Question about Buick LeSabre

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Miss under a load (up hill) when car is at operating temperture.worse when tranny shifts in to passing gear.Runs great cold and at slow speeds. I have replaced plug wires and plugs with some improvement but still does it. Also replaced egr valve,air filter,fuel filter,tranny filter and oil.replaced the coils and control module. Car has 70000 miles on it.

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  • etbreezie Aug 12, 2008

    I think I have a vacuum problem,perhaps manifold gaskets or a crack in the plastic manifold. When I step on the gas pedal the car is very reponsive even uphill.




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Explain problem in detail thanks.

Posted on Aug 12, 2008

  • Ginko
    Ginko Aug 12, 2008

    First you should have car compression checked , you can get this kind of problem when head gasket is starting to go. Check if coolant liquid level is gone down.
    Check also if one of the spark plugs is burnt or dirtier then the others car may be misfiring on one cylinder. Start replacing spark plugs, if you keep getting the problem you have a distribution problem.
    Have car computer scanned with a code reader to locate the problem.

  • Ginko
    Ginko Aug 12, 2008

    Exhaust tailpipe black on the inside is normal, check if you get white
    smoke from exhaust when engine is hot that means head gasket problem.
    If car fail going up an hill it is often a compression problem.

    If car has automatic transmission, it can be also tranny not shifting
    down gear, this usually is a module problem, but you told me you
    checked this already.

    Also a faulty throttle position sensor can give transmission problems,
    but when this is faulty you get troubles with gears on all kind of situation.



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name what works and what dont.
slips. (flare)
late shifts
early shifts.
skips gears, say 1 to 3rd?
down shifts wrong, early late or not at all.
only shifts hot or cold.
passing gear fails
down shifts on hills fails.
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the FSM covers the 50 ways to fail (chart)
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When my engine iscold it takes forever for the converter to finally lok up

TCC locks at high speeds. where is yours failing, how fast.?

so at what speed, do you expect TCC lockup.?
unless you have tranny slip.. a whole other problem in any gear.

this old tranny has, pure mechanical ops. no TCM here.
most old tranny have the foolwing inputs.
1: driver right foot called the TV cable or detent or passing gear cable.
it can stick and cause late shifting
2: Tail shaft speed, this is the tail speed governor that shifts by speed.
3: the load vacuum modulator that shifts by engine load (vacuum)
4:gear lever positions PRNDL.

the 5th input is the TCC relay that the ECU controls
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hesitation is engine, issues. unless its flare.

is the engine hesitating? or is the tranny slipping.

does this happen hot engine, cold engine or both

what speeds?

does the transmission pass the stall tests in the FSM?

does the ditto the pump tests in the FSM>

the answer to your suck out quesions , sure, there is no limits on what any person can do , with the book in hand, ,.. zero limits.

and for sure we can not tell you , your limits.

read any FSM made on any car, see the ON CAR service.

read that,.

then see online, people going behond that.

on TCM based trans (A/T brains) we can drop the whole

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google soleniod valve body service.... or use google image

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now let me back up.

why not post the full symptoms.>???? driving, shift , what it does good

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if the tranny is slow to shift or stuck in a gear.

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i scan it , hell with the CEL lamp i scan ever car first.

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the imput sensors are MALFING.

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Think of this problem in 3 parts

1 the Gear box.

2 the TCM

3 the INPUTS.

the job on the on car mech. is to find which of the three are bad

the FSM covers that. very well. buyone.

since you did not post engine hot or cold, i cant answer.

on a cold engine (and in Alaska worse) the FAST idle is normal

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