I have an 02 Excursion (family bus and pulling beast for the huge camper) I have taken this to a local dealership for a problem that they tell me is fixed, until the wife tries to pick it up and it does the same thing it did when we had dropped it off! First it would just die whenever it felt like it..picking up speed to enter the expressway..driving on the expressway at 70mph..with or without the cruise set. Sitting in a drive thru...coming to a stop no method to the madness! If you would stop,you could put it in PARK turn the key off then it would start back up and could run fine for a day or 7 days. Throwing no codes for the dealership. Then the dealership calls to tell me that it needs a new batt.& alt. I personally didnt believe it, so I picked up my beast and had them tested..alt. was fine the batt. was 65% so I replaced the batt. and moved on. 5 days later the wife calls me and says the truck died, and when she tried starting it like we always had to that the engine started reving and then died. Towed back to the dealer and was told it was the alt. "Didn't we tell you the alt. and batt was bad before?" After arguing with the service manager I asked will this fix the problem? He said YES! Well guess what the wife went to pick up the truck and the engine started reving again..the mechanics started scrambling..they checked the fuel pressure..its fine then they plugged in there computer..this is funny.."it says the engine is overheating"..(keep in mind it was only started 5mins ago) "maam does the vechicle ever overheat?"..Now it says theft "that means it could have the wrong key" WTH?? are wrong with these people..it never overheats,its the same keys we have been using for 2yrs that came with it. They keep it for 3-4 days, call me and tell me that it has 3 bad coils that are emitting an RF signal thats interferring with the PCM...still standing behind the bad alt. theory also...they replaced 3 coils and yep it died again, but this time like it used to just died then started back up. So another 3days away and they replace another coil..."its definitly fixed now" the service manager tells me..WRONG it died again. Now the facts that I have discovered, when I bought the beast it had 40k and change on it..now it has 73k it had a nice K&N air intake system with a Borg excaust when I bought it, I have now also found a Jet Performance sticker on my PCM. Would flashing the PCM with the factory settings cause this??? Maybe the Jet has gone bad?? I do know that everything that they have done has only cost me money and the beast is still doing the same thing it did when I first took it to them! Any ideas??

 

Well a few things come to mind for me.

1.) Get them to reflash the PCM to factory. It could be a bad flash and it's causing the issue. It will at least elminate that as a cause.
2.) Is there an aftermarket security system installed? I know the Ex's have PATS but there may be an additional system installed. It could be an issue with PATS as well. I don't know enough about that system to make an intelligent guess (not something I'm really good at anyway).

 

I just talked with the dealership and they said that they did flash the PCM and it was successfull, however they didn't know it had a Jet chip of PCM, wouldn't you think they would look at this? It has a K&N sticker along with a Borj sticker on the driver doorframe. Thats what made me think that maybe there is more performance parts.The truck does not have an aftermaket security system(I wish). I'm going nuts!

 

I don't know much about Jet chips but does it piggy back on the PCM? If so remove it and see if the problem goes away.

Also there is always the basics that can lead to problems like a bad ground. Have them check the battery ground.

 

I haven't dug into the PCM that far yet, I'm sure it shouldn't be that hard (I hope) The dealership said the ground is the first thing they checked? I dont know how good though

 

Take that Jet thing off the back side of the PCM (this is where it is). Those are a huge POS and I'm surprised that it lasted this long. Have the dealer re-flash it to the latest factory calibration for the engine. That engine package is pretty solid and should not give you these issues unless you are adding to the mess.

 

I removed the PCM, it was very easy..found the Jet chip, but I'm not sure what would go back into the slot that the chip is in once its removed? anything? Also there was a rattle in the PCM when I took it out...I removed the Jet chip and could see inside the PCM, turned it upside down and a little piece fell out (now this was not damaged when I removed it) I put it all back together with the Jet chip back on it because I didn't know what to put in that slot, minus the piece that fell out....started and drove it a couple miles with no problems. I just wanted to make sure it would run once the piece was all the way out, and confirm it was already loose. But as I said there is no method to the engine stalling. This is my 2nd Excursion with a V10, my 1st one had almost 200k when I traded it and the only thing I ever had to do the preventive maint.!

 

I'm not familiar with the chip but you should just be able to unplug it.

 

With the PCM out,,, I would recommend cleaning the harness and PCM contacts. Take a very close look at each pin and connector to make sure there is no corrosion, moisture or any miss aligned contact points.

Point being is,,, Several years back I was on a trip across Canada in a mid 90's camperized Ford Van (I think it was an E350). I was driving up a steep hill near Golden British Columbia and the damn thing simply shut down on me. I was able to get it started (it ran very rough) and pull into a rest area. I ended up getting towed into Golden and waisted over two weeks parked at a garage with the mechanics and myself trying to diagnos the problem. We tried many things including replacing the PCM with no luck time and time again. Sometimes even when it was running rough it would shut down and it would start up for me and every so often it would run pretty smooth for few seconds, but it would always go back to either not starting or running rough.
In the end I was just messing around with old PCM and decided to push a sharp pin tool into each of the pins on the PCM connector forcing them to expand to a slightly wider size. I plugged the silly thing back into the harness and it fired right up and ran as smooth as could be. Never had another issue with it driving across Canada then down through parts of North Eastern USA and all the way back to Vancouver BC.

Might be worth a look for you just in case.

Rick...

 

Remove the chip and tape over the hole. Put a piece of paper or cardboard over the hole, and tape it on. There is a small plastic or metal cover that goes in the hole, but it's obviously gone

Sounds like the chip is going bad.

Either that, or you have a sticky IAC or a vacuum leak, but first REMOVE THE CHIP and see if it fixes the issue.

Removing the chip, you will go back to the "stock" programming. What probably happened is they flashed the PCM with a new "stock" program, and because of the Jet chip, it didn't do anything, just took the reflash and didn't use it.