Surging Idle

ravensfan

Active User
Mar 14, 2016
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i have a 92 mustang, I just put on gt 40 heads, F cam, cobra upper and lower intake, throttle body and 75 maf.
Since that I have had a bad surging idle, but not all of the time,, ITs erratic, sometimes idles good , and it usually idles good at start up but after a short ride it surges almost always.. ITs also runs strong when getting on it, but cruising at 60, after a while it will sometimes have a slight miss in it.
I got a code 14 ? I saw that has to do with the ignition or distributor,. Has anyone had this and what should I change ? Can code 14 be the reason of the surging idle ?
 
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Fix the code 14 before attempting to do anything else.

Then do the Surging Idle Checklist if you still have idle problems...



Code 14 - Ignition pickup (PIP) was erratic – the Hall Effect sensor in the distributor is failing. Bad sensor, bad wiring, dirty contacts. Factory tach will sometimes read erratically.

Revised 10-Dec-2012 to add PIP diagnostic testing & Wells info

The PIP is a Hall Effect magnetic sensor that triggers the TFI and injectors. There is a shutter wheel alternately covers and uncovers a fixed magnet as it rotates. The change in the magnetic field triggers the sensor. They are often heat sensitive, increasing the failure rate as the temperature increases.

PIP Sensor functionality, testing and replacement:
The PIP is a Hall Effect magnetic sensor that triggers the TFI and injectors. There is a shutter wheel alternately covers and uncovers a fixed magnet as it rotates. The change in the magnetic field triggers the sensor. A failing PIP sensor will often set code 14 in the computer. They are often heat sensitive, increasing the failure rate as the temperature increases.

Some simple checks to do before replacing the PIP sensor or distributor:
You will need a Multimeter or DVM with good batteries: test or replace them before you get started.. You may also need some extra 16-18 gauge wire to extend the length of the meter’s test leads.
Visual check first: look for chaffed or damaged wiring and loose connector pins in the TFI harness connector.
Check the IDM wiring – dark green/yellow wire from the TFI module to pin 4 on the computer. There is a 22K Ohm resistor in the wiring between the TFI and the computer. Use an ohmmeter to measure the wire resistance from the TFI to the computer. You should see 22,000 ohms +/- 10%.
Check the PIP wiring - dark blue from the TFI module to pin 56 on the computer. Use an ohmmeter to measure the wire resistance from the TFI to the computer. You should see 0.2-1.5 ohms.
Check the SPOUT wiring – yellow/lt green from the TFI module to pin 36 on the computer. Use an ohmmeter to measure the wire resistance from the TFI to the computer. You should see 0.2-1.5 ohms.
Check the black/orange wire from the TFI module to pin 16 on the computer. Use an ohmmeter to measure the wire resistance from the TFI to the computer. You should see 0.2-1.5 ohms.
Check the red/green wire; it should have a steady 12-13 volts with the ignition switch on and the engine not running.
Check the red/blue wire; it should have a steady 12-13 volts with the ignition switch in Start and the engine not running. Watch out for the fan blades when you do this test, since the engine will be cranking.
If you do not find any chaffed or broken wires, high resistance connections or loose pins in the wiring harness, replace the PIP sensor or the distributor.

The PIP sensor is mounted in the bottom of the distributor under the shutter wheel. In stock Ford distributors, you have to press the gear off the distributor shaft to get access to it to replace it. Most guys just end up replacing the distributor with a reman unit for about $75 exchange

PIP problems & diagnostic info
Spark with the SPOUT out, but not with the SPOUT in suggests a PIP problem. The PIP signal level needs to be above 6.5 volts to trigger the computer, but only needs to be 5.75 volts to trigger the TFI module. Hence with a weak PIP signal, and the SPOUT out, you could get spark but no injector pulse. You will need an oscilloscope or graphing DVM to measure the output voltage since it is not a straight DC voltage.

See http://www.wellsmfgcorp.com/pdf/counterp_v8_i2_2004.pdf and http://www.wellsmfgcorp.com/pdf/counterp_v8_i3_2004.pdf for verification of this little detail from Wells, a manufacturer of TFI modules and ignition system products.




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. It includes how to dump the computer codes quickly and simply as one of the first steps. I continue to update it as more people post fixes or ask questions. You can post questions to that sticky and have your name and idle problem recognized. The guys with original problems and fixes get their posts added to the main fix. :D

It's free, I don't get anything for the use of it except knowing I helped a fellow Mustang enthusiast with his car. At last check, it had more than 200,000 hits, which indicates it does help fix idle problems quickly and inexpensively.
 
thanx for the info.. I actually have been going thru the surge idle check list and have already changed the 02 sensors bc of several symtoms matching that as well as gas mileage being now cut in half among other things, I have also changed the AIC, and I just got the TPS and temp. sensor,
that's when I noticed the code 14, and was wondering if that can be the cause of my trouble ?? Instead of things on the surging idle check list ??
 
The first step in the surging idle checklist is to dump the codes and fix the items that caused the codes. Then you look for other things on the list.

Like I said, fix the code 14 first.

A failing PIP sensor can cause all sorts of problem symptoms and will eventually keep the engine from running at all. No spark, no fuel injector pulse and the fuel pump won't run after the initial prime when you first turn the ignition switch to Run.