I just purchased a 1999 F150 (my first real truck) with the 4R70w and the 5.4

I scanned the codes and I got a faulty idle control valve. . . no other codes showed up. (it does idle around 900-1000 RPM).

Problem - the tranny seems to load up and rev about 1k higher before it shifts into 4th (3-4 slip), but like I said it trips no codes concerning the tranny. 1-2 is fine, 2-3 is really quick and 3-4 slips.

Is it possible that the ICV is causing this mis-shift?

Thanks for your help - looking forward to learing a lot here!

 

Please post the code numbers and not the description.

JMC

 

The shop mentioned the code number briefly - something like 0507 . . . I will call them and ask. . .why is that important?

The idle is too high. . .

 

P0505 - Idle Air Control System Malfunction. This occurs when the IAC cannot control the correct engine RPM at idle. Either clean the IAC or replace it. The tis the most likely cause. As for the tranny that is a seperate issue.

JMC

 

I am well aware that the idle control valve will cause the high idle. That is not why I posted.

I AM curious if anyone else has had the same shifting problems as I have described and if the two could possibly be related.

Thank you for the reply that they are probably not related - that is as I expected.

The OBDII trips no codes about erratic shifting. . .

 

The standard procedure is to rerpair all non transmission codes first. I would fix the IAC problem then have the tranny checked out.

JMC

 

Wow - nothing like my Mustangs - they put those things way back there on the intake it looks like. Do I bother trying to clean it, or with all that trouble should I just replace it?

It has 126K miles on it. . .