Coblasts

Heres some info that might help you understand what is going on


Normal Mode
During the operation of the throttle actuator control (TAC) system, several modes or functions are considered normal. The following modes may be entered during normal operation:

• Minimum pedal value--At key-up the powertrain control module (PCM) updates the learned minimum pedal value.

• Minimum throttle position (TP) values--At key-up the PCM updates the learned minimum TP value. In order to learn the minimum TP value, the throttle blade is moved to the closed position.

• Ice break mode--If the throttle is not able to reach a predetermined minimum TP, the ice break mode is entered. During the ice break mode, the PCM commands the maximum pulse width several times to the throttle actuator motor in the closing direction.

Joel

That's what I was thinking, I don't get it. I drove it 26 miles to work today and it didn't get any better. I'm wondering if one of my sensors is bad. I looked at the throttle body and it seems to close up fine, nothing is bent or seems wrong. I just don't get it. This sucks.

no_mo_tires

my buddy 06ion2coup is his username had this problem on his 2.2 when he put the 2.4 manifold and TB on his 2.2 so you might PM him , could be something simple I dont remember.

Joel

Well I put my brother's Throttle Body on my car and it works fine, so I'm thinking the Throttle Body needs to be replaced. Lame.

Red07SSNA

Actually, the TBs on the Cobalts are double spring-loaded. At rest the throttle blade IS NOT closed...you have to force it into the closed position and shouldn't see very much light when it is held fully closed. When you turn your engine off and listen closely you can hear the TB reposition itself from fully closed -- this is so the engine doesn't run on after shutting it off.

Coblasts

Try spaying some wd-40 on every thing that moves or rotates.
when you cleaned it the lubrication came off of the moving parts and they are now sticking a bit causing the problem.

Joel

Well, after ordering another throttle body, it's still doing the same thing. I don't understand. It's like it's not relearning where to set the idle position after I cleaned the original one out. What's even stranger is that it worked ok when I used my brother's throttle body. Any ideas?

shawn672

because the new one was clean, and your brothers was a tad dirty?
the small amount of crud buildup helps seal the TB at idle

drive it for 5k miles it should be fine

Joel

There has to be a way to reset it, I shouldn't have to get it dirty for it to work properly. And why haven't all the other people who cleaned out their TB's had this problem?

Red07SSNA

Dealer time????

outtamymind

you think thats bad. mine during the day if i go to stop when i put the clutch in the rpms jump up to about 1500 and i've seen it go all the way up to 3000 when i'm on a decline. but it doesn't do it in the morning.

Joel

Yep, that's how mine is too. Its so annoying.

outtamymind

ya then i'm in the same boat. and i work in a shop full of GM techs and we can't figure it out. i think its the barometer cuz it only does it when its mid dayish. never in the morning.

xxxxsh4d0wxxxx

iTrader: (1)

What did you clean it with?

If you use anything other than special TB cleaner, you most likely fucked something up.

shawn672

he didnt mess anything up since: when he uses his brothers dirty TB, it works fine
only messes up with a clean tb

try dc'ing the battery over night?

BCobaltSS

I cleaned out my TB and the IDLE was speratic. I disconected the battery and the ECU did a re-learn and everything was fine after that

umrdyldo

iTrader: (1)

I had a problem with putting the 2.4TB and Manifold on mine. I was an idiot and put the metal adapter on from the 2.4 manifold swap kit, which is not needed when you have the 2.4 TB and 2.4 Manifold together.

Joel

I've heard that unhooking the batter doesn't do anything. Is that not the case? I guess it's worth a try, I'll do it tonight. I wish there was a way I could just get all the carbon back in there. It takes time to build up 93,000 miles worth of carbon...

umrdyldo

iTrader: (1)

Of course unhooking the battery won't fix something like a leak, but it will fix the fuel and air tables to compensate for new mods.

I"m guessing reseting the computer won't do ****. I'd guess you have a leak or something . Recheck all connection from the Manfilold to TB gasket all the way to your intake filter.

NWAE Cobalt

iTrader: (1)

if you hurt your tb i have a one you can buy

Red07SSNA

Honestly I think you were just fine from start to finish...it is a misconception that disconnecting the battery resets the learn values. According to the factory service manual you have to do an erase of DTCs (even if you don't have any DTCs) to reset the learn values.

I'm beginning to believe that many of these erratic idle- after-TB-cleaning is cleaning fluid getting into the TB wiring/connections. If incorrect voltage (too high) gets sent to the ECM it's possible it will have some detrimental effect too.

SportredSS

It's not the throttle body, sensors or hoses knocked off.... It's the driver... I tested this theory 4 times: When I changed from letting the car(slow in gear {Preferably 4th}, right foot lightly on brake, left foot disengage clutch once rpm falls under 1800 rpm)>>>>> to using the gears to slow the car {which rasies rpms}, my idle would jump up to 1500 rpm from normal 800 rpm when stopped at a light and bounce a little even....... Went back to letting the car slow in the gear its in {typically 4th}, the rpms dropping- not rising, and take right foot off throttle and put on brake lightly, car continues to slow, rpm still dropping, then disengage clutch at 2000-1800 rpm or so... and apply light braking... No more high idle...... When a person uses the gears to slow, the rpms jump up and the ECM remembers this and plays with the idle speed at a stop.....

DONT USE YOUR GEARS TO SLOW THE CAR DOWN....... It's that simple ... I've tried it too many times now....

NWAE Cobalt

iTrader: (1)

i ALWAYS use my gears to slow...ALWAYS and dont have this prob

slowswap

That's wrong.

Joel

I don't use my gears to slow down, and never have. It's a stupid way to drive and causes unnecessary wear on the clutch.