Idle hangs up high! heeeellllpppp

[masospaghetti]

Hey all -- My ex has an idling issue. It's not rough, but it often stays up around 1500 rpm even when in neutral. (its a 5-speed manual). It's wasting gas and its annoying, too. After a few seconds it'll drop to normal, around 700 rpm. I've tried MAF cleaning, twice -- it has a new air filter, and a new IAC valve from Autozone. Before you own me for buying a part from Autozone, keep in mind the valve behaves the exact same as the old one, which was a NAPA part, so it seems unlikely to me that the IAC is at fault here. What else could cause this? I also just had the upper plenum gaskets replaced and the manifold leak checked.

Thanks!

 

[BigODave]

I ran into the same situation after doing much of the same work you've done. It ended up being that the computer needed to "relearn" after doing the work. This should help point you in the right direction, even though your vehicle's year is different than mine.

1995-96 GENERAL INFORMATION
Computer Relearn Procedures - Ford Motor Co.
INTRODUCTION

Vehicles equipped with engine or transmission computers may require a relearn procedure after the vehicle battery is disconnected. Vehicle computers memorize and store vehicle operation patterns for optimum driveability and performance. When the vehicle battery is disconnected, this memory is lost. Default data is used until new data from each key start is stored. As the computer restores its memory from each new key start, driveability is restored.

Driveability problems may occur during the relearn stage. Depending on the vehicle and how it is equipped, the following driveability problems may exist:

* Rough or unstable idle.
* Hesitation or stumble.
* Rich or lean running.
* Poor fuel mileage.
* Harsh or poor transmission shift quality.

To accelerate relearn process after battery removal and installation, vehicle should be road tested in the following manner:

* Vehicle at normal operating temperature (cooling fan cycles).
* Accelerate at normal throttle position (20-50%).
* Cruise at light to medium throttle.
* Decelerate to a stop, downshifting and using brakes normally.

Manufacturers identify specific relearn procedures. See RELEARN PROCEDURES. Always complete the procedure before returning the vehicle to the customer.
RELEARN PROCEDURES
VEHICLE PREPARATION

Ensure all components are connected. Ensure transmission fluid level is correct. Warm engine to normal operating temperature. If vehicle has been repaired, perform KOEO and Continuous Memory Code Self-Test and ensure fault codes are not present. See appropriate G - TESTS W/ CODES article in ENGINE PERFORMANCE section.
VEHICLE DRIVEABILITY RELEARN PROCEDURE

Place automatic transmission in Park (A/T) or Neutral (M/T). Start engine and allow to idle for one minute. Drive vehicle for 10 miles or more to allow processor to relearn values for optimum performance.
AOD-E & AXOD-E TRANSAXLE SHIFT RELEARN PROCEDURE

With transaxle gear selector in Overdrive, moderately accelerate vehicle to 50 MPH for a minimum of 15 seconds. Transaxle should be in 4th gear. While holding speed steady, lightly apply and release brake for about 5 seconds. Stop and park vehicle for at least 20 seconds with gear selector in Drive. Repeat procedure 5 times.
E4OD TRANSMISSION SHIFT RELEARN PROCEDURE

1. With gear selector in Drive, press Overdrive Cancel Switch (LED should light). Moderately accelerate vehicle to 40 MPH for a minimum of 15 seconds (30 seconds above 4000-ft. elevation). Transmission should be in 3rd gear.
2. While holding speed steady, press Overdrive Cancel Switch (LED should go off) and accelerate from 40 MPH to 50 MPH. Transmission should shift from 3rd gear to 4th gear. Hold speed steady for 15 seconds. While holding speed steady, lightly apply and release brakes enough to turn brake lights on. Maintain 50 MPH for about 5 seconds. Stop vehicle for a minimum of 20 seconds with transmission gear selector in Drive. Repeat procedure 5 times.

 

[BigODave]

I just found the relearn procedure for your vehicle's year (it indicates 1997, but applies to 2000's as well):

1997 GENERAL INFORMATION
Computer Relearn Procedures - Ford Motor Co.
INTRODUCTION

Vehicles equipped with engine or transmission computers may require a relearn procedure after the vehicle battery is disconnected. Vehicle computers memorize and store vehicle operation patterns for optimum driveability and performance. When the vehicle battery is disconnected, this memory is lost. Default data is used until new data from each key start is stored. As the computer restores its memory from each new key start, driveability is restored.

Driveability problems may occur during the relearn stage. Depending on the vehicle and how it is equipped, the following driveability problems may exist:

* Rough or unstable idle.
* Hesitation or stumble.
* Rich or lean running.
* Poor fuel mileage.
* Harsh or poor transmission shift quality.

