AzStar Posted November 11, 2009 Report Share Posted November 11, 2009 Guys, Could someone who believes they have a "normally" operating Automatic give me a good description of its operation. Things like... WOT it shifts at XXX RPM into 2nd.... XXX RPM into 3rd. At moderate throttle it shifts at xxx RPM into 2nd.... xxx RPM into 3rd. At xxx speed it will down shift from 3rd to 2nd if I want to pass. At xxx speed it the torque convertor locks up in overdrive. Things like that. What I am seeing with mine but I don't know if it is normal .... mine will not downshift out of OD if Im going over 40 mph or so. Mat the pedal and it just lumbers along. I have to manually shut the OD off and then it will pull in 3rd. Over about 40mph it doesn't downshift from 3rd into second or a passing gear or what have you. The Vac Mod is new. I haven't done any diagnostics concerning the kick down switch under the dash or any of the other items yet because I want to understand if mine is operation "normally" as it is. Thanks in advance for any help. Link to comment Share on other sites More sharing options...
mikec Posted November 12, 2009 Report Share Posted November 12, 2009 Go to www.starquestgarage.com or one of the other sites hosting a copy of the factory service manual in PDF format. Download the transmission chapter. Page 21-56 has a chart showing when the tranny shifts as a function of MPH and manifold vacuum/boost pressure. The vacuum/boost Y axis scale shows all sorts of units... except none match the dash boost gauge (psi). To convert the kPa numbers (the ones not in parenthesis) to the psi on your dash gauge multiply the chart number by 0.14504 Basically though the bottom third of the plot is "light on the throttle pedal" and the top of the main chart is "pedal mashed almost to the floor." The skinny band at the very top of the chart shows what happens when the pedal IS mashed to the floor - i.e. when the kickdown switch is activated. The solid lines show when the tranny upshifts, the dashed lines are the downshifts as you slow to a stop. Your symptoms sound like a bad kickdown switch or a mis-adjusted vacuum modulator. Mostly though a bad kickdown. With the engine OFF, just push the gas pedal by hand while you lean under the dash... listen for the "click" of the kickdown switch. If you don't hear it, follow the gas pedal linkage up and you'll see the switch. It has a locknut on it, loosen that to adjust the switch. If you DO hear the switch clicking, get a helper. Jack up the car, put it on jackstands, chock the wheels, etc. Crawl under and look for the electrical solenoids on the driver side of the tranny. The one a little behind the vacuum actuator is the downshift solenoid. With the ignition key ON this time, tranny in Drive, have your helper push the gas pedal all the way down, up, down, up several times. Listen/feel the solenoid for a click. No click? The downshift solenoid is bad, wiring bad, or the kickdown relay is bad. Disconnect the wiring to the solenoid and stick a voltmeter... look for 12 volts across the two wires as your helper cycles the gas pedal. No voltage = wiring or relay problem. If you get the +12volts, the solenoid is kaput. mike c. Link to comment Share on other sites More sharing options...
AzStar Posted November 12, 2009 Author Report Share Posted November 12, 2009 Go to www.starquestgarage.com or one of the other sites hosting a copy of the factory service manual in PDF format. Download the transmission chapter. Page 21-56 has a chart showing when the tranny shifts as a function of MPH and manifold vacuum/boost pressure. The vacuum/boost Y axis scale shows all sorts of units... except none match the dash boost gauge (psi). To convert the kPa numbers (the ones not in parenthesis) to the psi on your dash gauge multiply the chart number by 0.14504 Basically though the bottom third of the plot is "light on the throttle pedal" and the top of the main chart is "pedal mashed almost to the floor." The skinny band at the very top of the chart shows what happens when the pedal IS mashed to the floor - i.e. when the kickdown switch is activated. The solid lines show when the tranny upshifts, the dashed lines are the downshifts as you slow to a stop. Your symptoms sound like a bad kickdown switch or a mis-adjusted vacuum modulator. Mostly though a bad kickdown. mike c. Mike, Thanks... the kickdown switch is that the part under the dash or are you refering to the part that is on the transmission? Link to comment Share on other sites More sharing options...
