Inspect Your Wires for Chaffing!

[blaine109]

This is for those of you who haven't been following my problem in the "Game Show - What's wrong with the SHO?" thread (http://www.shoforum.com/showthread.php?t=117883) we found some chaffed knock sensor wires that seem to be the root of my aching troubles.

Although the permanent fix it not yet in place, the service manager and I both feel that this is the root of all my problems and the new knock sensor will be installed next week (7/27/2011) when it comes in.

Here is what I posted up in that thread regarding these Knock Sensor Wires

PROGRESS!!!!

So I got a call today from the service manager with some "news" on my situation. The data that he sent up to Ford was analyzed and they noticed that just preceding the opening of the wastegate one of the knock sensors was reading about 500 ticks more than the other knock sensors. What does the computer do when it detects excessive knock? It cuts power to the engine so that it doesn't go BOOOOOM!!!! Interesting. So, the engineer told the service manager to inspect for a chaffed wire. If one could not be found he was to replace the knock sensor giving the excessive readings.

So I immediately headed over to the dealership so we could start looking. After giving the engine 10-15 minutes to cool we started digging. And what did we find? If you said a chaffed wire then give yourself a cookie. The wires go to one of the knock sensors below the intake manifold. You can see that wires that come up into a connecter and were not wrapped in any electrical tape or in any type of protective plastic shrouding and it was resting right on a 90 degree edge on the engine.

This would explain how my issue started as a once and a while issue and degraded into a full-time issue as the chaffing progressed and got worse.

First remove the engine cover just to make sure it's out of the way so you can get a good look from all angles. Look down between the 2 intake pipes.
View attachment 926
Go Digging - Big Picture

We saw a connector with wires that were not wrapped in any extra electrical tape or plastic shrouding.
View attachment 928
Chaff - Big Picture

From this angle you can better see the wires resting on the engine.
View attachment 929
Chaff - Big Picture

The chaffing is on the sensor side of the connector which means that they will have to replace the knock sensor. In the meantime we have put a piece of foam insulation on the engine where the wires rest to prevent it from further chaffing and giving false knock readings. I must say that performance is starting to come back. Since we didn't reset the KAM memory, it is taking some time for new values/averages that the PCM uses to run the engine are being used and faded out as new values are factored in and averaged. Power is coming back, the erratic RPM's are fading, the wastegate is bleeding off less and less air with every mile I go.

The new knock sensor should be in Tuesday but depending on what time it comes in I may not get my car back in there till Wednesday. I will have them reset the KAM and also check to see if there are any more software updates available to get me all up to date on everything.

I'll report back Sunday/Monday as I put more miles on my car to let you know if the condition continues to get better as well as what it's like when I get the new sensor in. I will be taking a road trip tomorrow so I will get to get a good like to see if my HWY MPG's are improving. With this issue I was only getting 21 - 22 MPG tops on the HWY when I used to get 26-27 (while driving 80MPH - 90MPH).

Now I would suggest that all of you go out and check for those wires. If they are exposed I would inspect them for any chaffing and then I would recommend wrapping them up in some electrical tape or other means of protection.

 

[First-SHO]

Excellent write up and I will be looking today. No problems, just a good idea to inspect.

 

[SHOrod]

Great info, thanks for sharing. I'll be inspecting my knock sensor wires this weekend!

-Rod

 

[SHO U UP]

Wires rubbing on the motor huh? Sounds like the same problem the Gen 3s had under the rear intake years ago. :shakehead Least the new ones are much easier to address. Good find blaine.

 

[gregoire]

I did and it was, my car only has 4,500 miles on it but the insulation on the black wire was clearly chaffing. I would have took a picture but it looked exactly the same as the pics you posted. I was able to clear it with those nylon strap thingys. Thanks for the heads up.

 

[Crash712us]

Prolly not a bad idea to cut a small piece wire loom and slip over them.

 

[SterlingGraySHO]

Thanks for the info.
Looked at mine and noticed the same thing.
I disconnected the switch and routed the wiring harness behind the yellow wires.
Before and after pics. . .

