Startup issue

[Mstng93SSP]

I am having an irritating issue. Lets say an initial startup on a fox goes something like this. Fires up, rpm goes to around 1100, then slowly drops to 1000, the slowly settles down to idle rpm of 850ish (or whatever your normal idle is) and then idles normal. What mine does is this. Fires up, rpm goes to around 1400 for 1 to 3 seconds, then quickly drops to 1100, and then slowly to 1000, and then slowly drops to idle as it should normally. So, everything on my startup is normal except for that initial 1400 rpm for 1 to 3 seconds before dropping to the normal idle sequence. I scanned and got no codes to indicate a problem. Other than this the car runs and drives fine. I have had two different ECU's in the car, it did the same with both.

 

[General karthief]

Ever clean you egr or your air idle control valve?

 

[jrichker]

You guys with idle/stall problems could save a lot of time chasing your tails if you would go through the Surging Idle Checklist. Over 50 different people contributed information to it. The first two posts have all the fixes, and steps through the how to find and fix your idle problems without spending a lot of time and money.

Look for the base idle reset procedure to fix your problem. Unless you have a wild cam, the idle should be in the 650-725 range on a warm engine. Look for small vacuum leaks in the plastic hard lines that connect things to manifold vacuum.

 

[Mstng93SSP]

I have tried cleaning the egr and iap. I have spares, maybe I will try one.

 

[BlakeusMaximus]

I think my car does that too SSP. Only when it’s a cold start though.

 

[BlakeusMaximus]

I’m going to pull my intake off and redo it when I get it back home and I’ll probably replace all those lines.

 

[Mstng93SSP]

Yep. Cold only.

 

[General karthief]

I have a hard time starting when it's cold! And I stutter till after my first cup of coffee