A word about EEC-IV... (1985-1994/5 typically)
#1
03-06-2011, 01:21 AM
A word about EEC-IV... (1985-1994/5 typically)
I will start by qualifying this entire post with this statement. "No self-diagnostic system is fool-proof and I fully accept that there are SOME situations that pulling codes won't necessarily yield an answer to the problem."
However, I find it completely astounding that there are folks (and I am in no way singling anyone out) who seem to believe that the best way to diagnose engine/performance issues is by chasing down things that MIGHT be causing the "symptoms" when their vehicle has an onboard computer that will "TELL" them what is "ailing" the engine. I sit here and read... a lot. I sit here and respond... a lot. I see the questions time and again:
"My truck has these symptoms, so which sensor do I replace?"
"There aren't any codes so what is wrong when I have these symptoms?"
The problem with chasing symptoms the old fashioned way when the truck is equipped with EEC-IV is that you can spend time, energy and money for days and you MIGHT get lucky and find the problem child. However, if you don't happen upon the problem by guessing, you will spend more time, energy and money than you EVER had to because you COULD have simply pulled codes and ONLY had to replace/repair the parts that were actually causing the problem.
The question that asks to diagnose a sensor problem based on the symptoms is just not going to get you an answer. Why? Well because fault codes are what tell you which sensor is affected, NOT the symptoms. The fact of the matter is that there can be similar symptoms with different sensor problems.
A dying EVP sensor can have a similar effect to a faulty TP sensor or ECT sensor and vice versa. So, asking which sensor is causing the problem is asking us to guess. (And you won't be happy if we guess wrong). The most common response you will get is, "PULL CODES" because there is no point in anyone guessing when the system will virtually eliminate the need. We aren't being lazy... we are trying to keep you from spending the time, effort and MONEY replacing something (or things) that may or may not be the real cause of the problem. And since no one but you or your mechanic can pull the Codes from YOUR truck, this should be the first step towards resolving the issue anyway.
With all that said, let me put a misconception to rest. Many folks believe that if the CEL hasn't come on, there are no fault codes. Apologies, but this simply isn't true. There is ALWAYS at least one Code. (The only time there isn't is with a failed ECM/PCM which is extremely unlikely or damaged wiring between the STI connector and the ECM/PCM). The EEC-IV system generates a "System Pass" Code if there is nothing amiss. Code 11 or 111 (depends on the age of the system) will be the very least you will get as the result of a KOER or KOEO test. So, its an extremely slim option that "there are no codes".
Misconception number two is that you need some special code reading device to get the fault codes from the ECM/PCM. No, you need a short piece of wire or a paperclip and the keys to the truck. The rest of the procedures can be found on this and a host of other websites and in Ford and aftermarket service manuals.
Misconception number three says there is only one diagnostic test and since it didn't yield anything but Code 11 there are no other codes to be had. No, the KOEO test is one of two diagnostic tests. KOER is the other and requires a little more interaction with the vehicle while administering it but gets you Codes that ONLY occur while the engine is actually running.
The last point I need to make is about OE (Operator Error, not Original Equipment). Rest assured, we have all been there. If the KOEO and/or KOER tests are not administered exactly as the procedures are lined out, you will not get accurate responses from the ECM/PCM. Period. Do it again if you are unsure.
In short, take the time to pull codes first. Trust me when I tell you that among those of us who "hang out" in this forum, there are many who have all but memorized the meanings (and typical fixes) for many of the most common fault Codes. Post the Code numbers and we can give you a ton of information about how to proceed and what may be causing them to show up. This WILL save you time, effort and something EVERYONE likes to save... money.
Abbreviations you will see when dealing with fault Codes:
ABS/RABS - Anti-lock Braking System/Rear Anti-lock Braking System
ACT/IAT - Air Charge Temperature/Intake Air Temperature sensor (Can have issues and not throw Codes).
BOO - Brake On/Off (switch)
CANP - CANister Purge solenoid
CEL - Check Engine Light (dashboard indicator that not only tells of a problem but will flash out fault Codes as well).
