Hi guys!

2006 F150FX4 5.4L w/ 153k miles. Plugs were changed at 110k.

Symptoms:
Runs fine at speed
At idle it will now idle rough, engine is vibrating bad and hesitate on acceleration. And while at idle it will make a small popping sound from the exhaust.

Last time I had an idle problem it did not include the popping or the vibration and I fixed it by cleaning the MAF sensor.

Again, the truck runs fine at speed, no loss of power.

Thoughts??

 

With the truck running like that, surely there's a check engine light on or flashing. If it's flashing, don't drive it! Scan the codes and report back.

You can pull the plugs, check the gap, and look for inconsistencies in their color or damage. Report your findings. What plugs are installed? Anything other than the Motorcraft finewire or Autolite XP plugs can cause these symptoms. Could also be a coil, vacuum leak, failed injector, or a whole bunch more. Really need to know what the computer says.

 

OK, checked the code and it has a misfire in cylinder 5. I am going to change all the plugs again and change all the coils as well.

It was not happy driving home from work today.

 

Popping from the exhaust can be a burnt exhaust valve. If you pull the plugs do a compression test.

 

How much compression do these motors have?

 

You aren't looking for a specific number, you are looking for consistency between cylinders.

 

OK, I ended up just replacing the spark plug (Motorcraft) and the COP for #5. Now it still idles rough and has a hesitation when leaving from a stop, but picks back up with more rpms. No more popping from the exhaust but I am getting a flashing CEL randomly at speed and can definitely smell raw fuel. The flashing CEL comes and goes. So I think I still have a misfire/timing issue. CEL is back on solid at startup, it goes away when I start to drive. so I need to get Ford to read the codes again.

Tried to get O'Really! to read my codes and seems that they passed a law in CA. that auto parts stores cannot read codes for a customer. Only certified mechanic shops can do that now.

Would a bad VCT solenoid cause any of this?

 

You can get code readers for as little as 20 bucks. You need those codes to diagnose..

 

Ok, here are the new codes:

P0306 Cylinder 6 misfire
P2198 O2 Sensor Signal Biased/Stuck Rich Bank 2 Sensor 1
P0175 Too Rich Bank 2
P0300 Random/Multiple Cylinder Misfire Detected
P305 Cylinder 5 Misfire Detected
P306 Cylinder 6 Misfire Detected

I just cleaned the MAF sensor and it is idling better. I am not getting the dieseling knock from the motor that I was getting before. The motor at idle actually sounds fairly normal now. The problem is random. Sometimes it will leave from a light fine, other times it will hesitate and sluggish till the rpms come up. It will drive fairly normal and then around 45 it will start to shake and feel like the timing is off (misfire). But then it will settle back down and run decent. I also just changed the oil to a 5-30 and it sounded a lot better.

It's definitely low on power but I am sure that is because all the cylinders are not happy.
Oddly it is running better than before.

So, is it an O2 sensor, VCT Solenoid? I am guessing it's not plugs and COPS and that something else is causing the misfires.

I can fix the following as DIY: O2 sensor, VCT solenoid, plugs, COPS. I just don't know where to start first. And I am low on cash so I have to do this in stages. Truck has just been sitting in the driveway.

Thoughts?

 

Try something simple. Swap the coils from one side of the engine to the other and see if the issue follows them. It's a simple way of eliminating them as a suspect. Check your codes and see where you're at.

You can do the same with the O2 sensors, but at a different time. That way you're eliminating one system at a time.

It could be a lot of things causing it. But those are two simple and basic things that can be done to help troubleshoot.

Since you've been driving it in this condition, it's very possible the converter on bank 2 (Driver's side) are fried.

I also have to ask a stupid question... Did you set the plug gap? I only ask because I've heard too many kids at parts stores telling people that the plugs are pre-gapped and the customer believing it.

 

The SP515 plugs come pre-gapped and you can't change them.

Will a converter throw a code or is it just tied to the O2 sensor code? Is there any way to check the cat besides thumping on it?

I would think it isn't the cat as I have only driven it less than 10 miles in this condition.

I can do all of the things you mentioned easy, but then I need to drive it back to the dealer to read the codes again.

 

Indeed, you're right. Sorry, I forgot this was a 3V motor we were talking about. The cats wouldn't be the initial cause, but it is a result of driving with excess raw fuel in the exhaust. So you may be fine.

I would still advise you invest in a scanner. They can be bought for cheap and are invaluable with this stuff. A fancy one is nice, but a cheap one will get the job done. Every time the truck is driven in this condition is a potential for damage to those expensive converters.

 

Does a VCT solenoid have anything to do with this problem? I was thinking about removing and inspecting them as I know they tend to go bad as well. And I know they can affect the idle and timing.

 

 

Thanks glc. I'll pick one up this week and go from there.