Slow returning to Idle?

[BILLS_XLR]

Has anyone experienced a very slow or lazy return to idle (800 or so RPM). After removing my foot from the accelerator the idle will solwly drop to about 1200-1300 RPM and stay there until I come to a complete stop. I can hear and feel the transmission flaring as it downshifts which is usually a symptom of high idle. Is there an aux air or idle valve that might be sticking or dirty. The local dealer tech says its "normal", I don't think so... does anyone have experience with this condition in a V,
Thanks,
Bill

 

[harrower]

Mine does not do that. Try turning off the air conditioner and see if it still happens.

Dave

 

[HOMEGAMEROOM]

The clutch in an XLR transmission remains engaged when you pull your foot OFF of the accelerator. It will only disengage when you press the brake pedal - it's programmed to do that to feel almost like a manual transmission would during normal driving.

Try cruising at highway speeds. Now pull your foot off the accelerator - the RPMs may go down a bit, but they won't go to idle level due to the wheels, transmission, and engine are all still mechanically tied together. Now press the brake slightly; you should notice a return of the engine to idle speeds as the clutch disengages. (Um, obviously, watch for traffic behind you!)

This may help:

<FORM name=topNavForm action=/servlets/CellHandler><TABLE width="100%" align=center><TBODY><TR><TD width="25%" slign="LEFT"><INPUT onclick="JavaScript: history.back();" value="<- Back" type=button name=back> <INPUT onclick="JavaScript: history.forward();" value="Forward ->" type=button name=forward> </TD><TD width="50%" align=middle>Document ID# 1543030
2004 Cadillac XLR
1G6YV34A345604274 </TD><TD width="25%" align=right><INPUT onclick="JavaScript: window.print();" value=Print type=button name=print> </TD></TR></TBODY></TABLE></FORM>
<HR></FORM>Info - Operating Characteristics of 5L40E/5L50E Automatic Transmission #02-07-30-002A - (Aug 9, 2004)

Operating Characteristics of 5L40E/5L50E Automatic Transmission
2003-2005 Cadillac CTS
2004-2005 Cadillac SRX, XLR
2005 Cadillac STS
with 5L40E/5L50E Automatic Transmission (RPOs M82, M22, MX5, MV3)
This bulletin is being revised to include additional models, model years and additional operating characteristics. Please discard Corporate Bulletin #02-07-30-002 (Section 07-Transmission/Transaxle).
<A href="http://127.0.0.1:9001/servlets/BlobShtml?ShtmlFile=1543030&pubid=423#ss1-1543030">Operating Characteristics of 5L40E/5L50E Automatic Transmission

The Hydra-Matic 5L40E/50E automatic transmissions have some unique operating characteristics with which customers may not be familiar. They have been designed to provide more of a manual transmission feel than other Hydra-Matic automatic transmissions.
These transmissions are used in 2003-05 Cadillac CTS, SRX, STS, and XLR as indicated in the accompanying table. Here are descriptions of the unique operating characteristics.
<A href="http://127.0.0.1:9001/servlets/BlobShtml?ShtmlFile=1543030&pubid=423#ss2-1543030">Normal Mode Operation (CTS, SRX, STS, XLR)

During normal mode operation, drivers may notice increased powertrain braking after releasing the accelerator pedal. The vehicle will not coast freely when the accelerator pedal is released but will start to gradually slow down as if the brakes were lightly applied. This feels very similar to releasing the accelerator pedal on a vehicle equipped with a manual transmission.
<A href="http://127.0.0.1:9001/servlets/BlobShtml?ShtmlFile=1543030&pubid=423#ss3-1543030">Sport Mode Operation (CTS)

Typically, Sport mode delays upshifts. The Sport mode simulates the performance driving of a manual transmission. Under certain conditions, the vehicle will maintain specific gears longer than a traditional automatic would. When driving in Normal mode in 5th gear, depressing the Sport button causes an immediate 5-4 downshift, which will be maintained for ten seconds. In any other gear, no downshift takes place when Sport is engaged. In Sport mode, the vehicle has firmer shifting and increased performance, and the transmission may remain in a gear longer than it would in Normal mode.
<A href="http://127.0.0.1:9001/servlets/BlobShtml?ShtmlFile=1543030&pubid=423#ss4-1543030">Driver Shift Control (DSC) (SRX, STS, XLR)

The driver manually overrides the automatic gear selection. Various mechanization options for input device and degree of override are allowed.
<A href="http://127.0.0.1:9001/servlets/BlobShtml?ShtmlFile=1543030&pubid=423#ss5-1543030">Performance Algorithm Shifting (PAS) (XLR, 2004 SRX)

PAS overrides normal automatic gear selection during closed throttle high lateral acceleration maneuver. Lower gear is accompanied by near synchronous engine speed control for quick response upon re-opening throttle (enable threshold bias in Sport mode).

