Idle Drives me NUTS

[mok86]

So i replaced all the bulbs in the back of my car with LED bulbs...because whenever i braked...the idle would drop. After i installed the bulbs, everything worked fine but the idle was a bit lower than i wanted it to be with my HIDs, rear defog and blower on. SO i tried adjusting through the IAC screw but that always resulted in a bouncing idle when brake is applied (weird). So i reset it to what it was before and then i tried to tighten the throttle cable a bit to try to boost the idle... but that also resulted in a bouncing idle.

keep in mind the idle is where i wanted it to be... but the bouncing drives me NUTS haha

any suggestions as to how to fix this retarded bouncing? it's only when the brake is applied... i've reset everything back to a non bouncing low idle state.

help? haha

[mitmaks]

any vacuum leaks?

[mok86]

no leaks

[Ryan]

Adjust the idle properly, using diag. mode.

I'm too lazy to get you a link, but its in the FAQ's somewhere. Or just search.

[mok86]

yea i did do it properly...10 and ground.. etc etc...even adjusted the tps and probably every single solution on this board haha...changed the TB, IAC with a working one from my friends car...changed ecu...

[Inodoro Pereyra]

yea i did do it properly...10 and ground.. etc etc...

No, not 10 and ground. TEN (Test ENgine) and ground.

[Ryan]

yes yes, same thing

You know how when your brain says one thing... and your fingers do their own translation? Yeah.

[Ninjaskill]

i have been having the same problem ever since my engine swap, i replaced the IAC, i set the timing and idle, cleaned and adjusted the throttle body and set the TPS.
and now it only happens occasionally and only when the engine is warm and it is cold out.
i know i have NO vac. leaks.
i know it is electrical because while the idle is bouncing i can reach under the dash and push the brake light switch with my finger while the brake pedal is being pressed and the bouncing idle will stop.

i am currently thinking that our alternators are just not holding up to the amp draw any more. but i dont have the $ to just replace mine even though it is still producing 14.5 volts.........
if one of us figures out this problem it will help us both.

good luck friend

[jmdearras]

My idle drops when the brake is pressed. I assume the engine CPU drops the idle to save gas when the brake was pressed, as you aren't going anywhere until you let it up.

Jim

[Ryan]

Its electrical load.... Thats a lot of 30W bulbs.

[jmdearras]

Its electrical load.... Thats a lot of 30W bulbs.

I don't buy that. The idle self-adjusts for any other load, and the brake switch is an input to the ecu.

Jim

[Ryan]

I buy it. Idle can't self adjust perfectly. It DOES kick up if you, say, engage AC, defog, full fan, aaaand brake. but it can't really self adjust for 50rpm. Plus, all other loads change the idle a bit... why are brake lights any different?

[PilotSmack89]

I've had the same problem. It was reeeeeally bad until I took off the TB and cleaned it (using the method described by Tunes67 in the 4Cyl FAQ). Haven't had a problem with it since.

However, it does still bounce, but only when the engine is hot, tranny in neutral, stereo cranked, sat radio on, lights on, fan and heater on full, AAAND brake depressed. But as soon as i let off the brake pedal, its fine again. Go figure

[jmdearras]

I buy it. Idle can't self adjust perfectly. It DOES kick up if you, say, engage AC, defog, full fan, aaaand brake. but it can't really self adjust for 50rpm. Plus, all other loads change the idle a bit... why are brake lights any different?

We'll just have to disagree, then. The RPM change is greater than 50 rpm. feels deliberate and repeatable.

Jim

[mok86]

i know its not the brake bulbs..all replaced with LEDs, very low power consumption.