P0171 P0174 yet again - please help!

[tlestan]

THIS PROBLEM IS SOLVED. JUST EDITING SO PEOPLE DON'T HAVE TO ADD IDEAS. IT WAS FUEL PUMP

OK, I've read EVERYTHING related to these lean codes. 1999 Merc Mountaineer with 4.0 SOHC. Replaced the upper and lower intake gaskets, curing the rough idle when cold - still get the codes even in summer. Truck runs great, but hot starts are getting a little weird. Read the MAF signal with a scanner, and all looks good. Short term fuel trims running at 15 on one bank and 6 on the other. Did thourough check for vacuum leaks with propane and visual - nothing. I'm also getting P0741 on the trans when it does the flashing O/D light trick. Can these be related? Mileage is running 15-16, and it used to be 20. No codes for O2 sensors, except a pending P0137 one time, but real time signals look OK. Could TPS be an issue? Just cleaned the MAF tonight, running at .82 at idle, and smooth through the range. Can anyone give me a new outlook on this? Fuel pressure is rock steady at 33. Truck has 230,000 miles on it. Just getting broke in.

 

[ragajungle]

well it either means too much air or not enough gas... If your fuell pressure is good when idle what does it do WOT? Also these plastic intakes if it is not absolutely perfect and torqued to spec in order you may be ripping it back apart again. I am leary about spraying ether into a running motor but if the propane and hose didnt catch it ethers will. Where in WI?

 

[ragajungle]

Forgot to add, this weekend I did my upper intake and noticed that when I put gasoline in it to clean out carbon and blow by from inside of it (while out and on my work bench) I noticed that the seams in the plastic moulding seeped gasoline .. maybe its a seem leek? I used RTV Black to seal it.

 

[rightnwrong]

Absolutely good idea ragajungle. You got it right. Give him around of applause.

 

[2000StreetRod]

Low fuel pressure

. . . Fuel pressure is rock steady at 33. Truck has 230,000 miles on it. Just getting broke in.

Your 1999 should have a returnless fuel system with the fuel pressure regulator in the tank and a fuel pressure damper on the fuel rail. If so, your fuel pressure should be about 60 to 65 psi for all engine speeds. Have you replaced your fuel filter in the last 30,000 miles? If so, I suspect your fuel pump is weak, the fuel pressure regulator is faulty or the tank screen is clogged. Fuel pressure test procedure

 

[tlestan]

Good thought on the split manifold. I looked it over really well when I did the gasket, but I could have missed it. My friend, an actual mechanic, helped me with his scanner, and doused the motor with carb cleaner looking for leaks. I stepped back about ten feet, but he knows what he's doing. At this mileage, maybe a viking funeral would be the appropriate thing. The fuel pressure was 33psi from idle to 3500 rpm, and that's as high as I checked. It never sees over 3 grand in normal driving. Could TPS be a problem? Watching the average mileage meter, it will motor along at 55 getting 20, but as soon as I crack the throttle, it dumps to 16. Maybe bad signal causing mismatch between TPS and MAF? Mismatch between TPS and speed sensor causing P0741? Runs great otherwise, but a little rich on cold startup. I can smell gas for about 30 seconds from the tailpipe. Did the fuel filter last weekend with no change. If it's retunless, what's the little deal on the rail on the back drivers side of the motor? I thought I was looking at the FPR, no?

 

[tlestan]

I'm ten minutes from you, in Waterford, so if you want to get together, let me know. I'd appreciate it if you have any ideas.

 

[tlestan]

Yeah, I looked up the pressure spec, and it does seem I'm running about 1/2 of what it should, huh? The weird thing is that my buddy's scanner supposedly knows the specs for the car (it reads the VIN) and it showed in spec. It's definitely a 1999, and the pump is probably original. How bad is swapping the pump and or regulator on this?

 

[2000StreetRod]

fuel pump replacement links

Yeah, I looked up the pressure spec, and it does seem I'm running about 1/2 of what it should, huh? The weird thing is that my buddy's scanner supposedly knows the specs for the car (it reads the VIN) and it showed in spec. It's definitely a 1999, and the pump is probably original. How bad is swapping the pump and or regulator on this?

