when you advance the timing shouldn't the rpm rise??

MI95Cobra

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Aug 20, 2006

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Nov 10, 2006

#1

• Nov 10, 2006

• #1

when you advance the timing shouldn't the rpm's rise also...yesterday when i retimed yet again...i had it ilde up to 800rpm...this morning it was around 500 and surging down and back up...weird and i can't figure it out...help please...

 

final5-0

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Apr 6, 2003

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Nov 10, 2006

#2

• Nov 10, 2006

• #2

I would do the following things first:

Check for any v leaks
Clean the maf
Clean or replace the isc
Reset the pcm

If you have been working with the tb blade stop screw and or air bleed screw on the tb, they kinda work together.

If the tb blade is craked too far open it can be tough to get it all back to where the pcm helps as opposed to maybe causing issues.

There is a write up somewhere around here explaining how to set everything up as it should be.

One last thing ...............

When you reset the pcm you gotta give it a bit of time to gather up data.

It takes a bit more time to make its adjustmemnts based upon that data.

In a nutshell ... it needs to be exposed to all possible different idle conditons several times before it will become stable or has quit its adjustments.

Grady

 

MI95Cobra

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Aug 20, 2006

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#3

• Nov 10, 2006

• #3

whats and where is the isc??? do i need to unplug my battery to reset the pcm??? yes i played with my tb air screw but its just about where it was when i got it....

 

Methodical

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Nov 10, 2006

#4

• Nov 10, 2006

• #4

final5-0 said:

...One last thing ...............

When you reset the pcm you gotta give it a bit of time to gather up data.

It takes a bit more time to make its adjustmemnts based upon that data.

In a nutshell ... it needs to be exposed to all possible different idle conditons several times before it will become stable or has quit its adjustments.

Grady

Click to expand...

Agreed. Mine seems to take about 2 days (non DD) to start acting right after clearing the KAMs.

The ISC (Idle speed control) or IAC (idle air control) (same thing) is on the right side of the TB. If you are facing the car and looking at the TB, it is the larger black thingy on the right side of the TB. Once you spot it you will see the adjuster screw. It requires an allen wrench to turn. If close it(clockwise) the car will probably shut off and the wider you open it (counter clockwise) the idle tends to rise.

 

HISSIN50

"How long does it take to get help in here?

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#5

• Nov 10, 2006

• #5

Another yes vote for Grady's sentiments.

You set your hot idle to 800 RPM and it idles at 500 RPM when cold? That's just a little backwards (like fastball plunking into the stands being a little high). During a cold start it'd be cool to see what the ISC duty cycle is (if you have a means of DLing or a reader).
Make sure you don't have any vac leaks as well.

Regarding the timing and idle. The phenomenon is true but masked on an EFI car once you let the computer get back into the swing of things. Said another way, I would not rely on the timing to change the idle speed.

Good luck.

 

MI95Cobra

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#6

• Nov 11, 2006

• #6

ok...so i should just wait it out???

 

HISSIN50

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#7

• Nov 11, 2006

• #7

MI95Cobra said:

ok...so i should just wait it out???

Click to expand...

The items Grady mentioned will require some active participation from you.

If the idle was close but hunting a little bit, that's something to wait out. Having your cold idle at 500 RPM and hot idle at 800 RPM will very likely not work itself out without some help from you.

Regarding the floating info:
Here's some idle setting/MAF cleaning info.

Setting timing.

Codes.

Good luck.

 

MI95Cobra

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#8

• Nov 11, 2006

• #8

well...i cleaned the maf and its a new iac....so i'm really confused...my air bleeder on my throttle body is almost all the way open.......

 

HISSIN50

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#9

• Nov 11, 2006

• #9

MI95Cobra said:

well...i cleaned the maf and its a new iac....so i'm really confused...my air bleeder on my throttle body is almost all the way open.......

Click to expand...

In my experience, running that bleeder out more than about 1.5 turns can lead to a nasty vac-leak-like situation. I'd run the bleeder back in till it's about 1.25 turns out, and try it again (you'll probably have to reset your hot idle since you used the bleeder as a crutch).

When you set your hot idle before (at 800 RPM), was the IAC disconnected?

Some folks have reported issues with IAC's other than a replacement Ford or the Borg Warner brand.

Good luck.

 

MI95Cobra

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#10

• Nov 11, 2006

• #10

no....do i need to disconnect it?????

 

HISSIN50

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#11

• Nov 11, 2006

• #11

MI95Cobra said:

no....do i need to disconnect it?????

Click to expand...

There are a couple of different schools-of-thought with setting the idle. I choose to disconnect the IAC (on a hot engine with all accessories turned off). Then I set the idle where I want it (don't stray too far from the commanded idle). Now you know that this will be your hot, no-load idle, even if the IAC takes a total dump (you're simulating this because the IAC is disco'd). You only need the IAC to function to help with loads (big electrical loads, AC, etc) and when cold.

I choose to do it this way and it has worked well. Others' will have alternate methods.

Oh, I choose to do all idle setting with the threaded rod (not the bleeder). Take notes of all changes you make.

Good luck.

 

MI95Cobra

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#12

• Nov 11, 2006

• #12

the threaded rod???? sorry i might call it something else...

 

HISSIN50

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#13

• Nov 11, 2006

• #13

MI95Cobra said:

the threaded rod???? sorry i might call it something else...

Click to expand...

All this info has been in the links I posted.
Here's the one with a picture of the threaded rod (stop screw).

Good luck.

 

MI95Cobra

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Nov 12, 2006

#14

• Nov 12, 2006

• #14

sorry i called it the air bleeder screw...

 

chefster

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Nov 12, 2006

#15

• Nov 12, 2006

• #15

did you reset you computer after the timing adjustment?

 

HISSIN50

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#16

• Nov 13, 2006

• #16

MI95Cobra said:

sorry i called it the air bleeder screw...

Click to expand...

No problemo. I call the stop screw a threaded rod or threaded shank.

You mentioned that it's almost all the way open - is it propping the throttle blade open a bit? That can cause some equally craptastic issues. They key is to tweak things but not stray too far from the commanded and factory settings.