P0174 still coming up after new intake gaskets!

[smaidens]

Okay, so here is where I am at. Yesterday I took it upon myself to do the upper and lower intake gaskets on my 01 Sport 4.0 SOHC with 163K on it. The job was alot easier than what I thought it would be. The old o-rings were not in horrible condition but compared to the new ones you could tell they had shrunk. So I cleared the codes put her all back together, fired it up, ran just as good as it did before. drove it around for a while and thought okay, by now the CEL would have come on. So I thought everything was good.
This afternoon I went to go out and started to drive down the road and bang! The dreaded CEL came back on. When I got home I scanned it and P0174 was back! Where should I look next? I have also put new plugs in it, and both upstream O2 sensors, new filter, cleaned MAF, IAC, all vacuum hose are attached and in good condition. I have only owned it for just over a month now and I don't really know the history of it. I am really getting stumped here.
Any guidance will be helpful.
Thanks,
Scott

 

[ZBlackBeast]

well, according to the repair manual, a P0174 code is fuel too lean on bank 2. Try running some seafoam through the gas tank.

 

[Yomie]

Have you cleaned your MAF lately?

 

[smaidens]

yes, I have cleaned MAF, ran fuel injector cleaner through....ect.??
Could EGR have anything to do with lean codes?

 

[ZBlackBeast]

Reclean everything and reset your PCM again. Make sure all your connectors are pluged in right and there are no air leaks. As far as EGR goes, i would imagine it would throw an EGR code if there was a failure. but cleaning it with carb cleaner wouldnt hurt.

 

[Firestorm]

Also, did you torque your intake manifold bolts to spec?

Perhaps more air is entering the drivers side.

 

[smaidens]

Re-cleaned MAF, and yes I torqued everything to spec. I am still getting LTFT readings of close to 20% on bank 1 and just over 20% on bank 2 at idle. These values fluctuate when I rev it up, but bank 2 is always higher and will trow the code for bank 2.
I have had 0171 as well before come up but 9 times out of 10 I only get 0174.
Thanks for all the advice here, I really appreciate it.
Scott

 

[DGreatest]

To the original poster, was this issue ever resolved? Your symptoms sound exactly like my truck.

I've changed the intakes, checked all hoses, replaced the PCV, air filter, fuel filter. Cleaned and tested the MAF and IAC. Ran Seafoam through the gas tank.

Still, the CEL keeps popping up. I get code P0174 and then a good 20-30 miles later I'll get P0171 also. I've checked every sensor I can think of and they all seem to be working ok. If you figured it out your insight would be greatly appreciated.

 

[2000StreetRod]

Sea Foam in tank

Personally I don't think adding Sea Foam to the fuel tank is a good idea. It's purpose is to loosen deposits. Those loosened deposits could clog your injectors. I suggest adding Techron injection cleaner to your tank and wait a hundred miles or more to see if things improve.

 

[po-po 5.0]

Personally I don't think adding Sea Foam to the fuel tank is a good idea. It's purpose is to loosen deposits. Those loosened deposits could clog your injectors.

Generally speaking, people have fuel filters to prevent that....

 

[2000StreetRod]

Deposits downstream of filter

Generally speaking, people have fuel filters to prevent that....

There are deposits in the lines between the fuel filter and the injectors that can be loosened by Sea Foam.

 

[mshuler009]

If you have deposits in the fuel lines you have more issues than you want to know about. Sea-Foam.....hmmm.....it's not a bad idea, but in this case it's a wasted effort. I'd be looking more towards a small crack in the upper intake manifold. I've seen a few while working in the field.

 

[2000StreetRod]

P0174 criteria

. . . I've changed the intakes, checked all hoses, replaced the PCV, air filter, fuel filter. Cleaned and tested the MAF and IAC. Ran Seafoam through the gas tank.

Still, the CEL keeps popping up. I get code P0174 and then a good 20-30 miles later I'll get P0171 also. I've checked every sensor I can think of and they all seem to be working ok. If you figured it out your insight would be greatly appreciated.

According to the Ford 1998 OBD System Operations Summary DTC P0174 is set when LTFT > 25% and STFT > 5%. It is the same criteria for DTC P0171. If you're getting both DTCs then the PCM thinks both banks are running lean.

What engine do you have?

Are you using a high flow air filter?

Did you perform the "swiss cheese" mod?

Have you tested your fuel pressure? Your fuel pressure regulator could be faulty or your fuel pump could be weak.

Is your ECT sensor good? The PCM decreases enrichment according to engine coolant temperature as the engine transitions from cold start to warm.

Is your IAT sensor good? The PCM adjusts mixture according to intake air temperature.

Have you checked your TPS output voltage? When you rapidly depress the accelerator the PCM enrichens the mixture to compensate for the throttle change.

Does the DTC get set during idle or only when you drive?

Does the DTC get set when the engine is cold or only after warmup?

Does the DTC get set when you rapidly accelerate?

Do you have access to a scanner to check your fuel trims?

 

[2000StreetRod]

Fuel filters & deposits

If you have deposits in the fuel lines you have more issues than you want to know about. . . .

Most fuel injection filters only remove particulates greater than 15 to 25 microns. A typical fuel injector orifice is < 0.005mm (5 microns). Some filters are becoming available that filter particles as small as 3 microns. Every fuel injection system has deposits in the fuel lines. Some just have smaller ones than others.

 

[w4jwc]

Check your engine coolant temprature sensor to the PCM, not the sending unit to the gauge this one is usually on the left of the intake with 2 wires coming out of it.