Hello everyone. I have a 2003 Expedition that randomly died the other day. It hadnt acted up previous to that. So I was driving and all of a sudden my throttle lost function (cable throttle). No matter how hard I pressed the engine had no response. I was going about 30mph when this happened. The tach was reading that the engine was still running. I cant remember what it was reading off hand. About a block later I was able to pull off the main road. As I did this the engine died. No hesitation or anything. It was like I turned off the ignition. Tried to restart and it would just crank. Had it towed home and started tearing into it. I check with a noid light that fuel injectors were getting signal. Those tested good. I checked to be sure I was getting spark and I am for sure getting spark. I checked on the fuel pressure. I dont have a gauge but when I pressed on the test port fuel shot out. I cycled the key again and it did the same thing. So Im pretty sure I have good fuel pressure. I tested the throttle position sensor because of the way it died and that tested good. Cam position sensor was cheap so changed that. Checked my wiring near the battery that someone else mentioned had a similar issue and my wiring was fine. I noticed everyone saying to change the fuse panel because of the burned up R303 relay. I took it in the house over night and pulled it apart. The circuit board and R303 look perfect. Put everything back together and tried again. No start still. I tried using starting fluid just to see if it would work and it wont start on that either. No codes have come up at all. Im at a loss here now. It should be running being that it has spark, fuel and air. The only thing I can think of is the timing chain skipped teeth. The only problem I have with that idea is that it never ran rough and it didnt run rough before it died. Any help would be greatly appreciated.

 

If fuel, spark and air are confirmed, the next step is a compression test.

 

I am hesitant about pulling a spark plug while the engine is this cold. It's about 10° here.

 

I just tested the crank position sensor and Im getting about half the voltage im supposed to be getting. Would I still get spark but a weak spark if this test was accurate?

 

What was the voltage reading?

 

It fluctuates between 0 and .23 acv while cranking. I just changed it to see if it does anything. Its an inexpensive part anyways.

 

So no change with the new crank position sensor. I pulled out the number 1 spark plug and checked compression. It was at about 50lbs. So does that mean my engine is junk? Seems kinda odd that it would be with the way it was running just fine before this started.

 

Squirt some oil in the cylinder and do the compression test again.

 

I did notice once in a while while cranking since it died that I get a backfire through the throttle body.

 

You should first get a scan tool and check for codes. That might tell you exactly where to focus your efforts.

 

I have one and have checked. No new codes which is making this more difficult.

 

In that case I'd replace the crank sensor. The CKS reports RPMs and you already know your tach showed an erroneous reading when it stalled. Plus CKS don't always throw codes unless there's an actual break in the circuit.

 

Changed it last night. Made no difference.

 

Is it possible that It could have skipped a tooth on the timing and I wouldn't have noticed. I would think it would have made some noise I would have noticed. Would 1or 2 teeth be enough for it not to start?

 

From what I was reading, this seems like it could be a cam phaser issue. Does that make sense?