Idle screw/TB screw

Mark K · Post by **Mark K** » Tue Feb 21, 2006 10:34 pm

Hi Guys,
Was just wondering about the screw on the TB that connects to the accelerator cable thing and whether its a bad thing or not to adjust it?
Ive played around with it before so at the moment, im not too sure how close it is to the stock setting. But i fiddled with it yesterday so it revs a bit higher at idle (the accelerator pedal feels tighter too, which i really dont mind at all).
But yeah, i was just wondering if it can cause any problems or anything like that.
Cheers,
Mark

Audacity Racing · Post by **Audacity Racing** » Tue Feb 21, 2006 10:36 pm

it's just to make sure your car idles right depending on your elevation and engine breathing requirements. play with that all you want to achieve the best "tune" for your pedal and idle

Mark K · Post by **Mark K** » Tue Feb 21, 2006 10:49 pm

Depending on elevation? I dont get it, but thanks for the reply, its good to know im not doing anything i shouldnt

Just reminded me actually and ive been meaning to ask about this... a friend of mine reset the computer a long while back n the car basically hasnt been the same since.
When i start the car, the engine starts, the CDplayer starts... but thats it, no dash lights, no seat belt warning, nothing. Even the headlights seem weak.
They all start to work when i rev the engine. Sometimes i can even make digital clock on the dashboard get brighter when i rev the car

Im also thinking it may have affected the performance.
Since he did it, its been a really bitchy and temperemental car. The reason he reset it was coz i put an air filter on there, thats it.
Was it really necessary to rest the computer in the first place?

Thanks again, sorry for the long post,

Mark

MMamdouh · Post by **MMamdouh** » Tue Feb 21, 2006 10:54 pm

ECU reset doesn't hurt.

dimming and brightning is a ground wire(s) issue.

i'd leave the TB screw untouched... make sure your car idle at 850 RPM (lanos) or 900 RPM (nubira or Leganza).

MMamdouh

BosnianLanos · Post by **BosnianLanos** » Tue Feb 21, 2006 11:09 pm

If everything powers up and gets brighter when you rev your engine, it usually means you have a trippy alternator (generator). Maybe your friend managed to short it out when he reset the ECU.

Slammed · Post by **Slammed** » Tue Feb 21, 2006 11:53 pm

umm how would you reset your ecu??

panther · Post by **panther** » Wed Feb 22, 2006 12:58 pm

Depending on what car but the idle is usually set by the ECU and is not adjustable. You can move the screw on the TB to make the revs higher or lower but as soon as you re-start the car the ecu will automatically adjust the idle to the correct specifications (on a Lanos around 850rpm). If you move the screw too much it will be outside the parameters of the ecu to control.

RichieOzzie · Post by **RichieOzzie** » Thu Feb 23, 2006 9:39 am

DONT TOUCH!!!

This affects mixture, low speed driving etc.....

there is a setting of about .450 volts at 20 degs(from the potentiometer at the other side of the B/fly shaft), engine off. IT IS pre-set, i know, i have just ironed mine out.

only way to set is to go to get it done at a Woo garage, but then....

Seriously, heres what did mine.

Grease Monkey at the local test station changed mine, he said the emissions were out, so adjusted as he thought was near. IT actually was a stuffed CAT causing it. Changed cat, and jeez, it jumped about at rolling speed, and was VERY jerky to drive, it even caused mis-fires on Freeway!!

Try going back and getting him to put it back man!!

IT IS not an idle screw, the ecu uses sensors to determine idle speed, nothing else changes it. This screw sets mixture via initial throttle setting voltage.

Audacity Racing · Post by **Audacity Racing** » Thu Feb 23, 2006 2:53 pm

guys... it's just the butterfly backstop adjustment. it's not that dangerous of a thing. the point is that you can adjust the throttle stop where you want it. if your TPS is messed up because of that, then you need to look at the TPS mounting, not the screw plate on the other side. in the manual it is listed as the "Idle Speed Control Screw." it does nothing more but change the amount of air going in at idle.

if you adjust it, do so with the car on so you can tell when you choke it too much, or push the revs too far. in an auto, if you are moving fairly quickly, you know you set it too high. if you have a high stall torque converter on your tranny, you may want it set high so that you engine will climb revs higher and you launch better.

it's fine to mess with it as long as you don't push the car too far out of adjustment, which would be painfully obvious by you still moving even though you have the brake on and are in drive, or your car sputters and tries to die.

Mark K · Post by **Mark K** » Fri Feb 24, 2006 5:45 am

Well i havent touched it since i changed it (which was about 3 days ago), and i dont think i will change it.
Purely due to the fact that i like how its going now. If anything i may hav even set it back to its normal position without even knowing. (did i mentione that i had fiddeled with it in the past?)
Plus i didnt adjust it too much, i just wound it in just enough to hear the engine noise change slightly
It actually sounds much healthier now and its much more consistent performance wise.

