Strange things happening to my X

[Blue_Oval_Ford]

Saturday me and my girlfriend took a 500 mile trip up the coast and having to climb a few step hills. On one of the hills my check engine light came on but there seemed to be no problems that I could tell. However, I pulled over and stopped anyway to find out what the problem was, but did not have my scanner with me so I could not check the codes. The idle was a little rough but not bad, so I gave it a few romps on the gas and the idle became smooth again.
I then started driving down the road and about five miles later the MIL light went out and never came back on. When I got home I put my scanner on and there where no codes stored, so I took it to the dealer this morning and they said there is nothing wrong with the X. What could be cauing this?

 

[Diff Whack Daddy]

O2 sensor. Climbing the hills causes increased exhaust temps and if the O2 sensor is old it will throw a CEL. I had a VW jetta do this for years until I found it.

 

[Blue_Oval_Ford]

Nop, I just replaced the downstream 02 sensors about 100 miles ago so it can't be that. I don't think...Hummm.

 

[ntrpriz]

My 94 used to do that when I had big changes in altitude. I think since the air is thinner, its confusing the computer. The light always went out after a few starts. It returned to normal when I got back home. Never did find anything wrong.

 

[Blue_Oval_Ford]

Ok, I agree with the altitude change theory but after hooking up my scanner and monitoring the parimeters this is what I saw. All the fuel trims (long and short) where fine, but one thing that I have never seen was the timing advancing to 28 degrees with increased throttle, then it would decrease to about 5 to -5 degrees. I have noticed a power loss when accelerating and climbing hills, and a slight change in exhaust tone. No other problems though.

 

[gijoecam]

Ok, I agree with the altitude change theory but after hooking up my scanner and monitoring the parimeters this is what I saw. All the fuel trims (long and short) where fine, but one thing that I have never seen was the timing advancing to 28 degrees with increased throttle, then it would decrease to about 5 to -5 degrees. I have noticed a power loss when accelerating and climbing hills, and a slight change in exhaust tone. No other problems though.

I realize this isn't directly related to the topic at hand, but what are you using for a scanner to analyze it in real-time? Just curious as I'd love to have one....

-Joe

 

[ExplorerDMB]

Your saying the advanced timing is around 28 degrees when your foots on the peddle, but when your off it, it's around -5 to 5? The timing will advance more and more with higher RPMs. It's the way to compensate for the faster engine cranks. Now the is the -5 to 5 degrees at idle? Most Fords run a 10 degree advanced timing (at idle). Someone might be able to chime in about the other -5 to 5. Hope I somewhat helped.

-Drew

 

[mikeresin]

mine does the same thing on long road trips, the change in elevation makes the CEL come on it still runs fine, but the light is annoying when driving at night hehe.
as soon as i got home it went off and never came back on.

i think it was just homesick

 

[Blue_Oval_Ford]

The timing will advance to 28 degrees then back down to 5 to -5 degrees when I accelerate and just keeps jumping around. At idle the timing fluctuates from 15.5 to 18 degrees. I think the truck is possessed, and I need to get an exorcist to figure out what the problem is.

 

[RickOTR]

No exorcism is needed but a PCM flash may. Take it back to the dealer and ask them if you have the latest hardware in your truck. If the computer was programed to work at lower altitude, then it might set a MIL at higher elevations. Also you could have a knock sensor on it's way out.

 

[gijoecam]

Bump-itty-bump.... what scanner are you using to log that data? I'm interested in getting one myself (if they're not outrageous)

-Joe

 

[Blue_Oval_Ford]

Actron CP-1945

 

[Blue_Oval_Ford]

Well once again the MIL light started flashing again. This time I was lucky enough to get my code scanner and check the codes. Code P0303, $10, cylinder 3 misfire. I installed new injectors, and had timing cassettes replaced so I know it cannot be that. The plugs and wires are brand new ford motorcrafts. I am at a loss as to what could be causing my problems.

 

[nascar_intimid]

mine does the same thing on long road trips, the change in elevation makes the CEL come on it still runs fine, but the light is annoying when driving at night hehe.
as soon as i got home it went off and never came back on.

i think it was just homesick

adds a little romance to the interior doesn't it...that warm orange glow

 

[bwinterroth]

About a week ago i changed by spark plugs and soon after the check engine light came on when I accelerated in the 40-60 MPH. The idle was also pretty rough. I checked the code and it said cylinder 2 misfire. I took out the cylinder 2 spark plug I just replaced and the ceramic end sticking out of the engine was cracked, causing a loose connection. My point being that even though the spark plugs are new, the cylinder 3 plug may have been damaged when it was installed. or it could be a matter of a loose connection with the wire and plug. I would recommend checking both.

 

[Blue_Oval_Ford]

OK, I will check the plug tomorrow when I get home from work. One thing that surprises me is that it only does it after a long drive. On short city or around town driving it's fine, but take it on a long road trip and it will idle rough and the MIL light come on. Can carbon buildup cause a cylinder to misfire?