CFI Misfires/drivability issues

[kishy]

Ha! I mean, aw. You have my problem! Runs fine with SPOUT unplugged! Symptomatically it sounds like you're right where I was at the worst point.

Lift up the distributor cap and take a look at the contacts. You can see where the spark hits the contacts as the rotor spins, there's a discolouration/breakdown of the metal at the spot where the spark jumps. If that spot is right on the end of the contact rather than partway up it, try to find a new cap that has longer contacts. The new one I used was an Accel cap I just happened to have on hand. I do not know if this helped or not with mine, but it's one thing I did change in the last phase before it started running properly.

Ignition coil. That, and the coil wire to the distributor cap, are the two other things I changed in the last step before it worked properly.

Coolant temp sensor may be suspect. Invest in a pack of vacuum caps. Then cap off everything except the brake booster and MAP sensor. Check if issues persist.

I never did figure out 'logically' why my car worked properly-ish with SPOUT unhooked. That suggests the computer is adjusting the timing way out of whack because of an input it doesn't like. Yet my problem finally vanished with the coil, cap, and coil wire. Should have had no relation at all to computed timing.

[Master Shake]

Okay, update. Sorry for hijacking your thread, but figured since it's the exact same issue, I might as well post here.

So today I ran around with the SPOUT unplugged and it was ok. Rough but ok.

Found a Fireball coil I had lying around for the longest. Plugged it in and it ran a lot better. Plugged in the SPOUT and it still ran OK. Turned on headlight and it bogged down like crazy. Checked my voltage. Only getting 12.09 volts while running. Checked the alternator wires, jiggled the harness around, no change. So I can pretty confidentially call it a bad coil/alternator combo.

[kishy]

Okay, update. Sorry for hijacking your thread, but figured since it's the exact same issue, I might as well post here.

So today I ran around with the SPOUT unplugged and it was ok. Rough but ok.

Found a Fireball coil I had lying around for the longest. Plugged it in and it ran a lot better. Plugged in the SPOUT and it still ran OK. Turned on headlight and it bogged down like crazy. Checked my voltage. Only getting 12.09 volts while running. Checked the alternator wires, jiggled the harness around, no change. So I can pretty confidentially call it a bad coil/alternator combo.

Nah, it's appropriate. Symptoms are the same or similar. I'd say it belongs here.

I don't know how much of my garbage you read but when my alternator went, everything became much worse. So that could be a major contributor. Certainly if the power supply to the computer is not what is expected, it won't operate as expected. But, don't be like me and assume that's all it is. Fix it then see what you get.

3G alternator upgrade for these seems ever so slightly more complicated than the newer ones because of the usage of an electric choke heater to operate the fast idle. However I think there's still a way to do it, by wiring the choke heater to the stator, as they are not supposed to get a full 12V.

Otherwise, the cheapest reman on RockAuto is what I'm using right now until I work out the details of the 3G vs fast idle issue.

Also, in the interest of clarity for anyone who stumbles upon this: the issues in this thread are not "CFI" issues. CFI is not the problem, at all. The problem is 32 year old electronics and wiring that have not aged well. The same failures (causing varying symptoms) could happen to a SEFI car, or any car really. CFI may just fall victim to it more easily due to being a bit older, and wiring splice and crimp quality of the period.

[gadget73]

Low voltage to the ECM makes it super brain dead. Ran into that on mine after the cam swap. Apparently when I repainted the bracket, the paint was extra awesome and completely insulated the ground side of the case. It had a misfire and a buck and all sorts of BS and John noticed on the tuning software that the battery voltage was in the 11.x range. Fixed the charge problems, and the other issue went away too. Not sure if it was weak ignition, low voltage to the ECM not allowing it to fire the injectors, maybe some of both but it definitely ran shitty.

[Master Shake]

Okay. More updates.

This morning the U.S.S. Embarrassment started with extreme difficulty. Made it to work and measured the running voltage, 11.4 volts. It was time to act. Dove into a pile of parts I had gathering dust. In the pile I found an alternator out of my 2.3l Mustang. It looked a whole lot like the one in the wagon. Come to find out, it is the exact same casing. I think Mustang alternator is 70 amps over my wagon's stock 65, but both of them are old so that doesn't really matter.

It is amazing how many guides there are about converting a 2G alternator to 3G, but almost no guides for a 1G to 3G swap, or even to 2G which this is.

So after some fumbling with wiring inside the engine bay, the alternator was in and the car was running a lot better. Reading 13.7 volts even with load. Not perfect, but a very good improvement. I does start struggling when I have headlights on, wipers going full speed, flashers going, and AC running. But just headlights and blower seem to be fairing ok. My guess is that the Mustang alternator is also old and tired and when all this load is applied it just can't put out enough amps. Voltage never really drops, which is curious.

So for now the behemoth is running again. The throttle response is immediate, I'm tempted to say better than it was, but there is still some kind of roughness around 1500 rpm at 30ish mph. The whole car shakes. Probably cap and rotor + coil issue. With that sorted and proof of concept working, I need to look into doing a full 1G to 3G swap. I need to find a good guide though, because currently I have the external voltage regulator unplugged (since 2G alternator is self regulating) but most 1G to 3G kits I see feature a new external regulator that needs to be installed. Something is not right.

[BigMerc96]

My buddy's old Wagon had a rebuilt 2g in it. You had a choice to make. With the heat on, you could either use the headlights or wipers, cuz doing both would cause a voltage drop and wipers would barely work. A 3G is the ultimate solution since even the low output 3G is 90a, so still 25-30a more than the best 2G. Just never got to it on that car as it was retired from DD status and ended up being scrapped as it had too many small issues and enough rust to be worth restoring. It was SEFI and it had a lot of weird issues until the old alternator seized, most of which went away with the replacement. Its amazing what low voltage can do with electronics.

