Okay, well I had been having this issue of stalling when I was coming up to a stop. I was waiting, waiting, waiting to get a CEL or something to lead me towards the issue. Well, after testing fuel pressure, replacing things like the fuel filter and installing my 255lph fuel pump. Continuously checking my fuel pressure regulator for signs of leaking fuel, and searching for ways to determine the status of my FMU. It was after all this I came to the conclusion that my IAC had to be at fault. I remember I had bought a IAC from Vatozone awhile back when I was strapped for cash and my Motocraft one had completely fallen off of its rocking chair causing extremely high idle speed(3-4k rpms). The Vatozone IAC had lasted me some time, but like all other not Motocraft parts on these vehicles.. they go out quick! So I returned to Vatozone hoping to make an attempt at a new IAC just to confirm that my current IAC was causing the stalling issue I had been facing. Well little had I known.. they apparently changed the design- they put a spring on the plunger inside the IAC which kept the IAC from ever closing(thus making it defective OUT OF THE BOX ). So, I convinced them to give me a refund and it worked . I ordered a Motocraft IAC from the stealership because I can afford it now and it came out to be $155 . Well, I installed the new IAC, but I never re-set the computer (I have now though so dont worry ) I drove the truck and it continued to have the same stalling issue(before I re-set the comp). My question is.. could the reason that my truck continued to have the same issues simply be that I failed to do something as simple as let it relearn the settings? Or is there something more I should be looking at? My code reader and my edge both say that it has to do with circuit malfunction. Can the circuit malfunction be the IAC itself?

And what are the chances of me going out in the morning and driving the truck and it having 0 problems? Is there that chance?

 

Damn $155 , Yea Rock Auto has the Motorcraft for your model, - for less than half as much of what you gave. Yea, just looked , - 98 4.6L Motorcraft IAC for $70.

Test the circuit , -unknow ? Not the part.

Oh and - chances are pretty slim, lol.

 

Yeah man $155, and they got me because I needed it ASAP. Oh well, I have a 2 year warranty on it

Looks like the IAC didnt solve anything-ima have to crack out the old haynes manual for this one! Who would have thought that this little problem could be so hard to resolve. Atleast I am not picking up a 1504 anymore.. well not that I know about. Buddy/mechanic is suggesting the torque converter controller or module, but I dont know if that could cause the problem because it will still stall after a rev up in neutral. My idle rpms have been a little low lately.. probably 570-590.. its killing me. They usually run 650 +/- 10 so I am stumped.

Anyone got anything?

 

Have you tried cleaning the throttle body? You could be having an EGR issue that's not throwing a CEL.

 

I think it's a wire on that 98. I've had two break inside the insulation so far.

Not my IAC (yet), but the CHT and IAT. I caught the CHT hanging on by a thread, - Replaced the harness. The IAT completely severed inside the insulation and produced a circuit DTC , she ran goofy as well.

Thing is, without that DTC, I would have had fun trying to figure that one out. I couldn't see the break... - Only thru continuity testing.

So do your VREF test / KOEO/ KOER/ Cold Idle/ Warm idle etc. In my case, VREF was good, the signal wire was broken. They break, one thread at a time. It could be just about broke and loosing contact intermittently u know ? Wiggle the wire while it's running too.

glc, - his EGR ports should be spotless now, they WERE completely plugged at one time.

b2, Do you have the testing procedure?

 

The intake is completely clean as of this afternoon. The problem has become intermittent. Almost as though its messing with me.. my dad drove it and there were 0 problems to speak of and so I get in and drive it around with my dad and it couldnt find idle to save its life. Maybe that could be a wire? My scanner was telling me P1504, and replacing the IAC and resetting the computer has ridded me of the code. I have cycled it plenty of times and the code should be back already if it were going to be. Still an odd idle..

Its been determined that the torque converter is not at fault after testing out the gear selector on the edge as I was coming up to several stops. It shifted to 1st with no problems.

So here I stand- I have a completely clean intake with all new EGR components as well as IAC and EGRVR. MAF shows readings just where it should, and IAT's were about 20 above ambient no matter what. Fuel regulator checks in ok, and no signs of a leaking PCV hose or crank breather tube. Maybe it really is demon possessed


-no really, I need