Idle Issue 5.0 CFI / EEC-III

[TNTBird]

I have a 1984 Ford Thunderbird with a 5.0 CFI and auto trans. I'm in the process of restoring the car and it's all stock. The car has an idle issue. When I start the car it's in fast idle. After around 30 seconds it kicks down to a slower idle. This "second" idle is basically idling too fast to shift into drive or reverse. Maybe after five minutes, sometimes the car will then go to a third slower idle, which is the correct curb idle. Sometimes it will not go to the third slower idle (curb idle) and then I have to quickly press/release the gas pedal and then it will go to curb idle. So, at this point the car has three idle stages - fast idle, intermediate idle and curb idle.

Checking to see if any of the EEC-III experts here would know the correct sequence for the idle stages. The car doesn't have a tachometer, but I know, by sound, the intermediate idle is running too fast. Maybe around 1200-1300 RPM. The car has been in the family since new and I remembered that the car would go into fast idle and then automatically kick down to curb idle. I don't remember the car having an intermediate idle. Is there a procedure to adjust this intermediate idle to a slower RPM? I know there is a process to adjust the curb idle where you put the car in drive and then adjust it to 550 RPM. But, by sound, I know the curb idle is close to spec. I have the Ford Shop Manual, but it really doesn't give any information about an intermediate idle. I rebuilt the throttle body about three months ago. I'm looking for an external tach or multimeter with an "hz" setting so I can get a better reading of the different RPMs. Any ideas on where I should look for the problem at this point? Thanks!

[xctasy]

After performing four other checks below, Your pull down choke setting needs to be reset using a Miytvac set at 20 " H20 applied to Point A on the VECI diagram.

Before resetting this,
1. The AOD Throttle Valve line pressure has to be confirmed and set correctly,


2. the VOTM on the front of the throttle stop with its Air Con trigger needs to be visually checked.

3. Sensors like the TPS curb idle settings

4. the Brown Box Duraspark III under seat ECA's ability to remove and tip in advance.

Each are able to be checked by the Code reader below.

Others suggest using a Digital Multimeter with a sweep needle, because the Reference voltage for EECIII computers is between Zero and 9, sometimes 12 volts, while on the EECIV computers, it's Zero to 5 volts.

The information I've gotten is that Codes can be read easily via the normal STAR reader plug by the brake booster or battery. The Equis 3151 with the long 3149 cable.


The EECIII has a BMAP sensor that can be read another way, using the Miytvac to trigger two types of KOER, KOEO codes, but the normal code readers for EECIV will also work with the EECIII.



Normally, it's just the choke pull down, which is a simple Automatic choke with a powered wire and an Arrow, that needs to have the line checked for perforations, and then checked with the recommended at Idle Vacuum in Inches of H2O applied with a Hand operated vacuum pump.

Ford shares a large amount of components between other CFi 2bbls in the 3.8 and 5.0 HO engines, but they are subtly different in ISC (3.8 liter only ) and throttle base idle control ( 5.0 Mustang and Capri Auto HO ). The crank sensor is unique to the early Duraspark III ignition cars, and sometimes, there are faults which masked by the EECIII stalwart ability to always allow the car to run. It's fairly failsafe, people have even removed Feed back carbs and whole CFi systems, and the Duraspark III will still run for years with out handshaking.

[xctasy]

See post #7 in this link "http://vb.foureyedpride.com/showthread.php?182047-85-Convertible".

http://vb.foureyedpride.com/showthre...85-Convertible


There is a standard diagnostic six wire STAR connector on these, or a BMAP driven system like this.


1982 5.0 Panther
https://youtu.be/puAEJ3BYFeY

1984 Thunderbird EECIII ( I think)
https://youtu.be/puAEJ3BYFeY

[emerygt350]

Is it the HO? Not that it matters much but just curious.

I also assume you mean from a dead cold start. Is that true?

Startup from cold should be depress the throttle and release. Start the car. Idle should be 1400. After 30 seconds, the votm will kick the throttle and it should drop to 1100 to 1200. It will stay there for a bit till that electric choke actuator kicks it off the cam. The idle will still be around 1000 at that point since the car is cold, after the car is good and warm you should see 800ish at idle in park, 550 in gear.

Xctasy knows what he is talking about, however there are a couple of real quick things you can check.
1) check that vacuum line on the driver side rear of the air filter box. When that isn't reconnected you can get the same strange behavior.

2) check to make sure that high idle cam is working properly. If it isn't aligned properly it can stick on 1200.

3) pull the air cleaner, plug that vacuum line, watch the cold start procedure. See where it is hanging up. Those electric choke filaments can go bad.

[TNTBird]

Thanks for everyone's help. This is a lot of great information about the CFI EEC-III system... I have ordered a hand vacuum pump and a multimeter with an HZ setting, so hopefully I'll be doing some more testing on the engine idle soon. The car has a standard 5.0, not an H.O.

