transmission surging at idle in drive or reverse?
 

I have a 3.0 v6, with the 5r44e transmission. I've noticed this issue on occasion for about 6-8 months now... at first i thought it was related to the idle air control valve or something, but now i'm thinking its transmission related;

the problem occurs only when the truck has been sitting for awhile (couple hours or more). I'll start the truck, and it idles COMPLETELY fine while it is in park. If I then put the truck in reverse or drive, and let it slowly idle forward or back, the rpm's will rise and fall from about 1.2k down to 200 rpm, almost as if the truck is about to stall. it goes away after a couple minutes, or if i give it gas.

it doesnt happen every time i start the truck. it seems to happen less if i start the truck and let it warm up for a minute or so, and it seems to happen the most on cold mornings, when i get into my truck, start it and IMMEDIATELY throw it into reverse, with almost no delay after starting.

when is the last time you flushed the trans?

it might be seal in the VB, the low/reverse servo.

and i think you can check and see if it is the IAC by unplugging it and letting it run with the IAC unplugged. it does not sound like the IAC...

Also i have seen similar issues with a vacuum leak, check all the vacuum lines because with a vacuum leak it can mess up the air fuel ratio which will make it idle bad and make it struggle to run when out of park.

not a transmission problem!

if the idle is droping then its a IAC problem or maybe even a vacuum leak, dirty MAF, something along those lines. theres nothing in the transmission that will make the idle jump around like that.

now you may also want to check the tube from the TB to the MAF, if its loose then when you put it in gear it may be pulling apart causing idle problems, have someone put it in gear while you look at it under the hood.

mine does the same thing never has given me any problems i has done it for like two years now

the iac should only control it if the engine is cold, or if its coming back from a rev, like you let of the gas and its coming back to idle. it does not sound like an iac to me.

mine does the same thing some mornings, i dont know what the problem is but am interested in a solution

if it was the IAC/vacuum leak/MAF, then why does it not do it when its in park, but as soon as i pop it into drive or reverse, it starts doing it? if it were any of those, wouldnt the problem be evident in all gears, including park?

i'll check/clean the IAC and see if that helps since its such a quick fix.

I once had a MCSS that did something similar to this. In that case the TCC solenoid was bad. Appearantly it was trying to lock the convertor up.

If you have something like an X-cal2 you can see (live) the functions and determine what's going on.

Rich

in park the iac should control it.

you didnt read my entire post.

check the tube from the maf to the tb, when you put it in gear it flexes and if not installed properly idle/stalling problems can result

ahhhhh... gotcha. i'll check that out as well :)