Tardy Downshifts 2nd Gen - related to A/C?

[macboy]

I just got in to work after enjoying a spirited drive in. I had turned off the A/C since it was cool outside (15 C / 60 F). I noticed that the transmission was much less hesitant to downshift when accelerating.

Those of you with 2nd gens know that, when accelerating from a roll, the trans will tend to stay in a gear that keeps the RPM down around 2500 unless you really put the pedal down, in which case it reluctantly downshifts and takes off like a SOB. This morning, the only thing different is that I had the A/C off, but the trans would quickly downshift to 2nd or 3rd (depending on speed) letting me accelerate 'properly'. The car had a very different feel this morning. I don't think I was imagining it.

Has anyone else noticed this? It is not so strange (I suppose) considering that high RPMs are not particularly good for A/C compressors, so it sort of makes sense that the car would try to avoid high RPMs if it thinks it can deliver the same power with more throttle at a lower RPM (made possible of course by the TBW). I have noticed that when I push the car hard (6k+RPM) the A/C appears to cut out and I can smell that humid air come through the vents for a minute, just as if the A/C had been turned off manually.

 

[owlman]

iiiiiinteresting.... I haven't noticed any of that but I will have to do some experiments to see.

 

[NYC LS8]

AC compressors for years have had a wide open throttle cut out, so that's why you get that humid air when getting on it. That said, my car does the same acceleration thing, AC on or not. That drive by wire crap is maddening.

 

[BanginLS]

i've had the same problem and my CEL just turned on the other day...

 

[n8bachelor]

I too have noticed more of a lag in downshifts while the AC is on than without it. It is scary sometimes... as you mentioned it lags, you give more gas, then it shifts and is off to the races.

I also noticed another quirk the other day. AC on, steady speed about 45mph. I came to a hill and had to give a little more gas to maintain my speed. Well the car jerked a few times and appeared to be confused weather it wanted to be in 4th or 3rd gear. The tach jumped and dropped about 3/4 times before I adjusted my throttle input to command the transmission down to 3rd.

I attribute most of these items to a drive by wire system that is not quite as good as the old fashion mechanical linkage.

 

[BanginLS]

anything on this? Im having more problems

 

[MDavis0424]

Take the car to autozone or advanced to get the codes read if the CEL is on, that will give you a direction to go.

 

[BanginLS]

i did.. i got a misfire on my 5th coil.. which one is that?


also my AC is only blowing hot air.. no matter what..


can anyone help me out here? if i dont get much feed back on this thread i will have to start a new one.. but im hoping to kill two birds with one stone

 

[beaups]

...

 

[macboy]

Start a new thread. This one has nothing to do with misfires or broken A/C.
Better yet, search.

 

[smdandb2]

I'm glad I found this thread.

I think this is the one thing that pisses me off the most about my LS. It is REALLY hesitant to downshift. I have gotten in the habit of slapping it over to the sst mode and dropping it 2 gears.

I have an MSD Dashhawk, and I was watching the absolute throttle position (I think that is based off the TPS value) and during one of the hesitated downshifts I saw the throttle hit about 85%. I was maybe on the throttle a bit under half. Since the dashhawk cant view the pedal position, I would say it has to be about 3/4 pedal before it will downshift.

It seems like a good way to heat up the torque converter and cause all sorts of transmission problems.

Is there any known fix for this?