For a whiole, when i start my car, the idles is normal, biut when i press the gas wether i wait 4 seconds or 2 minutes, the time i press the gas, the car starts stumbling. If i hold the gas pedal, it stalls. What i have to do is sit there and wait for it to smooth back out (about 10 seconds). ANd then the car drives fine. It is weird though becuase it only happens when the car is cold. If I start my car, drive for 10 minutes, park, and start up 5 minutes later, it is fine. Occasionally it stumbles, but very lightly.
When it stumbles, the RPMS jump up and down as low as 200rpm to 2000rpm. Usually 3-5 times and it smooothes out. Lately I have noticed the stumbling gets worse, and my car feels a lot slower. I have a 1998 z24 with many bolt ons, and when it was completely stock, my tires would peel out when i shift from 1 to 2 gear. Now, no matter how hard I try, it won;t peel out.
FYI my Cruise control does nopt work, and it is becoase of this problem!! I know for sure becuase i replaced my motor (through a rod in my last) and the stumbling wasn't there any more, and suddenly my cruise control worked again, but the next day i started stumbling again, and the cruise conmtrol stopped working.
WHat do I need to do??
You should have an engine light - especially since the problem has disabled your cruise control. Your computer knows your engine is not running properly and won't allow your cruise to engage - it should be given you a trouble light too.
When you turn your key one click (so that the dashboard lights up etc) check that your check engine light is showing, and that the bulb is not burnt out.
If the bulb is burnt out, read the code to see where you go next.
no CEL. I had the ECU scanned anyway, in case the light was burnt out, but the OBDII scanner read no codes found.
I have narrowed it down to 2 things. 1. a vacuum leak, and 2. bad fuel pump (low fuel pressure at start up, and fuel pressure slowly builds after stumbling ends.
I have to say that the vacuum leak is out. I had the same problem with 2 engine both with the same mileage. It is close to impossible that both engine had the same vaccuum leak, and one thing in common is that the fuel pump has been on the car through the 3rd enine swap. I thing my fuel pump is bad. Just to make a note, the fuelpump sending unit, which measure the amount of gas in your tank is bad on my car. It stops at a 1/4 tank and stays there until you run out of fuel.
