idle problem
11-10-2004, 03:29 AM
#1
6th Gear Member
Thread Starter
Join Date: Dec 2003
Location: United States
Posts: 9,587
idle problem
i know theres been many topics on this problem but i cant seem to find an answer, when im driving and i come to a stop the cars idle starts to jump around and sometimes even dies just out of knowhere at a stop or making turns, ive already done the basics so what now??
11-11-2004, 08:37 PM
#6
2nd Gear Member
Join Date: Oct 2004
Location:
Posts: 450
RE: idle problem
i got some troubleshooting tips from www.pro-flow.com
they helped me out
"Idle Speed Instability and/or computer code (66).
Idle speed set on the throttle plate is too high; usually this error is characterized by a very erratic idle and stalling when coming to a stop.
Set the throttle by removing the connector from the idle speed control motor.
With engine warm and air conditioner turned off, set idle speed at 700 RPM using the throttle screw.
Reconnect idle speed motor and check for engine stability.
Check system for vacuum leaks and fix them.
Crankcase ventilation improperly installed; causes lean idles and lean pops at light loads and medium speed (1700 to 2500 RPM).
Throw away any breather to the crankcase that does not connect to the downstream side of the Pro-M meter.
If you have a turbo or Super-charged system the crankcase vent must be enlarged (5/8 inches to ¾ inches) and again plumbed between the Pro-M and the inlet of the super-charger/turbo.
If you must have your crankcase breather vented to the atmosphere, plug the line to the PCV valve at the manifold. This is illegal for road use and of doubtful benefit, but it will drive somewhat better and let you use a breather vented to atmosphere.
Check PCV valve for correct installation; on GT-40 manifold, the PCV valve is located so that the hose is short, and it sometimes pulls the valve out. This will cause idle problems and lean running at part-throttle loads. MOST COMMON PROBLEM!
Check system for vacuum leaks and fix them.
Fan wash causes engine to hunt for idle.
On some vehicle setups, the fan will cause a pulsating air current that causes idle. If you put your hand underneath the air filter with engine running, you can feel a strong pulsation. This is further characterized by electrical noise in the meter, which can be read by a digital voltmeter across pins C and D of the meter.
The voltmeter should read between .6 and .9 volts on the D.C. scale at idle.
The voltmeter should read less than .006 volts on the A.C. scale.
Note: With no shield between the air filter and the engine, the voltmeter will read above .010 volts and go too as high as .050 volts. This is known as the signal to noise ratio and is similar to trying to hear someone whispering next to jet engine!
A simple fan shield should be fabricated from sheet metal; it could be hung from the radiator hose and placed between the air meter filter and the major rotating components."
they helped me out
"Idle Speed Instability and/or computer code (66).
Idle speed set on the throttle plate is too high; usually this error is characterized by a very erratic idle and stalling when coming to a stop.
Set the throttle by removing the connector from the idle speed control motor.
With engine warm and air conditioner turned off, set idle speed at 700 RPM using the throttle screw.
Reconnect idle speed motor and check for engine stability.
Check system for vacuum leaks and fix them.
Crankcase ventilation improperly installed; causes lean idles and lean pops at light loads and medium speed (1700 to 2500 RPM).
Throw away any breather to the crankcase that does not connect to the downstream side of the Pro-M meter.
If you have a turbo or Super-charged system the crankcase vent must be enlarged (5/8 inches to ¾ inches) and again plumbed between the Pro-M and the inlet of the super-charger/turbo.
If you must have your crankcase breather vented to the atmosphere, plug the line to the PCV valve at the manifold. This is illegal for road use and of doubtful benefit, but it will drive somewhat better and let you use a breather vented to atmosphere.
Check PCV valve for correct installation; on GT-40 manifold, the PCV valve is located so that the hose is short, and it sometimes pulls the valve out. This will cause idle problems and lean running at part-throttle loads. MOST COMMON PROBLEM!
Check system for vacuum leaks and fix them.
Fan wash causes engine to hunt for idle.
On some vehicle setups, the fan will cause a pulsating air current that causes idle. If you put your hand underneath the air filter with engine running, you can feel a strong pulsation. This is further characterized by electrical noise in the meter, which can be read by a digital voltmeter across pins C and D of the meter.
The voltmeter should read between .6 and .9 volts on the D.C. scale at idle.
The voltmeter should read less than .006 volts on the A.C. scale.
Note: With no shield between the air filter and the engine, the voltmeter will read above .010 volts and go too as high as .050 volts. This is known as the signal to noise ratio and is similar to trying to hear someone whispering next to jet engine!
A simple fan shield should be fabricated from sheet metal; it could be hung from the radiator hose and placed between the air meter filter and the major rotating components."
11-11-2004, 08:43 PM
#7
2nd Gear Member
Join Date: Oct 2004
Location:
Posts: 450
RE: idle problem
this is also from the same sight
"What is the TPS voltage? Our recommendation is key on, engine off, (KOEO) 0.995-.998 D.C. High TPS voltages
are characterized by a very erratic idle or stalling when coming to a stop (ECM error code 66). Set the throttle by
removing the connector from the Idle Speed Control Motor, with the engine warm and the air conditioner off, using the
throttle screw set the Idle Speed at 700 RPM ( or desired RPM). On '94 and later models use the idle bypass screw
at the right side of the throttle body covered with a plastic cap. Reset the TPS to obtain 0.995-.998 volts D.C.
between the black and green wires on the throttle pot. If the unit has no voltage, check the voltage between the black
and orange wires. This should be 4.9-5.1 volts D.C. with the ignition on. If the voltage is 4.9-5.1 D.C. and there is no
voltage on the green wire, the throttle position sensor is no good. If there is no voltage on the orange wire, you must
find a break in the wire. Reconnect the Idle Speed Control Motor and check for engine stability."
"What is the TPS voltage? Our recommendation is key on, engine off, (KOEO) 0.995-.998 D.C. High TPS voltages
are characterized by a very erratic idle or stalling when coming to a stop (ECM error code 66). Set the throttle by
removing the connector from the Idle Speed Control Motor, with the engine warm and the air conditioner off, using the
throttle screw set the Idle Speed at 700 RPM ( or desired RPM). On '94 and later models use the idle bypass screw
at the right side of the throttle body covered with a plastic cap. Reset the TPS to obtain 0.995-.998 volts D.C.
between the black and green wires on the throttle pot. If the unit has no voltage, check the voltage between the black
and orange wires. This should be 4.9-5.1 volts D.C. with the ignition on. If the voltage is 4.9-5.1 D.C. and there is no
voltage on the green wire, the throttle position sensor is no good. If there is no voltage on the orange wire, you must
find a break in the wire. Reconnect the Idle Speed Control Motor and check for engine stability."
11-11-2004, 09:30 PM
#8
5th Gear Member
Join Date: Oct 2003
Location: Mishawaka,Indiana
Posts: 3,742
RE: idle problem
