problem getting 84 5.0 to correct RPM

[fgross2006]

I have an 84 5.0 LX. It has a CFI setup.

The issue I'm having is that when the car reaches full operating temperature the RPM's wont lower to the correct 550 in drive, 1000 in park. If I bring the car to full operating temperature then shut off the car for 10 minutes, then I re start it runs at the correct 1000 in park and 550 in drive. It will run correct all day long. Even if I shut down for a few hours and let it get completely cold, it will start back up at the correct RPM's. But when the car sits overnight or longer, the first run I have to finesse to get the RPM's right by driving, shutting down then restarting.

The choke functions correctly. It is vacuum controlled by the same solenoid and vacuum line that controls the dashpot which controlls the RPM's. It seems to me that the vacuum is supposed to cut off to the dashpot and the choke kickdown when the car reaches full operating temperature. I believe the issue is that the ECM isn't sending the signal to cutoff the vacuum to the dashpot when the car is warmed up. I can drive for an hour or 90 minutes and the RPM's will not come down until I shutoff the car for 5 to 10 minutes, then magically the RPM's are spot on after I restart.

The CFI setup is a beast to be tamed for sure, but when it runs right it purs like a kitten. I replaced all the solenoids and vacuum lines when I got the car a few years back. I do have a spare ECM I can swap just to check. I dont want to play with the curb idle because the car will find it's idle if I run, kill and re-run. If the curb idle was off, it would be off all the time.

It never was like this before. Now the car sits most of the time in the garage, but there was a time when I commuted in this car every freezing cold NY morning and it always warmed up and kicked down its idle gracefully without me needing to mess around.

Any ideas on this?

[xctasy]

The KAM (Keep Alive Memory) is limited with these cars. The first influence is the ECT sensor signal and stability in the idel SPOUT. Leaks in the pulldown choke and checking the obvious things when its restarted. Id just check the 60 pin plug, and look inside the ECA (Ford speak for the EEC IV ECM.), and photo the four IC capacitors. Something simple will be doing it. One continuity or out of range sensor value by use of teflon tape or as a result of corrosion is all it takes. EGR or AIR pump might be influencing things. Relax, but delicately check the basic six idle inputs.

[fgross2006]

The KAM (Keep Alive Memory) is limited with these cars. The first influence is the ECT sensor signal and stability in the idel SPOUT. Leaks in the pulldown choke and checking the obvious things when its restarted. Id just check the 60 pin plug, and look inside the ECA (Ford speak for the EEC IV ECM.), and photo the four IC capacitors. Something simple will be doing it. One continuity or out of range sensor value by use of teflon tape or as a result of corrosion is all it takes. EGR or AIR pump might be influencing things. Relax, but delicately check the basic six idle inputs.

I did replace the ECT this past summer because it went bad. When I say bad, I mean the car wasn't driveable. I used the latest part Ford has for the 5.0 that required replacing the pigtail connector as well. Motorcraft DY1145 was what I installed. I used teflon paste, not tape, as I do on all sensors. I have to say that the idle issue was there before the old ECT went bad, and still there with the new ECT.

As for the choke, there is a rubber diaphragm inside the choke cutoff that I replaced a few years back. I have tested for leaks in the light blue vacuum lines and found none. The only thing I can see being the cause of this, would be that the ECM is not telling the solenoid to stop pulling vacuum. When vac is continuous it will engage the choke pull off, but since its already kicked down I dont think its an issue, but teed off the same line is the dashpot and when vacuum is applied it raises the RPM's which it's supposed to do when engaging the AC. In my case, the RPM's actually drop a notch when I engage the AC.

I found this nice tutorial on the Ford EEC - IV but I still dont see any troubleshooting step I can take apart from swapping the ECM to see if the problem persists.

http://www.amopower.com/eec-iv.htm

[fgross2006]

An update on this issue;

I had an errand to run that required a parkway run. I took the 84 Mustang. Between my home and the entrance to the parkway, a drive of about 15 minutes, the car was still idling high at 2000 in park and 1100 in drive.

