So, when i start my car, it will run in park at around 1500 rpm for a few seconds then drop to around 1000 rpm and stay there. When i put the car in drive, the engine will surge and lag back and forth while idling and on the initial acceleration. The sooner i put the car in drive after starting the worse the surging is. After the initial acceleration, the car will run good although, it does idle at 500 rpm, which seems low to me, but it doesn't surge or lag anymore. i don't have any cel's or any other lights on in my dash. This is a 2001 Cavalier with a ld9 engine and auto trans. What is the normal rpm for an idling ld9 and what might be causing this surging and lagging?


There's no pain like wrecking your first J

I have this problem to. I have no idea what's the problem ,Mine is a 98 2.4 lt man. ... Things I done: cleaning the intake and throotle .. checked the spark plug ... looking for a vaccum leak at the engine and intake... change the gaz filter .... change one of the O2 sensor plug the car on a scanner ... and we found nothing .... and the thing that pissed me off is that cel is off...... I anyone have a clue whats the problem let me know .... thanks

Those symptoms point to the Idle air control (IAC)

could be the IAC....but do me a favor...unplug your 1st 02 sensor..the one in your manifold..just unplug it and let it hang..then start the car and drive it a bit..then tell me how it acts

allready done ... because the one on the manif is a brand new one ... at the begining I had a cel on for this sensor .. so I changed it .. and it still doing it ... I even put the scanner machine on it ... and we found nothing .... the only thing left is the injector cleaning machine .... I have a appointement next week .. I hope its the prob ... thanks for the reply guys ... I will let you know if it worked

Quote:

allready done ... because the one on the manif is a brand new one

hahahaha you pretty much just pinned it for me...i can almost garuntee thats the problem now.....unplug the NEW sensor you just put in....and run the car with it unpluged.....this will NOT hurt the car...do this and tell me how it drives

You are right scott (section8cav ) ...Its stopped when I unpluged the O2 sensor .... do you think Its the new O2 sensor that is defect or a problem with ecm because It whas doing that with my old sensor ???

most likely the BRAND...that idle problem is common of bosch o2 sensors from autozone or the like...we have to use ACDELCO o2s ONLY...theres something about how fast they heat up..or the signal..or something..all i know is change the brand and the problem will disappear......and in the rare occation that it happens WITH a delco sensor then its most likely defective and go get another one.....also this rarely if ever sets a CEL ...mine was bad for a year and never set the light or a code.....

its a Delco .. I'm going at GM tomorow to change it .. I hope its the problem.. I will let you know after the change.....

update ... I still have the same problem with the new 2 sensor ( its a Delco )... and when I unpluged it .. the car run nice ... so does anybody have a clue whats the problem ..is it the car computer or something else .. I dont know what to think about that anymore ......

How many miles have you put on it since the new o2 sensor change? If the other one was defective and reading wrong the computer would have changed it parameters to compensate. So maybe the computer hasn't clear adjusted or you might have to unhooke the battery for 10 or 15 mins to reset the computer and try. also with the o2 sensor brand i have my wideband o2 in place of the factory with the ouput on it set to narrowband settings and have no surging problams but is also on a 2200. I'd say iac or maybe fuel pressure becuase 500 is low i though 2.4 idles at 800 any way?

after a week with the new sensor it stll do the same thing .. I unplugged the battery for a hour ... and its still do it ... only when I unplugged the sensor it stop doing it ... maybe there's a problem with the wired betwen the computer and the connecter of the sensor ?? .... hope to solve the problem soon !!!!

dont have a crimp on it do you? it has the proper connector still right?

yep the connector is #1 .. I'm starting to think there is a problem with the wired betwen the connector and the computer ....

if I have the time I will take a small video when I start the car and send it to you Scott so you will have maybe a idea ...

I have the exact same problem but it only happened when I changed from the Bosch to Delco. It was really bad in the beginning but I was told that the carbon build up was causing it. I ran Seafoam through the throttle body once a week for 3 weeks and it seems to be better. It still sputters a little, for like 3 secs, but no where near as bad. Try Seafoam as well as running around @ 4500 - 5000 rpms for a few miles to burn off any carbon build up.