Well, as asked I'm giving an update. I found the distributor shaft to be extremely loose. Interesting in that the vane window wasn't striking the PIP - it was that bad.
Anyway, I replaced the distributor and in doing so replaced the PIP and TFI. The results, NOTHING changed. That was somewhat of a shocker being how loose the distributor was.
I replaced the O2 sensor, and NOTHING changed.
I cleaned the IAC, set the idle as described on this site and NOTHING changed.
I set the TPS as described on this site (.94 volts) and NOTHING changed.
So, just for the record since the post had gotten kind of long. The momentary (about every 45 sconds or so) engine drops in RPM at idle (but never stalling) has existed for years. This never had an effect on the drivability of the car otherwise. Underway it ran fine.
The acceleration power loss, accelerate again, power loss again, accelerate above 4,500 RPM but run somewhat crappy is relatively new. Note that this is with the throttle held to a costant position (1/2 to 3/4 throttle).
I've swapped out the plugs, wires, distributor (including PIP and TFI). I've replaced the fuel regulator, fuel filter and O2 sensor.
I've set the timing 10 degress with the spout removed (then reinstalled). I cleaned the IAC and set the idle to 700-800 RPM with the IAC disconnected (then reconnected). I set the TPS to .94 volts at idle. I've also checked the VAM to the extent that the wiper is not worn through the resistive pad. But NOTHING has made a difference.
Ideas?
Tom
I'd look further into the VAM. Have you checked the voltage of that VAM at various times? It almost sounds like you might have a flat spot on your VAM. For that matter, did you check the TPS for flat spots?
To test the VAM: measure voltage between white/black and black at the sensor connector. At idle should be .25-.28v. At warm idle should be .75-.9v. When you swing the door all the way open (via a screwdriver or the like) you should see an even increase in voltage with no drop outs (gotta use an analog gauge to know for sure).
Check the TPS for flat spots by measuring the voltage between the green and black wires of the TPS harness. Throttle closed you say you have .94v. With engine off, rotate the throttle plate from full closed to full open and watch for voltage drops (again, gotta use analog).
Let us know...
By the way... the fix to my problem was just a vacuum leak. :o
i think with the codes you stated the VAM or TPS are the likely culprits, as stated above. Have you checked out JT's site by the way? Tbird Heritage... search for it on this forum... he has step by step trouble shooting with EEC codes.
More update. When I replaced my wobbly distributor it was with a used one. Frankly I thought it ran worse than before. Today I swapped out the PIP/TFI. I also replaced the TPS and cleaned the ACT. In some ways I thought it was better and in others not.
I'm out of work and this is a "hobby" car, so my only option is to buy three used TPS/PIP/TFI etc. for about $3 each rather than $50 for a new one and hope I hit on one.
Most of my diagnosis has been with the car in the driveway, or on short drives. Today I took it out on the freeway for about 8 miles (twice). After the second time I felt the car ran better. Since this car sat for over four years I'm wondering if the injectors are contributing to my problem. Perhaps the freeway runs with longer injector opening times are helping to clean them out. Externally they looked clean when I could see the nozzle end doing the head swap.
So, here is where I'm at. It still has some miss at idle. If I gradually accelerate (like getting on a freeway on ramp) the car seems to run correct all the way to the redline.
The biggest problem is in the 2,500 RPM range going about 35 MPH. Either maintaining that speed causes a miss, or attempting to SLIGHTLY accelerate causes a Wa - Wa - Wa effect like the car is loosing gas or ignition. I'm kind of ruling out the gas side as it will accelerate fine in the above on ramp senario. So my assumption is the fuel delivery is adaquate.
I'll test the VAM in a few days. However, it basically only has a wiper on a resistive board. I repositioned the wiper to ride slightly below the old wear marks. This caused NO repositioning of the original alignment as the wiper still began and ended in the same radius. Also, this brought no changes.
I need to remember that most everything is 21 years old with 150,000 miles. When the motor was in the T-Bird if was well isolated and insulated to transmitting engine odities. Now that it is in the "beer can" Pinto every unpleasanty is felt. I'm not sure if that is good or bad.