I got on the parkway, drove another 20 minutes to my destination. car was idling at 1000 in park and 550 in drive when i got there. So what's happening is the car isn't dropping the RPM's when the car is running at full operating temp, but will eventually drop down if I keep driving. Keeping in mind that if I shut off the car for 5 minutes, and restart, the RPM's will land in the right zone.

Still an annoying problem. I have a spare ECM and 2 spare dashpot VOTM vacuum solenoids. I could try swapping to see if there's a change in behavior.

[xctasy]

Grab a Mity-vac. Change the pull-off choke pressure to 18 inches of H20.

Use the hand vacuum pump, but only pump it down to 18".

[fgross2006]

Grab a Mity-vac. Change the pull-off choke pressure to 18 inches of H20.

How am I supposed to do that? The Vacuum is metered by the solenoid. How can I change the metered vacuum to the choke?

[xctasy]

To start the early 1980 to 1984 CFi test sequence, the Ford vacuum pump pressure was applied to the BMAP sensor to invoke a test procedure. The same hand operated pump is used to set the choke pull-down. Its standard factory vacuum depression drop is ( or should be) 20 inches of water on the Gage scale. In mercury, its 13.5 lower. That setting can be varied depending on how much peak vacuum the engine generates. When the wax expands, the pull down vacuum energizes the lower idle setting. Varying the pull-down trigger vacuum should help control idle speed return.

[fgross2006]

To start the early 1980 to 1984 CFi test sequence, the Ford vacuum pump pressure was applied to the BMAP sensor to invoke a test procedure. The same hand operated pump is used to set the choke pulldown. Its standatd factory vacuum deoressiob drop is ( or should be) 20 inches of water on the gage scale. In mercury, its 13.5 lower. That setting can be varied depending on how much peak vacuum the engine generates. When the wax expands, the pull down vacuum energises the lower idle setting. Varying the pulldown trigger vacuum should help control idle speed return.

I still dont understand how I am supposed to change the vacuum on the choke when its set by the Solenoid and ECM. Do you have a step by step or a video of the process?

[xctasy]

the arrow takes you to the post

http://vb.foureyedpride.com/showthre...hoke-set-issue

Yes, it is. But you have to follow the time honored apply vac procedure as per VECI , also common with the early 3.3 1-bbl




It was also a primary way of triggering the code reader process in the 1980-1983 EECIII 5.0 CFI.

https://www.youtube.com/watch?v=puAEJ3BYFeY



The final test is page F155 as found here http://beta.askatech.com/AskATechLiv...Track/F050.pdf


See https://www.fordforums.com/threads/c...mation.289185/



https://www.youtube.com/watch?v=zfSe6Dy3qjc

https://www.youtube.com/watch?time_c...ature=emb_logo

[xctasy]

see below.

[xctasy]

The specifics don't exist, but the tool does.

You preload the Choke pull-down by application of Mityvac vaccum, just like in Fig 19, the 1 bbl 1946 Holley carb.

Holley,
Holley Weber,
Carter,
Carter Weber,
and Motorcraft use the choke pull-down on all passenger car Fords after 1980

Carter call it an un-loader adjustment,
FoMoCo a pull-down

or, Rockauto calls that thing the "Carburetor Choke Pull Off". Um, yeah, pull-off.

Ye Godzzz.

It is usually a vacuum-operated mechanism that allows the choke to close fully, but when the engine starts it's vacuum pulls the choke open enough to allow the engine to run. The "choke pull-down motor" as Ford calls it in the Ford Service Manual.


See this CFi 1982 video for the KEOR for the Standard Performance 5.0 Central Injection with EECIII.

2.30 on



https://www.youtube.com/watch?v=puAEJ3BYFeY

Note that after we filmed this I actually discovered an EEC test connector right by the pair of solenoids shown in the video. The connector is not mentioned anywhere in the tech manuals for the car...but it doesn't matter much, it just brings the same wires from the solenoids to a more convenient place for hooking up a test light.

[fgross2006]

I have a vacuum pump like the one used in the video. I can connect it and pump up the choke pull down but how am I supposed to reset it? Im losing something here. Am I supposed to reset the position of the pulldown bar after applying vacuum?