Important

On SRX, this feature is enabled in Sport. On XLR, it is always enabled.

<A href="http://127.0.0.1:9001/servlets/BlobShtml?ShtmlFile=1543030&pubid=423#ss6-1543030">Performance Algorithm Liftfoot (PAL) (CTS, SRX, STS, XLR)

PAL prevents liftfoot upshifts while maintaining engine braking during repeated aggressive cornering.
<A href="http://127.0.0.1:9001/servlets/BlobShtml?ShtmlFile=1543030&pubid=423#ss7-1543030">Winter Mode (CTS)

The vehicle launches in 2nd or 3rd gear instead of 1st, to avoid wheel spin in snow or ice, if selected by the driver.
<A href="http://127.0.0.1:9001/servlets/BlobShtml?ShtmlFile=1543030&pubid=423#ss8-1543030">Shift Stabilization (CTS, SRX, STS, XLR)

Shift stabilization is used to minimize shift business, or hunting between ranges. Based on several inputs and a map of engine torque at various RPM and throttle position, the TCM determines before making an upshift whether the engine will be able to maintain vehicle speed in the next higher range. If it calculates that it cannot maintain speed, it will prevent the upshift from occurring.
<A href="http://127.0.0.1:9001/servlets/BlobShtml?ShtmlFile=1543030&pubid=423#ss9-1543030">Downgrade Detection Brake Assist (CTS, SRX, STS, XLR)

Shift to lower gear with braking on downgrade based on fuzzy logic rules calculated from a thermal brake model, terrain detection, desired acceleration, vehicle speed, and mass detection.
<A href="http://127.0.0.1:9001/servlets/BlobShtml?ShtmlFile=1543030&pubid=423#ss10-1543030">Adapts (CTS, SRX, STS, XLR)

Adapts continually compares actual shift times to desired shift times. The transmission controls make hydraulic adjustments to assure the actual shift times approach the ideal shift time the next time the shift is made for similar operating conditions of vehicle RPM, engine load, and road load conditions. The adaptive shift process continues for the life of the vehicle to provide consistent and optimized shifts.
<TABLE border=1 width="100%"><TBODY><TR><TH vAlign=bottom align=middle>
</TH><TH vAlign=bottom align=middle>2003-2005
CTS
</TH><TH vAlign=bottom align=middle>2004-2005
SRX
</TH><TH vAlign=bottom align=middle>2005
STS
</TH><TH vAlign=bottom align=middle>2004-2005
XLR
</TH></TR><TR><TD vAlign=center align=middle>Transmission
</TD><TD vAlign=center align=middle>5L40E
</TD><TD vAlign=center align=middle>5L40E/50E
</TD><TD vAlign=center align=middle>5L40E/50E
</TD><TD vAlign=center align=middle>5L50E
</TD></TR><TR><TD vAlign=center align=middle>Normal
Mode
Operation
</TD><TD vAlign=center align=middle>X
</TD><TD vAlign=center align=middle>X
</TD><TD vAlign=center align=middle>X
</TD><TD vAlign=center align=middle>X
</TD></TR><TR><TD vAlign=center align=middle>Sport
Mode
Operation
</TD><TD vAlign=center align=middle>X
</TD><TD vAlign=center align=middle>
</TD><TD vAlign=center align=middle>
</TD><TD vAlign=center align=middle>
</TD></TR><TR><TD vAlign=center align=middle>Driver
Shift
Control
</TD><TD vAlign=center align=middle>
</TD><TD vAlign=center align=middle>X
</TD><TD vAlign=center align=middle>X
</TD><TD vAlign=center align=middle>X
</TD></TR><TR><TD vAlign=center align=middle>Performance
Algorithm
Shifting
</TD><TD vAlign=center align=middle>
</TD><TD vAlign=center align=middle>X
2004 Only
</TD><TD vAlign=center align=middle>
</TD><TD vAlign=center align=middle>X
</TD></TR><TR><TD vAlign=center align=middle>Performance
Algorithm
Liftfoot
</TD><TD vAlign=center align=middle>X
</TD><TD vAlign=center align=middle>X
</TD><TD vAlign=center align=middle>X
</TD><TD vAlign=center align=middle>X
</TD></TR><TR><TD vAlign=center align=middle>Winter
Mode
</TD><TD vAlign=center align=middle>X
</TD><TD vAlign=center align=middle>
</TD><TD vAlign=center align=middle>
</TD><TD vAlign=center align=middle>
</TD></TR><TR><TD vAlign=center align=middle>Shift
Stabilization
</TD><TD vAlign=center align=middle>X
</TD><TD vAlign=center align=middle>X
</TD><TD vAlign=center align=middle>X
</TD><TD vAlign=center align=middle>X
</TD></TR><TR><TD vAlign=center align=middle>Downgrade
Detection
Brake
Assist
</TD><TD vAlign=center align=middle>X
</TD><TD vAlign=center align=middle>X
</TD><TD vAlign=center align=middle>X
</TD><TD vAlign=center align=middle>X
</TD></TR><TR><TD vAlign=center align=middle>Adapts
</TD><TD vAlign=center align=middle>X
</TD><TD vAlign=center align=middle>X
</TD><TD vAlign=center align=middle>X
</TD><TD vAlign=center align=middle>X
</TD></TR></TBODY></TABLE>

