Im getting pissed...need help with idle

[NO_RICE]

I swapped the throttle body and the upper intake, and when I did this the idle completely went to crap. Now it idles at 1000 rpm on a good day, half the time it will idle at 1200-1300 rpm when I come to a stop, half the time it will idle normal. I usually wont have the hanging idle problem until its warmed up (closed loop related??). I have replaced the IAC and cleaned the ACT sensor, and adjust the TPS, it seems ok. I have checked for vacuum leaks with the carb cleaner. I also closed the screw to the IAC almost all the way. The only time I can get the car to idle worth a crap is when I unplug the IAC. So my question is, can I leave the IAC unplugged indefinately, does it do anything except act like a choke?

 

[NO_RICE]

bump

 

[HISSIN50]

The cold start up and idle compensation (for A/C), etc are affected. However, with the very mild climate in here, I dont see why you cant set the warm idle a little on the high side and just use it like that. They do sell block off plates should you want to use one.

Good luck.

 

[RIO5.0]

Yes you can get by unplugged...it'll be fine, or let's say it worked for me...only problem I had was when the AC was on...cruising is ok, at a stop light shut it off or it'll die..you may get some random hot start/dying issues to, not all the time though...just out of nowhere...As Grady mentioned "idle compesation" thats the IAC's job...You live where its warm, your lucky...mines could run all Summer unplugged...come cool weather i had to figure out a cure...Full idle res-set should be performed....it lets the puter relearn...
This one worked for me....complete the steps you think are needed...step 3 mostly...

http://www.muscularmustangs.com/maintain.php

 

[urban96]

what brand TB?

when i first installed my BBK i had problems similar to yours, i had to fully close thelittle screw on the top of side of the TB. it allows the IAC to introduce air into the TB and controll the idle, closing it sort of bypasses it. you can then set the idle with the idle set screw on the other side (near all the throttle linkage)

 

[NO_RICE]

It is a BBK, It is closed all the way and the throttle stop screw is not even touching. the only other things I can think of are the MAF and timing. I haven't touched the timing in a long time, but I have seen stranger things happen. I have another maf laying around, but it is calibrated for different size injectors.

I bought the unit used, and I noticed that there was a hole in the blade at one time, that is now filled with epoxy.

One more thing, I unplugged the IAC, and on the way home from work I noticed the idle dropped really fast when I put the clutch in, making every shift really firm. Im just throwing things out there trying to hit on something someone has experienced before, thanks guys.

 

[HoofnIt]

Try what RIO5.0 said. I've been putting up with idle & hanging idle issues ever since my HCI. I just finished resetting the idle per that article's instructions & so far so good. I would also check your timing & TPS voltage. I hope this helps!

 

[NO_RICE]

I cleaned the maf and reset the base idle, so I will see what happens on my way to work tomorrow. I'll let you know

 

[NO_RICE]

Well it idles better now, but it still hangs a little bit. I realized that I reset the base idle with the IAC screw completed closed. I think I will try it again with that screw open. Now when I come to a stop it hangs a bit and I have to tap the gas so RPM will go up a bit then drop back down to normal idle.

 

[xr8d302]

Subscribing! And this is post 800!

 

[NO_RICE]

Well the idle saga continues....it ran alright for a while just acted up every once in a while but it still idled around 1000 rpm, so I decided to see if I could reset the base idle again. Well I did the first couple steps with IAC screw backed out just a very slight bit and the idle went way up. I couldn't get it to idle under 1200 with the IAC screw open even the tiny bit. So I didn't get through the whole process. I checked the timing (it was set at 8* to my surprise) so I bumped it up to 12*

So my questions:

1) I was using a paper clip and pulling it out during KOEO to reset the computer, does this work or should I disconnect the battery for 30 min like the tech article says?

2) does anyone have any other suggestions?

I am at a loss here, I don't know what else to do, I am thinking about putting my old throttle body back on if I can't get this worked out soon.

 

[91LX_5L]

you set your TPS, clean your MAF, Clean your IAC, Clean your ACT sensor. Try all those and you might have luck shouldnt take longer then a hour to do them all.

 

[HISSIN50]

No Rice, you are not forced induction are you? Way-back, when you got this car (after the fox), I thought this was blown (I remember doing a little drooling). True? That can make a difference.

I would disco' the battery to clear the KAM. 2 mins disco'd (or pressing the brake pedal, turning on the headlights, etc for 5 seconds) is enough to discharge the capacitors (longer is internet myth).