CM - Continuous Memory (Codes stored in memory after having been triggered/existed after the last 40 operations of the engine).
E4OD - Electronic 4-speed Over Drive (Ford's fully electronic 4-speed overdrive truck transmission).
ECT - Engine Coolant Temperature sensor (not the same as the temp. gauge sending unit and can have issues without throwing Codes).
ECM/PCM - Engine Control Module/Powertrain Control Module (the main computer)
EVP - EGR Valve Position sensor
HEGO - Heated Exhaust Gas Oxygen sensor (EGO is the same but has no heating circuit built in)
IAC - Idle Air Control is a solenoid and valve assembly that controls air flow only during idle.
KOEO - Key On Engine Off diagnostic test administered with the engine hot but not running.
KOER - Key On Engine Running diagnostic test administered with the engine hot and running.
KS - Knock Sensor (except 5.8L {351} engines)
MAP - Manifold Absolute Pressure sensor
MLPS - Manual Lever Position sensor (E4OD transmission electronics)
O2 - Oxygen sensor (See HEGO/EGO)
PIP - Profile Ignition Pickup (internal to the distributor)
PSOM - Programmable Speedometer/Odometer Module (92+ models use this instead of a mechanical setup. VSS is required).
STI - Self Test Initiation connector allows access to the ECM/PCM self test functions (located on the driver's inner fender between the hood spring and the firewall)
SPOUT - SPark OUTput signal or jumper/shunt. Dictates timing control from the ignition module.
TAB - Thermactor Air Bypass solenoid that controls vacuum for emissions (AIRB)
TAD - Thermactor Air Diverter solenoid that controls vacuum for emissions (AIRD)
TFI/ICM - Thick Film Integrated Circuit Module (more affectionately referred to as the ignition module)
TP - Throttle Position sensor
VSS - Vehicle Speed Sensor (E4OD, PSOM, ABS, cruise control operations)
However, I find it completely astounding that there are folks (and I am in no way singling anyone out) who seem to believe that the best way to diagnose engine/performance issues is by chasing down things that MIGHT be causing the "symptoms" when their vehicle has an onboard computer that will "TELL" them what is "ailing" the engine. I sit here and read... a lot. I sit here and respond... a lot. I see the questions time and again:
"My truck has these symptoms, so which sensor do I replace?"
"There aren't any codes so what is wrong when I have these symptoms?"
The problem with chasing symptoms the old fashioned way when the truck is equipped with EEC-IV is that you can spend time, energy and money for days and you MIGHT get lucky and find the problem child. However, if you don't happen upon the problem by guessing, you will spend more time, energy and money than you EVER had to because you COULD have simply pulled codes and ONLY had to replace/repair the parts that were actually causing the problem.
The question that asks to diagnose a sensor problem based on the symptoms is just not going to get you an answer. Why? Well because fault codes are what tell you which sensor is affected, NOT the symptoms. The fact of the matter is that there can be similar symptoms with different sensor problems.
A dying EVP sensor can have a similar effect to a faulty TP sensor or ECT sensor and vice versa. So, asking which sensor is causing the problem is asking us to guess. (And you won't be happy if we guess wrong). The most common response you will get is, "PULL CODES" because there is no point in anyone guessing when the system will virtually eliminate the need. We aren't being lazy... we are trying to keep you from spending the time, effort and MONEY replacing something (or things) that may or may not be the real cause of the problem. And since no one but you or your mechanic can pull the Codes from YOUR truck, this should be the first step towards resolving the issue anyway.
With all that said, let me put a misconception to rest. Many folks believe that if the CEL hasn't come on, there are no fault codes. Apologies, but this simply isn't true. There is ALWAYS at least one Code. (The only time there isn't is with a failed ECM/PCM which is extremely unlikely or damaged wiring between the STI connector and the ECM/PCM). The EEC-IV system generates a "System Pass" Code if there is nothing amiss. Code 11 or 111 (depends on the age of the system) will be the very least you will get as the result of a KOER or KOEO test. So, its an extremely slim option that "there are no codes".
