Car idles at 1500

[leathernotch]

After the head install car idels at 1500 hundred, was ideling a 3000, fixed vaccume leak with new plenum gasket and bought a fuel pressure gauge and timed the car. Any ideas????

 

[leathernotch]

Mods now in sig

 

[noslow1986]

try to adjust the throttle body down. by putting an allen wrench in the bottom there a hole where u can adjust it up or down

 

[leathernotch]

already backed it down all the way

 

[Roland69]

you shouldn't touch that stop screw...

 

[Roland69]

http://www.50tech.com/portal.php?topic_id=50393

 

[HISSIN50]

I'd keep lookin for more vac leaks.

Good luck.

 

[jrichker]

You guys with idle problems could same a lot of time chasing your tails if you would go through the Surging Idle Checklist. Over 50 different people contributed information to it. The first post has all the fixes, and steps through the how to find and fix you idle problems without spending a lot of time and money. I continue to update it as more people post fixes or ask questions. You can post questions to that sticky and have your name and idle problem recognized. The guys with original problems and fixes get their posts added to the main fix.

 

[leathernotch]

Hooked a vacuum guage up, no vacuum leaks car still idleing 1600
went through checklist nothing helped, checked tps, checked mass-air, checked iac, nothing's helping, any other ideas, maybe too big an intake, probably not though.

 

[jrichker]

Hooked a vacuum guage up, no vacuum leaks car still idleing 1600
went through checklist nothing helped, checked tps, checked mass-air, checked iac, nothing's helping, any other ideas, maybe too big an intake, probably not though.

Did you use the checklist proceedure for setting the mechanical base idle speed?

 

[leathernotch]

Yea... adj. tps to .9 after adj idel screw... do I have that right

 

[leathernotch]

"An engine that whose idle speed cannot be set at 600 RPM with the IAC disconnected has mechanical problems. Vacuum leaks are the #1 suspect in this case. A vacuum gauge will help pinpoint both vacuum leaks and improperly adjusted valves. A sticking valve or one adjusted too tight will cause low vacuum and a 5"-8" sweep every time the bad cylinder comes up on compression stroke. An extreme cam can make the 600 RPM set point difficult to set. Contact your cam supplier or manufacturer to get information on idle speed and quality"

With the iac disconnected the car idles at 1500
Vacuum never goes below 10 even at 600 - 900 rpm range which I get by droping fuel way to low, or backing timing to -3, or disconnecting Maf

 

[leathernotch]

Ok I got up early before school and stoped by the advanced auto and bought the carb cleaner. I cleaned the IAC and then the TB. It seemed like there was a little change but not really. The car drives fine when ingauged in gear. Once the clutch is pushed in she surges to about 2000 then settles between 1200 and 1600 never any lower.
With the IAC disconnected and the car warmed up there is no change in the idle.

 

[jrichker]

At 625-750 RPM you should see 15"-18" of vacuum. At 1000 RPM, you should see 18"-21" of vacuum. Less than that with a stock cam and you have a vacuum leak.

 

[leathernotch]

I have a B-303 w/ 1.7rr if you could give me the general area it should be at 1400 - 1600 I will check it when I get home in 2 1/2 hours, if not I will post the results.
Thanks

 

[leathernotch]

W/ RPMs settled at 1450 the vac reads between 15 and 16

 

[leathernotch]

Just did O2 sensors. Idled fine when I started her up but the idle rose to 1300 when she warmed up. Since the vac gauge reads 16 at this RPM and does not move does this rule out valve problems and leave only Vacuum leaks????

 

[leathernotch]

Update: with the iac unpluged I car will idle at 1000 or 1100,

 

[v8only]

I just got done fixing a problem identical to this. I have a gt40p explorer motor, and I had to hog out the mounting bracket on the two holes to move the bracket up higher to clear the taller valve covers. hogging the holes caused the bracket to move backwards too toward the firewall when I tightened it. As a result I would turn the idle screw all the way out, but it wouldn't idle under 1500 or so because the screw wasn't touching the plate. I loosened up the two bracket bolts and slid the plate forward, which caused the plate to contact the adjustement screw, and fixed my problem. Not sure if yours is a similar deal, but worthy of throwing out there for sure.

 

[Roland69]

can you get use of a smoke machine....that will find a small vac leak for sure