Hi,
I seem to be having a similar problem to Bird351 with my '85 with a rebuilt V8 302 engine with headers, crane cam, the bearings are all new (10 over on crank), new hyp. pistons (9 to 1), (30 over on cyl walls), oil pump, heads had to be shaved a bit as right head was slightly warped, new valve job, with new rod guides and hyd. lifters.
I changed the oil yesterday, as the car was sitting for about a year, and put in new gas and some injector cleaner additive.
It's got the CFI on it, and it will start and I can keep it running if I keep throttling the gas, but will not go to an idle no matter how warm the engine gets !
I replaced the ACT sensor on the engine, as it was showing 2.7 volts with a cold engine, while the coolant sensor was showing 3.2, but that didn't help at all.
If I disconnect the ACT sensor, the engine will start and run at around 3000 rpm, with the occasional backfire before I shut it off.
After toying with the screw that's connected to the TPS I can get it to idle at around 1000 rpms, but really rough. I tried disconnecting the EGR electrical lines, and it started just the same.
Bird351 says he adjusted the TPS; how do you do that ?
Another thing is that today when I started it up, I began to hear a tapping sound on the right hand side of the engine, does anybody have any idea what it could be ?
Thanks !
Push pins into the green and black wires onto the TPS so you can get a multimeter on it. I use safety pins, but whatever works. Loosen the screws holding down the TPS but don't remove them. Take a reading of the two pins with a multimeter.. it should read between .92 and .98v. If it does not, rotate the TPS itself as best you can until it reads within that range, and tighten the screws back down. As I have had to, you may need to do this several times during the course of messing around with your engine.. and remember, changing the idle screw is going to change the voltage the TPS shows. One time I got the TPS as far as 1.01v and couldn't turn it anymore, but I knew the idle RPM was a bit high at the time.. like 1000+.. so I just tightened down the TPS at 1.01v and then turned the idle screw back down until it read like .977v. But, if it's a bigger adjustment than that, I believe you can gently file the mounting holes a little wider if you need to.
I assume you mean that the idle screw is the one next to the TPS. If so, what is the the screw on the other side of the throttle body, that is on the IAC motor ?
also, any idea why the engine would die while making a sucking sound when I plug in the ACT sensor when it's running ?
You'll have to ask the others what screws go where on the CFI 5.0.. I don't have one of those. The screw I'm talking about is the idle speed adjustment.
My CFI V6 setup MIGHT be similar in some ways, but I don't want to bank on that and steer ya the wrong way. I know a few here have CFI 5.0s.. someone will probably come in here and set things straight.
If that Crane cam has any different vacuum characteristics than the stock '85 CFI cam it will make your car have drivability problems. The EEC-IV CFI computer can't deal with vacuum changes. Since vacuum is usually highest at idle, and if your cam is creating less vacuum than the EEC-IV computer expects (or if it creates a pulsating vacuum) this could be causing your idle problem.
The car was running fine at one point in time, but the tranny died and had to be rebuilt, and it hasn't run properly since, or so I was told; I bought this car from a local ad, and I'm trying to get it into shape.
On the other hand, would going to a carburetor fix the vacuum problems, if any ?
Also, any ideas about the tapping noise ? It rises in frequency with the RPMs, and it sounds like metal on metal.
Nope, that's the fast-idle adjuster.
Because you've instantly changed the readings the computer is trying to work with, or the ACT is defective?
TYPICAL SENSOR VALUES ( FORD EEC IV )
Deg.F Deg.C Volts Ohms
------------------------------
248 120 .28 1.18k
230 110 .36 1.55
212 100 .47 2.07
194 90 .61 2.80
176 80 .80 3.84
158 70 1.04 5.37
140 60 1.35 7.60
122 50 1.72 10.97
104 40 2.16 16.15
86 30 2.62 24.27
68 20 3.06 37.38
50 10 3.52 58.75
The one on the throttle arm adjusts the TV rod's clearance. The ones on the "saddle" adjust or lock (theoretically :disappoin ) the idle speed.
.
Nope, that's the fast-idle adjuster.
Because you've instantly changed the readings the computer is trying to work with, or the ACT is defective?
TYPICAL SENSOR VALUES ( FORD EEC IV )
Deg.F Deg.C Volts Ohms
------------------------------
248 - 120 - .28 - 1.18k
230 - 110 - .36 - 1.55
212 - 100 - .47 - 2.07
194 - 90 - .61 - 2.80
176 - 80 - .80 - 3.84
158 - 70 - 1.04 - 5.37
140 - 60 - 1.35 - 7.60
122 - 50 - 1.72 - 10.97
104 - 40 - 2.16 - 16.15
86 - 30 - 2.62 - 24.27
68 - 20 - 3.06 - 37.38
50 - 10 - 3.52 - 58.75
The one on the throttle arm adjusts the TV rod's clearance. The ones on the "saddle" adjust and lock (yeah, right :disappoin ) the idle speed.
