Hi guys I just bought a used 1997 F150 5.4 V8 (4x2). This truck is awesome no leaks brand new a/c and no leaks on the engine whatsoever. It also runs excellent so long as it's in drive however, when I shift to reverse the idle drops and sometimes dies out on me. Can anyone help me figure out why this happens. The truck is completely stock with the exception of a borla exhaust system. Thanks everyone!!!

 

Do you have any Idea of prior maintenance history??
any code present?

Seems like the IAC might need attention, remove and clean. A place to start anyway.

checking for vacuum leaks would be another, as well as, cleaning the MAF sensor.

If that doesn't do it, then a removal of the throttle body housing and giving it a good cleaning including the EGR ports.

 

I removed the IAC it had a lot of carbon build up (at least to me it looked like a lot) soaked it and sparayed it out really good. Put it back together and same thing...should I just buy a new IAC?

The only time it goes into reverse without stalling is right after I start it up cold and after starting it up again when it stalls coming out of drive...

Vehicle was maintained really well...

Thanks enriched!!!

 

To clean an IAC, you need to use WD-40 or Deep Creep, not carb cleaner - and you need to work the plunger with a screwdriver till it's free and smooth.

If you soaked it in carb cleaner, buy a new one.

Have you scanned the OBD2 for codes?

Clean the throttle body off the engine with throttle body cleaner and clean the MAF with MAF cleaner.

 

Do you always back out?? meaning, even on warm starts, is your 1st move always in reverse? Seems odd that it only acts up in reverse. I would think that it would do it as well in forward motion too...maybe not??

 

LOL I did use carb cleaner, I'll just buy a new one it's like 60 bucks...I found some of the hoses to the intake and the intake neck are gummy I'm going to change those out as well I won't have time till this weekend will let you know how it goes...thanks!

BTW the only code showing is for an 02 sensor I'm guessing it's from the borla exhaust system...I'll check again tomorrow and google what the code is for exactly.

Depending on how I park but for the most part I reverse a little before driving off (I usually park out on the street). I think it doesn't die out because the idle is still a little high when the truck is getting warmed up. Once it's warmed up though the idle drops if I ever have to reverse and 8/10 times it dies out on me.

 

There's most likely your problem

Just post the actual code

example: P0132

 

You shouldn't get any codes at all with just a simple cat-back. Post the code for further info.

 

see there is a problem, it's just the owner neglecting to resolve the issue whilst complaining the truck isn't running 100%

 

mmmm I think I'm trying to isolate the problem so I can fix it no neglect here...

 

Probably needs trans fluid. Reverse is a fluid hog, allot more so than drive. When they get low, that's a common problem. You don't hear of it to often because most people at the very least, keep fluids in it.

Possibly the PCV valve as well. Just a hunch, it's most likely both

You have an O2 code. How do you know ? What's the code ? Is it a secret ?

These trucks will treat you right. A little respect goes along way. By little I mean at least general maintenance or in this case common sense.

Yea, no neglect here...Don't bet the farm on that one

 

I changed out the IAC valve and cleaned out the throttle body...drove around for a bit but it still stalls once in a while maybe 2/10 times now. I had it scanned and no codes are showing.

(I changed out the valve before I had it scanned. I did not disconnect the battery so it wouldn't erase any code if there was one).

The mechanic that scanned it said sometimes the vehicle needs to familiarize itself with the new part. Okay I guess I'll have to drive it more. Does anyone have any other suggestions?

 

It's been a while now since I changed out the IAC and still having the same problem...no codes showing and not a clue of what could be wrong.

 

You never gave us the codes. Go to an auto parts store that will retrive check engine codes and have them pulled/ Get the ACTUAL CODE NUMBER and post it here.