I am in the middle of raising my idle for my 96 auto max, and it says to first disconnect the TPS harness connector. I cannot find this connector. I have a picture but it is vague. Can someone tell me where exactly it is? Also, is the idle speed adjusting screw that big black plastic screw?

 

The TPS harness connector is plugged into your TPS.

 

Isnt that where you get your TPS reports from?

 

ok so where is the tps?

 

It's integrated with the throttle body...

...get a Haynes Manual.

 

Look at the picture I linked to you from Steve Cutchen's FAQ. The piece labeled Air Duct comes from the Air Box. Does this help?

 

On a related note, can anyone tell me why my car won't run when the TPS is disconnected?

The car was warmed up to normal temperature too. When I turn the key, it will rev up to just over 1k rpm and then sink all the way to 0 rpm where it stalls out. Usually the second after startup. I put the TPS connector back on (mine has only one), and the car starts up fine.

BTW, I was trying to up the idle a bit. Now sits just above 600 rpm on my manual tranny max.

Also, what is the correct procedure for adjusting the idle screw on top of the IAC?

 

Get the engine up to operating temp. Turn off engine. Disconnect TPS. Start engine. Jump out with screw driver in hand and slowly trun the idle screw to desired idle. Turn off engine. reconnect TPS sensor. Start engine, idle should still be raised to the new selection.

 

That definitely was the plan.

However, when I disconnect the tps and then go start the car, it just dies after the initial rpm surge, when you would normally expect it to go to idle rpm. Since the IAC and TPS work together to control idle, I'm wondering if this means my IAC is faulty.

Lately, I have noticed that when coming to a stop and take the car out of gear, the rpms will dip a little below idle (like 400-500) and the immediately bob back up to idle speed.

Still don't know what that black plastic screw on top of the IAC does... doesn't seem to change idle speed at all.

 

That black plastic screw IS for adjusting idle.
Yes, your IAC valve could be bad or need cleaning. Or it could be that your idle is set so low it's not coming into play and the ECU is compensating to make it idle. Dropping rpms at idle is another symptom of low base idle. Try screwing the idle adjust screw out a couple turns, disconnect the TPS, and see if you can now adjust idle to 650 rpms or so.

 

while we're on this subject...what happens if you adjust the idle screw WHILE the TPS is connected? does the car explode or something?

 

I had close to the same problem. My car died the first two times I started it w/o the TPS connected. I had to go as quickly as possible to the idle screw before it died. It took me 3 times to adjust the idle before it died.
I also get a dip in the rpm's sometimes when shifting into neutral and comming to a stop. It used to even die on me sometimes. Adjusting the idle fixed the problem for a while. It has been happening again lately.
My IAC valve may needs cleaning or replacing as well. Maybe ust not as bad as yours, that is why I am able to adjust it before it dies.

Adjusting the idle while the TPS is connected does not work because ECU will go back to the predetermined idle. That is why it has to be disconnected, so it learns the new idle once it is connected again. I don't think the car would blow up.

 

Exactly what I was going to say. He may also need to bump the throttle plate stop screw or clean his throttle body before making the adjustment. It may be so dirty that it's messing with his idle.

 

OK thanks guys for the input.

I will be trying some of the suggestions to get things idling w/o the TPS.

I am a little confused about the "idle adjustment" part. Is the throttle plate screw for major adjustment and the plastic screw for fine tuning? I am reading some people saying to adjust the plastic screw only and some say the throttle plate screw.

In any case, I'll try the plastic screw opened up, and if that doesn't work, will do the throttle plate screw. Can anyone tell me which way the throttle plate screw turns to increase the idle?

 

Update: When I looked at the throttle plate screw, I found that the end of the screw did not even come into contact with the thottle linkage assembly! With the TPS disconnected, I advanced the screw in until it hit the linkage and then pushed it in a little further. The car now idled high but it at least was able to idle! Backed the screw down to lower the idle and used the IAC plastic screw to fine tune the rpm.

A big THANK YOU for the helpful tips you guys provided. There is no more shuddering on coming to a stop due to the rpms dropping below idle.