Another rough idle P1131 and P1151 only codes

[home4sale2]

Didn't want to steal another thread. I recently replaced valve cover gaskets. In the process, I also changed the spark plugs, coil and wires. The engines started out pretty bad but then stablized itself. Now it runs fine except idle. So far, I have inspected the following:

1. the elbow everyone talks about seems to be fine (from PCV to manifold). If I disconnect it while running, the engine really gets a lot rougher and starts the whooshing sound of vacuum being created

2. Put the old PCV valve back in (which was working as far as I know) in case the new one is bad, same thing

3. Have cleaned the MAF sensor (carefully) and disconnected the electrical, it runs a lot rougher so don't believe it's the sensor

4. Ran an ulit propane test against all hoses coming into manifold and from air filter to IAF including one that connects to valve cover, no increase in engine RPMs

5. Triple checked to make sure wires are seated properly on the spark plugs and the firing order was checked (the corresponding number on the coil are connecting to the spark plugs 1 through 6)

I don't have a code reader but service engine soon light comes on after a while. I have driven at street speeds and the truck runs fine. I will go to autozone tomorrow to see what codes it's throwing. Anything else in the meantime that I have missed?

I have to say the EGR valve was a pain the butt to put back together to the intake manifold because I had to bend the tube and try to line it up again when done. Could that be a problem? I don't think I forgot to connect a hose in the process.

Thank you in advance.

 

[swshawaii]

Assuming the IAC valve is OK, you didn't mention it.
DTC p0 numbers should help you greatly. GL

 

[swshawaii]

Throttle body also.

 

[05explorer1974]

Sometimes cleaning a MAF or IAC will not help it run better or smoother. Could also be the O2 sensors and cat sensors. If any of those get fouled up you get 2 of them running lean or rich which could be telling the computer to change the fuel pressure. They sometimes don't send a code either. I know my exhaust has a leak at the cat where the gasket is and it has messed up my acceleration because they are running different. Could also be a clogged fuel filter. Could also be this PCV hose has a minor crack in it. Very common on the 4.0L V6 sohc engines. This covers Rangers, Sport Tracs, and Explorer Sport's (not sure if the used it on the Explorer 4drs.)they started using it in 2001 (this design). I put that out because I thought the 4dr. Explorer's used it. Here is a picture:

http://compare.ebay.com/like/150754336796?var=lv&ltyp=AllFixedPriceItemTypes&var=sbar&_lwgsi=y&cbt=y

 

[05explorer1974]

sorry forgot one other possibility check the coil pack itself you could have problems their also.

 

[home4sale2]

Ok, code reader says P1131 and P1151. I changed the PCV valve again, for now put electrical tape all over that elbow between PCV and manifold just to be safe and ensure if there are any microcopic holes, I got it covered. I sprayed carb cleaner on every hose on the intake, everything from air filter to throttle body, RPM's stay the same. I have noticed that the engine only begins to get rough after 10 minutes or so whether hot or cold (after I reset by disconnecting the battery). I don't recall if there are any hoses behind the intake (towards the firewall) that I might have forgotten to connect? There was a plastic object (round cylinder) which has a cover that rotates freely, I can see another one of those by the brake booster. I don't know its function but perhaps?

It is especially worse (RPM's fluctuate between 500-800 RPM, gasping) when I put it in drive or reverse and soon after that it throws a Check engine soon. Occasionally it stalls.

05 and SWS, I am thinking to try a new IAC valve anyway before I change the EGR valve or remove the entire intake again (pain I don't want to relive if I can avoid it). Is there a way to check the IAC valve to see if it's working or not? Thx.

 

[home4sale2]

Ok, the plastic object I described could be the EVR solenoid and it's near the firewall and intake. Thanks guys.

 

[home4sale2]

Took the intake off again and found that the EGR valve had not seated properly, with all that bending, it bent the plate on the intake manifold that mates with the EGR valve gasket, definitely a source of leak. I bent the metal as true as I could (looks pretty good) by removing it from the intake and then used RTV to attach the EGR valve, probably didn't need to use RTV but in this case I didn't mind. Also, everyone I talk to tells me not to use RTV on the intake gaskets so definitely not going there. Also bought new isolator bolts and new gaskets for the intake from the dealer. There is a TSB if you only get P1131 and P1151 and it recommends to either replace or not to re-use the bolts. I am sure my new gaskets are ok because they were only used once but not taking a chance here.

I am writing this because we all have other things in life and it's unfortunate that I haven't received a single response or ideas. Hopefully someone in the future will benefit when I am not around to answer your question.

Great forum though guys, couldn't have done it without everyone's help.

Waiting for RTV to cure, will get back to it once I get done with some regular work. Wish me luck.

 

[05explorer1974]

Good luck!!

 

[home4sale2]

woohoo!!! So, between the gaskets, the bolts for the intake manifold OR re-seating the EGR valve against the throttle assembly (which clearly had a leak), my problem is fixed. For a moment I got a weird code that my regular mechanic retrieved for me which was related to fuel injector issue (electrical not plugged in) but that soon disappeard. I think the first service engine light that lit up was due to PCM re-learning, once we reset the codes, they have not re-appeared.

I just seafoamed it (one can) and boy there is a lot of smoke. Waiting for it to sit for a bit and plan to run the truck soon. I owe my regular mechanic a starbucks card who helped me read the codes, cleaned the MAF sensor just in case and also recommended I replace the elbow from the PCV valve everyone here talks about as a precaution, a free chat and diagnosis that my dealer would not do. Also, the elbow wasn't in stock at Ford so I'll search the forum for part numbers to make sure I order the right one.

Btw, I can now take that Intake off, from start to finish in one hour! I bit more than I could chew but didn't choke so thanks again to this forum.

 

[swshawaii]

That's great! I got lost along the way, surprising the different configurations of the 4.0L SOHC.
Your problem was more than likely the leaking EGR valve gasket. Well done, and happy idling!