my car starts but it idles low and then it stalls out after running a couple of minutes. If I try to accelerate just a little when it idles it dies but will start again. I scanned it for codes and got a code 33 and 35. Where do I start replacing IAC sensor or MAP sensor?
engine stalls and has engine codes on 1991 Chevrolet Cavalier
by lvp714 in Peabody, MA on April 14, 2011
ANSWER by Superbob on April 19, 2011
First thing: diagnostic codes do not mean that a part like the IAC valve or the MAP sensor is necessarily bad. Also, code 33 indicates that the airflow sensor is out of range as well as the MAP sensor could be out of range. Code 35 indicates that there's an idle speed error. First thing I'd do is remove the IAC from the throttle body and clean it and the orifice it goes in. Also I'd clean the throttle body in general, throttle plate, throat, and all. then I'd check to see that there isn't oil or holes or kinks in the MAP vacuum line. The MAP sensor is attached with a clip to the engine bracket and has a 3-wire connector in addition to the vacuum line. Very likely, the cleaning at the throttle body and IAC will fix the idle. There may be nothing wrong with the MAP sensor, look for vacuum line problems first. If none of this helps, it may be that the parts are indeed faulty or that the airflow (MAF) is defective. It's good to have a meter and check things out but replacing parts is cheaper than buying a meter that could help diagnose these problems. Good Luck with it. If you want to find a specialist, here's a directory link for you: https://repairpal.com/directory?address=01960&car_brand_names=Chevrolet