To accelerate relearn process after battery removal and installation, vehicle should be road tested in the following manner:

* Vehicle at normal operating temperature (cooling fan cycles).
* Accelerate at normal throttle position (20-50%).
* Cruise at light to medium throttle.
* Decelerate to a stop, downshifting and using brakes normally.

Manufacturers identify specific relearn procedures. See RELEARN PROCEDURES. Always complete the procedure before returning the vehicle to the owner.
RELEARN PROCEDURES
Vehicle Preparation

Ensure all components are connected. Ensure transmission fluid level is correct. Warm engine to normal operating temperature. If vehicle has been repaired, perform QUICK TEST and ensure fault codes are not present. See appropriate TESTS W/CODES article in the ENGINE PERFORMANCE section.
Vehicle Driveability Relearn Procedure

Place automatic transmission in Park (A/T) or Neutral (M/T). Start engine and allow to idle for one minute. Drive vehicle for 10 miles or more to allow processor to relearn values for optimum performance.
AOD-E & AXOD-E Transaxle Shift Relearn Procedure

With transaxle gear selector in Overdrive, moderately accelerate vehicle to 50 MPH for a minimum of 15 seconds. Transaxle should be in 4th gear. While holding speed steady, lightly apply and release brake for about 5 seconds. Stop and park vehicle for at least 20 seconds with gear selector in Drive. Repeat procedure 5 times.
E4OD Transmission Shift Relearn Procedure

1. With gear selector in Drive, press Overdrive Cancel Switch (LED should light). Moderately accelerate vehicle to 40 MPH for a minimum of 15 seconds (30 seconds above 4000 ft. elevation). Transmission should be in 3rd gear.
2. While holding speed steady, press Overdrive Cancel Switch (LED should go off) and accelerate from 40 MPH to 50 MPH. Transmission should shift from 3rd gear to 4th gear. Hold speed steady for 15 seconds. While holding speed steady, lightly apply and release brakes enough to turn brake lights on. Maintain 50 MPH for about 5 seconds. Stop vehicle for a minimum of 20 seconds with transmission gear selector in Drive. Repeat procedure 5 times.

 

[410Fortune]

could also be a vacuum leak
Do you smell raw fuel when you stop at a light, like after exiting the highway?

This could be a bad canister purge valve, which is similar to a vacuum leak as far as idle is concerned

look for leaks in your intake before or after the MAS, check all your vacuum lines, check the lines for the EGR and Canister purge valves as well

I agree with the above, if you cleaned the MAS, etc you need to reset the pcm after you service each sensor

 

[masospaghetti]

I don't smell fuel. I'll try resetting the pcm.

 

[BigODave]

Status update, please!

 

[masospaghetti]

Hey, sorry its been forever, i'm still having this problem after resetting the PCM, new IAC, and a new intake manifold gasket. The shop that did the intake gasket said they had leak checked the intake system, so I doubt there is another vacuum leak.

Any suggestions? I try and coast a lot to save fuel but when the idle hangs up, it hardly does any good.

 

[budwich]

check your TPS.... make sure it is "smooth" in its readings and make sure that at idle, the reading is appropriate (ie. low). Has the TPS ever been changed??

 

[masospaghetti]

TPS is original AFAIK, but i just checked it...with ignition on, 0.97 volts. I also checked it's resistance while moving the throttle and it seems smooth.

 

[Turdle]

Actuate the TPS (throttle) by hand several times-just to be sure the voltage drops to .97 every time-instantly.

 

[budwich]

second that.... actually take it off and measure the resistance as you move it. My suggestion about the TPS comes from a recent GM experience where the spring broke on the TPS and even though it "responded" to the throttle position, there was "issues" with the resistance at various positions and as jtsmith says maybe it isn't always returning to the same place or possibly a "crudded" resistance reading is showing up. Ultimately, you might have to get a "data scan" to see if things are working right on a problem like this... of course, it would never show up when you have things set up for recording... :-(

 

[masospaghetti]

I will check this, however, I am suspicious that is has something to do with sensors or the computer, just because it doesn't have the problem when i'm sitting still and just rev the engine...but only when i'm moving. It'll hang up while i'm coasting, and drop when I stop.

 

[91-RT/TT]

I have been experiencing the same high idle problem. I have a 99' Ranger with the 4.0 OHV and a 5-speed Manual. I have replaced the IAC and cleaned the MAS, and reset the PCM multiple times, however my CEL is still on. The code was read a long time ago, and unfortunately I can't recal what it was exactly (1633?? or 1663??) But I do seem to recal it dealt with a fuel vent line (or the like). I thought it was the gas cap or fuel filter, so I installed one of each and nothing has changed.

Is there a fuel injection return line that could be plugged? This plugged line might prohibit any excess fuel from returning to the tank, forcing it through the injectors and increasing the idle speed after engine loading. It's just a theroy. Any help woudl be appreciated.
Thanks