Surging Idle

[raptor]

Ok brand new 331 stroker. At idle, the Idle goes low and high. I have an 88GT that is converted to 1990 Mass Air. I had this problem before with the old engine but not this bad.
Any suggestions??

[tmoss]

Always start by checking the basics: vacuum leaks, throttle position sensor voltage, resetting idle, cleaning the IAC, and pulling codes. Once all these ideas are checked out and crossed off the list, check the ten-pin connectors on the main harness. These connectors are notorious for developing loose contacts. Ford even issued a TSB on some model years, and dealers installed an "extension harness", thinking perhaps the original harness was too short causing the large connectors to pull apart.

The "ten pin" connectors are these salt and pepper shaker looking things found at the back of 5.0L engines -between the intake manifold and firewall. These connectors are notorious for developing poor connections and causing strange EEC quirks, like idle fluctuations, check engine lights, and unexplainable diagnostic codes to be triggered. On many Mustangs there may be a dealer installed extension harnesses, making it appear as if there are a total of four of these connectors.

To open the connectors squeeze the four side clips and pull apart. Do not pry the clips apart as with other connectors. The inner workings reveal ten male and female connectors. Using a nail or sharp punch spread the male connectors open just slightly. This will ensure a complete contact. If you open up the ends too much use needle nose pliers to sqeeze the "leafs" back together. Before reassembly, take some spray electrical contact cleaner and clean the male and female connectors.

After you have cleaned out EGR, IAB, TB, checked ECT, cleaned and tightened the 10-pin connectors, reset the idle, played with the TPS, on & on, and still no relief...idled smooth but now it takes way too long to DECELERATE, and hangs up around 1200-1300 rpms and then finally drop...real PITA to drive. Sound familiar? Without further embellishment. Here's a fix.

Start engine, turn idle adjustment screw counterclockwise reducing rpms to around 550-600. Blip throttle a few times and you should notice that the hanging high idle behavior is improving...i.e. it's actually decelerating the way it should and doing it's dashpot thingy at around 900 rpm. Fine, but now the idle is too low and almost gonna die. AH HAH! Not to worry. When you're satisfied with the rpms at which the IAB is doing its thing, shut off the motor. Set TPS to a pretty low setting like .87 (it's probably already at a low point because you've turned down the idle so much.) Disconnect the battery for 20+ minutes and do the reset idle drill according to the corral tech instructions except DO NOT touch the idle adjustment screw. Now the engine will still be loping along at 600 rpm. Don't sweat it. The goal is to teach the IAB some manners with a new memory by which it will do its thing. So now you've done 2 minute idle drill with accessories off, shut off the motor waited 2 minutes, started it with all electrical accessories on for 2 minutes etc., & shut off engine. Now the engine decelerates fine with the IAB doing its thing at around 950 or so but now you're stuck with a way too low of an idle. NOT!!! Start motor, turn idle adjustment screw clockwise to increase rpm’s. Adjust to the desired rpm’s. Blip throttle a few times and now you've got smooth idle at around 775+/- and you're not hanging high anymore. If you're a TPS freak you can measure it and discover it's around .93-.94 (at least mine was) which will still give you some room to make further tweaks.

[raptor]

Well I need to pull codes. I'm thinking I may need O2 sensors. But not sure.
Can someone tell me how to pull codes using a ohm/volt meter? Is there a web site that lists codes? Or a do it yourself page somewhere?
My problem is when I come to a stop I stall. I have set the TPS to .97 idle is about 800 rpm. I unhooked the battery for 20min. after setting and reved it a few times. It idles good. But still stalls when I stop. It starts right back up and surges alittle but then holds an idle fine. This is why I want to pull codes.
Thanks

[raptor]

Someone must know how to pull codes using a ohm/volt meter and what the codes are.

[Mountain Main]

Each code is usually two digits, sometimes three. Look for 2 second pause between digits.

example swing swing Pause swing swing swing = 23

Open the hood and look for Self Test Ouput (STO) and Self Test Input (STI) connectors under driver's side hood, near cowl by the strut tower.

The STO connector is hexagon with six connections on it. Two connections on top and four on the bottom.

The STI is little square with one connection.

You must connect a piece of wire from the STI to the STO top row second connector of the STO

Attach the Volt meter possitive to the STO second connector on the bottom row. Run volt meter negative to the Vehicle Batterys positive

Turn on key.

The first set of codes tells you that your car is a V8. Then you will start to see a patern

Then starts the the swing swing two second pause swing swing swing. Or what ever code you are getting.

This these are KOEO codes.

To get KOER codes you must erase KAM, which you pull the negative battery cable off the cars battery for 10 minutes

I personally bough a 22 dollar code reader from Walmart that you just have to follow there directions. It is much easier.

[ChunkFunky]

This should make it alittle more visual