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IDLE questions on a 1986 Fiero SE - V6 - 4 speed man by DJWINNI
Started on: 10-13-2013 11:04 AM
Replies: 10 (759 views)
Last post by: DJWINNI on 10-30-2013 06:13 AM
DJWINNI
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Report this Post10-13-2013 11:04 AM Click Here to See the Profile for DJWINNISend a Private Message to DJWINNIEdit/Delete MessageReply w/QuoteDirect Link to This Post
Hi guys

Don't know if I have to worry about that but here's my question:

I have a 1986 Fiero SE - V6 - 4 speed man.

When I start the car, it idles at about 1500rpm.
Once car is warm, it idles at about 1050/1100.

Then, if I drive the car and stop at a light, idle will be about 1200 a few seconds, and drops to 1050.

I'm asking if the engine is idling correctly, because I know that my car used to idle about 900/950 one year ago.

Thanks a lot for your advices!
------------------
Christophe **1986 PONTIAC FIERO - V6/2,8L**

[This message has been edited by DJWINNI (edited 10-13-2013).]

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TK
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Report this Post10-13-2013 11:15 AM Click Here to See the Profile for TKSend a Private Message to TKEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by DJWINNI:

Hi guys

Don't know if I have to worry about that but here's my question:

I have a 1986 Fiero SE - V6 - 4 speed man.

When I start the car, it idles at about 1500rpm.
Once car is warm, it idles at about 1050/1100.

Then, if I drive the car and stop at a light, idle will be about 1200 a few seconds, and drops to 1050.

I'm asking if the engine is idling correctly, because I know that my car used to idle about 900/950 one year ago.

Thanks a lot for your advices!


The target idle for the engine is 900 RPM but who knows if your tach is accurate. Only a scanner or other tach will tell you. It sounds like maybe something has changed but how it's acting is normal. That is called Stall Saver. They float the RPM to keep the engine from stalling when you release the pedal. The ECM has a timer and watches the speed. If its above 15 MPH, the saver is active. It slowly lowers the RPM to the final 900 RPM target.

As for the idle being a bit higher than before, it could be you have a small leak in the idle hose, or a seal or the IAC is hanging up. It doesn't take much additional air to raise the idle up. Idle air goes through the TB, through the IAC, down out the bottom of the TB through a tube to the bottom of the intake manifold - it doesn't go through the upper part of the intake. Check that hose and clamps.

They also float the RPM between shifts to make shifting easier (match the gear speeds). That is called Shift Anticipation.

[This message has been edited by TK (edited 10-13-2013).]

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Report this Post10-13-2013 03:37 PM Click Here to See the Profile for DJWINNISend a Private Message to DJWINNIEdit/Delete MessageReply w/QuoteDirect Link to This Post
Thanks a lot for your answer!!

My tach seems to work. I also used the Fiero Scan Converter and it also reads 1050/1100!

Engine is running nice and smooth, IAC is new, but will check for vacuum leak!!

Already fixed one last week! (Hose to EGR Solenoid was crackled and disconnected!)

Thanks again!

------------------
Christophe **1986 PONTIAC FIERO - V6/2,8L**

[This message has been edited by DJWINNI (edited 10-13-2013).]

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Report this Post10-13-2013 07:30 PM Click Here to See the Profile for TKSend a Private Message to TKEdit/Delete MessageReply w/QuoteDirect Link to This Post
Well, after think king about it, if you had a vac leak the iac would move in to counter it. If it hit the stops it should throw an error code. Soooo, disconnect both the throttle and cruise cables.

And since you have a scanner, what are your IAC counts?
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Report this Post10-14-2013 08:23 AM Click Here to See the Profile for DJWINNISend a Private Message to DJWINNIEdit/Delete MessageReply w/QuoteDirect Link to This Post
Thanks a lot for all your answers!

 
quote
Originally posted by TK:
Well, after think king about it, if you had a vac leak the iac would move in to counter it. If it hit the stops it should throw an error code.
Soooo, disconnect both the throttle and cruise cables.

-I don't have any trouble codes appearing
-I don't have the cruise control

So what do you mean by disconnect the cables?
 
quote
Originally posted by TK:And since you have a scanner, what are your IAC counts?

