Hey guys-

I've noticed recently that when I start the car or put it into park/drive, the rpms dip pretty low, like the car is almost going to stall out. It idles fine, but initially dips pretty low and then runs fine. I've been looking around but can't determine the culprit. I don't have any crazy audio system (base system w/a single din) or anything like that so I've narrowed out any draws (hopefully). I've switched tunes a few times recently, and did the throttle body bypass, but other than that, nothing much has changed.

Any ideas?

 

I have a similar issue but not as severe. Mine happens when I am driving and put it into neutral while slowing down for a stop light or w.e (I have an auto), it will drop down to like 500rpm right as I am about to completely stop than it will bounce right back up to normal. I think when I install my s/c I am going to clean the throttle body and see if maybe thats it

 

It possibly ould be something dealing with the fuel lines or something to that effect. I hope not but it could be likely since the rpm's come from the fuel igniting in the engine. Good luck!

 

Sounds like a vacuum leak possibly, mine does the same thing... Sometimes!

 

Clean the TB, MAF and replace the fuel filter for starters. If you haven't cleaned the TB then that's where I'll put my money, providing it's not an active component that's degrading.

 

That's what I was thinking. Fuel filter was replaced last fall, so I don't think it's that. Gonna clean the TB and MAF and see if that works and will report back

 

I'd do the TB first and see if that resolves it. No sense messing with the MAF if it doesn't NEED messing with.

 

True, I'm now wondering if when I did the throttle body bypass if maybe I got some dirt or whatever in there. I tried to be very careful, but it's definitely possible. IIRC the TB looked dirty but I didn't have any cleaner at the time

 

I get the impression that the TB, as it builds up some gum and varnish, doesn't provide a lot of symptomatic signs until it's pretty bad and then it just acts up like someone threw a switch. At least that's what I'm getting from reading these threads. I have over 36,000 miles on my Stang and haven't cleaned the TB yet. I may just do it before it acts up just to see if I notice any change.

 

I have the same issue, i cleaned my tb, maf sensor, ran seafoam, changed plugs, fuel filter, and re-ran the idle learning procedure. Although it did fix my issue with rpm dropping when ac kicks on, my car has the same issue as yours, rpm dip when i switch it in gear. I hate it, cause when that happens it dips low enough for my exhaust to vibrate, but i have not found a cure yet. Other than that the car runs great.