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Discussion Starter · #1 ·
need some help here:
Took out the battery to clean out the leaves. After reconnecting it, the engine has really lousy (slow) idle, definitely can't drive it. I read about the need to reset the ECU, any thoughts on how to do it (without vagcom etc)?

Much appreciated.
 

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need some help here:
Took out the battery to clean out the leaves and after reconnecting it have really lousy (slow) idle, definatley can't drive it. Read about the need to reset the ECU, any thoughts on how to do it?

Much appreciated.
SOUNDS LIKE IT NEEDS A THROTTLE READAPTATION,......ITS FUNNY ,SOME PEOPLE HAVE R&R BATTERIES W/O PROBLEMS,EVEN W/O AN AUXILLARY POWER SOURCE WHILE OTHERS HAVE ,................STRANGE STUFF
 

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Discussion Starter · #6 ·
thanks for the link, but I still cant find a solid description of the procedure for a B5... got to get it fixed tonight so I can go to work! will look for the TBA throttle body alignment procedure.
 

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When I replaced the battery in my 99 1.8T AEB, I just let it sit with the key on for a few minutes in the hopes the throttle body adaptation would occur. I then started it up, and it ran fine. I don't remember if I heard any clicks or not...this was a few years ago.

artPassat, just try turning the key "on" and letting it sit for those 2-4 minutes and see what happens. If it doesn't adpat and it still runs rough, maybe there is someone in your area with a VAG-COM who could help you out.
 

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Try disconnecting battery for a minute, then reconnect and do what michmedic24 says but do not press gas pedal during that time.
 

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Discussion Starter · #10 ·
Still no luck.
I checked to make sure there were no DTC codes with a scan tool, since having codes will not allow for the aligment procedure.
Disconected the battery, waited 10 min. Reconected and turned on the ignition for 10 minutes, listened closely, no ticking or anything.
Any other suggestions, blown fuse maybe?

Thanks for all the input.
 

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When I replaced the battery in my 99 1.8T AEB, I just let it sit with the key on for a few minutes in the hopes the throttle body adaptation would occur. I then started it up, and it ran fine. I don't remember if I heard any clicks or not...this was a few years ago.

artPassat, just try turning the key "on" and letting it sit for those 2-4 minutes and see what happens. If it doesn't adpat and it still runs rough, maybe there is someone in your area with a VAG-COM who could help you out.
Cable throttles don't have an adaptation procedure. The adaptation is just a way for electronic throttles to calibrate themselves, to make sure the actuator and the position sensor are in agreement. There is no actuator on cable throttles, hence no need for calibration, and no ability to calibrate even if it WERE needed.
 

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need some help here:
Took out the battery to clean out the leaves. After reconnecting it, the engine has really lousy (slow) idle, definitely can't drive it. I read about the need to reset the ECU, any thoughts on how to do it (without vagcom etc)?

Much appreciated.
Lousy idle is normal after removing the battery. The ECU forgets what it's learned about your engine when the power is disconnected, and it takes a few hours of driving before it re-learns the idiosyncrasies of your engine. Nothing to worry about.

If you have an electronic throttle (non-AEB engines), you need to let the throttle go through its adaptation procedure, but you already know that by now.
 

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Cable throttles don't have an adaptation procedure. The adaptation is just a way for electronic throttles to calibrate themselves, to make sure the actuator and the position sensor are in agreement. There is no actuator on cable throttles, hence no need for calibration, and no ability to calibrate even if it WERE needed.
100% incorrect.

Why do you think Bentley/vagcom have instructions to do throttle body adaptation on AEB engines?

The DBW throttle body is an evolved version of the AEB unit. The DBW uses the stepper motor to actuate the throttle valve for its entire range of movement. That means everything from idle speed to WOT is done by the motor in the throttle body.

The DBC throttle body uses the stepper motor to actuate the throttle valve for the first few degrees of its range of motion, this is how it controls your idle speed. The position or angle of the valve is learned by the ECM during adaptation. This is accomplished by the valve cycling itself open and closed, the ECM then records the potentiometer values and it can now control the engine's idle speed by using the stepper motor and the potentiometer feedback as a guide.

All the above notwithstanding, DBC's will re-learn the idle values after 3 complete cold-hot running cycles, you'll just have the bouncing rpm in the idle range until complete.
 

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100% incorrect.

Why do you think Bentley/vagcom have instructions to do throttle body adaptation on AEB engines?

The DBW throttle body is an evolved version of the AEB unit. The DBW uses the stepper motor to actuate the throttle valve for its entire range of movement. That means everything from idle speed to WOT is done by the motor in the throttle body.

The DBC throttle body uses the stepper motor to actuate the throttle valve for the first few degrees of its range of motion, this is how it controls your idle speed. The position or angle of the valve is learned by the ECM during adaptation. This is accomplished by the valve cycling itself open and closed, the ECM then records the potentiometer values and it can now control the engine's idle speed by using the stepper motor and the potentiometer feedback as a guide.

All the above notwithstanding, DBC's will re-learn the idle values after 3 complete cold-hot running cycles, you'll just have the bouncing rpm in the idle range until complete.
I have never seen my throttle do anything on its own, not while letting the car sit with the ignition on to see if the throttle would calibrate itself, not when plugging the intake to choke the engine so I could see if the throttle would move by itself, nothing.

