Shudder when just starting

[JLamb85742]

I receintly fixed a leaking intake air duct and replaced the O2 sensor. The odd problems w/ fast idle and CEL went away and seem permanently banished. Since then the vehicle is becomming progressively harder to start. It turns over fine but where it used to fire immediately it won't catch for a count or two (or three or four). Even more problematic is a shudder when I first pull away after startup. It doesn't seem to matter if I spin up the engine in park or not, or if it is warm. It doesn't do it when pulling away from idle but onle after it has been shut down for a few minutes. It feels like both motor stumble and tranny shudder. It happens in both drive and reverse. The vehicle is a 91 w/ ~160K miles. It drives smoothly within a block or so afterward. Any ideas? When I replaced the O2 sensor I disconnected the battery for several hours - I assumed that reset the map. Maybe not? I recently cleaned the air cleaner and MAF sensor as well.

 

[BrooklynBay]

It sounds like the converter is locked when it isn't supposed to be. Maybe there is a problem with dirt that is built up in the tcc section of the valve body, or the internal screens that are supposed to filter that area. The case also has a spring that is used as a filter, but you would have to drop the valve body to get to that.

 

[JLamb85742]

So... change the filter, replace the fluid? I don't think in 160k mi the ATF has ever been swapped. Something else? AT's are beyond my experience - but I'm always willing to learn... Is this something a DIYer can reasonable acomplish? Thanks for your help!

 

[BrooklynBay]

I would suggest that you read the A4LD valve body rebuild diary in the top of the transmissions forum. It will show you all of the things that are necessary in rebuilding a valve body. If you just want to replace the fluid, and filter, then it might be worth a try. The filters aren't designed to last for 160k miles. It is way over due.