What would cause a 4l60e to shift early
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My car is shifting about 400rpms sooner than it should be, also my rev limiter dropped, and the car is lacking some power. Could this be a transmission issue?
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The PCM controls the shifting. A bad transmission typically shift too late, not too early.
This sounds like an engine sensor problem - the PCM does not think you are at WOT. I would check the MAF and TPS first, then the MAP.
This sounds like an engine sensor problem - the PCM does not think you are at WOT. I would check the MAF and TPS first, then the MAP.
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I have replaced the tps and maf, so I will work on relpacing the map sensor. Out of all curiosity could this problem have anything to with speed sensors or the fact that the abs is unplugged in my car and it still has the abs distribution block?
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Changed my map sensor and it's still the same. It's supposed to shift at 6700 for all shifts, but it shifts at 5800 at the 1-2 shift and around 63/6400 on the 2-3 and will shift at 6700 at 3-4. Is it the trans?
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The 4L60E has no ability to shift on its own. Shifting is completely controlled by the PCM based on sensor input and the "shift tables" in the tune. Of the sensors, the VSS and TPS are the most critical. I suggest hooking up a scanner that can read TPS position and ensuring that it reads at least 98% with the pedal all the way down.
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You seem to be checking all the right things. Yes if the speedometer reads correctly the VSS should be right, and yes the VSS is located in the tailshaft.
Unless the tune changed, the rev limit is not going to change on its own. Maybe your tach is wrong. Can you compare the tach with a scanner?
Unless the tune changed, the rev limit is not going to change on its own. Maybe your tach is wrong. Can you compare the tach with a scanner?
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The scanner I used was my cousins snap on scanner not sure what model I will ask him and see if it will read rpms. I do have an autometer shift light with built in tach though and that's what I'm going by.
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Are you seeing any immature codes at all? Or any that
are set to no MIL, rather than No Error Reported? Short
shifting is a fault response to several things when the
PCM doesn't know what to trust (VSS, TPS, etc.). But
these shift RPM numbers don't seem like that kind of
conservative.
Now these RPM values you say, are they from logs
or from eyeballing the notoriusly slow and inaccurate
tach?
are set to no MIL, rather than No Error Reported? Short
shifting is a fault response to several things when the
PCM doesn't know what to trust (VSS, TPS, etc.). But
these shift RPM numbers don't seem like that kind of
conservative.
Now these RPM values you say, are they from logs
or from eyeballing the notoriusly slow and inaccurate
tach?
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I did have a maf low voltage code I think it was. But I replaced the maf and the light did not come back on.
The tach I'm going off of is the autometer digital shift light I have with peak recall
The tach I'm going off of is the autometer digital shift light I have with peak recall
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I'm not sure what sensors to look at anymore or replace. Which all are trans related? It may all be in my head at this point but it feels sluggish like its slipping. But I would much rather it be a sensor problem if I could just figure it out.
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I have the same thing but only in my 1st to 2nd shift programmed at 6000 and 37 with 3.73s but shifts at 5500 at 35 would love to here some possible solutions 2nd to 3rd 5900 at 75 is right on