@006 #,0L keeps running ruff and losing power after up to operating temp

[MikeS]

2006 3.0 L 6 cylinder 2 wd regular cab engine issues! Now what?
2006 3.0l with 169 k on it heads were remanufactured at 158k , had a check engine light for the catalytic converter poe 420 . Had the y pipe and secondary Cats replaced new o2 sensors, then took it out fior test drive ran fine for the first 45 minutes then acted like the cat was plugged again ( no power after you stepped on the gas, then actted like it was flooded pulled a codes po171,po174,po113 po 102 for the air intake temp sensor ( which is part of the MAF sensor on this engine ,checked all the wires so Cleaned the sensor with MAF cleaner no better, replaced MAF with a known good one exact factory match cleared codes and started truck, Idle at 750 rpms sort of roughf , stumbles when you give it fuel until 1500 rpms clears out to 3000 where it hits the govenor. left the truck Idle for about 20 minutes still afraid to taake it on the road don't need it stalling out again only when it is cooled down does it start right up also checked fuel pressure 40 while keyed and 65 while running held at 62 after key was turned off for 20 minutes, fuel filter changed about 25 k ago, running out of Ideas and money! any help would be great ,

 

[Dirtman]

With lean on both banks and maf codes, first thing I would be doing is carefully checking the maf connection, wiring, and ground straps.
It's running fine when cold because its in open loop mode and not using the maf sensor. If you are 100% positive you replaced it ith a god unit, that leaves wiring.

 

[91stranger]

At first I was thinking this was a fuel issue. Have you changed the fuel pump lately? Might be due for one. I remember I had a grand am that would run rough like that and at night you could see the cat glowing red. thought I had a plugged cat but it ended up being a bad fuel filter. new filter and good as gold. 25k doesn't seem like much but parts now-a-days are junk and I wouldn't bet on anything lasting like they used to. for me to go 25k is about a few years. I would change the fuel filter for starters and see what happens. fuel issues can have very weird symptoms and the computer can't tell when the pump is failing.

 

[8thTon]

I can't tell from the word jumble when the P0420 happened - is it current or was that when you did the heads previously? Your other codes all related to the MAFS/IAT sensor, so perhaps there is a wiring issue there.

Also, what do the plugs look like, and what kind are they? If you put something like Bosch fine wire plugs in there you'll only get a couple thousand miles before the electrodes on 3 of them are gone, and then you'll get misfires on both banks. The system does not always set a misfire code for that. Below is a description I wrote up before for another thread:

Lean codes and P0420 can all be caused by misfires from burned open plugs thanks to the wasted spark ignition. When a cylinder doesn't fire there is unburned fuel and excess oxygen in the exhaust - but O2 sensors measure oxygen.

The P0420 code can be tricky - it is looking at the upstream and downstream O2 sensors to try to figure out how much the cat is doing. It is expecting the downstream O2 sensor to show a different signal from the upstream O2 sensor. Unburned fuel and excess oxygen from misfires can mess that up - there was already excess oxygen upstream, and then the unburned fuel goes into the hot cat. It may not come out cleaner so the system thinks the cat is bad.

The wasted spark system has 3 coils, and each must fire the spark across one plug on each bank every time. Because one plug is firing "backwards" it removes material from the center electrode and the gap grows rapidly. Since the coil must fire across both gaps to make a spark, if it misfires it may do so on both banks. Also, as the gap grows the voltage required to arc grows, and if the wires are marginal the higher voltage may cause the wire to break down before firing a spark on the plugs.

 

[MikeS]

Update on my 06 ranger 3.0l Replaced fuel filter ,no change, checked wiring to maf sensor had good readings except the signal to the pcm it was not until I shove the wire back against the plug did I get a reading,so, I changed out the plug with ford Motor craft genuine part.. Still experiencing the po 171 and po174 codes after it runs up to operating temps and the ilde drops back to 760 rpms, The engine stalls out like it is running out of fuel, if I restart it immediatly I have to work the throttle to get it to stay running at about 1500 rpms if I let off the throttle it stalls out again . At a real loss with this issue what am I missing ?

 

[Rearanger]

after it runs up to operating temps and the ilde drops back to 760 rpms, The engine stalls out like it is running out of fuel, if I restart it immediatly I have to work the throttle to get it to stay running at about 1500 rpms if I let off the throttle it stalls out again .

