idle adjustment 575 sci
01-10-2017 | 12:16 AM
#13
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Joined: Jan 2004
Posts: 4,480
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From: Tennessee
If you open the blades to far, with the TPS still at 0, then the ECM will take out timing to get the idle down. If you have it idling and the IAC is closed all the way, you don't know if you are right where you should be or open too much. If too much, the ECM will pull timing and the engine will be lazy and have some lag going in and out of gear. With the IAC open a touch, you know the throttle blades aren't open too much. On the flip side, if the blades are closed too much, the engine will idle on the IAC and you won't have any IAC left to open when you put it in gear. It will stumble, idle low and possibly kill.
Eddie
01-10-2017 | 07:49 PM
#14
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From: San Diego
Sounds like the throttle stop screw may have backed off. You really need a scan tool to set the TPS. You really can't do it properly with a volt meter. Hook up a scan tool and see what the TPS reading is. Slowly advance the throttle and see if the TPS registers immediately. If not, you can open the throttle blades a little with the stop screw. You can open it as needed to get the correct idle as long as the TPS doesn't start to register. I like to set the throttle blades where the engine will idle at the desired rpm with the IAC open about 20 counts or so.
If you open the blades to far, with the TPS still at 0, then the ECM will take out timing to get the idle down. If you have it idling and the IAC is closed all the way, you don't know if you are right where you should be or open too much. If too much, the ECM will pull timing and the engine will be lazy and have some lag going in and out of gear. With the IAC open a touch, you know the throttle blades aren't open too much. On the flip side, if the blades are closed too much, the engine will idle on the IAC and you won't have any IAC left to open when you put it in gear. It will stumble, idle low and possibly kill.
Eddie
If you open the blades to far, with the TPS still at 0, then the ECM will take out timing to get the idle down. If you have it idling and the IAC is closed all the way, you don't know if you are right where you should be or open too much. If too much, the ECM will pull timing and the engine will be lazy and have some lag going in and out of gear. With the IAC open a touch, you know the throttle blades aren't open too much. On the flip side, if the blades are closed too much, the engine will idle on the IAC and you won't have any IAC left to open when you put it in gear. It will stumble, idle low and possibly kill.
Eddie
01-10-2017 | 11:21 PM
#15
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Joined: Jan 2004
Posts: 4,480
Likes: 43
From: Tennessee
Eddie. Why aren't you here in Cali.. No wait . I know . Cause too much horizontal snatch..lol!! I will quote you so i don't lose this info. Then I will look at the butterflies. Probly compare them to my Good motor and Go from there. I will check back to this thread and see if it's more than that I can do . If It's Throttle Position sensor or something in the mapping or fuel mixture, I 'll Probly pay Gordon to come down or take my boat up to LA. Thanks !!
Do you have access to a scan tool? have any buddies with one? I would think someone around there has one. That would be a big help in narrowing it down.
Let me know if I can help in any way.
Eddie
01-11-2017 | 09:58 AM
#16
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Joined: Jun 2011
Posts: 1,209
Likes: 141
Sounds like the throttle stop screw may have backed off. You really need a scan tool to set the TPS. You really can't do it properly with a volt meter. Hook up a scan tool and see what the TPS reading is. Slowly advance the throttle and see if the TPS registers immediately. If not, you can open the throttle blades a little with the stop screw. You can open it as needed to get the correct idle as long as the TPS doesn't start to register. I like to set the throttle blades where the engine will idle at the desired rpm with the IAC open about 20 counts or so.
If you open the blades to far, with the TPS still at 0, then the ECM will take out timing to get the idle down. If you have it idling and the IAC is closed all the way, you don't know if you are right where you should be or open too much. If too much, the ECM will pull timing and the engine will be lazy and have some lag going in and out of gear. With the IAC open a touch, you know the throttle blades aren't open too much. On the flip side, if the blades are closed too much, the engine will idle on the IAC and you won't have any IAC left to open when you put it in gear. It will stumble, idle low and possibly kill.
Eddie
If you open the blades to far, with the TPS still at 0, then the ECM will take out timing to get the idle down. If you have it idling and the IAC is closed all the way, you don't know if you are right where you should be or open too much. If too much, the ECM will pull timing and the engine will be lazy and have some lag going in and out of gear. With the IAC open a touch, you know the throttle blades aren't open too much. On the flip side, if the blades are closed too much, the engine will idle on the IAC and you won't have any IAC left to open when you put it in gear. It will stumble, idle low and possibly kill.
Eddie
