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Registered
2002 Deville
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81 Posts
Discussion Starter #1 (Edited)
my RPM was always 650 at idle, then the other day it was idling at 1100.
i drove for a while, then shut down and restart, it was back at 650.
it has not happen again.
current codes B0248 mode door actuator and B0429 a/c for backseat, dont care about these.

U1713 history, Loss of Front Door Module to Window Motor High Speed Comm.
DTC U1016 history Loss of Class 2 Communication with VCM
DTC U1016 history Loss of Communications with PCM
 

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Administrator
2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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68,404 Posts
When did you last clean the throttlebody and IAC system ??

Engines, Northstar, Cadillac Tech Tips or Google "cadillac forums northstar throttlebody cleaning".

The engine should cold start at 1200 for 20 or so seconds, then down to 900 for a while, then to 650 warm idle.
 

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Registered
2002 Deville
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81 Posts
Discussion Starter #3
Submariner409 said:
When did you last clean the throttlebody and IAC system ??

Engines, Northstar, Cadillac Tech Tips or Google "cadillac forums northstar throttlebody cleaning".

The engine should cold start at 1200 for 20 or so seconds, then down to 900 for a while, then to 650 warm idle.
i have never clean throttlebody or IAC.
i did dump a can of fuel injector cleaner into the gas tank, maybe that did it?
thanks, i will look into cleaning throttle body.
 

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Super Moderator
2003 Deville Base
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4,791 Posts
a can of snake oil (fuel injector cleaner) in the tank isn't going to clean the throttle body or IAC.
 

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1992 DeVille
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2,339 Posts
Had you just started the car and it was above 1000 rpm or was that after you had been driving around?
 

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Registered
2002 Deville
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81 Posts
Discussion Starter #6
dchavezo said:
Had you just started the car and it was above 1000 rpm or was that after you had been driving around?
it was after driving around, i looked down and was surprised it was 1200.

when i start the car, RPM is 1200, then goes down to 650 after 2 minutes, totally normal.

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1969byrdman said:
a can of snake oil (fuel injector cleaner) in the tank isn't going to clean the throttle body or IAC.
it has never happened before, but after adding the fuel injector cleaner was when i noticed this. it was only that one time.
 

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Super Moderator
White Diamond '03 DHS (with DTS floor shift)
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86,781 Posts
If the TB has never been cleaned, that is most likely your problem and you are probably WAAAY overdue. There is a tutorial in Tech Tips if you need it.
 

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It's worth at least removing the intake and checking out your throttle body. I just cleaned mine following the directions on this site and my 2004 DeVille is running nicely now. Just be sure not to hit the IAC with cleaner! You don't want to have to replace that bad boy.
 

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Administrator
2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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68,404 Posts
............. make that "remove the air intake flex ducting". And when you replace it, make very sure the ducting and band clamps have no leaks - ANY intake air leak at or after that divorced MAF will set mixture codes and the SES light.
 

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2002 Deville
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81 Posts
Discussion Starter #10 (Edited)
UPDATE:
thanks all for the tech tips!
car was stalling, a few times i had to step on the gas to keep it alive, RPM was dropping to 300 then stalls.

cleaned TB, it was very black.
removed IAC, the problem was the plug head was gummed up with black soot, maybe it was getting stuck to the hole it was supposed to plug up, also cleaned hole.
anyways, car is running smoother, less shuddering at idle, although RPM is a bit higher, it was always at 650 idle before cleaning, now it is 700, sometimes 750.
i did not do the relearn procedure, will try that next.
i also ordered a cheapo $9 from ebay, might put it in and see if any difference.
 

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Super Moderator
White Diamond '03 DHS (with DTS floor shift)
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Just give it a few days. It should relearn the idle on it's own. It is a true "smart car".
 

