• Mustang Forums
  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-
  • Fox 5.0 Mustang Tech

How low will my idle go? 1000 rpm?

  • Thread starter Thread starter AnthonyR23
  • Start date Start date Jul 8, 2009

AnthonyR23

Member
Sep 8, 2006
661
0
16
Ontario
Jul 8, 2009
#1
  • Jul 8, 2009
  • #1
Hey just wondering, when trying to get my car to rev lower at idle how low should I expect it will go. Doubt I will ever see 600 rpm again. Just may be helpful to know if my car is idling to high or if it is probably just right. Below is a list of mods.

347
Trick Flow Street Wedge Heads
Trick Flow Intake
***** powermax 2030 cam ******
65 mm throttle body
cold air intake
70 mm mass air meter/ cal. for 30lb inject.
30 lb injectors.
underdrive pulleys
billet alluminum flywheel
bbk equal length headers
x pipe with cats
borla 2.5 inch catback

One more question... read in some tuning manual's etc. that the a9l has a harsh rev limited around 7000. Um... unless I read that wrong... is that harsh, I haven't ever had my car reving that high. What would a safe rev limiter be, or shouldn't there be one at all. Thanks!
 

rock4451

20+ Year Stangneter
Nov 30, 2004
12
2
29
New Baden, IL
Jul 8, 2009
#2
  • Jul 8, 2009
  • #2
with that setup, you should be able to idle around 850 or 900. with my setup it idles at about 700, and that may be low but 1000 for you i wouldn't say is too high...it's prob good for revving it from there, i'd think it'd be real snappy and quick to rev
 

TechSteele

New Member
Mar 8, 2009
60
1
0
North Coast
Jul 8, 2009
#3
  • Jul 8, 2009
  • #3
Like he said, 900 would be normal for most V8s.
Below about 750 it wouldnt stay running on its own.

As for the rev limiter, i have that ECU, but if my engine ever gets to 7K, ive got a REAL problem, or the worst shift of my life,
Off the top of my head, i think 6500 is tops even when racing.
I know there are engines that will go higher, but, those arnt normally streetable.
 

apollo12

New Member
Dec 11, 2007
155
0
0
port st.lucie fla
Jul 8, 2009
#4
  • Jul 8, 2009
  • #4
it needs to idle @ 950 to charge the alt , I thought a9l cut off @ 6250
 

jrichker

StangNet's favorite TOOL
In Remembrance. Thank you for your contributions
Mar 10, 2000
27,512
2,813
234
Dublin GA
Jul 8, 2009
#5
  • Jul 8, 2009
  • #5
Go through setting the base idle speed as described in the "Surging Idle Checklist. It is on the second post in the tech note.
 

Foxfan88

My Grandpa has great wood.
Sep 13, 2004
2,487
4
0
Miami, Ok
Jul 8, 2009
#6
  • Jul 8, 2009
  • #6
I found my combo to idle best at around 950-1000. With the cam and etc. the initial tip in while taking off is alot easier than if the engine were idling at like 600-700 all groggy and lopey etc etc.
 

AnthonyR23

Member
Sep 8, 2006
661
0
16
Ontario
Jul 8, 2009
#7
  • Jul 8, 2009
  • #7
Well before I just installed this new fuel pump and different iac motor, could really only get it to about 1000 rpm. But thinking it might go a bit lower with the new IAC. But will be happy with 950.

Jricher, are you talking about where it says if you can't get it to idle at 650 700 that you have mechanical problems?

So your saying it should be able to idle that low with my setup??

So I bought these cheap fuel rails, maybe ARP, from ebay and they are such a nightmare, have had so many leaks and problems, replaced the o rings like 3 times on some, and with the regulator I should probably put some lock tight or something because the regulator gets loose. My dad got me some fuel rated thread sealant industrial stuff that I tested out today. So will jumper the fuel pump at the diagnostic test circuit to see if I have any leaks.

But curious anyways after this to see if some of my codes go away. Just such a nightmare so far with these rails. Seems very touchy. Just want to get it leak free than will never touch the f*ing thing again! Anyways...

So once that's cleared up will reset timing and fuel pressure, will dump codes, and see if the new IAC and everything else work.

Curious to see how low I can get it to idle without surging, even if I turn it back up.

Oh after you dump codes is it normal for it to surge for the first minute or so while the comp figures stuff out???

And are engine running tests supposed to be done after the car is up to temp?

Thanks
 
You must log in or register to reply here.

Similar threads

7
Engine Random hanging idle
  • 706 Saleen
  • Feb 11, 2026
  • Fox 5.0 Mustang Tech
Replies
9
Views
648
Fox 5.0 Mustang Tech Feb 19, 2026
86HO5.0
8
Engine 1990 LX 5.0L EFI Mustang Fuel Management Problems - HELP!
  • 5.0LXStanger
  • May 25, 2025
  • Fox 5.0 Mustang Tech
  • 2 3
Replies
45
Views
2K
Fox 5.0 Mustang Tech Jul 11, 2025
5.0LXStanger
A
Rough idle - cylinder 1 and 6 misfire HELP
  • austindavies935
  • Jul 24, 2025
  • SN95 4.6L Mustang Tech
Replies
12
Views
726
SN95 4.6L Mustang Tech Jul 24, 2025
gkomo
SURGING IDLE / NO IDLE CHECKLIST FOR 1996–1998 MUSTANG GT (4.6L 2V) - Work In Progress
  • Noobz347
  • Aug 30, 2025
  • 1996 - 2004 SN95 Mustang -General/Talk-
Replies
0
Views
743
1996 - 2004 SN95 Mustang -General/Talk- Aug 30, 2025
Noobz347
SURGING IDLE / NO IDLE CHECKLIST FOR 1999–2004 MUSTANG GT (4.6L 2V) - Work In Progress
  • Noobz347
  • Aug 30, 2025
  • 1996 - 2004 SN95 Mustang -General/Talk-
Replies
0
Views
913
1996 - 2004 SN95 Mustang -General/Talk- Aug 30, 2025
Noobz347
Share:
Bluesky Email Share Link
  • Mustang Forums
  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-
  • Fox 5.0 Mustang Tech
Menu
Log in

Register

  • Forums
  • What's new
  • Media
  • Resources
  • Contact
  • Sponsor
X

Privacy & Transparency

We use cookies and similar technologies for the following purposes:

  • Personalized ads and content
  • Content measurement and audience insights

Do you accept cookies and these technologies?

X

Privacy & Transparency

We use cookies and similar technologies for the following purposes:

  • Personalized ads and content
  • Content measurement and audience insights

Do you accept cookies and these technologies?