As far as I can tell, the only thing the AEBs adjust to control their idle is the amount of fuel injected, and this conclusion is based on seeing the exact same throttle position readout on my VAG-COM both at cold idle and hot idle, both with an obstructed intake and a non-obstructed intake.

It is for this reason, I have concluded, that the lack of an idle air bypass is such a problem for AEB throttles -- slight amounts of carbon buildup on the butterfly valve can clog the preset sliver opening in the throttle and cause the engine to choke every time the driver takes their foot off the gas pedal. Do a quick search for bitching about jerks and pops at low RPM when letting off the gas, if you don't believe me.
 

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Discussion Starter · #15 ·
after going through the procedure several times, with some variation just in case, I have absolutley no change. I attempted to drive the car a bit, but the engine cuts off at 1400RPM so its impossible to drive it any length, seems to run OK over 3500RPM.
 

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I have never seen my throttle do anything on its own, not while letting the car sit with the ignition on to see if the throttle would calibrate itself, not when plugging the intake to choke the engine so I could see if the throttle would move by itself, nothing.

As far as I can tell, the only thing the AEBs adjust to control their idle is the amount of fuel injected, and this conclusion is based on seeing the exact same throttle position readout on my VAG-COM both at cold idle and hot idle, both with an obstructed intake and a non-obstructed intake.

It is for this reason, I have concluded, that the lack of an idle air bypass is such a problem for AEB throttles -- slight amounts of carbon buildup on the butterfly valve can clog the preset sliver opening in the throttle and cause the engine to choke every time the driver takes their foot off the gas pedal. Do a quick search for bitching about jerks and pops at low RPM when letting off the gas, if you don't believe me.
What the f are you talking about?

This thread and your misinformation that I quoted have to do with procedures for throttle body alignment relating to idle control after the battery has been disconnected. I only threw out some other info regarding the TB differences to explain why adaptation is different between DBC and DBW models.

Here it is. An AEB TB cannot go through adaptation with the "key on" method. All DBW models can do the "key on" method for adaptation. ALL models have a vagcom procedure for adaptation.

See Ross-Tech link.
http://www.ross-tech.com/vag-com/cars/throttlebody.html

Try this. Disconnect your battery for an hour, reconnect and see how it runs. Probably like sht with stumbling idle, etc. Run the vagcom adapatation per the above instructions. Car will run fine.
 

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after going through the procedure several times, with some variation just in case, I have absolutley no change. I attempted to drive the car a bit, but the engine cuts off at 1400RPM so its impossible to drive it any length, seems to run OK over 3500RPM.
If you can struggle though 3 cold/operating temp cycles, the 4th start you should be good to go.
 

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after going through the procedure several times, with some variation just in case, I have absolutley no change. I attempted to drive the car a bit, but the engine cuts off at 1400RPM so its impossible to drive it any length, seems to run OK over 3500RPM.
I had the exact same problem for about two hours of contiguous driving time after I disconnected the battery on my car. Take the thing out on the highway and drive it at about 70mph for a good stretch to help the ECU re-learn the engine's idiosyncrasies.
 

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What the f are you talking about?

This thread and your misinformation that I quoted have to do with procedures for throttle body alignment relating to idle control after the battery has been disconnected. I only threw out some other info regarding the TB differences to explain why adaptation is different between DBC and DBW models.

Here it is. An AEB TB cannot go through adaptation with the "key on" method. All DBW models can do the "key on" method for adaptation. ALL models have a vagcom procedure for adaptation.

See Ross-Tech link.
http://www.ross-tech.com/vag-com/cars/passatb5.html
Group 098 is used for DBC, group 060 is used for early DBW. For 2002+ DBW using KWP-2000 protocol, it's a little different, using Basic Settings - 04 and then Group 060.

Try this. Disconnect your battery for an hour, reconnect and see how it runs. Probably like sht with stumbling idle, etc. Run the vagcom adapatation per the above instructions. Car will run fine.
What I was attempting to say (though I used too many words before) is that I've never seen any evidence that my throttle adapts itself at all, be it at idle or otherwise, and it still idles just fine -- I just had to drive it for a while so the ECU could figure out how to do its job again.

Does that mean there isn't any adaptation going on? No, it doesn't, I suppose, since I can't see the source code for the ECU I can never be sure, but I still see what I see.

Interesting how you say here that if he runs the VAG-COM procedure after resetting the ECU, the car will run fine, and yet, after he responded saying that this didn't accomplish anything, you reneged and said to just put up with it for a while, which is exactly what I recommended all along.
 

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Interesting how you say here that if he runs the VAG-COM procedure after resetting the ECU, the car will run fine, and yet, after he responded saying that this didn't accomplish anything, you reneged and said to just put up with it for a while, which is exactly what I recommended all along.
Where did he say he ran a vagcom TBA??????????????????????????????

He's talking about checking DTC codes with a scan tool and disconnecting his battery for 10 minutes. That's his "procedure". My post with the Ross-tech link went up after his last post. It seems pretty clear he's not using vagcom, so how the hell would he have failed in attempts to do the TBA with a vagcom.
 
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