[dtdees]

Hey guys,
I have a 95' 3.8 V6. I have replaced the throttle bypass valve (twice; a 95 version, then referring to the OEM# a 94 version) and I still have an idle of 2000+ RPMs. I have replaced the air filter and verified for leaks in the induction. I took a break line-lock and shut off the vacumn tree at the manifold to eliminate a vacumn leak as a possibility with no variation in idle RPM. I checked the voltage to the wiring connector of the throttle bypass vavle (IAC in later versions, I believe) and get 12v in one wire and nothing in the other (with the key on, of course). I then remove the valve and plug the bypass port off (with 1/2" PVC and cap) and the idle drops to approximately 600RPMs (around what I expect). What drives this bypass valve or am I looking for the problem in the wrong place?

Thanks for any help!

[alex96stang]

i think you have to adjust your idle screw or your IAC valve in some cars need to adjust you valve to your desire rpm's

[kscoyote]

Originally Posted by dtdees

Hey guys,
I have a 95' 3.8 V6. I have replaced the throttle bypass valve (twice; a 95 version, then referring to the OEM# a 94 version) and I still have an idle of 2000+ RPMs. I have replaced the air filter and verified for leaks in the induction. I took a break line-lock and shut off the vacumn tree at the manifold to eliminate a vacumn leak as a possibility with no variation in idle RPM. I checked the voltage to the wiring connector of the throttle bypass vavle (IAC in later versions, I believe) and get 12v in one wire and nothing in the other (with the key on, of course). I then remove the valve and plug the bypass port off (with 1/2" PVC and cap) and the idle drops to approximately 600RPMs (around what I expect). What drives this bypass valve or am I looking for the problem in the wrong place?

Thanks for any help!

One of your sensors is getting incorrect readings. It's usually a dirty MAF, it's reading low air/temp and increases the idle to compensate (electric choke).

Spray the MAF with computer contact cleaner, disconnect the battery and see what happens.

[dtdees]

I sprayed the MAF, though it looked as if the two wire sensor in the tube looked to have dirt on them, it made no change in the idle RPM.
After reassembly, I did disconnect the MAF wiring (trying to isolate) and my idle dropped off to below normal idle (which is a lot closer than where it is when it is hooked up). This is probably the normal response under normal conditions, but only having this stang for about a month, I'm not too familiar with any of it.

I referenced a few other strings prior to posting this string. There is no adjustment screw on the IAC. The throttle sensor connected to the throttle body does not have enough adjustment to pull the RPMs down to normal (or even close), and besides this problem started all at once. I believe a sensor or something went bad. I may be wrong (which happens often) but any adjustment to compensate for something else going wrong is not the right way to fix it.

[kscoyote]

Originally Posted by dtdees

I sprayed the MAF, though it looked as if the two wire sensor in the tube looked to have dirt on them, it made no change in the idle RPM.
After reassembly, I did disconnect the MAF wiring (trying to isolate) and my idle dropped off to below normal idle (which is a lot closer than where it is when it is hooked up). This is probably the normal response under normal conditions, but only having this stang for about a month, I'm not too familiar with any of it.

I referenced a few other strings prior to posting this string. There is no adjustment screw on the IAC. The throttle sensor connected to the throttle body does not have enough adjustment to pull the RPMs down to normal (or even close), and besides this problem started all at once. I believe a sensor or something went bad. I may be wrong (which happens often) but any adjustment to compensate for something else going wrong is not the right way to fix it.

Don't touch the IAC, It's probably a sensor. Most likely the throttle position sensor.

Did you disconnect the battery after cleaning the MAF?

[dtdees]

Yes, I disconnected the battery (even replaced the connectors while doing so). Should I replace the throttle position sensor?

[kscoyote]

Originally Posted by dtdees

Yes, I disconnected the battery (even replaced the connectors while doing so). Should I replace the throttle position sensor?

have it checked out first.