[xctasy]

Post 22 and then 23. Reduce the applied recomended 20 inches of water vacuum at the pull-down line, in 1 inch lower steps, untill it behaves the way you want it. Since all your basic settings are right, its just the amount of or degree of unloading that you need to vary.

The rest is self compensating, via the ignition, VOTM, EGR and AIR loops. See posts 22 and 23 again in the blue line link I noted before.

Youll get this working because you are thorough and will be able to tell if the pulldown vacuum is the X factor in the idle speed settle back on re- start.

I love your dedication, the CFi/ AOD is a really sweet engine combo.

[fgross2006]

Post 22 and then 23. Reduce the applied recomended 20 inches of water vacuum at the pull-down line, in 1 inch lower steps, untill it behaves the way you want it. Since all your basic settings are right, its just the amount of or degree of unloading that you need to vary.

The rest is self compensating, via the ignition, VOTM, EGR and AIR loops. See posts 22 and 23 again in the blue line link I noted before.

Youll get this working because you are thorough and will be able to tell if the pulldown vacuum is the X factor in the idle speed settle back on re- start.

I love your dedication, the CFi/ AOD is a really sweet engine combo.

I just checked out the choke set up. Its cold in NY today but not freezing cold.

I found that the choke pull-down diaphragm doesn't hold vacuum. It will engage the pull-down enough to trigger the cam to the second step with less than 10 on vacuum pump, but the vacuum bleeds out.

I also found that my electric choke thermostat isnt getting voltage from the stator as I read it's supposed to. Its spliced off a wire on the voltage coil. It currently has 12v keyed on source. i read that the choke should be wired off the stator which should get 6 or 7 volts only when the car is running and the alternator is turning. I read that over exposure to 12 v can damage the choke thermostat. Any truth to that?

Can I get part numbers for the correct choke thermostat and the correct choke pull-down diaphragm for the CFI set up? I am going to move the power source to the stator and replace the choke thermostat and the pull-down diaphragm and start from scratch.

[xctasy]

Yes, wire it off the Stator.

Any choke replacement meeting Fords Motorcraft Electric Choke with pulldown should work.

[xctasy]

try https://www.go-parts.com/ps-mmp.php?...oke+Thermostat

No one cares the CFi is Fuel Injection, they all think its a 2150E 2-bbl, or VV2700/7200 or 4-bbl 4180c


1985 Ford Mustang Carburetor Choke Thermostat 8 Cyl 5.0L (Hygrade CV237)
E4ZE-BA, E5AE-EA, E5SE-FA, E5ZE-BA, CA, DA

The 1982 Ford Mustang Carburetor Choke Thermostat 8 Cyl 5.0L (Hygrade CV237)
with VV Carb. with Ford Carb. 7200 E1AE-SA, E25E-ABA, AC, E2AE-AGA, MA, MB

Same as CFi.


1986 Ford Mustang / Mercury Capri "Carburetor" Choke Thermostat 6 Cyl 3.8L (Hygrade CV237)
E5SE-GA, HA, JA, KA, E6SE-AA, BA

[emerygt350]

Seems like you are getting there. I would remind you though that after the car warms up, that dashpot shouldn't be doing anything to affect your idle. It it is, than it is not adjusted correctly. All it should do is buffer the throttle after a quick release, no more.

[xctasy]

Seems like you are getting there. I would remind you though that after the car warms up, that dashpot shouldn't be doing anything to affect your idle. It it is, than it is not adjusted correctly. All it should do is buffer the throttle after a quick release, no more.

Looks like hes doing it pretty good, emery!

The broad sweep of the the basics needs to be done first.

The pull-down choke and electrical connecting is critical.
Then the VOTM,
then the TFi and its PIP,
then the ECT and others
the MAP,
the TPS,
the 02 sensors.

The AOD set up changes the pre-load on the CFi idle, if its in spec, its not an issue.


The only issues that generated a TSB is the the deflector for the CFi throttle body gasket, to correct heavy use air fuel ratio on both 3.8s and 5.0s. Without the The CFi restriction plate TSB item for all EECIV CFi's, 5.0 and 3.8's., it will always have an issue if its leaking or not working, or not present if its CFi.

