WHAT THE HECK controls the idle in these things?
- Thread starter 88GeeTee
- Start date
no, can't get the car to idle right AT ALL. i suspected vac leaks myself, and used my last bit of starting fluid to check for leaks, might have to again, as i didn't find any before. so, internal leaks? where would they be coming from? pardon my ignorance, just not sure what ya mean...
Josh
Josh
If you check your vacuum reading, it should be near 20" hg while idling. The vac signal is critical for SD stangs.
For internal leaks (upper to lower intake, etc), you can: remove all vac fittings on the upper and lower. Plug the fittings air tight. Back the throttle stop screw down so the throttle blade is closed all the way. Now leave one convenient vac port open. Connect a vac gauge to this port. Disable the ignition. Now crank the motor and note the vac reading. 3-8" hg is normal. Less than that suggests an internal sealing issue/leak.
Good luck.
For internal leaks (upper to lower intake, etc), you can: remove all vac fittings on the upper and lower. Plug the fittings air tight. Back the throttle stop screw down so the throttle blade is closed all the way. Now leave one convenient vac port open. Connect a vac gauge to this port. Disable the ignition. Now crank the motor and note the vac reading. 3-8" hg is normal. Less than that suggests an internal sealing issue/leak.
Good luck.
Kdubslugga
Active Member
This is what I meant by an internal seal issue.
Lwr Intake vac leak. Note the front port (right side)
The way I found it?
I put a vac gauge on the crankcase, and the crankcase was not under pressure, it actually had a vac.
Lwr Intake vac leak. Note the front port (right side)
The way I found it?
I put a vac gauge on the crankcase, and the crankcase was not under pressure, it actually had a vac.
ok, thanks, that's something like i was thinking...BTW, where did you hook up the vac gauge to check the crankcase?
Josh
Josh
willys1
Active Member
joel5.0
Member
Kdubslugga said:
Check this article at fordfuelinjection.com, it explains the procedure and how to make sure the pins make the best contact.
Regarding the thread's initial question: WHAT THE HECK controls the idle in these things?....everything EEC-IV related, input or output wise
....sorry....had to say it. GLIf you can't go below 1K rpm I suspect the following:
1. Vacuum leak. Rotted hose or PCV grommet is rotted out
2. stuck butterfly on TB. OR check the size of the idle hole in the TB blade. Maybe someone really drilled it out!
3. Engine may be relying on IAC valve. during idle.
4. Improperly set TPS sensor for base idle
5. Bad BAP/ MAP, temp sensor.
First off. with no accessories on and a properly set base idle TB and TPS sensor, with the IAC unplugged you should be able to start a stock motor and idle correctly with no assistance from the IAC valve and "touchless" start from the accelerator pedal.
Here is how I do it.
Disconnect battery. I short the + and - cables together to remove (stored)power from the computers capacitors. This way you don't have to wait 30 minutes to begin this procedure.
Unplug IAC connector. Remove and clean valve. Reinstall. Do not connect electrical connector.
Reconnect battery.
Verify TPS is below 1 volt DC at idle . Don't do anything else until you get the relationship of TB blade position and the TPS sensor set. Such that you can achieve the correct idle range when at operating temperature. Only adjust the idle screw when at operating temp. This may take a few minutes because each time you turn the base idle screw you change the TPS sensor output voltage. You may need to adjust the TPS sensor a few times to be correct (below 1 volt DC at idle rpm). If you go above 1 volt the computer thinks your on the gas pedal and changes from idle strategy to an accelerating strategy. DO NOT GO ABOVE 1 VOLT AT IDLE
Disconnect battery, short terminals, remove short term memory from puter.
Start car again, let run 2 minutes (NO ACCESSORES. DO NOT TOUCH GAS PEDAL, STEARING WHEEL, BRAKES, HORN OR ANYTHING). This now establishes the baseline computer idle.
Shut the car down (assuming your at operating temp and TPS to TB idle is now set and working correctly).
Reconnect the IAC valve. start car. turn on all accessores, lights, fan, brake lights, flashers etc. Leave on for 2 minutes.
Turn all accessories off. Turn off car. Restart car. Wait 30 seconds, Idle should step down in 2 or 3 movements (colder cars step down more slowly in RPM....warmer cars faster). Your car should be at operating temp. Should return to correct idle in under 30 seconds. While car is idleing unplug the IAC connector. IDLE SHOULD NOT WAIVER OR FLUCTUATE AT ALL!
Assuming no vac leaks and all sensors working correctly, you motor should not be relying on the IAC during idle.
1. Vacuum leak. Rotted hose or PCV grommet is rotted out
2. stuck butterfly on TB. OR check the size of the idle hole in the TB blade. Maybe someone really drilled it out!
3. Engine may be relying on IAC valve. during idle.
4. Improperly set TPS sensor for base idle
5. Bad BAP/ MAP, temp sensor.
First off. with no accessories on and a properly set base idle TB and TPS sensor, with the IAC unplugged you should be able to start a stock motor and idle correctly with no assistance from the IAC valve and "touchless" start from the accelerator pedal.
Here is how I do it.
Disconnect battery. I short the + and - cables together to remove (stored)power from the computers capacitors. This way you don't have to wait 30 minutes to begin this procedure.
Unplug IAC connector. Remove and clean valve. Reinstall. Do not connect electrical connector.
Reconnect battery.
Verify TPS is below 1 volt DC at idle . Don't do anything else until you get the relationship of TB blade position and the TPS sensor set. Such that you can achieve the correct idle range when at operating temperature. Only adjust the idle screw when at operating temp. This may take a few minutes because each time you turn the base idle screw you change the TPS sensor output voltage. You may need to adjust the TPS sensor a few times to be correct (below 1 volt DC at idle rpm). If you go above 1 volt the computer thinks your on the gas pedal and changes from idle strategy to an accelerating strategy. DO NOT GO ABOVE 1 VOLT AT IDLE
Disconnect battery, short terminals, remove short term memory from puter.
Start car again, let run 2 minutes (NO ACCESSORES. DO NOT TOUCH GAS PEDAL, STEARING WHEEL, BRAKES, HORN OR ANYTHING). This now establishes the baseline computer idle.
Shut the car down (assuming your at operating temp and TPS to TB idle is now set and working correctly).
Reconnect the IAC valve. start car. turn on all accessores, lights, fan, brake lights, flashers etc. Leave on for 2 minutes.
Turn all accessories off. Turn off car. Restart car. Wait 30 seconds, Idle should step down in 2 or 3 movements (colder cars step down more slowly in RPM....warmer cars faster). Your car should be at operating temp. Should return to correct idle in under 30 seconds. While car is idleing unplug the IAC connector. IDLE SHOULD NOT WAIVER OR FLUCTUATE AT ALL!
Assuming no vac leaks and all sensors working correctly, you motor should not be relying on the IAC during idle.
DMAN302
My mom says thanks for the pearl necklace.
With the iac unpluged you should be able to back that set screw to the point of stalling. If you can't get the idle down to the 600 range I'd check to see if the butterfly is binding just shy of the full closed point..my old BBK was notorious for binding and I did have to put some emery cloth to use. Keep looking for vac leaks as well especially with the EGR valve plumbing, those little lines can appear OK but infact be near broken through.
