did an oil change yesterday. put in 5qt (this is generally enough, even after draining for an hour.. don't think I've ever gotten 5.2 in), started the engine up to circulate the oil. Was pretty cold so engine was idling around 2k. I blipped the throttle once up to about 3k to circulate the oil, and after I took my foot off the throttle, it started going crazy. The RPMs dropped back to 2k, but then proceeded to rise and fall between 3k and 2k 5 or 6 times, like I was blipping the throttle. Anyone experience this before? After it stopped, I never saw it again. I'm not worried, just curious

 

Sounds like you have a sensor problem... have you tried wacking the MAP sensor???

 

And Idle speed surge of 2-3K rpm is usually from a faulty IAC motor. If the idle is currently stable, don't worry about it.

There is also no need to blip the throttle after you started the engine to circulate the oil.

 

I second the IAC motor, I've seen this quite a few times. The rotary vane is sticking. If it comes back, you can pull the valve and spray it with WD-40. Works great.

 

I agree, actually I have no idea about the IAC. However I agree you shouldn't blip the throttle when you start or are warming up a fuel injected vehicle. Didn't that used to really screw up the computer/ECU in very early fuel injection systems? It is my understanding that although blipping the throttle on a modern fuel injected vehicle does not really cause any lasting harm, it does however still confuse the ECU.

 

It's possible to induce a idle surge from "helping out" the idle speed with the throttle, but not common.

Cold engines flood much easier than ones at operating temp. Some drivers had a bad habit of pumping the gas on a EFI car just like they used to on a Carbureted one. Which would flood some cars.

 

I remember a guy years ago who had a like an 88-91 8cylinder T-Bird. He supposedly fried the ECU by gassing it while warming it up. Have you ever heard of such a thing? I knew the guy and the car, but I got the story as to what happened second hand.

 

EEC-IV controlled Fords are well known for reliability (or any Ford for that matter) I bet the ECU surrendered to go to it's happy place.

 

well I never did it before on any other vehicle, but xviper said to do it in his oil change write up, so I typically do it two to three times on the S.

 

mine does that too, but only for the first 3 minutes when my engine is cold, then it backs down to 1K