All the other matters were failure to follow the processes and standard operational procedures. This is common when a company actively manages an engine electronically like its Mission Control.

The 5.0 HO uses the high stall 2350 or 2.53 :1 ratio to unload the operation of the PIP 6 degrees spark removal idle control...it would be a problem in a V8 5.0 CFi 5 speed manual conversion, but Ford decided never to do a 4 or 5 speed stick CFi 3.8 or 5.0.

4 or 5 speed stick 3.8 CFi conversions seam to work well enough.

The lack of IAC isn't the issue people think because the EGR and AIR are self regulating and non electronic in operation, although monitored electronically.

On the 3.8 CFi, EGR is electronically monitored and operated, and it has IAC, so it differs a lot in controlling stable idle, and it has an ACT, Air inlet temp sensor. Ford decided to do the EECIV on the 3.8 CFi quite early, and debugged the HO 5.0 CFi with it.

The 5.0 HO CFi is really smart, the four long years of EECIII development pushed the EECIV into being a very good data logger and control system with the new TFi.

Heat riser vacuum issues and EGR blockage aren't a 5.0 problem like they are in the 3.8 CFi.

One last point. The huge improvement with the 1990 model year triple digit Fault codes was due to the planned OBD II architecture pioneered by the SAE to answer legislation on operational performance checks to ensure better emissions gear operation through the life of the vehicle.

None of that GFUB family of strategies and activated PID updates is really able to be foistered on the brain dead CFi 3.8 and 5.0's just don't rate despite the wounder-full howl and rasp the twin Bosch injectors made at idle and under load.

For the established Box Codes,

The 1985 E53F12A650AL1A 3.8 Engine Computer ECM Cougar Thunderbird LTD NL box code

the last 86 CFi engine was the DC 3.8 computer,

The FA 3.8 Mustang/T-Bird/LTD CFi for sure, with ISC/IAC/IAB for idle.
1986 Ford Thunderbird Mercury Cougar Engine Control 3.8L ECU EEC E63F-12A650-A1A = the FA box code


The 10 5.0 CFi questionables are:

GJ1 5.0 Mustang
VJ1 5.0 Mustang
AB2 5.0 T-Bird
D2L 5.0 T-Bird
E1X 5.0 T-Bird
H2M 5.0 T-Bird
H2M1 5.0 T-Bird
KF 5.0 T-Bird
MC2 5.0 T-Bird
MN 5.0 G. Marquis

Any of these will fall out of range if its not a 100% 5.0 HO CFi box code. The O2 sensor type changed, and the computer changed to suit that.

Aside form the four IC capacitor leakage, and the occasional Printed Circuit de-lamination, you can rest assured its Pinouts, vac lines, and the stock parts that supply signals back to the ECA that are your first port of call.

[fgross2006]

So I messed with it again some more today. I made a short youtube vid showing that the choke isn't kicking down off the 3rd cam. That's the gist of whats happening here. Vacuum is not an issue. The choke pull-down diaphragm does not hold vacuum, it bleeds down, but the constant pull when the solenoid is engaged is enough to keep the pull-down engaged until the ECM tells the solenoid to cut off.

I read that Ford original choke thermostats need 7.5 volts from the alternator's stator. I am thinking that the past few years the choke thermo has been getting 12 volts from the ignition coil and maybe it damaged the choke thermo? I moved the wire to the stator and its now getting 7.5 volts. I pulled the boot back a crack and probed the thermostats electrode directly and verified it's getting 7.5 volts from the stator.

The reason I'm thinking the choke thermo is shot is because if you watch this video you can see that the car is still hi idling because the choke is stuck on the 3rd step of the cam. It wont fall off until I push it with my finger. You see me snapping the throttle, trying to get the CFI to go into low idle but it doesnt until I push the cam with my finger.

The adjustment on the choke thermo has notches and you can see I'm at the last notch on the left. No more room for adjustment. Turning to the right keeps the hi idle longer, turning to the left shortens the time it takes for the lever to fall off the 3rd step of the cam and go to low idle. I can't adjust it any more to the left so I assume I need a new choke thermostat and a diaphragm,

[emerygt350]

Hmmm... When I had my engine rebuilt, the mechanic some how bent that part of the kickdown can thing. It did exactly what you describe. I had to pull it apart and line it back up. Not sure how that could have happened here but perhaps it is just aligned poorly?

