TPS and IACV Help

[grk nickafis]

I am using ZTalk and Conzult to aid me in adjusting my TPS and IACV. I have the TPS set to .44-.46. In conzult (free version) it has the Base Idle Adjustment. I click that and it stalls, so I adjusted my IACV so it idles perfectly in the given range, right now im at 800-850 rpms because my idle likes to dip when i come off the gas. When I close Conzult, the idle shoots up to 2200rpms and is steady there. The car runs fine at 2200rpms but thats obviously a High Idle. I was wondering what could cause this.

I've read that people are at 750rpms on Conzult and when it closes it jumps to 900 but not 2200.

Heres a picture of how my car is running, there are no codes except for Code 54: Signal Circuit from A/T Control to ECU.
(My timing is 15degrees btdc at 850rpms, i dont know why it says 95)

[GerryO]

Lots of idle speed control related info here:

http://home.swipnet.se/e-solutions/IdleTech.html

http://home.swipnet.se/e-solutions/IdleTech2.html

[grk nickafis]

Basically that article told me it was a vacuum leak or the AAC. The part two said its not a vacuum leak because my MAS is running ok and registering all the air. But my car is also running Lean. it doesn't smell like its lean but thats what the computer says and that would be a symptom of a vacuum leak.

Also what is the A/F Alpha on the picture of the program?

[grk nickafis]

Just took my IACV out and it looks fine.

[GerryO]

Also what is the A/F Alpha on the picture of the program?

A/F Alpha is Air/Fuel ratio? Set my TPS to 0.38 VDC, as lower numbers relate to lower idle speeds. Do you have a multimeter to check various sensor voltages and resistances, and have you checked/set the timing using a timing light?

[grk nickafis]

I have a multimeter and I know many things work including my TPS, I thought my IAC was broken mechanically so I took it off and apart, cleaned it. About to put it back in, I hope this works. I've been having this problem for a while now, the car would stall when i put it in nuetral after aplying the gas. I read that the idle needed to be adjusted. So i'm trying...

[Stadsport]

Your TPS is incorrectly set or is bad. If you look at the second screenshot (Conzult) you can see it says "CLSD THL/POS : OFF" The TPS is actually two devices in one: the throttle position sensor and the hard idle switch. You need to rotate it so that the throttle position sensor reads between 0.4v and 0.5v WHILE the hard idle shows on (it needs to say "CLSD THL/POS : ON"). If, when rotating, you're not able to get the two in spec, your TPS needs to be replaced.

[grk nickafis]

so even tho my TPS is at the right volts, it could still be broken? What does CLSD mean?

[Stadsport]

It means "Closed." Like I said, the TPS is two separate devices in one. The pigtail coming out of the device with the oval connector is for the Throttle Position Sensor--that's what gives you the variable voltage reading. Obviously that's working fine, which is all dandy. The three-pin connector at the front of the TPS is for the Hard Idle Switch. It's literally an on/off switch that, when the throttle is closed, turns "ON" to tell the ECU that the throttle is closed and it needs to idle.
When you're adjusting (rotating) the TPS, there's a "sweet spot" where the Throttle Position Sensor will read between .4 and .5v while at the same time the hard idle switch turns ON. When the TPS goes bad, a lot of times you won't be able to get the Hard Idle Switch to turn on unless you crank the Throttle Position Sensor down to like .2 or .3v, which is obviously too low to be within range.

The Hard Idle Switch consists of two metal "fingers" that push together when the TPS is closed all the way. Over the years, the spring material they're made out of gets tired and they won't make a solid connection. This is why you can usually get the Hard Idle Switch to turn on when you crank the TPS too low, because the more you turn it, the "tighter" you're squeezing the fingers together. You can actually take the TPS and clean/bend the Hard Idle Switch "fingers," but it's kind of tough to get them "calibrated" right, so you're probably better off just replacing it. Fwiw, they're all the same (other than the 96+). There's like 4 different models, but the only differences are the lengths of the pigtails, and some have a Wide Open Throttle Switch... which our cars don't even use.

Hope this helps.

[grk nickafis]

it does a lot. Thank you, i can finally have a normal car again. I changed the TPS a while back but didnt know about this stuff. I got it used so this is very likely. ill get a new one, thank you.