5r55e missing the downshift

[Maxinstl]

Sometimes when getting on the highway coming home from work, I accelerate to get onto the highway, then merge. After merging, I attempt to accelerate again, causing my trans to attempt to downshift, but it misses a gear (I think) and revs out with no power to the wheels. I think it's between gears, but I'm not sure. It catches when the revs get back to about 2.5k, not violently, almost like a normal shift. It has happened a few times now, all in this situation. I think it's the 4 to 3 downshift, but I'm not positive on that...

Is a shift solenoid going bad? It shifts properly 99% of the time when merging, just every once in a while it gives me the problem, never on the upshift.

 

[alwaysFlOoReD]

Have you checked the fluid?
That's all I got.

 

[Maxinstl]

Have you checked the fluid?
That's all I got.

It's just a little high, but it's been that way for 20k miles. This is a newer issue. Actually it only started when I started this new job and going home this way...

Thanks for the suggestion though! I appreciate the reply.

 

[Dirtman]

Turn the od off until your on the highway. Whats happening is the trans is shifting into overdrive, then immediately needing to unlock the converter, and downshift two gears which causes a massive lag of nothing. It's happened to me plenty of times in the same scenario you describe. If you leave the overdrive off until you're ready to cruise it wont happen. It's a computer controlled transmission, and computers are dumb.

 

[Maxinstl]

Turn the od off until your on the highway. Whats happening is the trans is shifting into overdrive, then immediately needing to unlock the converter, and downshift two gears which causes a massive lag of nothing. It's happened to me plenty of times in the same scenario you describe. If you leave the overdrive off until you're ready to cruise it wont happen. It's a computer controlled transmission, and computers are dumb.

This must be it, it makes a lot more sense. I'd buy you a beer if I could.

 

[Uncle Gump]

If that doesn't work... try another new job?

Kidding of course.

I think dirtman hit it right. I have a funky "on ramp" to the tollway that pretty much does the same thing you describe. Except the no power to the wheels thing. Mine will kick out the TC and downshift... pull until it's ready for the next gear.

Just try to cancel OD... and see what you get.

 

[8thTon]

Clean the MAFS and change the airfilter. It makes a huge difference in how it downshifts, as it needs to know airflow to determine load.

 

[Maxinstl]

If that doesn't work... try another new job?

Kidding of course.

I think dirtman hit it right. I have a funky "on ramp" to the tollway that pretty much does the same thing you describe. Except the no power to the wheels thing. Mine will kick out the TC and downshift... pull until it's ready for the next gear.

Just try to cancel OD... and see what you get.

I knew with the way I phrased it it was only a matter of time before a smarta$$ made that comment... ?????

I have a base model, so no tc for me.

 

[Dirtman]

TC = torque converter. You definitely have one lol. The Torque converter has a clutch in it that locks after the transmission shifts into overdrive so there is no power or rpm loss between the engine and transmission while cruising at highway speeds. It disengages as soon as the transmission goes to downshift.

 

[Maxinstl]

TC = torque converter. You definitely have one lol. The Torque converter has a clutch in it that locks after the transmission shifts into overdrive so there is no power or rpm loss between the engine and transmission while cruising at highway speeds. It disengages as soon as the transmission goes to downshift.

Oh I thought he meant traction control.

Doesn't it lock depending on rpm? So when it hits like 3500 its locked in any gear?

 

[Uncle Gump]

Torque Converter (TC) lock up is more related to load and vehicle speed then engine RPM.

 

[Maxinstl]

I did not know that

 

[Dirtman]

The 5r will only lock the converter in overdrive unless overdrive is off then it will only lock in 3rd (or 4th depending on how you wanna count the gears, the 5r55e is technically only a 3 speed with overdrive not a 5 speed). But it does depend on the load as well, as soon as you take your foot off the gas the torque converter clutch disengages and only re engages when certain criteria are met. You also have a coast clutch too lol but that's only functional with overdrive off for engine braking while towing.

I always drive with od off unless on the highway. For me at least, it just makes it drive nicer below 50mph or so.