CFI Misfires/drivability issues

[kishy]

Alrighty, redundancy time. Below testing done fresh today.

Checked ACT at ambient temperature (40 something Fahrenheit). Appeared in spec. Removed from manifold, brought flame of a torch near the sensing tip, observed voltage decreasing as expected. It isn't possible to backprobe this while it's installed because of its location under the throttle body, so this is as good as I can do. It did test out approximately the same as my spare as well.

Performed same test with ECT except just applied torch to the pipe it threads into. Seemed a bit off from spec based on my expectations but nonetheless changed as expected. There's about a 0.05 to 0.1 voltage variance from what the charts all say. This amount of variance stays the same both at cold and fully hot engine temps. The sensor seems to be saying the temperature is a bit colder than it actually is. Since it's off by such a small amount I doubt it's a concern; am I wrong?

Performed same test of 3 spare ECTs, found values all varied slightly but were all in the same ballpark or more accurate.

TPS...found my analog meter. Checked the TPS. Observed that throttle closed voltage is 0.80 which is lower than I left it previously. TPS does not appear to have shifted any so IDK. Hand operated throttle from closed to WOT and back again as well as a bunch of movements at various points, voltage changes as expected with no spikes or drops.

MAP...it's established the engine makes good vacuum and that swapping the MAP for multiple others known-good has not affected this previously. So I'm just going to say it works. The vacuum line to the MAP seems to be in functional condition as well.

Fuel. Primes to 40-42ish PSI. It will leak down but very slowly. The leakage is not via the injectors as the throttle plates stay dry. The CFI pressure regulator is 'fixed', there is no vacuum control over it, so there's no way the regulator is internally leaking fuel into a vacuum line. The leakdown is evidently via the regulator, back to the return line (or via the pump back into the tank, but regardless, it didn't even lose a full 10psi over an hour so it's no big deal).

Runs at a consistent 40-42 PSI. The needle stays steady on the gauge and there is no change in fuel pressure coinciding with how the engine is running. I watched the gauge face while the engine was doing it's choking missing garbage and it stayed steady. With 40PSI at the injectors, we can rule out the pump and filter, as the pressure would have to be a fair bit less before the engine would suffer from lack of fuel...right?

Injectors as determined above do not leak down. However, I don't really have much of a way to verify that they flow adequately. I'm tempted to say they're fine though because it runs fine with SPOUT disconnected.

Shook harness again. No correlation to improvement or degradation of engine running quality.

Played with the key while it was running, tried turning a bit closer to the start position and pulling back towards off, no correlation to engine running quality. I know that's not the most accurate way to test it but it seems like if the ignition switch were the problem there'd be some flakiness with key movement.

Found #8 plug wire may have been arcing on oil dipstick tube. Rectified situation. No change to engine running quality.

Problems seem not to affect a 100% cold engine, but they seem to come on once the engine begins gaining some warmth, but still before 130 degrees. Different from before, once problems begin, they basically continue intermittently with no real temperature pattern, except they will be more frequent and severe at operating temp. As before, much worse when engine is loaded (e.g. brake in gear).

Oh, and injector mini-harness in the throttle body assembly is good too. 0 ohms on each of the wires and no breaks or increases in resistance from wiggling wires.

[gadget73]

SOmething I remember from another CFI motor I played with once. It would misfire and do all sorts of stupid shit under load, like hill climbing. Ran fine on flat road for the most part. Finally figured out it was the nearly-new plug wires that were not happy. Stuck a set of used Ford Racing wires on that were laying around as a test and it ran like a watch. Might be worth having a good look at the wires and other ignition parts.


Doubt the ECT being slightly off is the end of the world. If it responds within reason you're probably OK. Could be a slight variance in the vref voltage, or your meter may not be dead on balls accurate. Those values have some amount of tolerance to them and the ECM can self-correct within reason.

[kishy]

After some further poking and prodding, I took it for a drive with SPOUT disconnected. Unlike the last time I did that, it ran kind of awful this time. Mid throttle didn't want to pull at all, it was like the throttle had to be either "on" or "off". I might have attributed that to the lack of timing advance except it wasn't like that last time I drove with SPOUT undone.

So that gave me the idea to test my TPS yet again-again, and it checked out again as expected, but I swapped it for another just because and for whatever reason it seems a little better. But there's no way to know if "a little better" actually means anything with an intermittent problem.