How To: 12/95 or 1996 Ford Explorer V-6 4.0 4 dr Fuel Pump Replacement

Fuel pump / Fuel tank - Tips and warnings

Fuel pump replace?

Here's a more radical approach:Gas Tank Access Panel

 

[ragajungle]

I'm ten minutes from you, in Waterford, so if you want to get together, let me know. I'd appreciate it if you have any ideas.

If you have a garage I am your new official bestest bud!

I am not sure about the FPR on that (or if it has one) but that's besides the point if the FPR was bad you would have chugging , and rich condition, and it wouldn't run good at all... Do you have a Ford Service Manual for the SOHC?
-Mike

 

[2000LXS]

I replace every part intake gaskets, tps, mass air, iac, oxygen sensors, fuel filter,over two years. My fuel pressure was 50 psi I finally said why not change the fuel pump everything else is new and that was it was truck has twice the power and no more codes for the first time in two years.

 

[tlestan]

Thanks, 2000XLS, that makes me feel like my diagnosis is dead on. My average mileage has been slowly degrading on the display. That must get calculated from the injector pulse width and RPM that the PCM is reading. This also explains hard starting when hot. I'm hopefully going to have access to a buddy's heated shop, with lift, so it should be a piece of cake. Plus he's an ASE certified mechanic and owns a 98 X, so he's been here, done that.

I'd like to get 300k out of it, but it still has some timing chain rattle even after the new front tensioner. Cassettes are probably trash, but it only rattles a bit when cold, and then it shuts up. I'm not going to yank the front end off the motor at this stage. I can pick up a 99 with V8 and half the mileage for $4k all day long, and still get a grand for this one if I have to. I'll post when it's all done and let everyone know the outcome.

 

[2000LXS]

I used the cut the hole in the floor method and it worked great and my gas tank was spotless probably from the 10+ bottles of injector cleaner trying to get rid the lean codes. My truck rattles on cold mornings for about 10-15 sec then is 100% quiet.

I used sheed metal with foam weather strips and self taping screws to seal the floor and it came out really great.

 

[fex98]

OK, I've read EVERYTHING related to these lean codes. 1999 Merc Mountaineer with 4.0 SOHC. Replaced the upper and lower intake gaskets, curing the rough idle when cold - still get the codes even in summer. Truck runs great, but hot starts are getting a little weird. Read the MAF signal with a scanner, and all looks good. Short term fuel trims running at 15 on one bank and 6 on the other. Did thourough check for vacuum leaks with propane and visual - nothing. I'm also getting P0741 on the trans when it does the flashing O/D light trick. Can these be related? Mileage is running 15-16, and it used to be 20. No codes for O2 sensors, except a pending P0137 one time, but real time signals look OK. Could TPS be an issue? Just cleaned the MAF tonight, running at .82 at idle, and smooth through the range. Can anyone give me a new outlook on this? Fuel pressure is rock steady at 33. Truck has 230,000 miles on it. Just getting broke in.

try this http://www.obd-codes.com/trouble_codes/ford/index.php

 

[ragajungle]

^^^^^^absolutely bookmarked!!^^^^^^

 

[ThePhoenix]

I replace every part intake gaskets, tps, mass air, iac, oxygen sensors, fuel filter,over two years. My fuel pressure was 50 psi I finally said why not change the fuel pump everything else is new and that was it was truck has twice the power and no more codes for the first time in two years.

wait...this could affect the mileage too?

mine has been dropping off...could it be a fuel pump?

 

[tlestan]

Actual mileage or displayed on computer? Either way, probably. The truck will actually run lean, the O2 sensors will tell the PCM, and it will compensate by increasing injection pulses to get more fuel. If it hits the limit on the fuel trim, you'll get a check engine light. Are you storing any codes?

 

[ThePhoenix]

me? No codes!

I had the O2 sensor codes before I did intake gaskets.

Now I just have 16-17 mpg continuous

 

[tlestan]

Fuel pump install question.1

OK, I have a pump now. I started cutting the hole to access the pump from up top, and unlike the pictures I've seen here, theres a rail in the way. It is a formed sheet metal stiffener that looks like it has the body mounts on it. Should I notch this thing, or leave it alone and drop the tank.

This is a four door 4WD 1999, by the way. Any advice?

 

[rego]

I notched mine.