Good day Gentlemen, I am stumped, and need some opinions. '94 3.0 When I start the van in the morning, It cranks on the first try, but lately it will idle up for about 1 second, then down, up, down, etc. about 5-6 times, then it will be normal for the rest of the day/night. Starts and idles normally when warm. I have noticed a drop in fuel economy as well. I replaced the ECT a few months ago, and when this problem started, I thought I had it traced to an intermittent short in the ECT plug wire; I would wiggle/adjust the plug wire before starting, and some of the time it would start normally with a
normal idle. But now that doesn't work. Is there anything besides the ECT sensor that would cause cold idle problems (AFM maybe?) It only idles funny for maybe 30-40 seconds before it straightens itself out. What am I looking for when I test the ECT plug wire with a DVM? Thanks in advance!


M

 

any codes, many do not set the MIL
http://fordfuelinjection.com/?p=13

replace ECT plug and section of wire, avail at better parts stores. splice in
coolant leaks destroy them

the wiggle test and output device tests are handy
may be your IAC which will cycle under this test
IAC's can develop a failure where they overheat and shut or lock open

Continuous Monitor Diagnostic Test Mode (Wiggle Test)


Special Note:

l The technician can ATTEMPT to re-create and detect an intermittent fault using the Continuous Monitor DTM (Wiggle Test) procedures.


Key On Engine Off Wiggle Test Procedure

1. Hook up a STAR Tester, VOM or Scan Tool.

2. Turn the ignition key to the ON position.

3. For STAR Tester or VOM, activate, deactivate and reactivate Self-Test. You are now in the Continuous Monitor Diagnostic Test Mode (DTM). For Scan Tool, enter DTM, then enter wiggle DTM.

4. Tap, move, and wiggle the suspect sensor and/or harness. When a fault is detected, a Continuous Memory DTC will be stored in memory. This will be indicated as follows depending on the type of equipment being used:

l STAR Tester: Red LED lights and/or continuous tone.

l Malfunction Indicator Lamp (MIL): Lights

l VOM: Needle Sweep

l Transmission Control Indicator Lamp (TCIL)

l Message Center (Continental Only)

l Scan Tool: Continuous Tone


Engine Running Wiggle Test Procedure


Special Note:

l The Engine Running Wiggle Test may be activated any time the engine is running.

1. Hook up a STAR Tester, VOM or Scan Tool as shown.

2. Key off.

3. Start the engine.

4. For STAR Tester or VOM, activate Self-Test, deactivate and reactivate Self-Test. DO NOT shut the engine off. You are now in the Engine Running Continuous Monitor DTM. For Scan Tool, enter DTM, then enter wiggle DTM.

5. Tap, move, and wiggle the suspect sensor and/or harness or drive the vehicle. When a fault is detected, a Continuous Memory DTC will be stored in memory. This will be indicated as follows depending on the type of equipment being used:

l STAR Tester: Red LED lights and/or continuous tone.

l Malfunction Indicator Lamp (MIL): Lights

l VOM: Needle Sweep

l Transmission Control Indicator Lamp (TCIL)

l Message Center (Continental Only)

l Scan Tool: Beeps


How to Clear the Continuous Memory

NOTE:
Do not disconnect battery to clear Continuous Memory. This will erase the Keep Alive Memory (KAM) information which may cause a driveability concern.

1. Run the Key On Engine Off Self-Test.

2. When the DTC's begin to be displayed, deactivate Self-Test:

-- STAR Tester: Unlatching the center button (up position).

-- All others: Remove the jumper wire from between Self-Test Input (STI) connector and the Signal Return Pin of the DLC.

-- Scan Tool: Pushing the STOP button.

3. Continuous Memory will be erased in the PCM.


How to Clear Keep Alive Memory (KAM)

The PCM stores information about vehicle operating conditions and uses this information to compensate for component tolerances. When an emission related component is replaced, Keep Alive Memory (KAM) should be cleared to erase the information stored by the PCM from the original component.

