Graeme
Forum Newbie
Posts: 5
Reg: 01-22-17
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01-22-17 08:15 AM - Post#2672764
Hi everyone , got a problem with my box and no one seems to know what the problem could be or what to check so I found this great forum which will be a great help.
My problem is . I have a LQ9 which is mated to a 4L60e in my 65 Impala. The car was running fine until the manifold cracked and then we ended up rebuilding the motor. This is where my problem started with the box . When the car is cold the box changes perfect but as it warm up after a long drive , the box will not go into 4th and when I pull away it has a hard shift into second almost like the line pressure has increased.I plugged a simple code reader into the OBDll plug and it reads fault code PO730. I just really don't know what do and need help to try figure out what is the problem or where to start.
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Graeme
Forum Newbie
Posts: 5
Reg: 01-22-17
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01-22-17 08:32 AM - Post#2672768
In response to Graeme
Sorry guys forgot to mention I checked the following .
Gearbox oil was perfect no smell or not burnt.
Gearbox oil is full and not low .
There is no sludge or bits in the oil pan. Gearbox is brand new
Gears are not slipping or jumping out.
I'm running a standard GM computer box no mods .
Hope the above helps
Thanks .
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 acardon
Ultra Senior Member
Posts: 10963
Loc: DFW TEXAS
Reg: 03-25-05
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01-22-17 09:33 AM - Post#2672776
In response to Graeme
Check ALL the round wires connected to the engine. It's easy to leave a ground wire loose or disconnected with an engine change.
Don
66 Corvair (driving)
57 2dr HT (driving)
56 2dr HT (waiting to be restored)
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Shepherd
Frequent Contributor
Posts: 1229
Loc: Lake George, NY
Reg: 11-11-15
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01-22-17 11:50 AM - Post#2672808
In response to acardon
Usually with bad connections the trans goes to limp mode, starts in 2 cnd or 3rd and stays there, is this happening?
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Graeme
Forum Newbie
Posts: 5
Reg: 01-22-17
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01-22-17 12:59 PM - Post#2672830
In response to Shepherd
Seems ok in 1st and second . Even when the box is warmed up , it will always start off in 1st then a hard shift into 2nd and smooth into 3rd and then of coarse no 4th. Could it be a solenoid problem ?
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Graeme
Forum Newbie
Posts: 5
Reg: 01-22-17
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01-22-17 01:00 PM - Post#2672831
In response to acardon
Will check wiring , does this cause intermittent gear changes ?
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Shepherd
Frequent Contributor
Posts: 1229
Loc: Lake George, NY
Reg: 11-11-15
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01-22-17 03:59 PM - Post#2672879
In response to Graeme
Normally control/ wiring would not affect 4th only.
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 someotherguy
Moderator
Posts: 28613
Age: 47
Loc: Texas
Reg: 08-01-03
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01-23-17 06:21 AM - Post#2672997
In response to Shepherd
That code generally results from excessive slipping; I would guess you've got burnt up clutches for 4th. Usually 3 & 4 go at the same time though; I don't know if it's physically possible for a 4L60E to lose just 4th. Will take someone more experienced with the transmission to say so.
The sudden hard shift into 2nd is likely because you have overall boosted line pressure due to the PCM detecting the slipping and trying to save the transmission. The 1-2 shift is generally firmer than the rest anyway, so when pressure is boosted, it will become noticeably harsh. There are other causes for a harsh 1-2 shift but considering this came along with the 4th gear problem, the situation is likely what I just mentioned.
If you know someone that can watch the data stream on the transmission, it can show them if it's slipping in all gears or just some. It only needs to slip about 5% to set the code, so it may be slipping in both 3 & 4 and you just aren't noticing until it gets to 4th.
Richard
| 06 Silverado ISS / 06 Silverado SS / 06 300C SRT8 |
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65_Impala
Very Senior Member
Posts: 3991
Reg: 12-29-02
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01-23-17 01:13 PM - Post#2673073
In response to Graeme
The 2-4 band could be causing you issues since it is only engaged in 2nd and 4th gear, but it's not normally what fails.
Does the speedometer work correctly, or at least does the PCM indicate the correct road speed at all times?
What does the line pressure do?
You will have to get a line pressure guage and a means to read the live transmission data from the OBDII port or else you're only guessing what is going on.
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Graeme
Forum Newbie
Posts: 5
Reg: 01-22-17
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01-29-17 01:15 AM - Post#2674038
In response to 65_Impala
Speedo not connect , will check the PCM . Going to do a full data check and see if the reading pick up slippage . Thanks for the responses , will do test and get back to you guys
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acardon
Ultra Senior Member
Posts: 10963
Loc: DFW TEXAS
Reg: 03-25-05
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01-29-17 07:49 AM - Post#2674071
In response to Graeme
Seems ok in 1st and second . Even when the box is warmed up , it will always start off in 1st then a hard shift into 2nd and smooth into 3rd
That doesn't sound OK in second. Have you checked ground wires? Since it started right after extensive engine work and everything is grounded to the engine at multiple locations, I would check that first. A bad ground will not act the same as a bad connection on 1 or 2 wires. It can cause havoc with computers.
P.S. Spell check didn't work in my first post. 
Don
66 Corvair (driving)
57 2dr HT (driving)
56 2dr HT (waiting to be restored)
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Edited by acardon on 01-29-17 07:51 AM. Reason for edit: No reason given.
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