MikeMeyerhoff Posted November 13, 2009 Report Share Posted November 13, 2009 Check to make sure the 1" piece of rubber hose that feeds the vac/boost solenoid at the intake manifold is good. Its common for it to go bad to the point of leaking pressure. Link to comment Share on other sites More sharing options...
AzStar Posted November 14, 2009 Author Report Share Posted November 14, 2009 Check to make sure the 1" piece of rubber hose that feeds the vac/boost solenoid at the intake manifold is good. Its common for it to go bad to the point of leaking pressure. Mike, When you say vac/boost solenoid... do you mean the line that goes down to the transmission or are we talking some other line. I've changed the rubber vac line on both ends of the metal vac line that leads to the Vac Modulator on the trans. Link to comment Share on other sites More sharing options...
mikec Posted November 14, 2009 Report Share Posted November 14, 2009 The kickdown switch is under the dash, above the gas pedal.It drives a solenoid mounted to the side of the tranny. There is also a vacuum modulator attached to the side of the tranny; this gets a vacuum signal from the intake manifold. If you see any signs of auto tranny fluid dribbling from the vacuum modulator (vac hose unplugged) the modulator is junk junk junk. mike c. Link to comment Share on other sites More sharing options...
AzStar Posted November 14, 2009 Author Report Share Posted November 14, 2009 The kickdown switch is under the dash, above the gas pedal.It drives a solenoid mounted to the side of the tranny. There is also a vacuum modulator attached to the side of the tranny; this gets a vacuum signal from the intake manifold. If you see any signs of auto tranny fluid dribbling from the vacuum modulator (vac hose unplugged) the modulator is junk junk junk. mike c. Mike, Ok... I am tracking. I replaced the Vac modulator already and the rubber lines on both ends. There wasn't any sign of trans fluid but all the parts didn't come to more than $10 and and a little bit of my time. I have "played" with the kickdown switch under the dash but not as the procedure in the manual calls for. (deflection of the pedal a certain distance begets X) I just cycled the plunger and noticed which circuits closed etc. Both of the circuits close. I am going to take some time (won't be this weekend sadly) and read the manual on the shift points and then go and drive the car and compare what I am seeing to what the books says. Link to comment Share on other sites More sharing options...
mikec Posted November 14, 2009 Report Share Posted November 14, 2009 When you replaced the vacuum modulator, did you do the procedure described on page 21-73? The pushrod of the modulator has to be a specific length to line up with the guts of your tranny - similar to using various thickness shims to get proper clearances on bearings. You can affect the tranny shift points if the pushrod is the wrong length... In fact, if the new modulator screwed in differently into the tranny case (more/less turns) that'll affect things too. Adding a gasket or RTV sealant can tweak the modulator valve position enough to affect the tranny. mike c. Link to comment Share on other sites More sharing options...
AzStar Posted November 14, 2009 Author Report Share Posted November 14, 2009 When you replaced the vacuum modulator, did you do the procedure described on page 21-73? The pushrod of the modulator has to be a specific length to line up with the guts of your tranny - similar to using various thickness shims to get proper clearances on bearings. You can affect the tranny shift points if the pushrod is the wrong length... In fact, if the new modulator screwed in differently into the tranny case (more/less turns) that'll affect things too. Adding a gasket or RTV sealant can tweak the modulator valve position enough to affect the tranny. mike c. The short answer is no.... I used the old rod... and used teflon tape on the threads. I noticed no change in the trans operation with the replacement. Link to comment Share on other sites More sharing options...
pitboss Posted November 14, 2009 Report Share Posted November 14, 2009 when I first bought my auto quest 2 years ago, you had to mash the S*** out of the gas pedal to engage the kickdown switch. Like almost putting your foot through the floor. You had to really stomp it. I adjusted the kickdown activation with a 14mm wrench on that lock nut Mike mentioned to the point where it wont quite kickdown when speeding up on Cruise control, but about mid throttle will kick it down to 2'nd gear and then you can take off. In between part throttle and halfway kicks it down from OD to 3'rd. BTW, you should see a yellow plastic dime sized thing attached to the pedal that the kickdown switches plunger comes in contact with. Is it there? Link to comment Share on other sites More sharing options...
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