hurt I guess.
 




manimal

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96 XLT
I have gained a huge amount of info using the BAFX Bluetooth scan tool on my 96, with Torque Pro for Android.

You can monitor fuel trims, O2 voltage, IAC and ECT readings, etc.

If something is reading incorrectly you will notice it really fast. By watching fuel trims you can also spot a leaking fuel injector, e. g. if trim for a certain injector is high negative it's dumping too much fuel and the ECU is trying to compensate.
 




45Frank

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This is my second Explorer and really didn't like the first which was a 2000 that was a headache from day one. That one had a 4 speed auto pretty well loaded and got around town 12-13 town and 21-22 MPG on the HWY. This one is also a 2000 with the v-6 but pretty well stripped other then power locks and windows and it has the 5 speed auto and I have had it for 10 months and never had it on the HWY for more than 5 miles or so. Around town I get was getting 16-17 then a month or so ago critters ate a bunch of wires so he changed some injector wires, ign wires, new plugs and fuel filter. The last few weeks I'm up about 18.5 or so. Don't plan on any trips so HWY will be a mystery for a while.
 




jmvb

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When I rescued the explorer in august 2015, I changed spark plugs (motorcraft platinum) , all filters, oil, etc.
Also I cleaned the injectors with ultrasonic method
Then, I changed the spark wires (chinese ones).
After the fire, one of them was melted, so I put an old one back

16-17 in city is very good average

I'll do that test, to catch vacuum leaks

 




jmvb

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Today, I cleaned the MAF again, and the air temp sensor of the intake, as Phil suggest....

Well, got the better idle so far!! really soft!

In warm, the RPM drop in tachometer to 500, maybe a little up of there.

My idle always had a cyclic little trembling, but today it is not there anymore.

Just in case, tomorrow I'll do the smoke leak test.
 
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jmvb

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Today, I spend all afternoon changing the intake o'rings

Sadly, the ford people sell me the wrong lower ones

Grey, the ones which the explorer have
Blue, the ones which Ford sell me




Part number 1L2Z 9461 CA

Anyone knows the righ part number for 98 SOHC?

As I can't leave the explorer without run, I wash the older ones, clean the site where it fit, and clean the head holes

I Changed the upper for new ines, they fit well, and run the engine.

What do you think? (no, I did not clean my engine, yet)


At the end of the video, you can ear my chain rattle

 
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koda2000

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jmvb

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Okay, after my orings change incident
http://www.explorerforum.com/forums...heft-light-flashing-on-dash-nightmare.448778/

I still had having some idle problems.
The short term fuel trim in bank 1 was about 30%.

Some upper intake holes of torx screw was loose, so I guess that I'm losing vacuum from there.

I puted oversize screws in the holes with troubles.

I performed a smoke machine test, and the only leaks come from the mid of EGR and the IAC black knob

Additionally, I get the P1131 and P1132 codes.
Doing some research, I found that a defective EGR could be the problem for this codes

Get new-old valves from junkyard, cleaned the IAC so well, and installed both

The idle is much better now, but remain a little hesitate..

The new fuel trims are

Idle
STFT bank 1 -3.8%
STFT bank 2 -1.21%
LTFT bank 1 -4.1%
LTFT bank 2 -1.1%

2000RPM
STFT bank 1 -3.6%
STFT bank 2 3.6%
LTFT bank 1 2.3%
LTFT bank 2 -0.7%

How do you think guys, the they look?
 




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