Hey!, where did 4th gear go?

[06T200]

More possible clues in this post: http://www.aveoforum.com/forum/f82/n...38/index2.html

[outinthewoodsnf]

If it was mine, I would've driven it off the cliff long ago!! Lol,,,, We gave it to our oldest daughter for graduating high school..... It lasted 3 days,,,,Kinda "married" to the thing now,,,If I had the funds, I'd just give up and bring it to the garage but such is not the case,,,, Thanks for all your help!

[GrambleShmou]

I had misfire codes, it was the O2 sensor on the exhaust, pull that and check it. I replaced it, I haven't had any error codes yet.

[outinthewoodsnf]

Thanks, ill have a look at those.

[GrambleShmou]

Hope it works out.

[outinthewoodsnf]

Well, I tried pulling the O2 sensors to have a look,,,, didn't have the socket for them and couldn't find anything else to get them out with, did find that the air filter was a bit dirty tho,,, idk if that would cause misfire enough to take away 4th

[outinthewoodsnf]

Apparently it wasn't the air filter either,,, there is a little nipple on the valve cover without a hose on it.... Does anyone know what is supposed to plug in there?

[outinthewoodsnf]

This one here

[outinthewoodsnf]

So just curious, does it throw these codes immediately, or while you are driving it? Were they there with the old engine? Also I assume you checked basic stuff like ATF fluid level, and that nothing was left disconnected during the motor swap. When I am hunting down codes, I like to use a process of elimination to arrive at the bad part. I often find codes that pop up in sort of a chain reaction, and often times was something simple like a loose connector, or I added in too much ATF - as examples. Seems like anything will put the trans in "limp mode" (no 4th gear). When you clear the codes does 4th gear work till the MIL appears? - There are ways to 'tweak' the code within the ECU/TCU, but that info is very hard to come by unless you speak Russian and are really handy with assembly code. There are "updated" software revisions that can be reflashed to the ECU/TCU via GM's Tech 2 hardware, or a tis2web subscription. I would suggest to go here: https://tis2web.service.gm.com/tis2web and enter in the VIN of your Aveo and see if there are any updates for your modules, some updates address false DTC's being thrown. Not sure if this is your issue, but it may be of some help in chasing down intermittent codes. From what I have read some Aveo's went out with some buggy firmware in the MR140 units. FYI

Now she's putting out a P0455 leak code, I checked the gas cap and it's ok,,,, I did find a small nipple on the valve cover that doesn't have a hose on it. There wasn't one on there before I removed the old engine either so I don't know what it's supposed to be connected to...... I'm guessing the evap system somewhere but the diagram on the bonnet ain't helpin..... I checked the vacuum on the intake and she's just barely 18

[06T200]

Im all out of ideas on what to try. Not sure on the open nipple on the valve cover. If not needed you might just cap it off. I am now again chasing codes myself, looking like a bad TCU in my black 06. Just when I think I have it dialed it throws another MIL! I love a challenge, but this is getting old LOL