At present the only vacuum items connected are the brake booster and the MAP sensor. The brake booster probably does not leak, based on how much vacuum the engine makes. I ran a new vacuum line for the MAP and have now tried 4 different ones with no change.

I hopped on here on my phone, saw your post re: ignition wires, so I started playing with those. Rearranging, pulling on them, twisting the connections etc. Unfortunately just as I began doing that, it smoothed out and decided to run normally. The only wire I had touched at that point was the main coil wire and what I did was change the funky angle I had the wire coming off the coil. I then went around the engine shaking and pulling on everything I could find and it wouldn't miss. Got in, brake in gear and revved it, stayed smooth. Engine was at operating temperature so following the pattern, it should have missed.

Came in to have some dinner. Curious to see what it does when I go back out there. If it's that coil wire I'm going to feel like a complete moron.

As an aside, I soldered up some adapters to go from old to new TPS and vice versa, as they are the same TPS and 1984 retains the EEC-III connector whereas 1985 uses the same one as SEFI...making these cars have "one year only" sensors that are in fact the same sensor with a different pigtail.

[gadget73]

didn't realize the 84 had a one year TPS. I dislike one year parts, especially when its just something dumb like a connector change. My 86 has a number of them. The oxygen sensors are on the list. Same sensor as tons of things use, but its a one-year plug for whatever reason. The rear ABS sensors on the late Mark VII are goofy too. Same sensor as a 90s Crown Vic, different plug. One sells for 40 bucks, the other is $200 if you can find one.

[kishy]

Eh, looks like it isn't 1-year-only...it's just "weird year only".

1980, 81 use the "adjustable" one per my understanding. Seems to be EOL as it's hard to find any info on.

1982, 83, 84 (note this spans EEC-III as well as EEC-IV, it's the same actual TPS)
Big connector, with through-hole for CFI throttle shaft. Non-adjustable.
Standard TH10
Wells 5S5113

1985
By all logical reasoning, should be the same as 1984 because EEC-IV CFI. But it isn't.
Small connector, with through-hole for CFI throttle shaft. Non-adjustable.
Standard TH48
Wells 5S5111

1986 (all onwards from here should interchange no problem)
Should be able to use the 1985 sensor because same connector, but there is no need for the through-hole anymore, so there are new sensors yet again!
Small connector, no hole required but some have it anyway, non-adjustable.
e.g. Standard TH18 (has a hole for the CFI throttle shaft...why?!)
e.g. Wells 5S5112 (does not have hole for CFI throttle shaft)

As far as I can tell they're all the exact same sensor operating in the same range of resistance with the same amount of rotation and same clocking of the screw holes. I've been collecting junkyard TPS off many vehicles to try to figure this out. As if I'm not busy enough fixing my own broken stuff...

BTW - sensor currently installed is from a SEFI Box Panther. I punched the hole out with a screwdriver.

[kishy]

New main coil wire, distributor cap, junkyard ignition coil and I'm back in business.

Observations:

• It was not the coil wire, as I replaced it and the problem persisted.
• Cap and coil were done at the same time; it could be either one of them
• The cap that was on it has very short "teeth" for the spark to jump over to from the rotor. As the shaft can move up and down, it's possible the rotor was sometimes higher or lower, and when lower, forming a larger gap. The new cap's contacts stick down much further so this problem can't exist. Just a theory.
• The coil appears to be factory original as it wears an E3 Ford part number. It also looks as if its housing has cracked or something in the past and it was epoxied shut. The new coil is a junkyard pull but it's not a Ford part, therefore it's newer.
• The problem could have been corrosion on the coil terminals, as the connection looked pretty poor.

Bear in mind this model year (and seemingly only this model year) has a weird distributor rotor that's different from newer years (circular, and held on with 2 screws). It's possible the cap I was using fits more appropriately with the more common arrow-shaped push on rotor.

Obviously I'm going to watch it very closely, but this time around those changes above are the only things I touched...so it has to be one of them. At this time, I'm not really wanting to think about the possibility that a flaky coil was behind all the problems from day 1, because that would mean I've invested a lot of time in basically learning how a fuel injection system works for nothing lol.

Happy New Year, folks. My car's usable again.

[kishy]

Well, still going strong, so I guess I kind of want to do a post-mortem discussion about what exactly was wrong here.

