Pontiac GTA Enhancement information and discussions with Technical DIY and performance tuning information for the hardcore Pontiac GTA Owners and Enthusiasts.
Forum | Register Now | Members | Search | How Do I... | Calendar

Go Back   The GTA Source Page Message Forums > GTA SPECIFIC > GTA TECH

GTA TECH Want to discuss technical topics about your GTA.... engine tuning, mechanical upgrades, problem areas, etc.? Then post it HERE!

Reply
 
Thread Tools Display Modes
Old 02-24-2008   #1
george88gta
Registered User
 
george88gta's Avatar
 
Join Date: Oct 2002
Location: holmes,ny
Posts: 904


correct idle speed

Quick question. What are you guys seeing as your idle speed, both in gear and in neutral? My car tries to drive thru the brakes at idle. It idles at 750 rpm, in gear and the scanner shows this as within spec. In neutral, it idles about 950. Engine was changed and a new chip was made for the engine. I seem to recall that when it was the stock 305, the idle was about the same. Getting ready to tear it down for a head replacement and some SLP runners, so if I need a higher stall converter, now would be the time. Timing is correct and I have checked for a vacumn leak several times. Vacumn is between 18 -19 inches. Cam is relatively mild, numbers are as follows: at .050" lift, intake 212 degrees duration and exhaust is 222 degrees duration. Lobe seperation is 112.5 degrees.
george88gta is offline   Reply With Quote
Old 02-24-2008   #2
FearThisGTA
"The only thing to fear is.............fear itself"
 
FearThisGTA's Avatar
 
Join Date: Jun 2003
Location: In front of you....
Posts: 4,742



GTA Year: 1991
GTA Engine: 350 TPI Automatic
Re: correct idle speed

Hmmmm, havent looked in a while I will hzve to ck it out next time I drive it.
__________________


Cliff Jones
1991 GTA Trans Am
w/305,231 miles
on the original motor!!!!
Time of Death on motor, 4:07pm on 05/29/2010.
Hp:211.2@4200rpms/Tq.328.5@2700rpms
Best et: 13.959@97.05mph
Best mph: 98.3
Best 60' : 1.875 on BFG Comp TA's w/ 32 lbs of air in them
FearThisGTA is offline   Reply With Quote
Old 02-24-2008   #3
george88gta
Registered User
 
george88gta's Avatar
 
Join Date: Oct 2002
Location: holmes,ny
Posts: 904


Re: correct idle speed

Quote:
Originally Posted by FearThisGTA
Hmmmm, havent looked in a while I will hzve to ck it out next time I drive it.
Hi Cliff, figured you would jump in on this. Its just one of those annoying things that pop up when you mess with Mother Nature. There are days when I felt it would have been best to just rebuild the damaged 305.
george88gta is offline   Reply With Quote
Old 02-25-2008   #4
FearThisGTA
"The only thing to fear is.............fear itself"
 
FearThisGTA's Avatar
 
Join Date: Jun 2003
Location: In front of you....
Posts: 4,742



GTA Year: 1991
GTA Engine: 350 TPI Automatic
Re: correct idle speed

I hear ya and know exactly what ya mean.
__________________


Cliff Jones
1991 GTA Trans Am
w/305,231 miles
on the original motor!!!!
Time of Death on motor, 4:07pm on 05/29/2010.
Hp:211.2@4200rpms/Tq.328.5@2700rpms
Best et: 13.959@97.05mph
Best mph: 98.3
Best 60' : 1.875 on BFG Comp TA's w/ 32 lbs of air in them
FearThisGTA is offline   Reply With Quote
Old 02-25-2008   #5
Coda
Registered User
 
Join Date: Aug 2006
Location: CZ
Posts: 102


Re: correct idle speed

I think it's supposed to be 600-700, or 650-750. I will have to check my manual.
Coda is offline   Reply With Quote
Old 02-25-2008   #6
merc3065
Registered User
 
merc3065's Avatar
 
Join Date: Aug 2006
Posts: 2,057


Re: correct idle speed

Should be 550-600 in drive and around 600-650 in neutral.