.
Hi,
I got an buttstuffog multimeter, and with KOEO, I took the following readings :
TPS: 2.1v , with the throttle closed.
3.4v, with the throttle wide open.
My TPS is not the kind you can rotate, it has the round holes. I don't know what to make of this, the Probst book is not very clear on the subject, but I suppose that my car has the EEC-IV and that the voltage with the throttle closed should not be this high !
Should I change the TPS or am I mistaken and it is actually an EEC-III ?
The ACT showed 3.2 with a cold engine, and around 2.2 after running it for a couple of minutes.
Thanks !
Between the orange/white and darkgreen/lightgreen? Not sure about idle, but my 1984 Ford Emissions Diagnosis says to expect 3.5v at a quick WOT while running, so it looks normal.
That looks normal too.
I wouldn't be surprised if it looked like this pic...
(Of course, looking at the back, there's a LOT of room for hole expansion)
.
My TPS looks about the same as the one you posted, I will take a picture of it today and put it here, the Probst book says it is the "Late" model.
Again, the Probst book states that for EEC-IV, which the '85 Thunderbird is supposed to be using, 0.6v is what it should output with the throttle closed. I have read on the forum that his book is not very trustworthy, I don't know whether I should think about replacing the TPS or not.
The readings I was taking were KOEO but when I did run the engine and read the TPS voltage, it stayed the same even if the RPMS were fluctuating within a 300 RPM range.
Also, I took the measurements on the black and green wires, as per Bird351's instructions. Should I have taken them on the orange and green ?
Thanks !
Update : Took a picture, sorry about the quality but my camera is a pos. I priced the TPS, it's $35 at O'Reilly, should I consider changing it ?
I was wondering if you looked into the operation of the cold engine speed control? The bimetal spring and heater position a cam which can control idle speed. The cam has a couple of different positions that are used depending on the engine status. Ford sold a seperate manual for engine/emissions diagnostic but the Chilton manual gives a pretty good chapter on that too.
If you've solved the problem, and I hope you have let us know what you found.
JP :welder:
did you get your car running yet? if it ran before and now does not then i have a couple things to add here.
btw,,, to anyone with a 3.8 cfi,,,,,,,,,,,this is the 5.0 cfi you want. Larger TB all together. Just r/r your injectors
That TPS voltage is too high...
I'd look into replacing it and make sure it's installed correctly. If the new one is not adjustable, take the metal bushes out of the holes or elongate them to be able to adjust it to the proper range..
yep,, chainsaw file will worble the holes out so you can remount the sensor then rotate it to the desired output.
I always just read off the green wire only grounding out my black meter lead.
Your best off to use the meter you have (buttstuffog) to read a variable resistor anyways. You can see intermittant opens with the buttstuffog meter which the digital type makes it harder to pick up on.
if the tps does not fix it,,, leme trow some CFI cleaning tips to you.
I'm sorry for taking so long to reply, what with finals and work I was kept pretty busy.
In accordance to "when it rains it pours", the engine developed a knock on cylinder 3, which turned out to be a shaved cam lobe. I then replaced the cam and the lifters with a Melling CL MTF 1, and now have it in running order, back to the original problem.
I got it to the point where if I disconnect the ACT sensor it will run and I am driving it around to break in the cam, but the mileage is horrible (average of 6 mpg, and when I'm accelerating it's 3-4) and when I stop and leave the car running, there's wet spots under the exhaust, which I don't really know what they're caused by.
I am thinking that the previous owner must have crossed some wires somewhere, so maybe redo the wiring ? I am just throwing some ideas around, please feel free to give me yours, as I would really like to get it running again.
My battery went flat this morning so I took it to Autozone to recharge/test it. I also hunted around the local salvage yards and found a wiring harness which I will pull tomorrow and install on it. For $20 I figured there was no reason to redo the wiring by hand.
The other option I have right now is to get the whole FI setup from an '88 , which the guy is asking $100 for, although I will try to negotiate.
Again, please contribute with any ideas you might have.
After swapping the harness ,computer and MAP sensor, things got a little better, but not by much, and I finally decided to go the old-fashioned way with a carb.
I have taken out the cfi, distributor and in-tank fuel pump and replaced them with a motorcraft carb and distributor and a noname electric pump sitting where the fuel filter used to be ( it has its own filter).
The car is running nicely now, and I have two wiring harnesses, two cfi computers and one set of working, almost new sensors for sale.