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2002 Deville
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81 Posts
Discussion Starter #12
this mornng after getting to work, put the shifter in Park and RPM went to 2300, so i quickly shut engine off and restart, and it was normal idle at 800 RPM.
the IAC valve cannot be responsible for that big of jump in RPM, can it?
also no codes.
 

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Administrator
2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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68,404 Posts
The IAC can increase fast idle higher than that 2300. Normal idle for these engines is about 650. Post #2.

Stick your elCheapo IAC in there - turn the key ON for 15 seconds, turn it off for 30+. Start the engine and let it go through the normal fast idle sequence.
 

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2002 Deville
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81 Posts
Discussion Starter #14
Submariner409 said:
The IAC can increase fast idle higher than that 2300. Normal idle for these engines is about 650. Post #2.

Stick your elCheapo IAC in there - turn the key ON for 15 seconds, turn it off for 30+. Start the engine and let it go through the normal fast idle sequence.
put in the new cheapo IAC, it arrived with the shaft retracted. did the relearn procedure, idle about 10 minutes, RPM came down to 700.
after driving to work this morning, shift to park, and RPM went to 3000.
will try the relearn procedure again later today.
 

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2000 DTS 194,000 miles, 2000 DHS 203,000 miles
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9.Perform the IAC Valve learn procedure.
9.1. Start and idle the engine for 15 seconds .
9.2. Turn the ignition switch to the LOCK/OFF position.
9.3. Wait 15 seconds .
9.4. Restart the engine, and check for proper idle operation.
 

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2002 Deville
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81 Posts
Discussion Starter #16
Caddy-EaRL said:
9.Perform the IAC Valve learn procedure.
9.1. Start and idle the engine for 15 seconds .
9.2. Turn the ignition switch to the LOCK/OFF position.
9.3. Wait 15 seconds .
9.4. Restart the engine, and check for proper idle operation.
this is with cheapo IAC
yesterday the RPM was acting erratic, jumping up to 3000 while in park etc... i had to brake harder at stoplights because RPM is high.
got a code while driving home last night, P0507 IDLE HIGH.
so i reset it and did the relearn, there are a couple of versions of them, i tried them all.
and this morning i think RPM is not surging as much. idle at 800.
 

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2002 Deville
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81 Posts
Discussion Starter #17
while the car is in Drive, no problems at all.
but as soon as i put it in Park after driving, RPM surges to 3000, and doesnot come down until i shut off And restart, then it back to 800.
is there a leak? should i check for ripped plenum?
 

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Super Moderator
White Diamond '03 DHS (with DTS floor shift)
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86,781 Posts
Vacuum leak and ripped plenum duct are all possibilities. Check them all.
 

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2002 Deville
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81 Posts
Discussion Starter #19
while cleaning the cheapo IAC, i decided to test if it works. i pushed and pulled on plunger, i can feel a motor spinning inside. plug in wire and turn key on, nothing happens.
key off, and the shaft pops off. is this a bad IAC?
so i pushed the shaft and spring back in, but i dont know if it will work correctly now.
might be time for a delphi IAC...
 

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Master of the Dark Art of Diagnostics
2003 DHS - two-2002 DHS, 2003 SLS, 1995 Sedan DeVille, 1989 Coupe DeVille
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19,250 Posts
while cleaning the cheapo IAC, i decided to test if it works. i pushed and pulled on plunger, i can feel a motor spinning inside. plug in wire and turn key on, nothing happens.
key off, and the shaft pops off. is this a bad IAC?
so i pushed the shaft and spring back in, but i dont know if it will work correctly now.
might be time for a delphi IAC...
===========================
i pushed and pulled on plunger,
i can feel a motor spinning inside.
plug in wire and turn key on, nothing happens.
key off, and the shaft pops off.
is this a bad IAC?

it is now -

might be time for a delphi IAC...
here ya go - $60.28 - with free shipping -
http://www.amazon.com/Delphi-CV10012-Idle-Control-Valve/dp/B000CGDCJ8
 
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