Idle hanging up?

[Fopar]

I was swapping around intake tubes/MAFs today to test out some things. When all was done I ended up with the same MAF (but different IAT) and the car drives about the same except the idle hangs up to 2100 or so if you put in the clutch when you're driving, once you get below 10 MPH or so the idle comes back down to normal . You can feel it when your driving as well as the car seems to want to cruise on its own. Obviously the IAC is suspect but it was working fine before the intake tube stuff and it comes back down once you get close to a stop . Idea's?

 

[sndrummer]

did you un-hook the battery each time you switched, because i know when we were messing around with my set up, we had to reset the computer each time by unhooking the batt otherwise the computer would freak out the idle.

 

[go-stang5.0]

Do you have a C&L meter....sometimes there sensitive to maf tubes and also how the meter is oriented into the airflow. Try rotating the maf and see if that helps.

 

[Fopar]

no meter, I tried unhooking the battery it didn't change anything. And now it was starting to hang up at 1500 even when stopped, I checked for vacuum leaks with carb cleaner and no problems there, tried unhooking vacuum lines and plugging still same thing. I adjusted the IAC feed restrictor and put it all the way in (was almost there already) now it comes back down to 1k at idle but still hangs way high until you get close to a stop... wtf

 

[Fopar]

it's getting worse it seems, hangs up in the 1500 range... tried different IAC same problem... disconnecting IAC kills car....

Could it be a bad TPS? Perhaps showing a higher reading than actual causing the IAC to hang? I disconnected the TPS once and the idle came down but then the motor stalled shortly after...

 

[Fopar]

....

 

[Fopar]

continuous bumping until I get replys

 

[Fopar]

daily bump

 

[Fopar]

bump

 

[m0l0]

LOL , the bump.


Have you tried setting the TB blade screw? maybe is a little more open that it should.

Now for the TPS there are 2 diferent versions on the correct volt. value some say " put the tps at .95, others say that it dosnt matter whats the volt. since the EEC "learns" the closed TPS volts.

But i think that anything below 1.0 v its good to go. so try setting the tps anything below 1.0v and adjust by the TB blade screw and the IAC screw.
There is here a how to to set the idle correctly on this cars

In a not so large write up its like this :

Start the car and let it stay so it reaches operating temperature ( 190 )
Stop the car , and disconnect the SP-OUT & IAC
Open the TB. screw arround 1.5-2.5 turns
Open the IAC Screw up to 2.5 turns ( Stock )

Start the car and see i it can idle arround 600 rpms, if not correct via TB Screw but keep an eye on the TPS volts.

If the car idles fine , shut it off and reconnect sp-out and iac , start the car again and enjoy your stock idle setting

Try that and tell us what happened.

 

[Fopar]

well I can try it but it worked fine before, have a feeling it'll just keep doing the same thing.... but i'll check when I go home this weekend

 

[HISSIN50]

Couple ideas:

When it hangs, if you disconnect the IAC, does the idle fall down to under 1000 RPM?

When it happens, if you shut the car off and restart it, does it work properly for a little bit and then act up again? If so, does shutting it off and restarting it fix it for a little while again?

I gotta feeling it could be a vac leak. In checking, make sure your idle bleed screw isnt run out too far. Personally, anything more than about 1.5 turns out from seated caused a hanging idle.

Good luck.

 

[Fopar]

ok I swapped TBs from my 94 parts car, its fixed and it appears it was the TPS as I suspected....