G213
Full Access Members
Hey All-
I've done a ton of reading on the Ecoboost 3.5 engine and read the many many comments made by owners regarding a slightly rough idle on cold start. However after the first minute or so of driving, the rough idle disappears. My truck has the same symptoms.
I've heard of mainly three causes....
1. This is a normal characteristic of direct injection engines.
2. The ECU purposely runs a rich fuel mixture at cold start to quickly heat up the catalytic converters to meet emissions standards.
3. Carbon build-up on the backside of the intake valves.
So those are all fine and if you told me definitively it was one of those, I'd probably believe it. (However, I'd be less convinced about number 3, since the borescope videos I've seen show remarkably clean intake valves on high mileage 3.5 EBs. Apparently FoMoCo has a patented timing technology which briefly keeps the intake valves open during the fuel injection stroke to give them the benefit of gasoline detergents.)
But here's something interesting....
I found a video on youtube of a guy with a 3.5 F150 who demonstrates a rough cold idle. He gives instruction on how to remove and clean both MAP sensors and the MAF sensor.
I've done this procedure twice now on my truck...each time clearly seeing and removing light gunk covering the topside MAP sensor. Upon the very first cold start after cleaning, the truck idles like a kitten...hardly any rough idle at all. But after that first idle, it goes right back to the way it was prior to the cleaning.
Is that because the ECU readjusts to the clean sensor after the first cold start? Or could it be that it's just ready to be replaced? The actual sensor itself is clearly discolored compared to the other MAP sensor (i.e. the top MAP sensor is brownish whereas the throttle body MAP sensor is white)
Let me know what you think.
I've done a ton of reading on the Ecoboost 3.5 engine and read the many many comments made by owners regarding a slightly rough idle on cold start. However after the first minute or so of driving, the rough idle disappears. My truck has the same symptoms.
I've heard of mainly three causes....
1. This is a normal characteristic of direct injection engines.
2. The ECU purposely runs a rich fuel mixture at cold start to quickly heat up the catalytic converters to meet emissions standards.
3. Carbon build-up on the backside of the intake valves.
So those are all fine and if you told me definitively it was one of those, I'd probably believe it. (However, I'd be less convinced about number 3, since the borescope videos I've seen show remarkably clean intake valves on high mileage 3.5 EBs. Apparently FoMoCo has a patented timing technology which briefly keeps the intake valves open during the fuel injection stroke to give them the benefit of gasoline detergents.)
But here's something interesting....
I found a video on youtube of a guy with a 3.5 F150 who demonstrates a rough cold idle. He gives instruction on how to remove and clean both MAP sensors and the MAF sensor.
I've done this procedure twice now on my truck...each time clearly seeing and removing light gunk covering the topside MAP sensor. Upon the very first cold start after cleaning, the truck idles like a kitten...hardly any rough idle at all. But after that first idle, it goes right back to the way it was prior to the cleaning.
Is that because the ECU readjusts to the clean sensor after the first cold start? Or could it be that it's just ready to be replaced? The actual sensor itself is clearly discolored compared to the other MAP sensor (i.e. the top MAP sensor is brownish whereas the throttle body MAP sensor is white)
Let me know what you think.