Greetings & a Question

[wrightz28]

Well thank you very much sir.

No, I honestly have not had any time, nor availabe weather to poke around much with anything on the truck since purchase, so I'm kind of being lazy and hoping there was a known cause for the A/C compressor. As said, not a major issue, just curiousity, but I will definatley look into it soon as I will have tons of 'extra' time on my hands for some time until life's little issues are resolved and miss being in the garage (will have to buy all new tools, but like I'm going to complain about that )

As to the knock, that's interesting, I'll be more attentive to it tomorrow morning, however it seems to eminate from the right rear of the motor. I did notice this morning a slight exhaust flange squeak that just started as of today from that side so I'm starting to think the 2 are related as the collector may just be loose, and both went away at about the same time.

[wrightz28]

Well, happy to report all 3 codes present at purchase are now resolved:

Right bank lean indication, resolved by $2.99 injector cleaner

2 EVAP codes resolved by $21 locking gas cap this morning.

Ironically now that the check engine light off, the A/C cycling has stopped?

[shorod]

That's great, very inexpensive fix. Thank you for the follow-up detailing your success. Good information!

-Rod

[wrightz28]

Ehhh dang it, spoke too soon. Ran all day yesterday just fine, no pesky CEL. Then it came back on upon restart running some errands last night. And, now that it's back on, the A/C is cycling again when not being called for, so somehow the 2 ARE intertwined.

Going to have to go get a new scan tool next paycheck to get a clear picture of wht the hebbie-gebbie is going on here.

[shorod]

Wow, that's an interesting correlation. When I get back home from travel I'll have to check the service manual to see if there are any possible ties between the two. I wonder if there's a chance a power steering pressure switch or Throttle Position Sensor (something that could cause the A/C to cut out) could be faulty and causing both issues.

-Rod

[wrightz28]

Yeah, let me know what you find if anything. Luckily the weather picked up into the 60's so I don't need the heater all that much, the load drag from the cycling is killing my mileage.

[shorod]

Any chance you'll be near an Autozone or similar this weekend to get the codes read? I just realized that you never reported any code numbers, so that limits the service manual research.

As for the manual A/C system circuit, the compressor clutch relay is controlled by the PCM. The PCM controls the relay coil ground, which has to also have continuity to ground through the cycling pressure switch which is in series with the cutoff pressure switch. The input to the PCM to request A/C compressor clutch lockup is from the function selector switch assembly, and the request is made whenever the selector is set to Normal A/C, Max A/C, Defrost, Defrost/Floor, or Panel/Floor (which surprises me). You don't happen to use the Panel/Floor selection when the compressor is cycling, do you? Looks like the only setting that don't request A/C are the Panel, Off, and Floor settings. I seem to remember you mentioning that the compressor still cycles even when set to Panel or Off.

I certainly don't see a correlation between the CEL and the compressor though, unless there is some sort of ground or backfeed issue between the transistor driving the relay coil and the transistor for the CEL internal to the PCM.

-Rod

[wrightz28]

Thanks again Rod. I almost always use the panel/floor setting, so that is strange indeed that the A/C would be called for in that mode. But i swear when when the CEL was off, it wasn't cycling Maybe I'm just losing it who knows.

Only codes i had when purchased were Right bank lean indication and 2 EVAP codes. Don't have the exact ones.

[wrightz28]

Ok, the prognosis (and it's getting worse 4 codes now).

First off is this dang DPFE ordeal (code reads as "BBDPFE sensor upstream hose off or plugged). Where is this? The hose I found broken off was coming off the air injection tubes to the intake, so I would assume the sensor that the two hoses plug to on the intake is DPFE? I replaced only the broken hose and left the other alone for now since I didn't have a replcement on stand by, guess I'll just get some more hose and pray for the best. Seeing the broken hose was corroded to near shut in spots I would imagine the other being near the same and triggering the code?

Now for the big enchelada. Originally I had a right bank lean indication code, now I have a lean reading on both and "EVAP small leak/no flow condition" which a probable cause is a vacuum leak at engine. So apparently there is vacuum leak somewhere past the MAF sensor. I am letting the engine cool right now so that I can take a detailed look and the intake tubing and all other vacuum hoses for signs of breakage. I don't think it's the intake manifold at this juncture as she runs smooth and the idle speed is not excesive, but we'll see. If all else fails I'll just spend the couple of hours next weekend and replace the darn gasket anyway. Oh, and what's the deal with the cut-off dates for the motor? 2 different gasket sets came up depending on build date, just curious. Further more, could the DPFE hose problem cause this?

As for the EGR, I'm assuming this is the valve on the end of the left side air injection tube running to intake, just behind the throttle body?

[way2old]

Can ya post the exact code numbers? SOmetimes the description can be more than one code.

[wrightz28]

Originally Posted by way2old

Can ya post the exact code numbers? SOmetimes the description can be more than one code.

Absolutely:

P1405 - DPFE sensor upstream hose off or plugged. (I did pull the other hose off the air tube yesterday and it is fine, no clogs.

P0442 - EVAP small leak/no flow condition (found a loose fitting vacuum hose on this issue)

P0171 - fuel trim bank 1 condition

P0174 - fuel trim bank 2 condition

I would be almost certain everything must be related to the sensor that the 2 emission hoses plug into, that I'm assuming is the DPFE as I only had the P0174 prior to finding the broken hose and replacing it which must have triggered the P0171.

Would it be recommended to to get a factory replacement DPFE or are the aftermarkets suitable?

[shorod]

I think you're right that the DPFE is a good place to resume your troubleshooting. They've been a common issue on many Fords. Just be sure not to get the hoses reversed during the installation. I haven't really seen people complain about the aftermarket DPFE sensors, but Way2Old may have some suggestions there.

As for the P0442, I've seen that sporatically (twice over 1 year span, most recently about two weeks ago). Between the two instances I replaced the fuel cap, so that evidently didn't fix it. Both times were within a couple days of filling up with gasoline.

-Rod

[wrightz28]

Originally Posted by shorod

As for the P0442, I've seen that sporatically (twice over 1 year span, most recently about two weeks ago). Between the two instances I replaced the fuel cap, so that evidently didn't fix it. Both times were within a couple days of filling up with gasoline.

-Rod

Yeah, I bought a new cap already and that did rememdy the other EVAP code I was getting but not this one. As said, after having it scanned yesterday morning I checked over all the vacuum hoses and did find the small line for the EVAP canister was loosely fit at the junction valve by the valve cover, so I patched that up for now and got a "better" fit on it.

I think I will just replace the DPFE sensor next weekend and go from there.

Edit, I should also note that during my inspection yesterday it appears that the intake manifold gasket had already been replaced as some of the wiring looms that attach to it were not put back on, so I'm really straying away from it being an issue.