Over the last 3 months my 2004 F-150 would occasionally idle really rough - as if misfires were occurring. As soon as I accelerated, it ran fine. It did this maybe 4 or 5 times. There was no CEL or pending codes at any time. Last week, while pulling into my mechanic's parking lot, it idled rough and the CEL came on - P0340 (CPS Bank 1). I shut off the engine then restarted it. It idled fine for about 2 minutes then got rough again.
My mechanic drove the truck for an hour or so with his diagnostic equipment and could not identify anything problems. He said it sounded like the Cam Phasers. He suggested checking the oil pressure just to make sure oil pressure was ok. He later called me and said that the oil pressure was at the minimum pressure at hot idle - 25 psi and said that could be the cause of the problem.
I picked up the truck and drove it home with no problems. Still had the CEL (P0340) and also a pending P0345. As a precaution - I replaced the Bank 1 CPS and VCT solenoid (I had replaced the other VCT solenoid 18 months ago when it failed due to a broken screen). I also checked the oil pressure and it was 25 psi at hot idle (625rpm). After some internet searching I found that the oil pressure should be 40-60 psi at 2000 rpm but I could not find any minimum idle oil pressure. Anyway - at 2000 rpm the pressure was steady at 57 psi.
I haven't driven it any where yet as I had it up on the jacks (its a bear getting the oil pressure fitting off and installing an oil pressure gauge). It ran for about an hour total - mostly idle and no CEL or pending codes so far. That might not mean anything but I plan to drive it Monday.

So after all this - I have the following two questions for the experts:

(1) Is there a minimum oil pressure below which could cause misoperation of the phasers?
(2) What is the desired idle rpm?

Thanks in advance -
JR

 

good that you got a real oil pressure gauge in there.
mostlikely...you have a bad/weak COP ( Coil on Plug). Until the PCM gets a hard enough fault it won't trip the CEL...but it may blink a few times when it idles/runs rough, you'll have watch close.

couldn't hurt to clean your MAF sensor and clean the throttle body ,& check for vacuum leaks

yes the phasers are a concern with 3v engines and can cause low oil pressure too...(the plastic shavings clog the pick up screen of the oil pump). If the phasers are shot it will sound like a diesel. IMO your oil pressure is pretty good...but the tensioners require oil presssure to keep tension on the timing chains...so the standard of 20-30psi @ idle maynot be good enough?? IDK. Depending on how many miles you got on your unit...it maybe a good idea to have it looked into.

 

Thanks -

Mileage is 86,000. I also recently had the oil changed at a "Nationwide Service Center" because they coupon matched and I had a $9.95 oil change coupon (and not much free time on my hands). I have always done my own oil changes using Motorcraft 5W20 and Motorcraft filter. I forgot to specify the filter and they put their own brand on (made by Champ I believe). I also noted that the oil level was 1 qt above the dipstick however the paperwork says they put in 7 quarts. I did remove the filter and put on a Motorcraft yesterday when I saw the non-Motorcraft filter.

I will keep an eye on the COPs as they are all original equipment. I replaced the plugs at 65,000 miles when I replaced the first VCT solenoid. During the one hour run yesterday, misfire counts on all cylinders were zero.

I also I forgot to mention that I noticed a small amount of sludge when I replaced the VCT solenoid yesterday so I drained a quart of oil and added a quart of MMO to be on the safe side.

I believe we can all agree that there is a high probability that if I take it to Ford - they will want to replace the cam phasers or the entire engine . . . .

 

So I drove it to work today. No problems for the 15 mile drive - did have to stop several times but the idle was ok. Drove to Lowes at lunch and the rough idle returned in the parking lot. It ran fine going back to work but again the rough idle occurred while parking.

I had my scanner hooked up but no codes were indicated and misfire counts were zero for all cylinders. Normally the rpm at idle with the A/C on is around 625-640 rpm. While it was idling rough, rpm was all over the place from 400 - 750rpm which you would expect.

(1) Is it possible the idle is too low and given the 25psi oil pressure at 625 rpm that the oil pressure drops too low sometimes affecting the VCTs? Is VCT position an available data point.

(2) Can a COP be going bad without showing a misfire?

(3) Is there anything else I should be checking?

Thanks in advance for any more insight . . . .

JR

 

It sounds like a bad COP! I am going through the same stuff with my 2006 5.4. Never has set a CEL at all. I am considering cleaning the the entire TB maybe its dirty. fFor some reason I see A LOT of people have misfires from #1 and # 3 cylinder with the 5.4 3v here. So with out a CEL light I am going check into cleaning the TB and inspceting those two cylinders for bad cop boots.

