Trans Shifting Problem.

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Hi all,98 Ram 1500,5.9 4x4 Quad Cab.90715 miles. For the past week,it has started shifting later than it used to,and a couple of times wouldnt shift out of first unless I let off the gas,then it shifted with up
through the gears. When this happened,I just got off the freeway,pulling away from a stop sign. It hanging on longer to shift.Any ideas ,and suggestions would be appreciated. Thanks. snipped-for-privacy@webtv.net
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On Mon, 14 Aug 2006 08:55:27 -0500, snipped-for-privacy@webtv.net (e lowejr) wrote:

Shift point are linked to engine performance (manifold pressure) and if engine is lagging a bit it will delay shifts. Maybe you should start with a fresh tuneup and oil change and if that fails try better fuel (higher octane) in hot weather. Also if you have oversized tires this throughs things of too which many do not realize. ----------------- TheSnoMan.com
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Huh?
Larry Behold Beware Believe
(e lowejr)

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On Mon, 14 Aug 2006 12:12:27 -0600, "Larry Crites"
I guess that "of" missing a second "F" for off realy confused you.

TheSnoMan.com
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Shift points are determined by more than just engine performance. Many inputs are taken by the PCM and used to determine transmission shift points.

A tune up might help, but not likely. An oil change will do nothing for the shift points. Better fuel won't change shift points.

Oversize tires won't make a difference from one day to the next, unless its the day you install or remove them.
First step would be to check the PCM for codes. Since its a 98, you'll need to have it scanned for these codes. Second might be to change filter and fluid in the trans and put a new set of solenoids for the governor pressure sensor and transducer.
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wrote:

Not really, road speed and engine load and load is primarily used and it is calculated by RPM and manifold pressure (as this is a measure on engine output against speed/load, throttle position play a roll but only realeted to the resulting manifold pressure) When a engine is out of tune, it will have a higher manifold pressure (lower vacum) at a given speed than one that is in good tune so the shift will delay or hang whether it is a Dodge, Chevy or Ford. And as mentioned earier if it has oversized tires this increases the effort required by a untuned engine (as well as a tuned one) and it can change shift points as well. ----------------- TheSnoMan.com
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Um, no. According to the 2000 FSM, inputs to the governor control come from
Fluid temp TPS speed sensor Gov pressure sensor PCM Gov pressure solenoid valve
Notice that this list has no MAP sensor or tach signal.

More false info. Vacuum is a factor of RPM vs throttle position. state of tune is irrelevant unless mechanical problems are present in the valvetrain.

Correct, but the state of tune would have to be drastically degraded to have a change in shift point, no something that generally happens overnight.
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wrote:

Max Dodges Max crap. Engine tune HAS EVERYTHING to do with it because a detuned engine requires more throttle for the same output. but I guess the escapes him. I will be he believes rolling resistance has no effect either. ----------------- TheSnoMan.com
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SnoMan wrote:

Huh?
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While you are correct that a detuned engine may require more throttle, the PCM isn't looking for just TPS or just RPM. As such, the state of engine tune has little effect since the TPS and RPM inputs vary independent of one another. This produces an infinite number of possible combinations that the PCM would see. That infinite number of combinations is possible with or without a well tuned engine.

I see your claim that MAP had anything to do directly with trans shift points has now escaped you.

Certainly it has an effect, BUT.... we still don't know the size of the tires. What we can bet on is that the size of the tires didn't change from when the trans shifted correctly to when it started shifting incorrectly. Thus rolling resistance probably hasn't changed all that much, at least not suddenly as the OP seems to feel his trans did.
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You're forgetting the TV cable, a large throttle input at low road speed is the classic scenario for a delayed upshift.
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Not forgetting it at all. If the TV cable were out of adjustment, it would happen all the time, not just select incidents, as the OP infers. Second, it wouldn't happen suddenly, as the OP mentions, unless something broke and then the problem would be constant, not selective. Further, if the cable broke or stretched, the shifts would be too soon.
Sorry, I'll stick to checking codes, then looking for physical damage.
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As usual you're missing my point, I'm not saying the TV cable is out of adjustment, I'm saying there is a possibility that a sick motor would require more throttle and more throttle means more TV cable extension; the overextended TV cable would delay the upshift.
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I'm not missing your point John. Infact, I've agreed that a sick motor could cause that effect. However, the OP made no mention of a sick motor, and claims the problem isn't always present, at least not to the same degree of severity. I'm not sure just how bad the engine would have to be for it to affect TV operation as severely as has been described, but its a fair guess its gotta be bad enough to notice more than a bad shift point. Further, since the OP noticed it in the last week, its also a fair bet its a noticable change, not a gradual one such as an out of tune engine.
Again, I'd check codes first, and go from there.
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As I stated earlier, the operator might not be aware of a sick motor especially if there is no obvious misfiring, etc.
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And as I stated earlier, poor performance of the negine would have to be fairly serious to change a shift point to the degree the OP described.
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And what exactly is the PCM basing its input on? How about engine load and it determins that baced on the MAP, TPS, and RPM of the engine.

