99 Pontiac Bonneville SE Stalling at idle

caddman6425

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Hi all,

I've got a 99 Bonneville SE that stalls intermittently at idle after reaching operating temperature. It did this before consistently after reaching operating temperature, but I found that it was a dirty air filter.

I wonder at time if it is just my wife, but now it just does the same thing intermittently. I am thinking the CKP but have no idea how to test it, any ideas, or is there some other cause? Oh, I forgot, it doesn't throw any codes, which makes me think that it isn't the IAC or EGR.

Any help would be greatly appreciated.

--
Nick
 

melsg5

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a dirty IAC, throttle body, and EGR may not always throw a code. I would start by checking/cleaning them.
 

caddman6425

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I did just that, and while I was taking off the IAC, I bole a screw off in the TB, but I found so much carbon that I'm concluding that this is the problem. When I fix all my "Oops" and clean the pintail, I test and let you know. My Jesus be with me today and guide my hand.

--
Nick
 

melsg5

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good luck and sounds like you found a possible cause for the stalling
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melsg5

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just because you cleaned the IAC doesnt mean it's working correctly not sure which engine you have but read below

Testing & Replacing is for the 2.4L, 3.1L, & 3.4L.

The IAC regulates the air by passing the Throtle body(TB) by moving its pintal in and out of the passage way.
If this is even partially pluged it can effect Idle.

The IAC is controled by the PCM, adjusting idle speed depending on running conditions ,
AC, powersteering, cold or warm. Other wise Idle is not adjustable.



The IAC is on the right side of the Throtle Body(TB).



*V6 Location Picture here (http://i28.photobucket.com/albums/c242/xeroinfinity/11X17RW24/TBIAC.jpg).

Testiing the IAC

- With the engines cold the IAC should increase the idle and vary as it warms up.
- With the engine warmed up and place a load on the engine by turning on hte AC or turn the steering wheel.
- The idle should remain steady or increase a little.
- If it stalls or stubles then the IAC is not working proprly.

- Shut the engine off, disconnect the electrical connector from the iAC.
- The terminals are # left to right.
[1][2]
[3][4]

- Using an Ohm metter test the resistance acrossed terminals 1-2, then measure acrossed 3-4.
- The readings should be about the same on both sides.
- If one of them shows an open circuit replace the IAC.

- If the IAC checks ok, it could be your PCM which a dealer will have to check.

-- Replacing the IAC--
Warning - DO NOT push or turn the pointy tip of the IAC.
This will mess up the calibration.

- Disconnect the negative battery terminal.
- Remove the air intake tube is needed to gain access to the IAC, like on the 2.4L.
- Disconnect the plug in on the IAC.
- Remove the 2 torx screws.
- Remove the old "O" ring.

** If installing a new idle air control valve it'll need adjusted.
- Measure the distance of the valve plunger that is extended.
**Measurement should be made from the edge of the valves mounting flange, to the end of the cone.

- The distance should not exceed 1-1/8 in. (28mm),
or damage to the valve may occur when installed.

-If the measuring distance is greater than specified above,
use your finger pressure to slowly retract the pintle,
by using a slight side to side motion to help it retract it easier (valve with collar at electric terminal end),
or compress the retaining spring from the valve while turning the valve "in" with a clockwise motion.

- Return the spring to its original position with the straight part of the spring end aligned with the flat surface of the valve (valve without collar at electric terminal end).

-Use a new gasket "O" ring, then position the idle air control valve in its mounting position.
-Install in reverse procedure.
 

caddman6425

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Oh, I'm sorry. It has the 3,6l V-6, non turbo. I hope that the testing is the same. And, what if the resistance on both sides are way different?

--
Nick
 

melsg5

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Then the IAC should be replaced.
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caddman6425

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Well it's been awhile. I did replace the IAC and it seemed to work, the definitive word is SEEMED..even though the engine will now go to a higher ide when cold and them back down, tells me that the IAC is working correctly. BUT, still when it warms up, it stall at idle. With this in mind, I did take pains to look at the tach when starting, the rpm goes to 1000 rpm and then back down to 750 rpm. Alter it warms up, the rpm still goes to 1000 rpm but when it backs down it just dives to 0. Any thoughts would greatly be appreciated.
 

melsg5

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when is the last time you changed the fuel filter?
how many miles on the plugs?
have you tested the plug wires, no more than 1k resistance per foot of wire?
have you cleaned the throttle body?
 

melsg5

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The thread is almost 4 years old and the OP hasn't been here in 4 years. How about a new thread clearly stating your problem.
 
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