Shifts to 4th then back to 3rd
Thread Starter
Staging Lane
Joined: Jun 2013
Posts: 76
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From: Rochester
Shifts to 4th then back to 3rd My car has been on the road for about 2 months. Haven't intill this week got into any highway driving. I noticed rpms rly high, I have 4.56s but im sitting at 3300 at 60, thats third gear. Driving slow and counting shifts i can feel its go into 4th then out into 3rd. come to a stop again and count gears same thing hapens. Any ideas? Ive changes my rear end gears and tire size in HP tunners, I also changed part throttle shift mphs. Did I mess somthingup in the tune?
Moderator
Joined: Aug 2010
Posts: 7,323
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From: Ann Arbor, MI
If indeed it is commanding 4th and the trans drops to 3rd, then yes, I would also start with the 4th gear servo piston, checking it for cracks or a bad seal.
Thread Starter
Staging Lane
Joined: Jun 2013
Posts: 76
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From: Rochester
hope its just a seal. 4th servo piston seal is only 5 bucks. Talked to the guy i got the trans from and he said it has a vette servo in it so i hope he boogered up the seal on reinstall
Thread Starter
Staging Lane
Joined: Jun 2013
Posts: 76
Likes: 0
From: Rochester
Got tech 2 on the car today, and its going into 4th. What im feeling is the car trying to engage TCC. I can comand it to engage and it will hold while driving, 30 rpm slip plus minus 25. Cruise speed goes right down to 2500. So I know the trans is functioning, mechanically and electronically. So is the stall converter doing somthing with the TCC logic? 3000 stall btw.
Thread Starter
Staging Lane
Joined: Jun 2013
Posts: 76
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From: Rochester
Ok what I thought was the tcc trying to engage was acctually Tourqe managment pulling 30 degrees of timming between shifts, so thats gone now. So trans is shifting into 4th and tcc is not being comanded on. Whats up with that? ive put it on a switch for now but i would like the PCM to control this function
Moderator
Joined: Aug 2010
Posts: 7,323
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From: Ann Arbor, MI
First be sure there are no codes - not all codes produce a MIL light - so scan it.
Jimmyblue recently posted all the PIDs to scan for to determine why the TCC won't engage, but I cannot find it.
Jimmy: if you see this please link to the detailed post of yours.
PowerAdder: in the mean time, if you do an advanced search for "TCC Lockup" and user "Jimmyblue" for a lot of good information. Here is one:
https://ls1tech.com/forums/pcm-diagn...cc-lockup.html
Jimmyblue recently posted all the PIDs to scan for to determine why the TCC won't engage, but I cannot find it.
Jimmy: if you see this please link to the detailed post of yours.
PowerAdder: in the mean time, if you do an advanced search for "TCC Lockup" and user "Jimmyblue" for a lot of good information. Here is one:
https://ls1tech.com/forums/pcm-diagn...cc-lockup.html
Last edited by mrvedit; Jun 22, 2013 at 09:52 PM.