LOL, you really do like making a fool out of yourself, don't you? How do you make an out of tune engine deliver the same amount of power? How about stepping on the gas a little harder and what happens when you do that? ANSWER: For a given RPM, that means that the throttle is opened more and the vacuum is LESS. So while you are correct on throttle position in relation to RPM, you seem to have no concept on what is can effect it..

Really??? What if the cap cracks or an injector hangs or fails the regulator in the fuel pump goes bad or a sensor fails. All of these things can happen in an instant.
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Um, no. It determines shift points based on RPM TPS and input from the governor pressure sensor. Remember that list I posted? No? Here:

You'll notice that the MAP sensor isn't on there. Notice also that ALL of those inputs go to the PCM. So if all the inputs go to the PCM, they could say that the PCM determines shift points. But they listed the inputs that the PCM uses to shift the trans, and MAP isn't one of them.

How well the engine is tuned has very little to do with RPM and throttle position when looking at vacuum. Those two variables are what determine vacuum in the engine. Not the sparkplugs, or the plug wires, or the cap and rotor, or the coil, or coil packs. None of those change vacuum.
If you want to argue that TPS signal is changed, thats true, and I'd agree, but lets look at something....

Clearly he is describing a problem that has to do with PCM control of the trans, NOT a change in tire size, or a poorly tuned motor (no mention of sluggishness). Furthermore, the problems he describes have been attributed to the governor pressure sensor and the governor pressure transducer. Thus, we're not looking at a tune up, we're looking at pulling the codes and seeing what the PCM has to say.

Interesting, since thats the first thing I mention doing.

Really.
It causes a misfire, something that might be a bit more noticable than shift points.
the

Poor engine operation would result, but the OP doesn't mention that.

Wow, a sensor fails.... what was it that I said to check?
Oh yeah....

Just full of relevant info today, aren't you?
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Yes Max, I remember and your list includes the PCM and if the PCM is controlling the shift points, why is it mentioned as an input?

But they included the PCM itself as said above. Why do you think that is??? Perhaps because engine load is also a factor determined by the PCM and there is no need to further complicate matters by including all of the sensors and inputs that the PCM uses to determine engine load.

That is just about the dumbest thing to come out of you so far. It has everything to do with it when the engine is under load.

They don't change the engine vacuum in relation to throttle position but they do effect the amount of power the engine can deliver at specific throttle position which means to recover the lost power at the same RPM the throttle needs to be opened further which increases manifold pressure.

What exactly are we going to look at Max. By saying the TPS signal will change only proves that the manifold pressure will also change for a given RPM which basically is you saying that YOU are incorrect in your previous statement.

I never said that it was due to the tune of the engine. I simply disagreed with your crap that engine load has nothing to do with shift points.

And I never said that you were wong there.

Misfires are not always so easily detected, especially when the PCM will do all it can to correct such things, including things that can have a significant drop in performance but as I say again, I am not saying that this is the cause, only that you are full of shit that these things can never happen overnight.

Possibly, it depends on how badly it failed.

LOL, once again you prove your ignorance. Not all failures flash a code since not all failures are complete failures and if the PCM is not aware that the sensor is not functioning properly, no code is generated.

No, just like watching you dance when proven wrong..
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You guys are complicating the issue, if the motor is lacking power the accelerator pedal will have to be depressed further to get the expected performance; this will result in the throttle valve cable being extended farther than normal for a given road speed and this results in delayed upshifts.
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