How do you bench test the IAC
11-15-2006, 10:04 AM
#1
Advanced
Thread Starter
Member Since: Aug 2006
Location: Frederick Colorado
Posts: 56
Likes: 0
Received 0 Likes
on
0 Posts
How do you bench test the IAC
I removed the throttle body and took the IAC out and I need to know how to bench test the IAC to see if the new one had a short life. Problem with engine starting with a short run of 2 seconds annd shuts off. found the measurement from tip to shoulder where gasket sets to be 1.088
11-15-2006, 10:24 AM
#3
Melting Slicks
If it was still on the car, I could suggest a test.
1. Perform the normal min air procedure and determine idle rpm with IAC fully closed and disconnected.
2. Reconnect IAC and with the IGN on and the engine not running, open the throttle to WOT. This should command the IAC to open as well, but I haven't verified this. The IAC normally responds to the throttle. While holding the throttle fully open, disconnect the IAC again. It should now be fully open to 145 or 160 counts depending upon the year of car (89's will go to 160 counts, previous years 145).
3. Restart the car and determine idle rpm again. It should have gone up by about 800-900 rpm, maybe a bit less with an auto trans.
A fully open IAC should increase airflow by around 8-9 gm/sec. This is enough flow to raise the idle rpm by 800-900 rpm, depending upon the load in park or neutral.
If the rpm goes up as expected the IAC is opening and flowing correctly.
1. Perform the normal min air procedure and determine idle rpm with IAC fully closed and disconnected.
2. Reconnect IAC and with the IGN on and the engine not running, open the throttle to WOT. This should command the IAC to open as well, but I haven't verified this. The IAC normally responds to the throttle. While holding the throttle fully open, disconnect the IAC again. It should now be fully open to 145 or 160 counts depending upon the year of car (89's will go to 160 counts, previous years 145).
3. Restart the car and determine idle rpm again. It should have gone up by about 800-900 rpm, maybe a bit less with an auto trans.
A fully open IAC should increase airflow by around 8-9 gm/sec. This is enough flow to raise the idle rpm by 800-900 rpm, depending upon the load in park or neutral.
If the rpm goes up as expected the IAC is opening and flowing correctly.
11-15-2006, 10:32 AM
#4
Advanced
Thread Starter
Member Since: Aug 2006
Location: Frederick Colorado
Posts: 56
Likes: 0
Received 0 Likes
on
0 Posts
Originally Posted by AGENT 86
11-15-2006, 11:57 AM
#6
Race Director
Member Since: Sep 2000
Location: The Top of Utah
Posts: 17,298
Likes: 0
Received 23 Likes
on
22 Posts
Originally Posted by juanway
found the measurement from tip to shoulder where gasket sets to be 1.088
RACE ON!!!
11-15-2006, 01:01 PM
#7
Advanced
Thread Starter
Member Since: Aug 2006
Location: Frederick Colorado
Posts: 56
Likes: 0
Received 0 Likes
on
0 Posts
Originally Posted by CFI-EFI
That is wide open. Since that was the position when the engine died, it would have been at the maximum idle speed. Of course the engine wasn't idling fast, or it wouldn't have died. This doesn't tell us if the IAC is working or not, but it pretty much clears the IAC as being the cause of the stalling.
RACE ON!!!
RACE ON!!!
Is there a way to apply voltage to the IAC to see it move out and in.
11-15-2006, 01:07 PM
#8
Melting Slicks
From Agent86's trouble shooting information, it sounds like the IAC should be fully open when the IGN is off.
From the info provided, it also sounds as if the IAC is fully open now, which makes sense since the IGN was most likely off when you removed the throttle body and IAC.
Since it is off the car now, can't you just plug the IAC and tps back in, cycle the ignition to on and then open and close the throttle to verify that the IAC is moving under ECM command?
From the info provided, it also sounds as if the IAC is fully open now, which makes sense since the IGN was most likely off when you removed the throttle body and IAC.
Since it is off the car now, can't you just plug the IAC and tps back in, cycle the ignition to on and then open and close the throttle to verify that the IAC is moving under ECM command?
11-15-2006, 02:16 PM
#9
Race Director
Member Since: Sep 2000
Location: The Top of Utah
Posts: 17,298
Likes: 0
Received 23 Likes
on
22 Posts
Originally Posted by juanway
The 1.088 measurement is the same when you buy a new one right out of the box.
Is there a way to apply voltage to the IAC to see it move out and in.
Is there a way to apply voltage to the IAC to see it move out and in.
To check that the IAC motor functions, reconnect the electrical connector to the IAC, and then jump terminals "A" and "B" on the ALDL with the ignition on, engine off. The pintle should fully extend. For fear of damaging an otherwise good IAC, I would only observe the initial movement of the pintle. I would be afraid that without the TB to stop it that the pintle night over extend and damage the IAC. I don't know that would happen, but is can't hurt to err on the safe side. If the pintle starts to move you know the IAC is operational.
RACE ON!!!
