Hi, I just installed a bypass control valve assembly with the vacuum tank and all for emissions, because when I got the car from the previous owner it was taken out. Now when I am driving if I come to a light and stop the rpms drop to like 200 then goes back up. Other times it will drop so low and stall out...I tried to reset the ECU, and still have the same problem. Also when it wasn't installed on the car my CEL was on, and it still is. I am gonna bring it to a friend to pull the codes. What do you think it is???

Thanks!

 

I'm betting that you'll get a P0411.

You probably don't have the system back the way it's supposed to be. Trace everything in this thread and see what you've got hooked up wrong:
https://www.s2ki.com/forums/index.php?showtopic=105368

Your idle going down may simply be the typical "hot weather, dipping idle, near death experience" syndrome that many S2000s suffer from. Your first issue is only relevent after a cold start as that system shuts down after a minute or two. This one is not associated with it. The fact that yours actually stalls is very annoying. Ordinarily, if you just leave it alone (IE, don't help it with throttle when it dips), it will learn after several episodes, but actually stalling can be a problem. You may need to look into a few things - wiggling the MAP sensor harness to ensure a good connection, checking routine stuff like air filter cleanliness, injector cleanliness and spray (injector cleaener), spark plug condition and gap.

 

Hmmm... does it matter if I have a ap2 engine??? Also it didnt do this before i put the stuff on...

 

No, both AP1 and AP2 engines have the same secondary air injection system (except for the '06) and both have had this dipping idle thing as well.
Maybe the operating conditions before was not the same (climate wise) as it is now. Also, having done such an implant, there can be all sorts of other things going on that can contribute to odd characteristics.

 

ya, all the lines are correct.... I am gonna get the codes pulled then post them back up

 

UPDATE!! got the codes....

P0132
p0141

 

P0132 = Primary Heated Oxygen Sensor (sensor 1) Circuit High Voltage.

P0141 = Secondary Heated Oxygen Sensor (sensor 2) Heater Circuit Malfunction.

There are a set a numerous tests that must be done, the end result (worst case scenario) being replacing the O2 sensor or sensors, fixing the wiring to them, replacing the cat or replacing the ECU.

Having no 2ndary air injection system on the engine for a time may have damaged one or both sensors or cat.

 

hmm, what tests are these that I should try??

BTW thanks for helping me out

Would this be the cause of why the car is running bad??

 

This may very well contribute to why your car is running crappy. The primary O2 sensor provides the ECU with information it needs to run the engine. The secondary (in your cat) is not so important for running the engine. It mostly monitors cat function.
I'm no longer at home where my service manual is, but nevertheless, the steps are extensive and covers several pages. I don't think I'm inclined to type it all out. This is best diagnosed by a dealer.

 

Not a problem. Thanks for all your help!