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  • Loss of power?

    I hope the reason for this is due to the prolonged excessive heat and humidity the past several days. I had the car out yesterday (still pretty hot outside, but not as hot as the days before) and was cruising about 25 mph. I hit the gas, it immediately downshifted to 1st like it should, but the engine felt like there was a slight stumble/hesitation (It wasn't abrupt, it just felt like I had less power since it seemed to acelerate smoother and quicker after the downshift before). Part-throttle seems normal. Any other ideas if the heat and humidity is not the cause? SES light is not on.

    Mods are Moroso CAI, Relocated IAT sensor, 1LE elbow, airfoil, HPP+ w/160 stat (power tuning and firmer shifts selected), Spintech muffler

  • #2
    It might be the transmission slipping if the fluid gets too hot. I used happen to me on hot days when I have driven for a long time. I changed the tranny fluid and filter regularly and put in a cooler and never had a problem since. The fluid might be foaming causing it to slip. That is my best guess.


    LT4KM, 160' TS, MAF ends, TB-BP, GMPP 1.6 R/R, SLP CAI, LCA, Adj. tierod, BMR tower brace, 17x9"F/R, 275/40R17 GY F1 tires. WS6 Muffler, LS1 DS. 21mm rear sway bar. Soon to be LT4 heads, intake, & HOT cam

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    • #3
      Thanks. The car isn't driven everyday, and the fluid was completely flushed 4-5 years ago at about 14000 miles. Car currently has 23000 miles.

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      • #4
        Not sure what slippage is. The transmission still shifts firm enough to make the tires "chirp" in second when WOT.

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        • #5
          Well, I'm at an "Express Lube" place getting the tranny and coolant flushed right now. I hope I did the right thing (they're the only place that's open when convenient for me). They mostly use Shell and Mobil fluids. Not sure if that counts for transmission fliud also.

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          • #6
            Well, the techs told me the transmission fluid was pretty dirty! So I'm glad I got that done. Also, I'm not sure about the coolant they used. I asked if they used Dexcool, and they said the stuff they put in is better than Dexcool. It seems to do the job, but is this a new coolant I'm unaware of? Thanks.

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            • #7
              If yout car gets hot enough, the trans actually uses different kick-down shift tables. Possible you were feeling that. It protects itself if it is too hot or too cold.

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              • #8
                If were referring kickdowns to the downshifts, they were still nice and strong. It was after the kickdown where it felt like power loss.

                Well, I hope the transmission is not damaged. Although just 2 days ago I floored it just after the car reached operating tempatures and it felt stronger and definately did not slip (strong 1st gear, chirped in 2nd and even went sideways a little during the shift).

                I'm just shocked when the tech told me how dark the old transmission fluid was that only had 9000 miles on it? It was about 5 years old though. Hope I didn't hurt anything.

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                • #9
                  Seems that since I did the flush, the transmission sometimes shifts a lil later 1-2 at WOT (5900 vs 5800). What could be wrong? I checked the tranny fluid after driving 10 minutes and it's at the 80* level (transmission fluid is not too hot to touch). Could it be too low? Thanks.

                  P.S. - The loss of power feeling I originally posted about is not occurring anymore.

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                  • #10
                    You must be talking about 80 deg C.....which would be 176 deg F. That is perfect. You want to keep your trans temp under 200 deg F if at all possible. Above 220 deg F and varnishes start to form in the ATF and can harden seals and damage clutches.

                    How are you measuring the ATF temp?

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                    • #11
                      It said 80* on the dipstick. Probably 80* C. I have the 160* thermostat so it shouldn't be too difficult to keep it less than 220*. Tranny fluid is still clean and reddish-pink.

                      It's just strange that it shifts to 2nd gear at 5900 instead of 5800. I reset the PCM (pulled the PCM BATT fuse), drove in the city for a little and it shifted normally at partial throttle. I then tried it out on the highway, still shifted to 2nd at 5900 rpm, but shifted to 3rd at 5800. I then got off the highway, tried a backroad with the speed limit at 50mph, floored it at 20-25 mph, and it performed like it should (shifted nice and crisp to 2nd at 5800 rpm). Go figure!

                      If it continues to shift 2nd gear at 5900, what does that mean? Shift points were left stock. Thanks.

                      Sorry if I seem paranoid, I just don't want there to be something wrong with the transmission. No SES lights at this time.

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                      • #12
                        Originally posted by Jeffs Black 97 Formula A4
                        It said 80* on the dipstick. Probably 80* C. I have the 160* thermostat so it shouldn't be too difficult to keep it less than 220*. Tranny fluid is still clean and reddish-pink.

                        It's just strange that it shifts to 2nd gear at 5900 instead of 5800. I reset the PCM (pulled the PCM BATT fuse), drove in the city for a little and it shifted normally at partial throttle. I then tried it out on the highway, still shifted to 2nd at 5900 rpm, but shifted to 3rd at 5800. I then got off the highway, tried a backroad with the speed limit at 50mph, floored it at 20-25 mph, and it performed like it should (shifted nice and crisp to 2nd at 5800 rpm). Go figure!

                        If it continues to shift 2nd gear at 5900, what does that mean? Shift points were left stock. Thanks.

                        Sorry if I seem paranoid, I just don't want there to be something wrong with the transmission. No SES lights at this time.
                        What do you mean the dipstick showed 80 deg?

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                        • #13
                          The dipstick has a rolled tip on the very bottom, go up a little it says 80*, up a little more to the crosshatched area where it says HOT.

                          UPDATE: I looked again, and it says 80* F on the dipstick, then WARM, then HOT (crosshatched area).

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                          • #14
                            Tranny fluid was a little low (but not really low, fluid was on the dipstick), and only a small amount was added. Seems like it fixed the problem.

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                            • #15
                              Don't ever gauge the temperature of your trans by looking at your ATF level as shown on the dipstick. ATF does expand as it gets warmer, but only use your dipstick markings as a ATF level indicator.

                              If your ATF was low, it could have very well caused the shifts to be late.

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