car lurching

[samus21]

when i slow to a stop at a light or stop sign my car's rpms drop to 700 then jump up to 1200 then when im at a complete stop it idles around 750rpms. what would cause this. I blocked off the egr but this was happening before I did that.

 

[undefined0000]

Boost leak, biss, is it cold? coolant temp sensor, isc. I'm trying to figure out why mine does this too. Try unplugging your throttle closed sensor. It helped me a bit

 

[samus21]

My car doesnt have a turbo so that cant be it. its 50 degrees. so its not terrible. usually it drives better in colder weather. did you mean iac? wheres is the throttle closed sensor on s 420a?

 

[undefined0000]

You might not have the throttle closed sensor because tps handles the same thing. If its not throttle related, it sounds like a vacuum leak. I have nasty ones and my car does the same thing. I think the computer notices the lean mixture and tried to fix it, and just can't, so you end up with crappy idle. I could be wrong though. Do a vacuum leak test by either spraying soapy water around vacuum connections, OR you can blow smoke into a vacuum line past the air cleaner and you should see smoke forming elsewhere. Seems like a pretty legit test to me.

 

[Roberti 2G]

2gs dont have knock sensors right?... i had same problem with my 1g but it was the knock sensor?

2g turbos have knock sensors I am not sure about the 420As