<TABLE width="100%"><TBODY><TR><TD width=778 align=left>GM bulletins are intended for use by professional technicians, NOT a "do-it-yourselfer". They are written to inform these technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions, and know-how to do a job properly and safely. If a condition is described, DO NOT assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See your GM dealer for information on whether your vehicle may benefit from the information.
</TD><TD width=42 align=middle>

</TD><TD width=167 align=middle>WE SUPPORT VOLUNTARY TECHNICIAN CERTIFICATION
</TD></TR></TBODY></TABLE>

© Copyright General Motors Corporation. All Rights Reserved. ​

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2004 Cadillac XLR
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[HOMEGAMEROOM]

PS The basic information still applies even though your transmission is different on your 2006 than it is on my 2004.

I always type in the VIN of my XLR to get the info rather than fill out the tedious drop-down menus - hence, pretty much everything I post from there will say 2004.

 

[BILLS_XLR]

PS The basic information still applies even though your transmission is different on your 2006 than it is on my 2004.

I always type in the VIN of my XLR to get the info rather than fill out the tedious drop-down menus - hence, pretty much everything I post from there will say 2004.

Thanks HOME<
But I'm experiencing exactly the opposite of what the bulletin calls "NORMAL MODE" When I lift there is no engine braking as the engine continues to turn at 12-1300 RPM. I can't tell if it's mechanical (sticky throttle plate, dirty air valve sticking slightly open), electrical or a vacumn leak. The fact that it will eventually return to normal idle makes me less inclined to think it's mechanical. Also, I'm guessing that the '06 V set up might be different from the normally aspirated motors. I could PM my VIN if it would help.
Your thoughts??

 

[Cadillac Tech]

You could try cleaning the throttle bore. It is not an easy job. The throttle body faces the firewall. You will need to use a mirror to see the throttle bore. Have someone hold the throttle open for you. Your other option is to remove the throttle body to clean it and that will require removing the supercharger assembly.

 

[BILLS_XLR]

Thanks Bruce That's where I'll start (cleaning the TB without removing it).
Bill

 

[klaptrapper]

Trans. shift

Hello Homegameroom, can you tell me, or point me to a place where I can find, the differences between the 2004-2005 transmission for the V model and the 2006 V transmission???

Thanks,
Rusty '06 XLR-V


Thank you. The information does not seem to be available to we neophites.

PS The basic information still applies even though your transmission is different on your 2006 than it is on my 2004.

I always type in the VIN of my XLR to get the info rather than fill out the tedious drop-down menus - hence, pretty much everything I post from there will say 2004.

 

[cubby558]

Rusty,

There was no V model in 2004 or 2005. The first year was 2006.

Hello Homegameroom, can you tell me, or point me to a place where I can find, the differences between the 2004-2005 transmission for the V model and the 2006 V transmission???

Thanks,
Rusty '06 XLR-V


Thank you. The information does not seem to be available to we neophites.

 

[klaptrapper]

I guess I framed the question wrongly. I intended to ask
"Hello Homegameroom, can you tell me, or point me to a place where I can find, the differences between the 2004-2005 transmission and the 2006 V transmission???" The 6L80.

Thanks

Rusty,

There was no V model in 2004 or 2005. The first year was 2006.

 

[HOMEGAMEROOM]

Sadly, the information I have at my fingertips only goes to 2005.

 

[klaptrapper]

OK, thankd for the response.

Rusty

Sadly, the information I have at my fingertips only goes to 2005.

 

[mtrocket]

OK, thankd for the response.

Rusty

PM Cadillac Tech... he probably has the info you are looking for.

 

[BILLS_XLR]

High Idle???????

