Proper way to set idle?

Topic: Proper way to set idle? (Read 1615 times) previous topic - next topic

Proper way to set idle?

February 01, 2007, 06:28:06 PM

For awhile I just left the car as it was, since it normally idled fine but sometimes would out (especially after warm when put into neutral or park, drive worked fine). The TPS was set at 1.00v, idle screw turned completely out, and entire intake(w iac) carbon free. HO intake. According to the STOCK 'gauge', idle would settle at ~600 after warmup.

Here's exactly what I did, let me know if it sounds about right:
1) pulled battery cable for 30 minutes and reattached
2) unplugged idle air controller
3) start car, wouldn't run on its own
4) turned idle screw in
5) key in "run" position and adjusted tps from 1.5 -> 0.98v exact
5) started car and ran ~1000 rpm
6) turned idle screw down until the car began to stumble and bumped back up to a "smooth" condition.
7) turned car off, adjusted tps from 1.4 -> 0.98
8) repeat 6&7 - got slightly lower than before
9) ran for a couple minutes, ignition off, plugin iac, start up again and idle for another few minutes.

So far its at that and idles 700-750 according to stock cluster. Will this work as a "proper" idle setting?

Proper way to set idle?

Reply #1 – February 01, 2007, 07:40:43 PM

why did you unhook the battery?

Proper way to set idle?

Reply #2 – February 01, 2007, 08:13:07 PM

Clear ecu memory of any settings. Idle shouldn't be any different than any other part of the engine that the system has to learn, so I don't see any harm done in doing it. Is it not needed?

Proper way to set idle?

Reply #3 – February 01, 2007, 11:08:12 PM

Here's the fun thing about the stock digi dash. The bars on the tach are roughly equal to 200 rpms each. So if your car is idling at 4 bars it could be any where from 601-800 rpms :hick: . So if you have a digi dash and the car is idling at 4 bars when warm it's probably fine.

Proper way to set idle?

Reply #4 – February 02, 2007, 08:12:33 AM

I try and keep mine 1 bar under 1000 rpms and I'm happy. If your getting 700-750 rpms and its solid with no crazy rpm spikes and no stumbling/stalling I would leave it alone.

Proper way to set idle?

Reply #5 – February 02, 2007, 01:09:55 PM

Took it for a drive and it doesn't appear to have any problems after warmed up anymore. From a cold start, it doesn't want to stay idling high for more than 20 seconds though, which caused it to start dropping/stumbling once it started settling to "900"rpm's, but it pulled itself back up above 1k a couple times. Its acting the same way as it did when it'd drop to "600" rpms before on a cold start, but a bit higher on the tach now. I sorta liked the lumpy idle at "600" though, even if it isn't supposed to do that with the SO cam

I'm not sure if I can ignore this on the fact that the computer still needs to relearn some numbers. More than this though, long ago the car used to idle at a good 1500rpms for a couple minutes on a cold start before dropping. Is this controlled by the o2 sensors heating up?

I still don't get any codes for sensors, but no matter how hard or long I try, the sensors won't break free from the exhaust manifolds. Tried years ago to swap them out (who knows how old those things are, I've never replaced them in the 44k miles I've had the car) but gave up after nothing worked. Although all thermactor/egr systems are new and fully functional, I still get codes about them from lack of o2 sensor reading changes being relayed to the ecu.

I haven't gotten any more stalls when in park or neutral after warmed up though. Main problem solved. A lot of these problems I have to start attributing to the fact that the engine's getting up in age with over 210k. Not sure if it'll change after these tweaks, but still getting a fair 30-31mpg at 60mph, 27-28 at 75mph.

Proper way to set idle?

Reply #6 – February 04, 2007, 09:13:55 PM

Okay, settles to idling ~700rpm's in drive and 900 in park or neutral. Not a single problem anymore. No more cold start stuttering after driving around for a couple days. All's good!

Proper way to set idle?

Reply #7 – February 04, 2007, 11:03:45 PM

Is that the V6 or V8?

Proper way to set idle?

Reply #8 – February 04, 2007, 11:06:29 PM

i could post the procedure straight from the mitchell guide if you'd like.

Proper way to set idle?

Reply #9 – February 05, 2007, 01:37:56 AM

Quote from: jncocowboyx;127650

i could post the procedure straight from the mitchell guide if you'd like.

That'd work. I'm just curious what the "correct" way is to do it.

Its the 5.0, but I don't see why setting idle would be different on the 3.8, unless the tps voltages are different.

Proper way to set idle?

Reply #10 – February 05, 2007, 02:17:17 AM

alright. i'll try my best to remember to do it tomorrow.

Proper way to set idle?

Reply #11 – February 05, 2007, 11:35:11 AM

Quote from: Seek;127101

Here's exactly what I did, let me know if it sounds about right:
1) pulled battery cable for 30 minutes and reattached
2) unplugged idle air controller
3) start car, wouldn't run on its own
4) turned idle screw in
5) key in "run" position and adjusted tps from 1.5 -> 0.98v exact
5) started car and ran ~1000 rpm
6) turned idle screw down until the car began to stumble and bumped back up to a "smooth" condition. <-do not do this step
7) turned car off, adjusted tps from 1.4 -> 0.98
repeat 6&7 - got slightly lower than before
9) ran for a couple minutes, ignition off, plugin iac, start up again and idle for another few minutes.

So far its at that and idles 700-750 according to stock cluster. Will this work as a "proper" idle setting?

The car will idle high when you first start it up, at idle when the car has learned the new settings you will be able to unplug the iac with no noticeable change in engine rpm.

Proper way to set idle?

Reply #12 – February 05, 2007, 04:50:22 PM

Quote from: CougarSE;127716

The car will idle high when you first start it up, at idle when the car has learned the new settings you will be able to unplug the iac with no noticeable change in engine rpm.

I only get maybe 20 seconds of a high idle (1400 or so) before it drops to where it always is. The idle screw adjustment was made after the drop in rpm's. I'm pretty sure its not supposed to drop that fast, but I have no clue as to what controls how long the car is in "warm up" mode.

What would you recommend for setting the correct idle then? Obviously, thats the step where the first adjustments were being made as originally adjusting the idle, with the car off to get it to stop stalling with iac disconnected, put it just above 1000.

Exhaust smells like its running a little more rich than it was before adjusting everything though. Does a higher voltage on the tps make it run more lean? IIRC, rotating it clockwise raised the voltage and counter clockwise dropped the voltage. Wouldn't be surprised if its running more rich right now, as the voltage was extremely high (for idle) before I messed with it.

Proper way to set idle?

Reply #13 – February 05, 2007, 06:04:12 PM

If this is a 5.0L CFI, I can tell you what the 84 shop manual says if you are interested. I do not have a 5.0 so have no personal experience.
The CFI has two idle speed adjustments, Fast idle and Curb idle.
The adjustments are on opposite sides of the throttle body.

Proper way to set idle?

Reply #14 – February 06, 2007, 12:09:00 PM

i hope these might help.