Does anyone have any idea why my truck turns off immediately when put in reverse? Yesterday it had a rough idle when at stop light and today I could not back out of driveway, 03' Supercrew 4.6L 180,000 miles, thanks in advance.

 

Had a nearly identical problem. Would run rough, stalled at stop lights, and died when shifted into reverse. I also had a shuddering problem with light throttle around 40-55mph.

I replaced the IAC to no effect.
Cleaned the throttle body to no effect.

What fixed me was all new plugs. ( I also put on all new coils just in case since I was already taking the old ones off).

some of the gaps on the old plugs were ridiculously huge. Its like a whole new truck now.

 

Thanks from what I've been reading sounds like I may need to replace the IAC. my plugs are about 1yr old and my coils are about 2 months old. about 2 years ago I replaced my Intake Manifold, cleaned throttle body, replaced MAF sensor, throttle body sensor, MAP sensor, EGR tube, front oxygen sensors.. so im thinking possible IAC needs replaced just not to sure.

 

Try cleaning your IAC first. I have heard a lot of people have had good luck cleaning it instead of replacing it.

Did you do the plugs yourself? Did you use motorcraft? Ford changed the torque spec on them because there are so few threads holding them in, that they were backing out and blowing out of the plug hole.

I didn't want to mention it before but during my research into my stalling issues, I found a few people that said a bad torque converter has caused them to stall out going into reverse. but none of them mentioned anything about stalling in drive at stop lights etc.

 

ok I will try cleaning the IAC first, and as for the plugs I try to stick to motorcraft products and I did not torque to spec. just tightened until snug but I will check them.


I have also read that the torque converter may have similar symptoms but I hope it doesn't come to that.

 

I hope its not the TC either. I know at least one of the videos talking about it was an expedition... if that makes any difference.

Plugs torque specs? I don't blame you. With as difficult as it is to get to them, I was tempted not to add further complicated difficulty to the job either, but I figured as long as I was doing it, I better do it as specified, especially considering how everyone talks about it, and the possibility of the plugs working themselves out. I believe the new torque spec is is 25ft Lbs, but, the prominent Ford Tech on Youtube said to do 28. I did 28.

You're not getting any codes I assume?

 

no, not getting any codes. Scotty Kilmer on YouTube mentions to connect a code reader to vehicle and punch in record data and when the vehicle turns off a few codes may show up as to why the engine turned off, unfortunately I don't have a code reader and its too difficult for people at autozone to understand.

 

You would need at least a medium-to-high end scanner for that as well. Or roll the dice with one of those panglong and bluetooth/App scanners.

I watched one guy used a $90 actron to view misfires on each cylinder individually, which would be super convenient. Check craigslist for the best scanner you can get? I'd say try ebay, but I have had trouble getting a quality scanner twice now due to scammers. Maybe ask around, and see if anyone you know, or anyone they know have one and maybe you could go by there house and have them help you.

Aside from that... My money is on plugs or coils. (I bought 8 coils for jut over $30 off amazon btw. They seem to work fine so far)

One other possibility is a dirty or bad MAF. You might want to investigate that. Just did my sons, but his issues were a bit different. (taurus) But in the end it caused stalling and erratic (but not rough) idle, that led to stalling, less so when shifting into reverse. If you try cleaning it don't touch it, just spray it as directed.

I should also tell you, I did a LOT of research on the no-code/stalling. This is how it broke down as I saw it:

75% Plugs/Coils
15% IAC
5% TC
5% miscellaneous

Whatever it ends up being, please come back and post your solution.

 

I will check everything possible, I have lots of work to do. Thanks for your time and advice I will keep you updated.

 

ok so I cleaned the IAC, MAF, checked all hoses, plugs and coils and results remain the same. The parts are not old however I don't know if any are defective. Back to drawing board.