Upshift on acceleration, is that weird? - Ford Powerstroke Diesel Forum
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post #1 of 8 Old 03-02-2013, 02:13 PM Thread Starter
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Upshift on acceleration, is that weird?

I just test-drove a 7.3L 1995 e450 bus (with the Ford RPM control module on the dash). I noticed that in accelerating, it would shift into 4th (around 1750rpm) and then on coasting it would downshift and jump to ~2000 rpm. If I really gunned it accelerating, it would downshift back to 4th. I'm a diesel guy, but I work on tiny diesel engines (with manual trans only) and I've never driven an automatic turbo diesel - so maybe this is just auto trans engine computer magic that I don't understand. Is it engine braking on coast? Can someone help out the noob?
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post #2 of 8 Old 03-02-2013, 03:43 PM
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With an automatic transmission...there is no engine braking!

Found that out the HARD way!

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post #3 of 8 Old 03-02-2013, 05:11 PM
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If the torque converter stays locked, it'll engine brake.

BTW, it can't downshift into fourth gear. It's a four-speed transmission.
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post #4 of 8 Old 03-04-2013, 04:00 PM Thread Starter
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Thanks for the replies. I suppose 4 speed makes sense, again I'm totally out of the loop on automatic transmissions. So to word it correctly, I should have said:

"I noticed that in light accelerating (just barely pushing the accelerator), it would up shift into 4th (around 1750 rpm) and then on coasting it would downshift and jump to ~2000 rpm. If I really gunned it accelerating, it would eventually downshift back to 3rd."

What I'm not understanding is why it doesn't stay in the gear it's in already when I accelerate... it should stay in gear, or downshift - no? Instead, it upshifts...
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post #5 of 8 Old 03-04-2013, 04:22 PM
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You may be noticing the converter doing something, hard to tell.



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post #6 of 8 Old 03-04-2013, 04:35 PM
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When you were coasting, were you touching the brake pedal?
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post #7 of 8 Old 03-04-2013, 05:02 PM Thread Starter
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Negative. Just coasting.
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post #8 of 8 Old 03-04-2013, 05:07 PM Thread Starter
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Just found this; http://www.ramforumz.com/showthread.php?t=80546
Apparently it's normal?
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