My idle drops right after start up then comes back up???

[2000_SSEi]

New to this forum. I just bought a 2000 SSEi last month off Craigslist with 118k miles from the original owner. I'm having a weird issue every time I start the car that it had when I bought it... As soon as it fires up the idle IMMEDIATELY drops to almost stalling then IMMEDIATELY jumps right back up to normal idling RPM, it never actually stalls but feels like something that isn't supposed to happen. No SES or any other warning lights on.

I just replaced the MAF to resolve a random stalling issue it also had when I bought it, but it didn't fix the idle quirk too so I'm guessing it's a separate issue. It also has a little bit of a long and sloppy start after it sits overnight, but it starts up fast and smooth the rest of the day after that 1st initial start of the day. It seems like it could be a fuel pressure regular issue, but anybody have any ideas here??? Would appreciate any comments.

[96 SSEi]

normal maintenance - plugs, wires, air and fuel filters - unplug the vacuum line from the fuel reulator, there should be no gas or smell in the line

[nos4blood70]

Welcome to the club!

As mentioned above, basic maintenance can go a long way. I would also remove the IAC sensor and give it a good cleaning.

[redfury]

I agree, clean the throttle body/IAC of any carbon. It could be a partially plugged EGR valve as well. My car starts, drops idle and then evens out and there's nothing wrong with it. Usually it just depends on how cold it is. The computer will always start the car on the last known good starting parameters until it discovers better ones. Check the large vacuum connection by the throttle body that goes to the fuel pressure regulator and the evap solenoid on the front of the engine. You can't just "buy" a new one, you have to order the hard lines and the fitting for about 30 bucks...or fix it with a little liquid electric tape and a large piece of shrink wrap like I did. Got the large shrink wrap at Menards for 4 bucks...makes 3.

[maxi426]

As already said, clean the throttle body bore real well with carb cleaner right where the throttle blade rests at idle. You'll have to remove the throttle body to do this. Sounds like the engine isn't getting the air that the PCM assumes is entering the engine. May want to replace the PCV valve with a AC delco valve, just in case the valve has been changed to one with an incorrect amount of air flow. Aftermarket valves are known for this.

[MajorsSerj]

Hello -

I too have a similar problem as 2000_SSEi has mentioned with my 2003 SLE with 140k miles, however my situation is after the car has been driven for awhile with a warm motor, it will either start and then stall or it will not start at all until after 5+ seconds and I would need to give it some gas as it turns over to prevent it from stalling. After that it will stay at a normal idle but the smell of gas can be smelt near the exhaust. I will try the tips given to 2000_SSEi as well to start but am wondering if my issue is more complex as it does stall on me.


Thanks,
Mike