IDM circuit codes make sense if a coil is in some way flaky, as the IDM circuit is basically the tach signal...

But, how is it that an intermittently flaky coil can perform as expected when SPOUT is disconnected? OTOH - it did in the past, then more recently it did not, so maybe they've legitimately been separate issues showing the same symptoms. Is it possible for the coil to be "lazy" and start screwing up when timing changes occur? I've always understood the coil to be nothing more than wire coiled up around an iron frame, somewhat akin to a transformer. Is there more going on inside there that I didn't realize?

Ditto for mechanical delivery of spark e.g. cap. No logic to it at all.

[DerekTheGreat]

You're making me want to own a CFI car again lol. What do you want for your TC?

Oh I finally got to Ryan's. Turns out that interior is a shade darker than mine and the seats aren't good enough for Dave. I did find another Townie loaded with JBL goodies that I horded, well, what wasn't destroyed anyway. Also found a ride height sensor for the load leveling suspension, hoping that's what the issue is with Ashley's Townie. So farkin' rusty though and the assholes charged me $25 for it...

[kishy]

Ha. You don't want this car. This car clearly doesn't want to be alive anymore. If ever there was an example of a car begging to be scrapped, it's this car. But I resist, because for my time investment thus far, I'd better get to drive it.

Apparently my car sat stationary for sale for 3-4 years, at minimum, and possibly longer. It did so for reasons, and I've been finding them.

If it turns out it's the controller (gold coloured box, behind one of the trunk interior panels), I have one of those in my random junkyard bits box. There's also a wagon with that suspension in Flat Rock complete with compressor etc.

[DerekTheGreat]

Haha, I hear that.

Yep, "Car that sat" and/or "mechanic owned" are two things I've learned to stay away from.

Oh cool, I'm betting its either the sensor or that. Dumb me looked right at that thing on the parts car and didn't take it. Not sure I want to waste more gas and give Ryan's another $4 for Ashley and I to get in there...

Post more pics of this TC, curious to see interior lovely ness and engine compartment. Yours a digi dash car?

[gadget73]

I've seen coils with cracked insulation before. At night they have a purple haze around them and you will randomly see arcs through it. Often there is a discolored area where the arc has burned through the plastic.

I doubt its screwups would be timing related, but they could be temperature related. Possible that its just more obviously screwing up when advanced. I remember once upon a time we were out boating and the coil died. We packed it in ice and it ran us back home. Wouldn't run when hot, fired just fine when cold.

[Master Shake]

Hey, OP I wanted to let you know that I am in the exact same boat as you. I haven't solved mine, so don't get excited.

I have a 1984 Country Squire. And for the last 2 months it's been displaying the 'stumbling when hot' symptoms. It has been getting progressively worse since. Two weeks ago it outright refused to run even when cold. It sat in the driveway trying to idle could only continuously bump it's idle just to have it drop again. It felt like somebody was constantly stabbing the throttle to try and keep a stalling car alive, but it was doing it all by itself. Swapped out the distributor (figured might as well get new TFI and PIP at the same time), TPS, fuel filter (that was stuffed), triple checked the timing. It still does the same thing, but now it starting to do it when it's still cold, and the bucking and stumbling is getting stronger, plus it stalls out half the time when stopped in gear. I will try to let it run with the SPOUT unplugged tomorrow, but last time I tried that it didn't seem to like it.

What I have been considering is the timing chain. Maybe it stretched to the point where it still runs OK when its cold, but once it warms up and ECU tries to adjust timing it goes out of range and start bucking.

Also a friend of mine suggested checking the intake manifold for coolant leaks. I know mine has an external one. But it's possible it's also leaking internally, and that it very temperature related condition.

Just know that you are not alone, I am sailing the same sea of misery.

[kishy]

Post more pics of this TC, curious to see interior lovely ness and engine compartment. Yours a digi dash car?

Will do, just need to sift through the flash drive on which I put all my car pics and get some decent ones together.

No digidash. Was going to retrofit it (have a cluster and message center box) until I studied the wiring and decided maybe not. I'm still considering frankensteining a cluster together to get everything except the message center, then put a tach of some kind where the clock is. When I inevitably replace the radio (even with a newer factory Ford unit which I may do, idk yet) I'm sure it will have a clock anyway.