you need an external tachometer to properly set the idle speed with the idle set screw on the TPI as well as adjusting the TPS and the IAC. Its a pain in the ass to get it set properly without the external tach.
__________________
merc3065 is offline   Reply With Quote
Old 02-25-2008   #7
george88gta
Registered User
 
george88gta's Avatar
 
Join Date: Oct 2002
Location: holmes,ny
Posts: 904


Re: correct idle speed

Quote:
Originally Posted by merc3065
Should be 550-600 in drive and around 600-650 in neutral.

you need an external tachometer to properly set the idle speed with the idle set screw on the TPI as well as adjusting the TPS and the IAC. Its a pain in the ass to get it set properly without the external tach.
I read thru the procedure, in the shop manual, and I can see that it wont be fun. Cant use my scanner since you have to ground a terminal at the ALDL. Too bad my old dwell tach wont work. I will look around to see if there is a tach laying around. Think the procedure would work if I grounded the terminal from the back of the ALDL connector and plugged in my scanner?
george88gta is offline   Reply With Quote
Old 02-25-2008   #8
MunsonGTA
Bad luck or no luck
 
Join Date: Jun 2004
Location: Ravenna, OH
Posts: 1,948



GTA Year: 1987
GTA Engine: Custom
Re: correct idle speed

whoever burnt your chip can change the rpm speed with no problem. i have mine set at 850 in my car. i bet a good converter will help you out. i know my car did the same thing with all the mods i have and the stock converter. when i switched to a 2500 stall, the problem went away.
__________________
87 GTA: Forged 408 LSX short block, TEA stage 2 cnc ported 243 heads, BTR Stage 3 stroker cam, Fast 102 intake, NW 102 TB, Longtube headers, custom 411 ECM, custom harness, custom tuned, Performabuilt stage 2 4l60E with PTC 2800 stall, 9 bolt rear with 3.70 gears and TAP girdle.

11.16 at 123 mph.
MunsonGTA is offline   Reply With Quote
Old 02-25-2008   #9
george88gta
Registered User
 
george88gta's Avatar
 
Join Date: Oct 2002
Location: holmes,ny
Posts: 904


Re: correct idle speed

Quote:
Originally Posted by MunsonGTA
whoever burnt your chip can change the rpm speed with no problem. i have mine set at 850 in my car. i bet a good converter will help you out. i know my car did the same thing with all the mods i have and the stock converter. when i switched to a 2500 stall, the problem went away.
Update.. I had some spare time this afternoon and I verified that the idle was indeed 750 rpm, in gear, closed loop. I then went thru the procedure, as outlined in the shop manual, to check correct idle speed. FYI, it is 400 rpm for a 305 and 450 rpm for a 350, while performing this check. Could not find a spec for idle speed in the normal configuration. Anyway, car would not idle, it stalled, while in the test configuration. If you pressed on the accelerator, it would run, but as soon as you released the pedal, it stalled. The seal is still installed in the throttle body, so I know that it wasnt messed with. Put everything back to normal and the car idles at 650 rpm, in gear, and 800 in neutral. Doesnt feel like it is trying to drive thru the brakes. No idea as to what changed, and I am not yet convinced problem is gone, just hiding, waiting to strike again. Guess I have to dig thru the manual to try and better understand the idle system and find out why it wouldnt run in the test configuration.
george88gta is offline   Reply With Quote
Old 02-25-2008   #10
Coda
Registered User
 
Join Date: Aug 2006
Location: CZ
Posts: 102


Re: correct idle speed

Checking the Chiltons manual...

The 1988 5.7 AT should idle at 700 RPM.

Just for comparison....

A 1987 5.7 MT is listed at 450, the AT is 400 RPM!

and also 1989 is 700, 90-92 is 600.

If anyone wants a scan of this table I can happily oblige...
Coda is offline   Reply With Quote
Old 02-25-2008   #11
george88gta
Registered User
 
george88gta's Avatar
 
Join Date: Oct 2002
Location: holmes,ny
Posts: 904


Re: correct idle speed

Quote:
Originally Posted by Coda
Checking the Chiltons manual...

The 1988 5.7 AT should idle at 700 RPM.

Just for comparison....

A 1987 5.7 MT is listed at 450, the AT is 400 RPM!

and also 1989 is 700, 90-92 is 600.

