ISV at idle
06-22-2006, 03:32 PM
#1
Racer
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ISV at idle
At idle should this valve be completly closed(warm engine) I try the jumper and adjust idle and trim fuel out seems ok then when i take the jumper out O2 sensor just makes idle go all over the place. Often making it idle very slow no matter my adjustment to screw. So my second question )2 sensor bad was fairly new but ran rich for so long ??? With jumper in what position is the valve in on ISV ?? any pics of this position ??
06-22-2006, 06:17 PM
#2
Addict
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No, it should be in the middle position. There is a procedure to set the idle speed on the car. It should idle at 840+/- 40 rpm warm.
The O2 sensor shouldn't make a difference to the idle speed. With the O2 sensor disconnected all the car is doing is running on it's open loop maps (like the ROW cars which don't have O2 sensors). It'll basically run a little bit richer than with the O2 sensor connected.
Dal.
The O2 sensor shouldn't make a difference to the idle speed. With the O2 sensor disconnected all the car is doing is running on it's open loop maps (like the ROW cars which don't have O2 sensors). It'll basically run a little bit richer than with the O2 sensor connected.
Dal.
06-22-2006, 06:52 PM
#3
Three Wheelin'
Dal:
Close but no cigar. When you disconnect the O2 sensor the idle RPM will change because the fuel/air ratio goes rich.
As far as the ISV goes, if the throttle body mechanical stop and the TPS are set properly, the ISV will be closed when the engine is at idle. Think about it: The sole purpose of the ISV is to maintain a consistant idle RPM as mechanical loads are added. For example, with just the engine running the ISV should be closed. If you turn the A/C on the ISV will open to maintain 840 RPM.
To set the mechanical stop you need to remove the throttle body. With the TB out, loosen the TPS screws and loosen the 7mm jam nut on the stop screw. Back the stop screw out until it is not touching the stop arm. Turn the stop screw in until it just touches the stop arm, and then turn the screw in 1/2 turn. Tighten the 7mm jam nut. Hold the throttle plate closed and set the TPS. Reinstall the throttle body, install the jumper at the diagnostics connector, and set engine idle to 840 RPM.
NOTE: If the mechanical stop was in too far (Throttle plate was open too far) when you started, you may have to open up the mechanical idle screw some to get the engine to run. I've found that a good "ball park" setting for the mechanical idle screw is 2 turns open.
Close but no cigar. When you disconnect the O2 sensor the idle RPM will change because the fuel/air ratio goes rich.
As far as the ISV goes, if the throttle body mechanical stop and the TPS are set properly, the ISV will be closed when the engine is at idle. Think about it: The sole purpose of the ISV is to maintain a consistant idle RPM as mechanical loads are added. For example, with just the engine running the ISV should be closed. If you turn the A/C on the ISV will open to maintain 840 RPM.
To set the mechanical stop you need to remove the throttle body. With the TB out, loosen the TPS screws and loosen the 7mm jam nut on the stop screw. Back the stop screw out until it is not touching the stop arm. Turn the stop screw in until it just touches the stop arm, and then turn the screw in 1/2 turn. Tighten the 7mm jam nut. Hold the throttle plate closed and set the TPS. Reinstall the throttle body, install the jumper at the diagnostics connector, and set engine idle to 840 RPM.
NOTE: If the mechanical stop was in too far (Throttle plate was open too far) when you started, you may have to open up the mechanical idle screw some to get the engine to run. I've found that a good "ball park" setting for the mechanical idle screw is 2 turns open.
06-23-2006, 01:19 AM
#4
Racer
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i believe i have everything setup correctly. Now I increased the fuel pressure a previous post mention about the MAF will not feed the DME info correctly if fuel pressure to hight or to low. With the increase cleaned up the idle so far but i still need to now redo the jumper cable procedure to see if will help. Other than idle car seems to be running better and better. All new TPS/sensors and ISV. Stupid idle gremlins leave me alone!!!