 

Thanks Mike -

I will inspect the #1 and #3 COPs as well as a start. Then maybe I will do the rest if those two look OK. I have a spare sitting at home as a matter of fact.

JR

 

I'm having the same problem on my 2005 3V 5.4l. It's driving my crazy! I've replaced all COPs and the problem still occurs. I'm going to replace the plugs next. They looked good when I pulled them, but the truck has 98K on it. I don't know if they're original or not, I got the truck used. I've replaced the cam phaser on the driver's side, but I still get the multiple misfire code. Also, when i put the gas pedal to the floor, I get the CEL light to blink. My research on this showed the gas wasn't burning properly. Could be an air leak, O2 sensor, injector, etc... I've cleaned the TB and the MAF also. I'll try the plugs next.

If anyone has any insight on this, I would appreciate a little advice. Thank you.

 

I don't have much to add to a potential oil pressure problem BUT the issues of bad or faultly COP's I might add something useful.........

Also had the occasional misfire, rough idle and MIL showing Lean Bank 1, Lean Bank 2 and sometimes misfire indication on ALL COP's !! Eventually tracked it down to two things: bad COP connector and vacuum leak.

My '00 E250, 5.4 gas motor and 254K miles experienced a bad PCV which I'm sure allowed oil to pool in the intake ducts between the TB and air cleaner assembly. This probably caused a deterioration of the rubber compound allowing a vacuum leak BUT only when it was "cold" outside. If the noticeable rough running occurred after normal operating temps were acheived a simply restarting would "cure" the problem----temporarily. Replacing that duct solved the problem---cost about $85 ($105 MSRP).

Also discovered a bad COP connector on the wiring harness to my #7 cylinder. The locking tabs had broken and not latching completely into the COP---replaced that connector with a NAPA part EC-259---all is well with that issue now.

Maybe these two things are contributing to your situation JRoth----hope its even a bit helpful!

 

Where was the vacuum leak and how did you find it?

 

Check the pressure to your cylinders

 

You need a new engine and the non-Motorcraft oil filter maybe the cause (filter shedding gauze).

Ford says minimum 40psi hot oil at idle in gear.

I have found that phasers can barely operate at 30psi.

If you want my credentials? ---
ASE Master Technician
Former Auto Shop Teacher
35 years experience

 

I have encountered the same symptoms as many others on 2 different 5.4L tritons. A 2004 Expedition, and 2001 F150... both showing intermittent missfire code (P0303), intermittent rough idle, sporadic hesitation and stumbling in light acceloration, low idle when stopping fast (450-500rpm), and everything smoothes out with heavy acceleration for a while. After contemplating all the possible causes, AND performing every test possible without throwing parts at the problem, I have discovered the simplest and cheapest way to be free of those nightmares!
1st.) Treat the fuel system thoroughly (I used Z Max, and then BG44K)
2nd.) Change the oil, desludge if necessary, and treat 5W-20 oil (MMO, SEA FOAM, ZMAX OR BEST)
3RD.) Replace fuel, oil and air filter, and clean MAF sensor
4th.) Inspect intake ports behind throttlebody for blockage (none in mine, light dust)
5th.) If carbon blockage is present remove, clean and reinstall with NEW GASKETS. Double check All vacuum lines are clear of build up and connected tightly.
FINEALLY...Early in the morning, just after warm up, you are ready to clear the frog out of its throat.

Rev to about 4000rpm and let off. Only do this once or twice. You should hear some nasty stuff thats ready to purge. Check the exhaust for some gently warm steam. (Not smoke, if its smoking keep cleaning fuel system...unless it gets worse :-O)
Now slowly cover passenger side exhaust tip for about 30 sec.
You should see massive steam out the drivers side exhaust. Clean up the carbon on the ground below the drivers side exhaust and repeat until there is only steam. IMMEDIATLY after it clears rev to 4000rpms, 3000rpm, and repeat until it growls nicely. Let it purr and watch engine temp(stop if temp RISES and address cooling system).
My total cost for both vehicles is only $200, $100 each which includes:
Fuel additive, fuel filter, oil additive, oil, oil filter and air filter. Gas doesn't count:-Q

 

"Ford says minimum 40psi hot oil at idle in gear."

Actually, with all due respect, Ford does not say that. The minimum oil pressure specification for the 2004-2013 5.4 3v is 15 PSI, idle speed, in neutral, engine at operating temperature. See Ford SSM32051, dated January 19, 2013.

STG, 2008 F150.

 

What is your fuel pressure doing when you have a rough idle episode?