If the engine coolant temp sensor ECT is malfunctioning it may not tell the ECM that the engine is at running temp, so the ECM thinks cold start and sends too rich mixture - hence flooding when hot.

Check resistance on ECT engine cold and hot.

 

[stmitch]

The fact that your codes are for both banks indicates it's an issue in a location/sensor that's common for both banks. Things like MAF sensor, O2s, Fuel pump/filter, intake manifold gasket, random vacuum leak etc.
O2s are expensive, you've already checked the MAF and fuel filter. It's worth checking your fuel pressure at the rail to confirm the fuel pump is healthy. It's cheap and easy, but if it runs fine when cold that's not likely the issue. That leaves vacuum leaks which are usually a cheap/easy fix but can be difficult to track down. There's a rubber vacuum elbow on the back of the upper intake manifold that is known to leak. I'd probably start there and work my way through the tree of vacuum lines by misting them with some carb cleaner to see if the engine rpms change at all.

 

[MikeS]

what should I get as fuel pressure readings at the rail?I tested it and got 40 psi not running ( just keyed the ignition 5 times then while running I had a reading of 65 psi. Thinking this is rather high for a stock pump, could it be the fuel pressure regulator that is going bad ?

 

[Rearanger]

what should I get as fuel pressure readings at the rail?I tested it and got 40 psi not running ( just keyed the ignition 5 times then while running I had a reading of 65 psi. Thinking this is rather high for a stock pump, could it be the fuel pressure regulator that is going bad ?

Shop manual on my 2003 says: Key on Engine off = 64 +- 8 psi, Engine on = 64 +- 8 psi.

The fact that your problem occurs when engine hot/engine on is not a sign of fuel pressure.

 

[MikeS]

Question for all of you , After replacing the Mass air Flow sensor and the wiring do I have to take the truck through a Ford Drive cycle to get rid of the hard code that is present on the PCM and teach the PCM the new MAF sensor I have cancelled the PO171 and
PO 174 codes a few times but they still come back after a few miles , The truck is running good even when the codes pop up! , so could it just be a matter of teacking the computer?

 

[Dirtman]

If you clear the codes and they come back you didn't fix the problem. There's no re-learning process. Hard kam reset is to disconnect the battery and touch the leads together for 15 seconds.

 

[MikeS]

OKAy I am at a LOSS! After all the repairs and parts replacments ( Y Pipe cats,, Main Cat, o 2 sensors($) MAF sensors,MAF sensor wiring harness, Fuel Filter, Fuel Pump triple checked all vacum lines took intake plenum apart ro check that it is sealing flush to the intake manifold. Drive cycle as per ford recommendation , all went well no light no stalling no miss fires, stopped at a store after the drive cycle and upon restarting the truck the check engine light came back on and I got PO171 and PO174 , truck still runs well no hesitations or other issues. What else could it be ? Got too much in parts to scrap it at this point !

 

[MikeS]

Updates Double checked all mounting urfaces associated with the air box, intake air tube and throttle body, cleaned the throttle body with seafoam and a toothbrush ( throttle blades were pretty tarnished/carboned up so that needed done, ran better with alot crisper throttle responce, took for a ride after 15 miles stopped upon restarting the truck it pulled the same PO 171 and PO 1734 codes lean both banks ,
Smoke tested the Manifold found slight leak at Maf Sensor connection on Air tube,( Dumb Me , Didn't replace the gasket from the original MAF sensor so it was leaking there, only other smoke I saw was at the intake of the air box before the air filter. .. so after that cleared codes and went on a 30 mile 45 minute mixed driving condition test run. all temps and pressures normal stopped again and upon starting back up it blew the codes again! . it only seems to blow the codes at start up after truck is warmed up an within 45 seconds of restart
not during the drive cycle Next plan is to have it put on a scanner and check fuel trims and injectors as well as the maf sensor trims .

 

[MikeS]

UPDATE I think we have fixed it!!!! Smoke it one more time and found when I put the intake back on that the rear urethane gasket had slipped and was letting air into the intake at the fire wall, ordered another set of intake gaskets and tore it down once again about 3 hrs later I was back in busseness and had the codes cleared, 35 miles on it and no cdes , stopped and restarted it no codes! so Been driving it since Sunday afternoon and no codes at all! about 250 miles on it since the fix and all seems well. now to get it e checked !