Checked the vacuum lines and fast idle cam. All looked good. Choke thermostat seems to be working. I can turn the thermostat housing left and right and this will change the time the engine is in fast idle when doing a cold start.

In the meantime, I'm trying to figure out the sequence of events when the engine starts. I took off the air cleaner assembly to have a better view of the throttle body. I manually put the fast idle cam into the first position or notch (fastest position). So, I started the engine and it went into fast idle. Went to the front of the engine to take a look. Maybe after 20 seconds of fast idle, the control diaphragm rod pulled in and moved the fast idle cam to the third position or notch. Then about 10-15 seconds later, the control diaphragm rod moved back to its original position. With the control diaphragm rod pulling in, the engine went into an intermediate idle. The engine stayed at an intermediate idle for about 5 minutes and then I quickly pressed/released the gas pedal and the engine slowed down to a curb idle.

Questions: When the engine is at curb idle, should the fast idle cam be in the third position? Or should the fast idle lever be complete off the fast idle cam?

Also, when the engine was at curb idle for around five minutes, it suddenly increased rpm and went back to an intermediate idle. When this happened, the control diaphragm rod pulled back in again and then went back to its original position. Then the engine went back to curb idle again. It started this same process of switching between curb idle and intermediate idle for about ten minutes and then I shut off the engine.

I'm trying to figure out the terminology and location of the idle parts. I can't find the VOTM, or is the VOTM the same as the control diaphragm or the throttle positioner assembly?

Note on xctasy 's link to those other forum posts... Indeed, my Thunderbird was bought new in Northern California, and thus has California emissions. And the car was bought at a dealership located in a high altitude town. Maybe this information will help concerning an idle issue. Thanks!

[emerygt350]

The CFI has a barometric pressure sensor (front of the driver side wheel well) so altitude and Cali (it's fi) probably aren't a worry.

At idle it should be at the third level on the cam.
The kicker/votm/throttle actuator has 4 purposes. One is to kick the throttle after cold start, 2) bump the throttle up for AC 3) in odd circumstances, rescue the idle when something goes wrong 4) work as a cushion to keep the engine running when you rapidly pull your foot off the throttle.

If the car is have doing odd things when it is warm I would look to my thermostat and the engine temperature sensor. If you put a cool thermostat in the car the ECU might be switching back to cold start. It is very sensitive to this. 180 is just on the edge of "engine cold" and the ECU will use timing to raise the idle. Same for a bad temp sensor.

[TNTBird]

Thanks for all the info! I took another look at the start up sequence. Cold engine, fast idle cam on first position, engine starts and goes to fast idle. Kicker/votm/throttle actuator is extended out about 1/4 inch. About 30 seconds into the fast idle, the control diaphragm rod pulls in and moves the fast idle cam. The kicker/votm/throttle actuator retracts back to a zero position and is no longer extended.

First issue is that the fast idle cam gets hung up between the 2nd and 3rd position after the control diaphragm rod pulls back on the cam. I tried to adjust the control diaphragm rod, but it's still getting stuck between the 2nd and 3rd positions on the cam. I will try to adjust the rod some more. I can manually move the cam to the 3rd position and it seems the engine goes to the correct curb idle.

Second issue is the control diaphragm rod will always stay pulled in after about 30 seconds of run time. I was watching its operation a few weeks ago, and the control diaphragm would pull in for maybe a minute and then it would release and extend again. But, now it just stays pulled in even at curb idle.

Third issue is that the engine runs fine at curb idle for maybe 30-60 seconds, but then it goes into a variable idle. Idle will speed up to an intermittent idle and then go back to curb idle. Sometimes it might go to curb idle and then to a fast idle. Sometimes goes back to a fast idle and it will stay there. All very random every time I do a new cold start.

Also, the engine is now having a hard time starting when it is warm. When it does start, the engine misses badly and runs very rough. Engine runs normally on an initial cold start.

emerygt350, Thermostat is newer and I tested it before installing it. Yes, it might be an issue with the temperature sensor. I tested the old sensor with a multimeter and it tested good, but still might be faulty since it's so old and original. Also, I had to replace the original heater hose fitting on the manifold that holds the temperature sensor since the hose connector rusted out. The original fitting is unique and no longer available. So, I had to replace it with a T-fitting, so this might affect how coolant is flowing on the sensor. I will have to check...

[emerygt350]

I bet you are on the right path. This all sounds like a confused computer. You may want to make sure the manifold is well grounded and you don't have tape on that temperature sensor.

The votm is a pest. The little extension arm should extend after contact. I wonder if the vacuum line to the votm is all correct? That votm position is adjustable. It should give a hard enough kick to bring the cam into the right position. If push comes to shove I can make a video of mine doing a cold start.