 

[Showgun]

Thanks Blaine -- checked mine and it's fine, but I believe you've helped many find the source of some nagging issues.
Cheers,

 

[ChrisBnDE]

woohoo, called it on post 19 of the other thread... gonna have to take a look at mine

 

[Billm0066]

I want to make sure im clear on this. The problem are the two yellow wires being exposed and rubbing on the engine? Is it advised to wrap them in electrical tape?

 

[Crash712us]

I want to make sure im clear on this. The problem are the two yellow wires being exposed and rubbing on the engine? Is it advised to wrap them in electrical tape?

that would probably be very difficult to do. I would recommend a piece of 1/4 inch wire loom.

 

[Billm0066]

I was able to wrap them in electrical tape but it was a pain. Not very much room to get your fingers in there. I also put the wiring harness behind it as well.

 

[SHOrod]

Putting wire loom over my wires wasn't all that easy, I cannot imagine trying to wrap them in tape. Bill, you have more patience than I do.

-Rod

 

[mjhpadi]

I know I'm going to sound stupid, but after taking the engine cover off, I still am not sure where on the engine to look to find these wires. I looked all over the engine, and still am not sure exactly where I am looking to find them. The close-up pictures are great and show the detail, but a picture to point me in the right direction of where the wires are at on the engine would be a big help to me.

 

[Crax]

Oh I am even dumber when it comes to cars I am sure. Listen after 20 minutes I finally found it. Basically the first photo is from what I can tell shot from the right side of the car. So stand by your battery. The pipes you are looking between are black in color and right on top. The wires are only like 6 inches deep into the compartment but yes hard to reach. Try that, stand by battery and look at pipes on right side of the compartment.

 

[markathome]

I have to admit I read this post and blaine109's finding and thought to myself....surely not...
I had noticed the same symptoms, and they seemed to be getting worse as the heat increased. I too noticed the car seemed to idle rough, sometimes enough to see vibration in the steering wheel.
Sunday I pulled the cover. Thanks to all for the pictures. I just looked on the right side for the bright yellow tag, then saw the wires resting against the engine to the left of the tag. It's a tight fit to unhook the wires and put the other insulated wire behind them, but, I got it.(thanks SterlingGraySHO)
The smoothness was immediately apparent. I'm really surprised there is no TSB on this issue. Next time I'm at the dealer for an oil change, I'll be pointing this out so they can report it and check to see if the wires are worn/chaffed.
As we've all said on this thread...EVERYONE needs to check this out. Its an easy 10 minute fix.

 

[itguy08]

Just checked mine as I've had this weirdness under acceleration and cruising that seems like a miss. Comes and goes and I've had some random heavy spark knock as well. Whaddya know? Mine is chaffed too. I'm due for an inspection so I'll let the dealer know then.

But does anyone know if Ford changed the knock sensor so it has a loom around it? Would hate to replace another out of warranty.

 

[Billm0066]

Just checked mine as I've had this weirdness under acceleration and cruising that seems like a miss. Comes and goes and I've had some random heavy spark knock as well. Whaddya know? Mine is chaffed too. I'm due for an inspection so I'll let the dealer know then.

But does anyone know if Ford changed the knock sensor so it has a loom around it? Would hate to replace another out of warranty.

Just put loom around the new one. They sell it at any auto parts store for cheap.

 

[itguy08]

Just put loom around the new one. They sell it at any auto parts store for cheap.

I plan on doing that but won't that still have an effect on the sensor? Mine seems to be chaffed down to the wire underneath. When I checked it, I could see aluminum wire where the insulation was rubbed off.

 

[Billm0066]

I plan on doing that but won't that still have an effect on the sensor? Mine seems to be chaffed down to the wire underneath. When I checked it, I could see aluminum wire where the insulation was rubbed off.

I think the problem is the metal in the wire is touching metal on the engine. If you wrap it with tape the issue should go away. However I would take it in, get it replaced, and make sure they wrap it up good with tape and or loom.