Misconception number two is that you need some special code reading device to get the fault codes from the ECM/PCM. No, you need a short piece of wire or a paperclip and the keys to the truck. The rest of the procedures can be found on this and a host of other websites and in Ford and aftermarket service manuals.
Misconception number three says there is only one diagnostic test and since it didn't yield anything but Code 11 there are no other codes to be had. No, the KOEO test is one of two diagnostic tests. KOER is the other and requires a little more interaction with the vehicle while administering it but gets you Codes that ONLY occur while the engine is actually running.
The last point I need to make is about OE (Operator Error, not Original Equipment). Rest assured, we have all been there. If the KOEO and/or KOER tests are not administered exactly as the procedures are lined out, you will not get accurate responses from the ECM/PCM. Period. Do it again if you are unsure.
In short, take the time to pull codes first. Trust me when I tell you that among those of us who "hang out" in this forum, there are many who have all but memorized the meanings (and typical fixes) for many of the most common fault Codes. Post the Code numbers and we can give you a ton of information about how to proceed and what may be causing them to show up. This WILL save you time, effort and something EVERYONE likes to save... money.
Abbreviations you will see when dealing with fault Codes:
ABS/RABS - Anti-lock Braking System/Rear Anti-lock Braking System
ACT/IAT - Air Charge Temperature/Intake Air Temperature sensor (Can have issues and not throw Codes).
BOO - Brake On/Off (switch)
CANP - CANister Purge solenoid
CEL - Check Engine Light (dashboard indicator that not only tells of a problem but will flash out fault Codes as well).
CM - Continuous Memory (Codes stored in memory after having been triggered/existed after the last 40 operations of the engine).
E4OD - Electronic 4-speed Over Drive (Ford's fully electronic 4-speed overdrive truck transmission).
ECT - Engine Coolant Temperature sensor (not the same as the temp. gauge sending unit and can have issues without throwing Codes).
ECM/PCM - Engine Control Module/Powertrain Control Module (the main computer)
EVP - EGR Valve Position sensor
HEGO - Heated Exhaust Gas Oxygen sensor (EGO is the same but has no heating circuit built in)
IAC - Idle Air Control is a solenoid and valve assembly that controls air flow only during idle.
KOEO - Key On Engine Off diagnostic test administered with the engine hot but not running.
KOER - Key On Engine Running diagnostic test administered with the engine hot and running.
KS - Knock Sensor (except 5.8L {351} engines)
MAP - Manifold Absolute Pressure sensor
MLPS - Manual Lever Position sensor (E4OD transmission electronics)
O2 - Oxygen sensor (See HEGO/EGO)
PIP - Profile Ignition Pickup (internal to the distributor)
PSOM - Programmable Speedometer/Odometer Module (92+ models use this instead of a mechanical setup. VSS is required).
STI - Self Test Initiation connector allows access to the ECM/PCM self test functions (located on the driver's inner fender between the hood spring and the firewall)
SPOUT - SPark OUTput signal or jumper/shunt. Dictates timing control from the ignition module.
TAB - Thermactor Air Bypass solenoid that controls vacuum for emissions (AIRB)
TAD - Thermactor Air Diverter solenoid that controls vacuum for emissions (AIRD)
TFI/ICM - Thick Film Integrated Circuit Module (more affectionately referred to as the ignition module)
TP - Throttle Position sensor
VSS - Vehicle Speed Sensor (E4OD, PSOM, ABS, cruise control operations)
The following users liked this post:
#2
03-06-2011, 07:22 AM
Join Date: Apr 2005
Location: Longview, TX
Posts: 2,018
Likes: 0
Received 0 Likes
on
0 Posts
#3
03-06-2011, 07:37 AM
#4
03-06-2011, 11:16 AM
Thread
Thread Starter
Forum
Replies
Last Post
fordpride
1994.5 - 1997 7.3L Power Stroke Diesel
7
06-26-2012 10:49 PM