Concerning my IAC counts, I'll tell you by next week-end! (out of land for this week)

Thanks again,

------------------
Christophe - 1986 Pontiac Fiero - V6 2.8l - 4 Spd Man

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Report this Post10-26-2013 11:59 AM Click Here to See the Profile for DJWINNISend a Private Message to DJWINNIEdit/Delete MessageReply w/QuoteDirect Link to This Post
Hi again!

Finally had the time to scan the car!

Finally, with ignition ON, IAC steps are at 95 and after warming up and idling, steps are at 30!

Does this sound correct?

My scanner also read that the car idles between 975 and 1025 RPM.

Thanks for your help!
------------------
Christophe - 1986 Pontiac Fiero - V6 2.8l - 4 Spd Man

[This message has been edited by DJWINNI (edited 10-26-2013).]

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Chelo Fiero
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Report this Post10-26-2013 07:42 PM Click Here to See the Profile for Chelo FieroClick Here to visit Chelo Fiero's HomePageClick Here to Email Chelo FieroSend a Private Message to Chelo FieroEdit/Delete MessageReply w/QuoteDirect Link to This Post
If your IAC is new try cleaning the throttle body, you can find spray cleaners at your local auto parts.
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Report this Post10-28-2013 01:40 AM Click Here to See the Profile for DJWINNISend a Private Message to DJWINNIEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Chelo Fiero:

If your IAC is new try cleaning the throttle body, you can find spray cleaners at your local auto parts.


Thanks!
But my IAC is not new.
It has been replaced about 4 years ago, and TB has been cleaned.

Someone to comment my IAC steps?

Thanks a lot!
------------------
Christophe - 1986 Pontiac Fiero - V6 2.8l - 4 Spd Man

[This message has been edited by DJWINNI (edited 10-28-2013).]

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Report this Post10-28-2013 02:04 PM Click Here to See the Profile for masospaghettiClick Here to Email masospaghettiSend a Private Message to masospaghettiEdit/Delete MessageReply w/QuoteDirect Link to This Post
I swapped to a LX9 3500, but my IAC counts are around 30 when engine is warm.

I had low IAC counts when I first did the swap, around 10, and discovered a couple major vacuum leaks. The IAC counts rose after the leaks were fixed. I imagine the IAC counts should be the similar for the 3500 or the 2.8.
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Report this Post10-29-2013 09:28 AM Click Here to See the Profile for TKSend a Private Message to TKEdit/Delete MessageReply w/QuoteDirect Link to This Post
Does your idle go up when you first connect the cable? If so, the cable has the resistor to put it in ALDL mode and that forces the idle to go to 1000 RPM. You won't get 900 RPM when you are scanning it in ALDL mode.

IAC counts of 30-50 are fine. When they get towards zero, you have a leak somewhere so the IAC is removing idle air (closing more). Also, if your minimum idle screw has been tampered with, your IAC counts could be anywhere. If the plug to the screw is missing you probably want to re-adjust it.

As long as the IAC isn't trying to control the idle at either stop, it should be ok but I generally adjust the minimum idle RPM first and then, confirm I am idling at 900 +/- 50 RPM and then see what the IAC counts are. I will adjust the minimum idle screw to get the counts to 30-50.

I don't know what cable you have or if it can be switched between normal or ALDL mode.

[This message has been edited by TK (edited 10-29-2013).]

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Report this Post10-30-2013 06:13 AM Click Here to See the Profile for DJWINNISend a Private Message to DJWINNIEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by TK:

Does your idle go up when you first connect the cable? If so, the cable has the resistor to put it in ALDL mode and that forces the idle to go to 1000 RPM. You won't get 900 RPM when you are scanning it in ALDL mode.

IAC counts of 30-50 are fine. When they get towards zero, you have a leak somewhere so the IAC is removing idle air (closing more). Also, if your minimum idle screw has been tampered with, your IAC counts could be anywhere. If the plug to the screw is missing you probably want to re-adjust it.

As long as the IAC isn't trying to control the idle at either stop, it should be ok but I generally adjust the minimum idle RPM first and then, confirm I am idling at 900 +/- 50 RPM and then see what the IAC counts are. I will adjust the minimum idle screw to get the counts to 30-50.

I don't know what cable you have or if it can be switched between normal or ALDL mode.




Thanks again for your help
Yes, my idle goes up when cable first connected.
I have the cable from the Fiero Store scan tool

The plug on the TB idle screw is still here, so I guess it did not has been touched!
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