Bad MPG, ran codes
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Senior User
Joined: Apr 2008
Posts: 448
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From: Iowa
Bad MPG, ran codes
My truck only gets 11.3-11.4 MPG even when I take it easy. It doesn't have much power either- the best 0-60 time I can get is 20 seconds. '91 F150 4.9 5 spd 4x4 3.08's
I just changed fuel filter-that helped it out a lot.
I ran codes and got-
KOEO-
553- Air management 2 circuit failure (AM1/TAD)
565- Canister Purge Circuit failure
KOER-
111- System pass
Would either of those cause my poor MPG?
I just changed fuel filter-that helped it out a lot.
I ran codes and got-
KOEO-
553- Air management 2 circuit failure (AM1/TAD)
565- Canister Purge Circuit failure
KOER-
111- System pass
Would either of those cause my poor MPG?
Senior User
Joined: Dec 2006
Posts: 164
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From: Gray, TN
I don't think so. Those are more emissions related. Code 111 is meaningless. I would check your ignition timing and your fuel pressure. Timing should be 10 degrees btdc with the spout connector unplugged and engine idling at operating temperature. I believe the fuel pressure should be 35 to 40 psi. Be sure to use the timing scale on the passenger side of the engine, not the one embossed into the timing cover, I've been fooled by that before. Other than those you'd have to check the regular tune-up type stuff. My 300 was low on power and mileage when I got it. It turned out to have clogged fuel injectors. The main symptom was that it was real hard to keep it running on a cold start. It also would give a lean code with the KOER test.
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Senior User
Joined: Apr 2008
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From: Iowa
So then the 553 and 565 aren't worth fixing? The Check engine light is on 90% of the time while driving.
I'm going to check timing and do a full tuneup this week. I need to get a fuel pressure gage.
I'm going to check timing and do a full tuneup this week. I need to get a fuel pressure gage.
Post Fiend
Joined: Apr 2004
Posts: 6,473
Likes: 4
From: Lafayette, IN
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Senior User
Joined: Apr 2008
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From: Iowa
So then it would give me-
56- MAF circuit above maximum voltage of 4.5volts / TOT sensor output is greater than Self-Test maximum value of 4.8 volts.
55- Keyed power input to processor is open
53- TPS failed / above 4.5 volts
Also, my compression ranges from 120 (lowest cyl) to 140 PSI (highest cyl), what is it supposed to be? The book only says lowest cylinder must be within 75% of highest
I have noticed this thing will barely hold itself on a hill in 1st gear
56- MAF circuit above maximum voltage of 4.5volts / TOT sensor output is greater than Self-Test maximum value of 4.8 volts.
55- Keyed power input to processor is open
53- TPS failed / above 4.5 volts
Also, my compression ranges from 120 (lowest cyl) to 140 PSI (highest cyl), what is it supposed to be? The book only says lowest cylinder must be within 75% of highest
I have noticed this thing will barely hold itself on a hill in 1st gear
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Post Fiend
Joined: Apr 2004
Posts: 6,473
Likes: 4
From: Lafayette, IN
A bad TPS causes all kinds of drivability issues, and can cause other codes to be set. I'd double-check (re-read them, I'm guessing you just re-grouped the digits) the codes, then start with the TPS. I think the Haynes manual has the resistance values for full-closed and full-open on it, and there should be no "hiccups" throughout the range.
Jason
Jason
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Senior User
Joined: Apr 2008
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From: Iowa
I put all new exhaust on it right after I got it- cut off cats and put glasspacks that dump out under the bed (need to get tailpipes).
I will check codes again. Would you like me to post a video of it so we can verify if I'm counting right?
I will check codes again. Would you like me to post a video of it so we can verify if I'm counting right?
Thread Starter
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Senior User
Joined: Apr 2008
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From: Iowa
I changed the fuel filter and my mileage highway crusing at 60 was 15.15 MPG -Definitly an improvement, but still not where it should be. It starts a lot easier too. I will run codes again when I get time.
Post Fiend
Joined: May 2004
Posts: 11,289
Likes: 6
From: Lakewood, Ohio
you are not going to get much better then that mileage at 60 mph.
a code reader knows if 2 or 3 digit codes and is well worth the investment.
the paper clip method only wasted my time and my time was worth enough to buy a code reader.
and fords have limited slip not posi, that is gm speak.
a code reader knows if 2 or 3 digit codes and is well worth the investment.
the paper clip method only wasted my time and my time was worth enough to buy a code reader.
and fords have limited slip not posi, that is gm speak.