To clear KAM: Disconnect the negative side of the battery for a minimum of five minutes.

After KAM has been cleared, the vehicle may exhibit certain driveability concerns. It will be necessary to drive the vehicle 10 miles or more to allow the processor to relearn values for optimum driveability and performance. (Distance is dependent on the vehicle application.)


Output State Diagnostic Test Mode (DTM)

The Output State DTM aids in servicing output actuators associated with the EEC system. It enables the technician to energize and de-energize most of the system output actuators on command. This DTM is entered after all DTC's have been received from Key On Engine Off and Continuous Testing. At this time, leave Self-Test activated and depress the throttle. Each time the throttle is depressed the output actuators will change state from energized to de-energized or from de-energized to energized.

1. Enter Self-Test.

2. DTC Output Ends.

3. Do Brief WOT.

4. EEC Output To Actuators Energized.

5. Do Brief WOT.

6. EEC Output To Actuators De-Energized.

7. For vehicles with LFC and HFC circuits:
To cycle the LFC and HFC outputs after code output ends, depress and hold throttle. For LFC, wait until the MIL flashes once (10 seconds). For HFC, wait until MIL flashes twice (15 seconds). Release throttle. The LFC or HFC output is now on (to cycle output off, depress and release throttle).

 

I did try to pull the codes, but the only code I could decipher was 412 ? "cannot control RPM" ; and many other flashes that I couldn't keep up with...lol I'll try again with a helper ASAP; I've been super busy.
Would the 412 code indicate a TPS or IAC problem, or what? Thanks for the reply 96! I'm pretty sure my AFM is shot, you may remember the photos I posted. I need to replace that soon.

Thanks

M

 

http://fordfuelinjection.com/?p=64

see the section on cold start/warmup
could be your TPS

test it
http://fordfuelinjection.com/index.php?p=30

 

ECT sensor is basically a thermistor ,(Heat dependant resistor), Basically the resistance of this sensor changes with temperature, which the EEC uses to assess engine temperature & fuel strategy. It also uses ACT (air charge temp, another thermistor) & IAC to control mixture & RPM's at start up. O2 sensor is not used during this phase of open loop operation.

I have noticed that ECT & ACT have a drastic effect on injector pulse duration, especially for the first 30 secs of operation on a cold engine. However if ECT was wrong, your engine would also have problems when warmed up, which it does not. Although even if several sensors are failed the system is able to run on emergency engine control , since it is programmed to use data tables which can feed this info to the ECU without direct sensor readings.

Sounds like the IAC is trying to compensate for a sticky injector or something. IAC sounds like it is having problems controlling idle speed, or cold start fuel/air ratio is incorrect. Def sounds like fuel/air control problem to me.


In cases like this I'm glad I have OBD-II, much easier to troubleshoot.

ATB Aeroman.

 

I replaced the ECT plug with a new one ($12.99), but no dice. I tested the TPS and it checked out OK; I pulled the IAC and cleaned it, and the throttle body as well, and no more surging idle. I'm sure the IAC is original, and I read that cleaning it might help, but the cleaning probably won't last long if it does. So, at some point I'll replace it I'm sure.
Thanks for the help guys!


I need to replace the bushings on the "transmission crossmember"...I can't find them online, or any information about them at all. Can anyone help?



M

 

Yeah, sometimes they can be cleaned, but it is really only a temporary solution. They need a better method for keeping the oil fumes out of the intake. A check valve on the breather hose perhaps, or some kind of free flowing filter.

 

the transmission/engine rear cross support member bushing are not listed as separate parts even in the Ford Service CD, shown as one item, not good.

you may be able to find what you need at Energy Suspension
i use their suspension bushing products, hold up well on rough logging roads
http://www.energysuspension.com/pages/univ1.html

or Prothane
http://www.prothane.com/