Hate to go back to the original topic but... Has any one experienced a hesitiation about 1200 RPM when decellerating. My throttle holds at 1200 while decelerating, with or without taping the brakes, with or without the AC on and with leaving it in drive or shifting to neutral. As soon as the speed (speed signal) goes to 0 the idle drops to 800 or so. Something is reading the 0 speed signal and dropping the idle. I have thoroughly cleaned the throttle body (that's another story) and checked for vacumn leaks with none found. The local dealer said this is normal on supercharged cars but I don't buy it! There may be some slight compensation for the additional air volume when the throttle first closes but but I don't think it should "high idle" all the way down to 0 MPH. Its definately effecting Gas mileage, brake wear and It could be considered a safety issue as simply llifting off the throttle does not generate anywhere near the engine braking effect that you would expect.

 

[cubby558]

Rusty,
One difference between the two is the '04-'05 tranny's are five speed hydromatics and the V's tranny is a six speed. I don't know any of the other specs, but I'm sure as MTrocket stated; Cadillac Tech will know.

Don't know what all you are looking for, but there is info in the Model Center on this site i.e.:
2006 XLR-V info:
https://www.xlr-net.com/specs/2006/2006_xlr-v_specs.html
2005 XLR info:
https://www.xlr-net.com/specs/2005/2005specs.html

I guess I framed the question wrongly. I intended to ask
"Hello Homegameroom, can you tell me, or point me to a place where I can find, the differences between the 2004-2005 transmission and the 2006 V transmission???" The 6L80.

Thanks

 

[klaptrapper]

Hi idle

My Corvette ZR-1 does the same thing. I am told on that forum, that it is done that way, and quite normal. I think it is done to alow the engine to rev more quickly after trailing throttle. The computer keeps the Idle Air Control stepping relay at that positioin until the car stops.It is much more noticeable on a standard transmission car,because coasting to a stop at a traffic light, for instance, the revs don't drop to zero until the vehicle stops.
My V is under wraps now, but this week, when I have it out again, I will verify that this car does the same. If my memory serves, my V does the same thing, therefore I did not find it exceptioinal and note it before.

Hate to go back to the original topic but... Has any one experienced a hesitiation about 1200 RPM when decellerating. My throttle holds at 1200 while decelerating, with or without taping the brakes, with or without the AC on and with leaving it in drive or shifting to neutral. As soon as the speed (speed signal) goes to 0 the idle drops to 800 or so. Something is reading the 0 speed signal and dropping the idle. I have thoroughly cleaned the throttle body (that's another story) and checked for vacumn leaks with none found. The local dealer said this is normal on supercharged cars but I don't buy it! There may be some slight compensation for the additional air volume when the throttle first closes but but I don't think it should "high idle" all the way down to 0 MPH. Its definately effecting Gas mileage, brake wear and It could be considered a safety issue as simply llifting off the throttle does not generate anywhere near the engine braking effect that you would expect.

 

[klaptrapper]

HIGH IDLE

Nope, took the car out this morning, if I kick it into neutral at say 15 mph, the engine returns directly to 800 rpm. it does not hang higher for any apreciable length of time. Seems you do have a problem. Still under warrantee??

Rusty

My Corvette ZR-1 does the same thing. I am told on that forum, that it is done that way, and quite normal. I think it is done to alow the engine to rev more quickly after trailing throttle. The computer keeps the Idle Air Control stepping relay at that positioin until the car stops.It is much more noticeable on a standard transmission car,because coasting to a stop at a traffic light, for instance, the revs don't drop to zero until the vehicle stops.
My V is under wraps now, but this week, when I have it out again, I will verify that this car does the same. If my memory serves, my V does the same thing, therefore I did not find it exceptioinal and note it before.

 

[onalaska]

I have had my V out serveral times since your first post and have not noticed any delay with the throttle returning to idle. It sounds like the throttle plate is not closing as it should. On the V it's not in a good place to service unless you remove the supercharger.

 

[BILLS_XLR]

Thank you!!

oalaska and KLAPTRAPPER thanks so much for answering my question, as it does now seem (as I expected) that this condition is not "normal". I'm going to try another dealer and twist arms till I get someone to ride with me and experience it first hand. I was beginning to give up on finding anyone who could try this with their V for a comparison, got a little scarey with this discussion turning to the number of gears in a given trans. It is NOT a sticking throttle plate as 1.) I thoroughly cleaned it and 2.) it always returns to idle (800) when revving the engine in neutral but will hang when in gear and decellerating, it cannot be a mechanical issue... it's electrical, as something is sending a "high idle signal" until a 0 speed signal is generated. . Thanks a million and I'll keep you posted.
Bill

 

[onalaska]

I'm amazed you were able to get to the throttle plate to clean it. It looks real tight back there. That is a strange problem, sounds like software causing it. Did it do it when you bought the V or did it start later?