RichieOzzie,
Ive noticed that its a bit jerky at rolling speed (only slightly coz i didnt adjust it much remember).
I would tend to think that because the cord connected to the accelerator is tighter, it would maybe close the air intake quicker? Maybe not giving the car time to match the revs with the speed? Something along those lines? (speaking totally in theory here trying to justify why it jerks as it does

)
At higher speed however it hold the revs alot better... It takes longer for the revs to drop when u take your foot off the throttle.

Mark

RichieOzzie · Post by **RichieOzzie** » Fri Feb 24, 2006 3:37 pm

Adjusting this screw alters the position of the Butterfly valve shaft axially......

.......The other end of the shaft that holds the Butterfly in place(known as the Butterfly valve shaft), engages with a slot in the TPS and changes the position of the TPS's internal workings(a Potentiometer), which gives out an analogue voltage, for the ECU to read,......!! essential for engine fuelling.

The T.P.S. is one of the sensors the ECU uses to make the decisions on how long the Injector opening pulse should be on lo-mid throttle openings, and thus fuel to air mixture. Sure, opening the B/Fly valve will allow more air into the Intake, but out of range of the ECU's control..... No control, bad fuelling.... even kangaroo-ing when you feather the throttle!!!

It is not to adjust the idle directly, the stepper motor does this(Idle speed controller-By name, and it does what is says on the packet!!).

Look at the throttle body carfully, you will see that there is an orifice on one side of the butterfly valve, goes through to the Idle controller valve, and then into the Throttle after the Butterfly valve.

This little motor adjusts an Air-bypass valve, which as it says, adjust the air by-passing the Butterfly valve..... This adjusts idle speed, be it fast idle at warm-up, compensation for Engine loading, Alternator loading or normal idle.

If you open it too wide, the Stepper valve(Idle speed controller) cannot compensate for too much air, and not enough Fuel, and WILL cause rising and falling Idle speed, plus other things as well!!!. Worth keeping clean in this area too!!

Try closing the Butterfly alltogether, and the stepper motor valve will pick up the RPM for you. try disconnecting the idle speed controller, and then you can use the screw to adjust RPM, but put any loading on the idling Engine, and watch the RPM drop, and may even cut-out.... bad if you got an auto!!.

This setting also makes the car a little "Bichy" to use on normal road useage, which has been identified as a problem here!!

The setting of the TPS should be 0.450 volts + or - 0.06 at 18-20 degrees c coolant temp. And then the control of idle, and low-to-mid range throttle is back in control of the ECU, and is a good start point to use.

THIS SETTING has an effect on the mixture at lo-mid throttle, and that is why it feels like a Accelerator cable problem, actually, the mixture is out. put this sensor right, and i promise, you will find the engine more useable around town etc. On both of my Woos, it is the diff between one gear higher at the same speed... cos the mixture is right, and torque is being developed by the motor at the correct RPM for the Cam profiling etc etc. The T.P.S. setting is very important.

Lo-to-mid range throttle is where you drive around under normal circumstances. the TPS stops taking effect at 60% throtle opening, and relies upon info coming from MAP, AIS, coolant, Crank speed sensor and Lambda sensors to fuel correctly.

Probably why it is ok when going for a "thrash about", 'cos the throttle is Wide Open.

If you want, i can write how it is done, and give more details, 'cos it sounds like yours may well be out a litlle, but like everything, it changes with age, and should be set-up periodically.

Daewoo garages have a plug-in tool to set it up, if you dont want to attempt it at home.

MMamdouh · Post by **MMamdouh** » Fri Feb 24, 2006 6:04 pm

RichieOzzie wrote:If you want, i can write how it is done, and give more details, 'cos it sounds like yours may well be out a litlle, but like everything, it changes with age, and should be set-up periodically.

Please do.

MMamdouh

panther · Post by **panther** » Fri Feb 24, 2006 8:29 pm

Yes please post the TPS set up procedure.
If the TPS / butterfly is not in the exact correct position, For smoother low to mid range throttle is it generally better if the butterfly is too much closed instead of too much open?

Brian5475E · Post by **Brian5475E** » Fri Feb 24, 2006 11:30 pm

You don't have to take it to a daewoo dealer to set the TPS. just use a Ohm meter. With your leads on the TPS and a closed throttle adjust to factory specs and tightened. it's simple, I've done tons of TPS's

MMamdouh · Post by **MMamdouh** » Fri Feb 24, 2006 11:43 pm

i got to ask this... is the TPS adjustable?? the way i see it it is only held by 2 screws and thats it... no latral or horizontal adjustment available.

when i replaced mine myself i just slapped the thing on the TB and thats it... is that wrong??

MMamdouh