If anyone wants a scan of this table I can happily oblige...
Thanks Coda. Looks like I am right in the ballpark.
george88gta is offline   Reply With Quote
Old 02-26-2008   #12
MunsonGTA
Bad luck or no luck
 
Join Date: Jun 2004
Location: Ravenna, OH
Posts: 1,948



GTA Year: 1987
GTA Engine: Custom
Re: correct idle speed

my 87 idled at 600 with an auto tranny before the custom tune. i've always prefered an idle speed of around 800-850, it gives much better throttle response off idle. since i've owned my car, if it ever got below 500 rpm idle, it would stall.
__________________
87 GTA: Forged 408 LSX short block, TEA stage 2 cnc ported 243 heads, BTR Stage 3 stroker cam, Fast 102 intake, NW 102 TB, Longtube headers, custom 411 ECM, custom harness, custom tuned, Performabuilt stage 2 4l60E with PTC 2800 stall, 9 bolt rear with 3.70 gears and TAP girdle.

11.16 at 123 mph.
MunsonGTA is offline   Reply With Quote
Old 02-26-2008   #13
george88gta
Registered User
 
george88gta's Avatar
 
Join Date: Oct 2002
Location: holmes,ny
Posts: 904


Re: correct idle speed

Quote:
Originally Posted by MunsonGTA
my 87 idled at 600 with an auto tranny before the custom tune. i've always prefered an idle speed of around 800-850, it gives much better throttle response off idle. since i've owned my car, if it ever got below 500 rpm idle, it would stall.
The test procedure has you jumper the ALDL diagnostic terminal, to ground,then remove the connector from the IAC valve and disconnect the SET connector. Remove the ground and start the engine. Somehow, the engine is supposed to keep running at the low idle numbers. If the idle speed is incorrect, you are supposed to remove the seal from the screw ( in the throttle body) and adjust the idle speed. Since my original problem was idle speed too high, I didnt think adjusting the screw, to increase the idle, was the best way to go. Anyway, it is idling better and for now, I will leave things as they are.
george88gta is offline   Reply With Quote
Old 02-26-2008   #14
MunsonGTA
Bad luck or no luck
 
Join Date: Jun 2004
Location: Ravenna, OH
Posts: 1,948



GTA Year: 1987
GTA Engine: Custom
Re: correct idle speed

well as long as it works then that's cool. like i mentioned, whoever did the custom tune could have just lowered the idle speed in the chip. glad you got the problem fixed.
__________________
87 GTA: Forged 408 LSX short block, TEA stage 2 cnc ported 243 heads, BTR Stage 3 stroker cam, Fast 102 intake, NW 102 TB, Longtube headers, custom 411 ECM, custom harness, custom tuned, Performabuilt stage 2 4l60E with PTC 2800 stall, 9 bolt rear with 3.70 gears and TAP girdle.

11.16 at 123 mph.
MunsonGTA is offline   Reply With Quote
Old 02-26-2008   #15
george88gta
Registered User
 
george88gta's Avatar
 
Join Date: Oct 2002
Location: holmes,ny
Posts: 904


Re: correct idle speed

Quote:
Originally Posted by MunsonGTA
well as long as it works then that's cool. like i mentioned, whoever did the custom tune could have just lowered the idle speed in the chip. glad you got the problem fixed.
Well, it is still working today. When I add the next mods, I will discuss the idle speed with the tuner. Leaning to a mild stall converter, 2000 - 2500 for the next mod. Thanks, everyone for the help.
george88gta is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Stall/erratic idle on cold start up 355GTA GTA TECH 6 05-13-2006 06:17 PM
cheap and easy speed whoneedsahonda GTA TECH 17 10-17-2005 01:33 PM
Good idle speed? MrNova GTA TECH 1 11-16-2002 06:28 AM
Please Help...thinking of a 6 speed swap REMOVED USER GTA TECH 6 08-25-2001 05:00 AM
Speed Density Vs. MAF REMOVED USER GTA TECH 5 08-21-2001 05:14 AM


All times are GMT -5. The time now is 11:11 PM.


Powered by vBulletin® Version 3.8.5
Copyright ©2000 - 2018, Jelsoft Enterprises Ltd.