"Dead Zone" When Accelerating From Slow Speed

[BarryCarey]

Hey All,

Not sure if this is an actual issue or just how 3rd Gens act.

When coasting slow, maybe 5 to 10mph (parking lot speed), and step on the gas there's a dead zone before it engages. RPMs need to run up to 1500ish before it catches. It's super noticeable in parking lots and slow traffic.

My 2nd gen does not do this.

My torque converter was already failing so I figured it was related.

It's been in the tranny shop for the last 2 weeks. Torque Converter, Forward clutches, bands all replaced and servo bores sleeved.

Just got it back today and it still has this behavior. Is this just normal for 3rd gens? It's the only one I've ever driven so I have no idea. In my 2nd gen the response is immediate when coming on and off the gas.

 

[Joe in NY]

That is normal for any car. The engine slows to idle at that speed and you have to get it off idle again. What is going is that the output side of the TC is spinning just below 1,500 rpm. In order to accelerate, you have t o get to 1,500 rpm+ on on the input side in order for torque to go from engine to transmission. Not vice versa.

 

[BarryCarey]

Thanks for the info.

I'm aware the converter needs to hit it's stall speed to engage. I just don't ever recall driving a vehicle where it was this noticeable. I could be mistaken, the only other vehicles I've driven in the last few years are my 2nd Gen and a 2012 Impala.

Any idea what the OEM stall speed is off hand? I've checked a few OEM replacements and they list the stall speed as low, no specific value.

 

[Joe in NY]

These are quite high stall converters IMO. People call the GM 4L60E a slush box... Wait till they drive one of these! I can't stand the TC and Trans in these cars... Makes the V8 feel absolutely gutless and pathetic. It has to rev to 3,000 rpm to do anything.

2007 Suburban, easily shifts at 2,000 rpm and accelerates the same if not faster than my Explorer revving to 3,000 rpm for each shift.

I know the stall is 1,700 rpm in Suburban. Based on the fact that it is 320 HP and 340 ft lb of torque.. I bet the Explorer stall is 2,500+ for 240 HP