Smoke testing is generally done for the evaporative emissions system and won't help find a vacuum leak in the engine's intake system. If they plugged a smoke machine into a green port on a tube they were testing the evap system. I've never heard of smoke testing for a vacuum leak, tho I guess it could be done. Regardless, if the booster were the culprit it wouldn't show up by filling the intake with smoke since it's blocked by a check valve.

 

Thanks, i will try the brake pedal trick and see if it still holds pressure.

 

You were correct. Cam and crank sensors didn't fix the issue. However, the truck has 240k miles on it now and I figured it was good maintenance anyhow. The truck seems to have quicker reponse time now to the pedal and no delay. I could push the gas pedal a bit (almost like the throttle cable was stretched) and it would hesitate before it wanted to go. That seemed to cure that issue.

However, the stalling issue is still happening and I think you may be on the right track with the truck. I have owned this truck 3 years now and ever since I bought the truck the brake pedal always seemed soft until I would put the truck in gear drive around and then the pedal seemed like it was at the top of the stroke and had much better pressure. I could still brake, but the pedal was at the bottom of the stroke instead of up towards the driver.

I turned the truck off and counted 1 one thousand, 2 one thousand all the way up to 60. Pushed the brake pedal and it didn't have any pressure.

I then went ahead and tried to start the truck and push on the brake pedal, no difference. Put the truck in drive, drove it a few feet and the brake pedal pressure seemed better.

I am going to try the same test on my wifes SUV and see how hers feels in comparison.

 

Here's some info on vacuum brake boosters - AGCO Automotive Repair Service - Baton Rouge, LA - Detailed Auto Topics - Vacuum Brake Boosters

 

Yeah, I let the truck run for two minutes then turned it off. I could push the pedal 3-4 times before it became rock hard. I then turned the engine on and the pedal fell to the floor slowly. I would assume this indicates the booster is working correctly without testing the exact measurement of vacuum.

The only other thing I can think of that I haven't checked or changed is the torque converter.

The only sensor on the engine left that I haven't replaced now is the TPS.

I checked vacuum and I get 20hg at the intake at idle.

 

Have you checked the OBDII data on the Engine Coolant Temp/Cylinder Head Temp sensor?

 

No codes, I only have an X4 by SCT to scan or my free tools using my laptop. I have never been able to pull a code. Last time I had it into ford they could duplicate the issue but couldn't fix it. (no codes found by them either). They basically said bring it in when it has a check engine light. My SCT X4 monitors my trans temp, engine temp, rpm, mpg etc. Coolant temp always looks normal.

Again I want to let you know, the stalling issue occured on the old engine and the new engine. I have tested everything I can think of and or replaced everything (besides tps) to eliminate the issue.

Calling Mark Kovalsky and Krewat to see if something transmission related could cause my stalling issue. I would assume the PCM sends a signal to the torque converter clutch control solenoid to lock it up? Diesel forum shows a purple wire. I assume I could just cut the wire or unplug it so the trans doesn't lock up... If that fixes my issue, then at least I would know the Torque Converter is ok and its something solenoid, wiring or pcm related?

****EDIT****

Made an appointment with my local FORD dealer for next Thursday. Hopefully it's not the transmission/torque converter, but that's what my gut was telling me before... I wouldn't be surprised if that was it. I am just that lucky. :P

 

Well, I wanted to report back that I have tracked down the issue and fixed the stalling issue... This issue has been happening for years, with the old engine and new engine as I stated earlier.

Thanks guys for the advice and help.

 

What was the cause?

 

I removed the tune and the tuner from my truck. I have spoke with Mike and he is making it right.

 

Well, at least it is not a mechanical issue. Hopefully he will get you remedied in quick fashion.

 

I've followed the other posts on stalling with the V-10 engine and have great sympathy. Mine just did it for the second time in the exact (within inches) spot as the first occurrence. I had just driven up a 20 degree slope onto a knoll and parked on a flat area at the top for about 15 minutes with the engine off. I had 1/2 tank of gas. Then I restated the truck and reversed down one part of the knoll slowly in order to turn around. The slope was about 10-15 degrees.At the maximum incline the engine cut out and would not restart. Same identical action both times, probably two months apart. The Ford dealer fixed it the first time (after towing back to town) and said it was the Master Air Flow Sensor, OK. It ran fine on flat highways for the last two months. But back to that knoll again and the same thing happened. It is obvious to me that there is no fuel being delivered, for whatever reason. The battery cranks strong but no fuel. I unclipped and reclipped every single plug I could access under the hood. I pulled the Master Air Flow sensor out of the air tube behind the filter. It was pristine. I jiggled all the wires associated with it. I also jiggled all the cables associated with the throttle control. Finally, I undid the gas cap in case of vacuum build up in the tank. I restarted the truck by flooring the accelerator pedal and cranking the ignition. It fired up at 4K RPM and I quickly drove off the incline so the engine was pointing down the hill. The engine continued to run from that point forward. No clue what the successful action was. Too many electronics and flow paths to do a real failure analysis. I now avoid that knoll and I am looking for a pre-80s manual shift pickup.

2003 F-250 V10 engine, 120K miles.

 

I had the same problem, it would be very intermittent every few months then every other day , Dealer could not figure it out. ended up being a short in the fuse box. replaced and all is good.

 

I'm having the same problem and have done lots of parts replacements. There are two fuse boxes on my 05 Excursion. Which one had the short and how did you access it? Also, was the short obvious and visible or did you have to check all of the connections? Is your Ex still running good with no stalling? Thank you very much!

 

I had the same problem, stalling at random would usually start right back up but sometimes took up to 2 hours before it would start. No codes would be thrown and stumped many mechanics. Had planned on having the fuel relay fixed by the guy on Ebay but found an almost identical excursion being parted out locally so I bought his central junction box and have not had any problems since.