[fgross2006]

Hmmm... When I had my engine rebuilt, the mechanic some how bent that part of the kickdown can thing. It did exactly what you describe. I had to pull it apart and line it back up. Not sure how that could have happened here but perhaps it is just aligned poorly?

No reason why that should be. I had the engine rebuilt 4 summers back. I had the CFI out, disassembled, had the fuel injectors flow tested and cleaned. The whole thing went back together like cake and has run fantastic until this past summer when I first started having issues with the idle not kicking down when its supposed to.

You can see in the vid that i can move it freely with a finger. If I loosen the 3 hold down screws and rotate the choke thermostat I can clearly see the cam moves with the direction of the choke as I rotate it. I just ran out of adjustment when I get to the last dash on the scale and I need another dash or 2 to get the thing in the right spot.

I'm gonna put a new choke thermostat and diaphragm for the pull down.

The choke thermostat isn't hard to locate but I do need a correct part number for the choke pull down diaphragm Its hard to locate Googling.

[fgross2006]

Im pretty sure this is the correct diaphragm for the choke pull off. It is listed ror 80-85 and specifically says for CFI on the box. What else could it be?

https://www.ebay.com/itm/283452968300

Reasonable price for NOS. I see lots of Choke Thermostats listed so i need to narrow it down to the exact one that came on my 84 5.0.

[xctasy]

The choke thermostat isn't hard to locate but I do need a correct part number for the choke pull down diaphragm Its hard to locate Googling.

1986 Ford Mustang / Mercury Capri "Carburetor" Choke Thermostat 6 Cyl 3.8L (Hygrade CV237)
E5SE-GA, HA, JA, KA, E6SE-AA, BA.

Everything that was Motorcraft used the same part stating with the Variable Venturi 2-bbl. 1978 I think was the first year of the pull-down choke, it was very early on.



For 1981, it gained a new common part number.

It was Hygrade CV-280 choke thermostat 1975-1980 Ford Mercury Lincoln 2BBL from 1975 to 1980.


Continued right on till with the first 1979 4180C 4BBL in the 429 trucks. And then till, oh, 1988 on the 4180c and other 4-bbls governed carbs like the 4195EG F-Trucks and E-vans 4-bbls in 370, 460 and some of the last 351 carb trucks.

You should be good with any Hygrade CV237 interchange.

Like the Ford Thunderbird Carburetor Choke Thermostat SMP 37792VX
1981-1982, 1984-1987 1985 1986.

Bewares, its Counter Wallied, and miss-named.

eg https://www.ebay.com/itm/Carburetor-...gAAOSwKINdiESO


The drill down is for Hygrade Standard CPA 81 Carburetor Choke Pull Off - CPA81.


Interchange part #779-6278, 1C1003, CP380, CPA81



The earlier 1975-1980 Carburetor-Choke-Thermostat-Standard-CV382 isn't a pulldown choke.

[emerygt350]

If I remember right it is included in the easy to find CFI rebuild kit too.

[fgross2006]

If I remember right it is included in the easy to find CFI rebuild kit too.

I had purchased one of those kits a few years back when I had my motor rebuilt to re-do the CFI at the same time. Convenient but kind of pricey for what amounts to 10 cent O rings, 25 cent nuts, a paper slide ruler, and 2 gaskets, one of which I could not use. The choke pull down diaphragm I just got for $7.99 NOS Motorcraft. The one pictured is black rubber and the one that comes in the kit is orange but I'm not sure what difference that really makes.

I got a NOS choke thermostat from this seller, he still has one left. He lists for $24. I made offer of $15 and he accepted. https://www.ebay.com/itm/Carburetor-...72.m2749.l2649

Just wondering if the choke pull down is supposed to hold vaccum or if its supposed to leak down. If It should hold vac should I use a small dab of RTV around the edges of the cup the diaphragm goes into?