RJ has a slightly different method for setting the idle - if nothing else is working, I might try his method if all else fails.

Good luck bud.

 

[final5-0]

With all of these idle threads that seem to come up more often than in the past I think the reason is cause more peeps are going past typical bolt ons with their combos.

That means airflow during idle has gone up and so much so that the pcm has more trouble maintaining a stable idle.

A few things to think about................

The screw on the tb is not an idle set screw.
It is a stop for the tb blade to prevent it from sticking.

The idle is set in the pcm. That is not to say you can't play with mechanical things and get an idle rpm that is higher but when you do ... it is only because of the pcm's ability to be flexable.

That flexability of the pcm is what I find so interesting. Its ability to adjust for various things (drivability) can be so different for combos that are similar.

As for the isc, it along with the amount of air that is passed at closed throttle through the tb is a balance act kind of deal. If you pass too much air past the tb blade the isc is gonna freak and it goes the other way as well.

Never forget that the pcm expects these things:
1) an idle speed of 650 rpm IIRC (I'm at work at this time)
2) a defined value of airflow at that 650 rpm
3) a defined value of airflow at various rpms like 500, 650, 850, 1200, 2000

We go and put hot rod parts on our cars and items 1,2, & 3 are now way inaccurate and what can happen is that flexability in the pcm we talked about above, may or may not be able to stabilize the idle.

My thoughts for trying to find a stable idle on a h/c/i combo WITHOUT access to the pcm are these in this order ......................

1) Make sure your isc, tps, etc are ok and in good working order
2) Make sure you don't have any v leaks, bad electrical connections
3) Do a pcm reset
4) Make the adjustments to the tb blade stop screw and isc screw as instructed in the threads that have been given
5) Drive around for a few days without making ANY adjustments. This will give the pcm enough time for its flexability strategy to do its thing and allow you to see how much help your gonna get from it.

If you feel a need to adjust things a bit more don't forget to reset the pcm again.

Last thought is this .................................

The pcm can only do so much when we do things that cause it to not understand what is goin on and if those things are too radical... it freaks, lol.

Grady

 

[NO_RICE]

I forgot about the KAM, yeah it was supercharged when I bought it, but the powerdyne gave me nothing but headaches and terrible gas mileage. I sold it and the guy who bought it claimed it blew up on him! What a nightmare. I am going to mess with this thing one more time, thanks and wish me luck.

 

[NO_RICE]

Im about to drive this thing off a ****ing cliff. Friday I got so pissed that I change the intake back to the one that I had on it, and took out the spacer, I changed the elbow back and was going to change the throttle body back, but the TPS does not fit in my FMS 65mm TB, it is too big. Now I don't know WTF to do. I think maybe BBK TBs are just ****. It idles worse than before now it sits at 1700rpm when I come to a stop and drops to 1300 when I have been sitting there for a while.

 

[HISSIN50]

Are you sure you dont have a vac leak right now (after the intake swap)? That is what it sounds a bit like to me (notwithstanding any tune isses).

Dont get discouraged. But if you do and decide to torch it, let me know and I will come get the car first. I will buy a junker and leave it with you for pyro experimentation.

 

[NO_RICE]

I checked for vacuum leaks again sprayed carb cleaner at every joint...nothing. I unplug the IAC when the car is sitting at 800 rpm when I first start it, then I give it a rev, sits at about 2000 for about 3-4 seconds then drops to 1300 and will not drop below that. I cannot figure this thing out. Vacuum seems to sit steady at about 14" Hg (this sounded a little low to me but I do have 1.7 roller rockers) I check tps voltage one more time .910 at idle, moves to ~4.50 at WOT. looks like the movement is pretty smooth. I think I might just buy another tps and put the FMS TB back on, that would leave the car with nothing more than a cold air tube from the last time it idled correctly.

 

[NO_RICE]

UPDATE:

took the BBK TB off and replace it with the old FMS TB and the thing runs like a champ, I didn't have to set the base idle or anything, just started it up and it ran. I have now completely lost all faith in BBK products. I have also realized, that though not always aesthetically pleasing, Professional products (edelbrock knockoffs) are better designed than original edelbrock parts. oh well I learned several things is the midst of all this madness. Thanks HISSIN

 

[HISSIN50]

Nice work man - glad you got it whipped. After having read enough on here, half the products out there seem to have bit one person or another at some point.

Being up and running is what matters.