I've seen coils with cracked insulation before. At night they have a purple haze around them and you will randomly see arcs through it. Often there is a discolored area where the arc has burned through the plastic.

I doubt its screwups would be timing related, but they could be temperature related. Possible that its just more obviously screwing up when advanced. I remember once upon a time we were out boating and the coil died. We packed it in ice and it ran us back home. Wouldn't run when hot, fired just fine when cold.

Although hardly scentific, it's still going strong since replacing the coil with the junkyard item. So although I had done the night time, lights off, inspection for arcing in the ignition system and found nothing, I'm going to have to assume the coil was flaky. I didn't think transformers really went bad but anything is possible.

Hey, OP I wanted to let you know that I am in the exact same boat as you. I haven't solved mine, so don't get excited.

I have a 1984 Country Squire. And for the last 2 months it's been displaying the 'stumbling when hot' symptoms. It has been getting progressively worse since. Two weeks ago it outright refused to run even when cold. It sat in the driveway trying to idle could only continuously bump it's idle just to have it drop again. It felt like somebody was constantly stabbing the throttle to try and keep a stalling car alive, but it was doing it all by itself. Swapped out the distributor (figured might as well get new TFI and PIP at the same time), TPS, fuel filter (that was stuffed), triple checked the timing. It still does the same thing, but now it starting to do it when it's still cold, and the bucking and stumbling is getting stronger, plus it stalls out half the time when stopped in gear. I will try to let it run with the SPOUT unplugged tomorrow, but last time I tried that it didn't seem to like it.

What I have been considering is the timing chain. Maybe it stretched to the point where it still runs OK when its cold, but once it warms up and ECU tries to adjust timing it goes out of range and start bucking.

Also a friend of mine suggested checking the intake manifold for coolant leaks. I know mine has an external one. But it's possible it's also leaking internally, and that it very temperature related condition.

Just know that you are not alone, I am sailing the same sea of misery.

I'm sorry to hear you've hopped on this particular carnival ride, but on the bright side, maybe my thread has given you some insight into possibilities that might help you out.

The probability that your coolant leak through the intake gaskets does leak into the cylinders is pretty high. I say this based on all 3 of mine being that way. It's something you should prioritize doing. My timing chain did have considerable slop but it still had a long way to go before it could jump, at 106k miles. Obviously many conditions will make this vary.

A couple things fairly easy to check: make sure you're getting good power (13.8-14.4 is my range, so if you're in there, it should work alright although the higher end of that range is preferable), and make sure your fuel pressure is good. I think spec is 35PSI while running? Mine started getting stupid (though it could have been for other reasons occurring at the same time) at 25. New pump woke it right up. Then my symptoms came back.

My car (the '84 anyway) evidently had a multitude of problems, all of which showed the same symptoms in similar conditions. Fix one, looks good, symptom returns...because there was an additional cause with a similar effect.

My car does presently continue running without issues*.

*: as best as can be expected for a 32 year old car

[Master Shake]

Holy s************ ** ** ***** ****** what a day.

My commute from home to work is literally 2 miles. So today after having the rental agreement on my 'borrowed' car ran out, and I had to take the stumble-mobile home.

It started out okay. Light bucking and stumbling as it ran down the road. It kept getting worse the longer I drove. By the time I was about 500 feet from my home it was almost undriveable. It couldn't hold idle, throttle response was almost non-existent, and it has no power to speak up, did I mention bucking and stumbling? But this is where all hell broke loose. It snowed 2 inches today and it was like 20 degrees. So the roads were crap. But, knowing that this is south New York and we are used to winters I gave my fellow drivers the benefit of a doubt. Big mistake. Don't want to get into details, but I almost rear ended a Police Explorer and almost got myself rear ended, but thankfully they decided to veer off and plow into a bush instead.

Made it home, just. It wasn't even driving at this point. The engine would occasionally sputter to life and kick the car along for a few feet, then go back into a coma.

Pulled into my parking spot, got out and unplugged the Spout connector. Man, did it make a night and day difference. It is still not great, but it actually drives and response to throttle input. Didn't test drive properly yet, just a little lap around the parking lot.

The mystery continues.

[gadget73]

Ever checked the fuel pressure? How are your ignition parts? Are all of the vacuum lines good? CFI is braindead, but you can't overlook the common crap either. It'll run every bit as stupid because the plugs are bad as it will because of electronic gremlins.