My car suddenly, and when I mean sudden, I mean the car was running fine, I ran into the beer store, came back out and started her back up and now she idles ridiculously high. My 2002 Cavalier Z24 normally idles at the normal rpm of about 950. Now, out of no where, she decides to idle anywhere between 1300 and 1700. Let me explain the symptoms as they're very specific:
Symptoms
-When the problems first began, the car would rev all the way up to 2000 RPM on startup and settle at 1500 and rhythmically fluctuate between 1500 and 1600 RPM.
-Now, (after replacing the IAC valve) the car starts up much more gracefully and settles at about 1300RPM where they fluctuate, again, rhythmically between 1270RPM and 1350RPM.
-Shifting is a damn chore. I have to wait about 1.5 seconds or so for the revs to fall to the correct RPM while shifting.
-I can roll around in 2nd gear at 1000RPM just fine in a parking lot, but as soon as I press in the clutch pedal, the revs shoot back up to about 1500RPM
-Throttle reads 1.2% at idle.
What I've tried
-Cleaning the throttle body and the IAC Valve
-Replacing the IAC Valve
-Disconnected the Battery for 10-15 minutes and then reconnected. Then I turned the car to ON for 60 seconds, then started her up. This resulted in a much smoother startup and lower idle speed, but it's still way too high. So I don't think a broken IAC is the issue. (waste of $80)
-Adjusting the cruise control cable.
Pertinent info:
-2002 Cavalier Z24 2.4L with 168,000 Miles
-Fresh Oil Change
-Coil pack housing and sparkplugs were replaced last spring.
Idle readings
Idle Fluctuation NOTE: I'm not pressing the throttle AT ALL
Please help!
Also forgot to mention, 5 Speed Manual, no Check Engine Light or trouble codes.
TPS issue perhaps.
I would check the voltages in and out of the sensor.
"A car just isn't a car without a little blood, sweat, and beers." -- Shadowfire
Matt Linke wrote:TPS issue perhaps.
I would check the voltages in and out of the sensor.
Just replaced the TPS. Now throttle position at idle is 4%. Did a hard reset and a relearn technique I found online. Didn't help at all. The car is now impossible to drive.
I re-read your first post. Did you check for vacuum leaks?
"A car just isn't a car without a little blood, sweat, and beers." -- Shadowfire
Matt Linke wrote:I re-read your first post. Did you check for vacuum leaks?
Not exactly. I replaced the one vacuum hose that goes from the throttle body to the MAP sensor and that helped the idle and startup a bit. But as soon as I changed the TPS, it just got worse. I've been reading anything and everything I can. Some of the information on this site seems risky. I've read multiple times that putting your finger over the IAC hole in the throttle body or over the throttle body and general is a good way to gauge if theres a vacuum leak. The car should stall, if it doesn't then there's a vacuum leak. Correct?
I'm also going to try disconnecting the battery for 10 minutes to see if that helps with the throttle percentage.
Mine randomly reports tps voltage at idle. Idle never changes for me though. I've seen it as high as 10%.
I would use a volt meter to check the actual voltage through the sensor. One wire should be 4.5-5v with key on engine off. One ground, and one should be .5-4.5 as you cycle the throttle with koeo.
Check all vac lines.
"A car just isn't a car without a little blood, sweat, and beers." -- Shadowfire
Matt Linke wrote:Mine randomly reports tps voltage at idle. Idle never changes for me though. I've seen it as high as 10%.
I would use a volt meter to check the actual voltage through the sensor. One wire should be 4.5-5v with key on engine off. One ground, and one should be .5-4.5 as you cycle the throttle with koeo.
Check all vac lines.
I don't have a volt meter or anything. I actually just moved into my apartment at school and much of my tools are back home.
Steve D. wrote:Intake manifold gasket.
I sprayed the top of the gasket in every spot i could reach with carb cleaner, it did not effect the idle.
I did however seem to fix the issue, although I'm not sure for how long. I went back outside, disconnected the battery. I then cleaned the butterfly valve and IAC area more thoroughly and made it super ridiculously clean. This process took approximately 11 minutes. Afterwards, I reconnected the battery and started up the car. Perfect idle at around 950, 0% throttle usage at idle. Took her for a 10 minute drive. At first she still drove a little funky, but by the end of the drive, the old Cavy that I was used to driving was back. At the end of the drive, the idle was actually low, around 890 to 900. Sounds great, smooth, started up great. I'm hoping it lasts and isn't a temporary fix that some people claim it to be.
I'm fairly certain it is a vacuum leak. Probably at the MAP senor to throttle body hose. They are known to fail....
While idling pull the Fuel Pressure Regulator hose off, and see what the car does. Then pull the MAP sensor off the hose...report back.
PRND321 Till I DIE
Old Motor: 160whp & 152ft/lbs, 1/4 Mile 15.4 @88.2
M45 + LD9 + 4T40-E, GO GO GO
