Hi all,

After starting my engine after the swap, it idled rough, but it would be smooth up top near the rev limiter of 3000.

Quick revs, too

I picked up a Bluedriver OBD2 reader and scanned my 4.0 SOHC. Here are the results:



In researching, vacuum lines seem to be the consensus. I've checked my connections and they seem tight. Hoses look okie day.

Has anyone had these codes come up?

Thanx in advance!

 

P0xx, P2xx and P3xx are generic powertrain OBD Codes
P1xx are manufacturer specific, i.e Ford code

P2195 and P2197 are not quite the same as P0171 and P0174 which are more common
But both sets mean BOTH sides of the V6 engine are showing miscalculation of air/fuel mix by the computer
The P2xx is usually from a Test run by the computer, which is why it is a "pending" code and usually won't turn on CEL(check engine light)
Its a Maintenance code, this set of codes would tell mechanic to check fuel pressure and MAF sensor, and look for upper intake vacuum leak to head off P0171 and P0174 codes which would turn on CEL

On the 4.0l SOHC engine the most common cause of Lean on BOTH BANKS is PCV Valve hose at its elbow(under side), it rubs and cracks then starts to allow air to be sucked in, so computers air data from MAF sensor is incorrect, unreported air is coming in so its calculated fuel mix is Lean

On any Ford vehicle you should clean the MAF sensor once a year or every two years, its easy, but the 4.0ls, OHV or SOHC, seem to need it once a year

 

I'll be taking a closer look at the hoses (both sides) to the PCV system when I get home. It should still be good sunlight to see, Passenger side is easy, but the clearance in the back for the driver side... Ow.

I cleaned the MAF before I installed the engine, so there's one off the checklist.

Thanx for the tips, Ron. I know suspension, tires, and making spaghetti, but computer triggers are not my thing.

 

Update...

I checked the vacuum hoses from the PCV to the intake (back driver side to passenger front intake) and the valve cover (passenger side) to the air intake tube.

They "look and feel" in good condition, but I ordered them anyway and will be replacing them.

2 notes:
Neither end of the PCV to Intake tube had a hose clamp on them.
Loose attachment/connection from valve cover to air intake tube.

Would these go ahead and trigger those codes? A simple hose clamp(s) and new connector? The contact seemed fairly tight.

I will be replacing both anyway because why not?

Also...would cleaning/replacing the IAC valve help? It DOES have a rough idle and dies at times. I was hoping that changing the aforementioned vacuum lines would correct the idle problem.

Full disclosure. Old gas. I planned on draining the old gas, but haven't gotten around to it because I needed that little tool. I finally received the tool after 5 weeks shipping time. That guy got a negative review for losing my order. (middle finger)

After I replace the lines and drain the tank and fill with new gas (and new filter), I will report back.

Another question...

I've been cleaning my MAF over the years, and it's been working well (before timing chain debacle), but it's the original 15-year-old sensor, so I'm looking at replacing it.

First feeling is to replace with Motorcraft, but it says remanufactured and they need my core for 70 bux credit, the sensor costs 120 and change, so total is 190.

The cheap bastard in me sees an off-brand, new sensor for 20 and change from Amazon.

With periodic cleaning, do these things from other brands fail much?

Thx much in advance!

 

Vacuum hoses rarely have clamps, no real need since connections are sucked together by the negative pressure inside, other types of hoses usually have positive pressure inside so are pushed apart and need clamps for that reason.

Important vacuum hoses like Power Brake booster hose will often have clamps, this is because of back fires into intake, which will blow off an unclamped vacuum hose, most vacuum hoses that would blow off would just cause rough running, loss of power brakes would be a bad thing for most people, lol.

The Vent hose also doesn't need claps in most cases, valve cover to fresh air intake, its part of PCV system and allows air to be pulled in or blown out but its always low pressure flowing


MAF sensor is a Main sensor, not sure why you should replace it unless if fails, you will get a Circuit failure code if it does.
Its not that hard to replace MAF sensor so $20 part won't be hard to swap out if it doesn't work well
I tend to look at 3rd party parts in the view of how hard are they to get to and replace, if they fail, lol, and whats the downside if they fail

i.e. fuel pumps, I use motorcraft because they are hard to get to to change and will strand me if 3rd party pump fails, so I will to spend the extra money on them, but still look for a deal on one

O2 sensors are about the only sensors that wear out, they use a chemical reaction so chemical gets used up after 150k miles on Upstream O2's, Downstream(after Cat converter) O2's last 3 times as long usually

 

Thanx, Ron.

Maybe I'll buy 2 MAFs at 20 bux each, then

In addition to the new tubes, it may be a good idea to change both O2 sensors, too. They're OEM from new, so that 150k figure is long gone in my situation.

Any input on the IAC valve?

Once I get them installed, I'll report back.

Much thanx Ron!

 

Update:

The codes have changed to the ones you've spoken of AFTER I changed the PCV vacuum and intake lines:



Pending codes...is it waiting for something?

I just bought down and upstream O2 sensors just because the OG ones are 16 years old. Will be installing them this weekend.

Dumb question, but should I run the engine until the O2 sensors come up to the proper temp?

I also bought a new MAF sensor (20 bux...why not?) and a fuel filter.

I'll be trying to locate any more vacuum leaks that may be fudging with my truck's resurrection.

 

Very few computer codes are set when they first appear to computer, they go to Pending memory and computer waits for them to reoccur a few times before setting the code and turning on the CEL
Pending codes will go away after 30 or so drive cycles if they don't reoccur
Drive cycle = one coolant heat up above 170degF and cool down below 120degF

All kinds of glitches can occur in normal driving, a little water in the gasoline or you run out of gas, lol, this can cause pending lean codes

It takes about 5 minutes for O2s to start working from cold start, already warmed up maybe 2 minutes, they need to be above 650degF for the chemical reaction to detect oxygen to occur
Computer is in Open Loop during this time so no lean or rich codes would be looked for by computer, these can only be look for when computer has feedback from the upstream O2 sensors, in Closed Loop

 

Here's the 64 dollar question...

Would "pending" codes prevent you from smogging your car?

That's mainly what I'm trying to do...clear all the codes by proper repair first, but if it takes 30 or so cycles to clear pending codes, I fear these codes will be lurking in "pending" mode telling the smog tech "HEY! DON'T PASS THIS THING!"

In CA, that's how they smog, meow...ODB2 codes. I haven't been on a car treadmill in years. They plug me in, run it a few minutes, check codes, and if no codes pop up, you're finished. Have a nice day.

I'll be Googling the possibility as well as stopping by my Pep Boys to find out.

 

Never mind...got my answer.

 

I wouldn't think pending Lean codes would cause a no pass, EGR, EVAP, O2 sensor 2 codes might, those are emissions related

Lean or Rich codes are air/fuel mix calculation related so wouldn't effect actual emissions since computer has corrected the mix and engine is not actually running lean or rich