Rough Idle / Poor Performance in Hot Weather?

[feelthemusic8]

I have a 2007 Limited Expedition 5.4 with 208,000 miles. It's having a problem with a rough idle in hot weather.

Typically, at night or when day-time temps are below 90, it runs fine and I have no idle issues, even after the truck is warmed up. But, if the outside temperature gets into the upper 90s, I'll have the rough idle when I'm stopped at a red light somewhat consistently. The problem gets worse the longer the engine is running and the longer I stay parked with the engine running.

Even in warm, but not hot, weather, if I let the truck sit and idle in park for 10-15 minutes, it seams to get "hot" and will start the rough idle. A couple of times it has even stalled out. If I press the gas and then let up, it will usually stop the problem except in the hottest weather.

I don't know if it is related or not, but I also have a very significant performance reduction (power) if the truck idles for long enough to heat up and especially if it is hot outside. The performance issue disappears after several minutes of running at highway speeds.

I also notice that the fan gets really loud, like an airplane, in the same hot conditions.

Finally, the rough idle reappears every time I pull into my garage at any temp. My driveway is very steep and I gas it up the hill but let off half way into the garage so I don't hit the wall. Right as it idles/coasts into place, it stutters.

I don't get any codes during any of these events. My temp gauge never moves past half way to hot. The oil pressure stays at approx 60% of the gauge.

Recent problems/repairs:

- 12 months ago had a heater hose burst which I replaced.

- 9 months ago fuel pump went out. At that time replaced:

- Fuel Pump
- Fuel Filter
- Spark Plugs
- COPs

- Dealing with this problem, I have done:

- Replaced Air Filter
- Seafoam crankcase and changed oil and filter twice last week.
- Cleaned MAF
- Cleaned Throttle Body
- Replaced Throttle Body Motor
- Have PCV Hose on Order, yet to install

I hate to just throw parts at it, but I'm at a loss now. Any ideas?

 

[JUST4FUN]

This almost sounds like vapor lock ,but its fuel injected. unless the fuel pressure regulator is not working or it is leaking gas into the vacuum line at the regulator

 

[feelthemusic8]

This almost sounds like vapor lock ,but its fuel injected. unless the fuel pressure regulator is not working or it is leaking gas into the vacuum line at the regulator

Any idea how I would test that?

 

[feelthemusic8]

Any input on whether the Vapor Canister Vent Solenoid or O2 sensors may be involved?

 

[stamp11127]

Those would throw codes. The Ford Service Manual basically says that when no codes are present - start hunting since you don't have a direction to follow.
Fuel pressure is checked with a fuel pressure gauge attached to the fuel rail.

Did you remove the throttle body to clean it? If so, did you use a new gasket?

 

[feelthemusic8]

OK, I'll see if I can get a fuel pressure gauge. Will I be able to test it idling when no problem present or does it have to have symptoms at that moment?

Yes, I did replace the gasket under the Throttle Body. It actually came with the TB Motor for some reason.

 

[stamp11127]

The other forums I've read have listed just about everything on the engine from oil, cam phasers, tb's, egr and clogged cats as being possible culprits.

The odd thing here is you can reproduce the rough idle when on an incline at any temp. When it is on level ground the high temps may be the cause of something else happening that result in the rough idle.

If there were egr passages at the throttle body & manifold did you clean them when you cleaned the TB?

I would also keep a record of what you check and how it was checked. You're basically looking for the needle in the haystack. The more information you gather the easier it will be to spot any trends. I would perform all the testing on your inclined driveway so that you don't have to wait for the higher temps.

If you have a code reader, just barely keep it running to see if a code will eventually set.
Will it idle rough when parked downwards on the incline?
Does removing the gas cap have any effect?

 

[feelthemusic8]

So an update:

The rough idle remains with gas cap off.

The rough idle on incline disappears when the incline is nose down.

Replaced the PCV hose, no change.

Cleaned the ERG passages, no change.

Re-inspected the vacuum hoses I could identify when TB was off. None appear to be leaking or cracked and I don't feel any air movement around them when running.

Trying to get a code, I let the rough idle go in drive with foot on brake until it started getting out of control near stall. I finally got 2 codes, both were the same: P0012, which is "A" Camshaft Position - Timing Over-Retarded (Bank 1). I'm guessing this is not a cause of my problems, just a symptom coinciding with the excessive "shaking" during idle when I didn't relieve the issue by depressing gas pedal.

Have not been able to check fuel pressure. I don't have the equipment and still not sure how. I noticed a threaded port or valve on the top of the driver's side fuel rail. It that where I can attach a gauge?

I also want to note that I don't have any additional knocking, rocking, or ticking noises besides what I described in my original post. I read about several people's problems with similar symptoms but also had ticking problems that ended up being involved in the rough idle problems they had.

Finally, after reading other forums online, I began suspecting some issue involving the Variable Camshaft Timing (VCT) Solenoid. A suggestion was made to disconnect the wiring harness from the VCT solenoid and observe engine behavior. I disconnected the harness on the passenger side VCT solenoid due to ease of access, but did not on the driver's side. I did this both when the truck was off and when the engine was running.

The auto gas mileage indicator showed a severe reduction in gas mileage when it was disconnected and also I feel that the power of the engine was reduced, although it was hot outside and it could just be a misperception.

I was not able to get the rough idle at all, in any scenario, when that VCT solenoid was disconnected. It did cause the truck to throw the P0010 code, due to being disconnected. From what I read, the solenoids can have problems getting stuck open, clogged with debris or the screens in the solenoid break. Is it a problem to temporarily drive the truck with this disconnected until I resolve the problem?

So based on the current symptoms and diagnostics, is at least one of the VCT solenoids a likely culprit? If so would it be the one on the passenger's side since that was the one I disconnected? Or, does this behavior, when disconnected, just indicate another issue with the oil, oil pressure, camshaft, etc?

I see where the driver's side VCT solenoid on the 2007 is a pain to get to and also requires the valve cover being removed. Also read some people saying that is not the case, but obviously someone is wrong. Does the passenger side also required the removal of the valve cover?

Unless I get some good feedback indicating something else, my plan is to replace and inspect the passenger's side VCT solenoid only and see where that gets me.

Other thoughts I had were maybe my 9 month old fuel filter already needs to be replaced. I do put around 30,000K per year on this vehicle. Also, maybe an oil weight/engine life issue? Would a lower weight oil than the 5W 20 help at all? Should I change weights anyway considering the 208,000 life span? I don't think I have any low oil pressure issues. If any, I'd guess slightly high based on the instrument cluster gauge. I recently changed the oil and it does have exactly 7 quarts of oil and I have never noticed any leaks anywhere.

Thanks for all the feedback, and sorry for the long post. I'm hoping to not only resolve my issue, but to also provide good detail in case someone else stumbles across this in the future. It's nice to save some money and time by good advice and comparable issues.

 

[JUST4FUN]

im not sure if this year has a feed back fuel rail or not , look on the rail and see if there is a small canister looking thing on the rail it will have a vacuum line going to it. Pull off the vacuum line and see if it smells like gas.

 

[stamp11127]

Both solenoids are the same age and mileage, if it was me I would change both
based on that alone. When you change spark pluge, do you change all of them or just a few? Same reasoning.
How many miles are one the oil?