[TNTBird]

Yes, it seems the computer is thinking that the engine is always cold. This is what might be causing the variable idle and the hard starting when the engine is warm.

Still trying to fully understand the sequence for the start up. Thinking on the fast idle cam that the first and second position are different RPM positions for the fast idle and the third position is for curb idle. Because in the owners manual it talks about pressing the gas pedal half way and pressing the gas pedal all the way to the floor to select between the two fast idle speeds before starting the engine. When the control diaphragm rod pulls in, it should always pull the cam far enough to set it on the third position of the cam, which would be the curb idle.

For the VOTM, it doesn't really do that much on this engine. When the engine starts, the VOTM is slightly extended during fast idle and then the VOTM pulls in to a zero position when the engine goes to curb idle. The engine will go into curb idle, but then the engine will start changing idle speeds and go into a weird variable idle situation. During this variable idle, I don't see anything physically moving around the throttle body, so it must be the computer that is trying to adjust the idle by adding fuel. Although, the control diaphragm rod is still fully pulled in when the engine is in the curb idle stage. Not really sure what actually causes the variable idle.

I'll work on the fast idle cam adjustment and check the temperature sensor again to see if I can find the problem... Thanks!

[emerygt350]

Your suspicions are correct. Don't mess with the cam and stuff yet. The CFI sets idle with timing. The searching idle with nothing moving means it is most likely that temp sensor. Either it is not working or it is a ground issue. Or your engine is actually that cold. Mine had all kinds of stupid issues when I had a half failed thermostat that never allowed the engine to get over 180.

[TNTBird]

I went ahead and tried some different adjustments on the control diaphragm rod. I now have it where it will pull the lever off of the fast idle cam completely. Looking at the three notches on the fast idle cam, these positions should only be used before starting the engine. Depending how hot the engine is, one of the positions on the fast idle cam will be selected when the gas pedal is pressed before starting the engine. Then maybe a minute after starting the engine, the control diaphragm rod pulls in and pulls the fast idle cam off of the fast idle lever. Is this how it should work?

I've been having some radiator issues and I noticed that the radiator wasn't completely full of water. (using water temporarily) I filled up the cooling system completely and now, after starting the engine, the engine idle is steady when it goes to curb idle... I think part of the problem is with my homemade heater hose fitting. I don't think the complete flow of coolant is passing over the engine temperature sensor. Hopefully, I can find the stock heater hose fitting in the future, but they seem to be very difficult to find.

At this point, here is what happens when I start the engine:

Press the gas pedal
Fast idle cam goes to first position
Start the engine
Engine goes to fast idle
After a minute, control diaphragm rod pulls in and moves fast idle cam off of the fast idle lever
Engine goes to intermediate idle
Control diaphragm rod remains retracted for approximately five minutes
Engine goes to curb idle
Control diaphragm rod extends back to resting position
Engine idles steady

From the amount of time the control diaphragm rod remains retracted, around five minutes, this might indicate there is a problem with coolant flow over the engine temperature sensor. Also, I don't see the VOTM doing anything. Should the VOTM plunger extend during the engine start up process? I'll take a look at the VOTM to see if it's working properly. Thanks for your help!

[emerygt350]

Looks good. What are the rpms for each stage? There are basically 4 stages, high idle start up. The kicker (votm) knocks it out of that after roughly 30s. Then it sits on the second lobe till the electric choke actuator pulls it off that. Then it is slightly fast idle set by the computer using timing until the engine is up to temp. Then it finally lays down into the regular idle of 850ish in park, 550 in drive with the brake on.

The only point at which the votm does anything here is when it kicks it off the high lobe of the cam on that initial high idle.

The votm is then really only a buffer on a quick throttle release, AC idle bump, and those very rare times the computer tries to rescue a faltering idle.

[TNTBird]

Looks like I have the engine idling correctly now after adjusting the control diaphragm rod.

Push gas pedal, fast idle cam goes to first position.
Start engine, engine goes to fast idle.
After around a minute, control diaphragm rod pulls in, engine kicks down to a lower rpm and fast idle cam moves to 3rd position.
Engine is at intermediate idle for around three minutes, control diaphragm rod extends to resting position.
Engine speed slows down to a curb idle.

I tried to get the RPM readings during the start up by purchasing a multimeter with a hertz setting and an infrared RPM gauge, but can't get any accurate readings from either of them, or I'm not using them correctly. From the sound of the idle speed, it sounds like the engine is idling properly. I might just install a hard wired RPM gauge.

The only thing I'm concerned about is that the VOTM does nothing during the start up process. Still not sure when the VOTM should extend. I turned on the AC, and this does increase the idle, but the VOTM still does nothing.