Thanks everyone for your help, Tom
I have found that the tps cannot be tested with a voltage reading. It can only be set with a voltage reading. The same holds true for the VAM. The proper way to test TPS and VAM is with a scope. The scope will show a non interrupted pattern with the TPS or the VAM. The scope shows a clean sweap without noize spikes if the components are good. If the conponents are bad the scope will show spikes and noize on the components. The Vam and Tps are the only adjustible component in the system and must be set perfectly to operate correctly. Rmember both of these units provide a variable voltage to the computer. But at WOT the voltage is constant. (throttle set in one position and the same for the VAM) I have found over the yiers of working on TC. Ignition problems are the root cause of most problems along with vac or boost leaks. Hope this helps Tom Senior
I had been chasing the same elusive miss for over a week now...mine turned out to be a vacuum leak, coupled with too much plug gap. Tightened the plugs up to .028 and fixed the leak, purrs like a kitten at idle and no stumble under load.
This was all after fp adjustments, tps adjustment and replacement, o2 sensor replacement, intercooler coupler replacement, etc.
Hi 87 I AGREE we have found most misses related to the 2.3 is spark blow out. The ignition system must have the power to spark the plugs at high boost. I run wide gaps on my 2.3 but alot of the cars we work on cant. I have built hundreds of preasurized motors that are not ignition sensetive. I build tuns of supercharged and turbo hondas with no ignition blow out. I personally have 2 hondas one turbo and one supercharged and every one of my cars are turbo or supercharged. I think the tune has a lot to do with the condition. Point being my TC dynows at 378 HP and runs .040 gaps. I boost app 28 lbs. The ford TFI system has the ability to provide more than enough spark. But in some applications it can't. The state of tune is the key with high boost. The stock TC tune up spec for plug gap is .035. A bone stock TC should run perfectly at gaps in excess of .040. When ford certified the 2.3 it had to be able to hold a tune for 50,000 miles and the engine did. This is the test all engines must pass to get a carb certification for sale in this country. Some of the the engines on this web site have very high milage and requires more spark energy. Toss the dice on this one and do what works for your setup. I run a scope on engines when dynowing and most of the time the ford TFI ignition system is adequite. Tom Senior
Tom Senior, thanks for the tips. I was a TV studio tech. prior to teaching the same. So, I have access to a scope.
One thing that baffles me about the Orange wire that goes to the turbo. "Connectively" the aluminum of the turbo connects to the cast iron of the turbo that connects to the exhaust manifold and then to the block (which ultimately goes to battery minus (ground).
There is a LOT of rust involved in getting that Orange wire to ground. Why would they have run the wire to ground that way? Why not just ground it to the body? That was the way I origiginally did it. Properly putting it on the turbo made no difference in my problems.
Anyway, since you were talking scopes I thought you have an electonic background that might explain the Orange ground wire on the turbo.
Thanks, Tom
Having worked in a similar field (recording studio) I'm willing to bet you're familiar with the technique of star grounding. Where every device has its own ground wire. Its a similar concept with that orange wire.
There is already a large amount of current flowing through the engine block and the primary ground wire as this is the negative return for the alternator.
Now, that orange wire is the ground reference for the O2 sensor. The sensor itself only outputs a small voltage to begin with so as much accuracy as possible is needed. Instead of the computer reading the voltage on the O2 sensor in relationship with the engine block which is dependent on how much power the alternator is flowing and how much power is flowing through the other computer grounds, the computer measures it directly off of the orange wire.
I'd draw a picture but its 2am here and I'm a bit tired. I hope this helps
Yep, follows my experiences also Tom. I have owned 4 TurboFords and ALL of them required different ignition setups to be happy. Some would only run on Motorcraft wires/plugs or Magnecores....had one that would run on cheap Autozoo wires AND, get this, Bosch Platinums! Damnedest thing I ever saw. Anyone know why these motors are so sensitive?