[kishy]

My buddy's old Wagon had a rebuilt 2g in it. You had a choice to make. With the heat on, you could either use the headlights or wipers, cuz doing both would cause a voltage drop and wipers would barely work. A 3G is the ultimate solution since even the low output 3G is 90a, so still 25-30a more than the best 2G. Just never got to it on that car as it was retired from DD status and ended up being scrapped as it had too many small issues and enough rust to be worth restoring. It was SEFI and it had a lot of weird issues until the old alternator seized, most of which went away with the replacement. Its amazing what low voltage can do with electronics.

Truthfully, I think the 60A 1G may be acceptable if all variables are right:
-No losses due to wiring or terminal resistance
-Electrical loads in good condition (e.g. brushes and bearings in blower motor are like-new)
-Alternator and regulator in like-new condition

However, there remains an Achilles' Heel, and that is the low RPM output which is quite poor. It seems to be normal for these to be incapable of making even 14V at idle.

Therefore the output of the 2G is sufficient, though I believe it suffers the same low RPM issue. It just has the added bonus of a nice fire hazard, resistance-increasing connector that threatens to burn your car down. It's self-perpetuating too, because poor connection = resistance and/or arcing = heat = melts connector = widens connection and the cycle just keeps repeating until it melts down.

The list of conditions above is never perfect though. There are harness losses and loads go above original design spec, so the 1G and 2G don't quite cut it.

Then there's the 3G, which makes good low RPM output, has a stud terminal, is a physical fit, and is dead simple to wire*. It's a no brainer really.

As for the 3G swap the only concern I have with it is the use of the choke heater as a type of "electric timer" for the cold idle, since that's exactly what it does. CFI does not have a choke, but it uses "choke parts" to operate the fast idle. The rest of the wiring re: external regulator should be pretty simple to eliminate. But I'm also not afraid to hack up a harness.

[Master Shake]

Things are looking up today. Checked running voltage this afternoon and we're up to 14.5v.

The issue seems to be sub-2k rpm range. On cold start up the car sometimes stumbles hard and doesn't often respond to throttle. After a few minutes of idling, it clears up and acts OK. Below 2k rpm the car vibrates pretty rough, but does accelerate and respond to inputs. Above 2k things smooth out and it drives amazingly.

Could it be that the ECM is learning how to run and idle properly or am I placing too much faith into that thing?

[gadget73]

The 2G is bad at low rpm output. The electrical connector method is absolutely stupid though. The push-on connector is great for assembly line use, but it fails over time and catches fire. No bueno. Tthe current capacity is marginally enough if all things are right but I don't personally care for having things running at 100% capacity all the time.

You can easily wire the choke heater into the 3G. It ties into the stator line, which is the white/black wire going from the voltage regulator to the side of the alternator. Simply tap it and run it out to the choke heater. You could do the same thing with the 2G, but its a move that requires effort for no gain. Same work to go 3G and get double the charge power.


Thinking its just warming up. The ECM runs in open loop mode when cold, there is no learning going on. It uses pre-programmed settings and relies almost entirely on the engine temperature, throttle position and manifold vacuum to figure out what to do. If any of those are lying, the ECM will have no clue what to do and respond (poorly) accordingly. These things have very few inputs really, and it really needs all of them to work right.

[Master Shake]

The ECM runs in open loop mode when cold, there is no learning going on. It uses pre-programmed settings and relies almost entirely on the engine temperature, throttle position and manifold vacuum to figure out what to do. If any of those are lying, the ECM will have no clue what to do and respond (poorly) accordingly. These things have very few inputs really, and it really needs all of them to work right.

Good to know. I need to check my air temp and coolant temp sensors.

[DerekTheGreat]

Love this thread..

[kishy]

Little update on mine again, since it's been another month.

With the exception of fluid-related reasons, I have not been under the hood since December 31. I can't find the emoticon blowing a kazoo but imagine I put it right...here!

On two occasions, both late at night on very cold nights, it threatened to stall when coming down to idle, both times when arriving in my driveway. No clue what's up with that.

Also on two (different) occasions, I have noticed a wavering/uneven hot idle speed. This would best be described as a mild surge. I figure it's probably an intermittent vacuum leak. The dashpot/throttle kicker does have a minor diaphragm leak but this part is unobtainium so I'll just deal with it.

It gets oddly jerky when zero-throttle-decelerating while still cold or when getting back into the throttle at certain speeds and throttle positions. However these don't really bug me much and I have a feeling they're just part of the nature of the beast.

Fuel economy is pretty much right where my '91 MGM was...11-14MPG, 99.9% city and perhaps 75% of the time below operating temp, and being driven somewhat aggressively. So it's not doing bad at all.

Any updates on yours, MS?

[DerekTheGreat]

Hmm, throttle blade icing perhaps on the driveway stall out thing?

I bet it is the dashpot thing causing weird idle stuff. Unplug & plug the line and see if it goes away. I might have a dash pot from an '85 TB...

What voltage are you getting from the TPS at idle? Perhaps maybe it's too high?

That seems to be decent MPG considering winter blend gas, open loop conditions and city driving. My '85 at best was good for 16's.

[VicCrownVic]

Derek mentioned TPS, that would be on my list of things to check as well.
Just swapped the TPS on The Ice Car ('91) last Saturday and the random stalling/threats of stalling seem to be gone. Mine was mostly after startup and sometimes while sitting idle in traffic but extremely intermittent. Cold weather seemed to aggrivate it more but it wasn't limited to cold.

[atlantic3000]

You can buy a common ground adapter from crutchfield for 10$ and avoid running new wires. It goes between new radio and the adapter to the stock harness