NeverGiveUpYota
Dare me.
I met a guy not long ago who did side work on old tube amps. Sounds like similar work.
Emission Computer testing? (1 Viewer)
- Thread starter gregnash
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- ecm issues fj60
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Ha! i remember those shops littering my home town, most of them were out of their homes! Yet @Landpimp, I wouldn't necessarily call Gig Harbor a small town, Its no Tacoma or Seattle, but definitely bigger that my hometown of Sumner!!! Well at least back when the valley was still farms and turf fields, not the warehouse district and Seattle overflow as it stands now!!!I have access to the same guy in a vintage hi fi shop right here in my little town, he has down some small non Hi Fi work for me to nothing. We they opened a a few years ago it was like a gift from god...........seeing how I am an old Hi Fi nut
also have an old Ma Bell Telephone guy(grandpa of my guys at the shop).......he can do some amazing things.
NeverGiveUpYota
Dare me.
Welp too bad I scared him away.That's exactly the guy you want.
Alright, slight thread revival here, luckily this isn't too old.
I got my truck running (after a long hibernation) and drove it a bit with all vacuum ports capped on the carb, no air cleaner, the ICS not hooked up, etc. It ran pretty good but of course, it had a slight hesitation around 2500 RPM, idled rough and back fired a lot on deceleration.
When I finally desmogged it properly and reinstalled the air cleaner, proper vacuum routing and ICS and vacuum switch, hooked back up it ran very smooth, great idle, no back firing on decel, smooth acceleration through the RPM range.
I put about 200 miles on it and started to get the earlier symptoms again, rough idle and more notably backfiring when decelerating again. This was intermittent at first, one time it would be good, next time it would be bad again. Now it's pretty much constant.
Yesterday after work I did the "green wire mod" and it was perfect for all of my errands, smooth, no backfiring, etc. Then the last time I started it driving to the house it was idling rough and backfiring again. Dang it.
Right now I'm sitting at work thinking about it and can't do anything but type this out... That's why we're here! When I get home I plan to tear into it, it could be as simple as my green wire mod pulled off the spade connector and broke the circuit. Fingers crossed.
I had a question for the cruiser heads that I think I know the answer to but here goes, the decel fuel cut vacuum switch it was is used to tell the ECM what to turn the ICS on and off with. So the green wire mod eliminates the need for the vacuum switch altogether, correct?
Meaning I can cap the decel fuel cut port on the carb?
I got my truck running (after a long hibernation) and drove it a bit with all vacuum ports capped on the carb, no air cleaner, the ICS not hooked up, etc. It ran pretty good but of course, it had a slight hesitation around 2500 RPM, idled rough and back fired a lot on deceleration.
When I finally desmogged it properly and reinstalled the air cleaner, proper vacuum routing and ICS and vacuum switch, hooked back up it ran very smooth, great idle, no back firing on decel, smooth acceleration through the RPM range.
I put about 200 miles on it and started to get the earlier symptoms again, rough idle and more notably backfiring when decelerating again. This was intermittent at first, one time it would be good, next time it would be bad again. Now it's pretty much constant.
Yesterday after work I did the "green wire mod" and it was perfect for all of my errands, smooth, no backfiring, etc. Then the last time I started it driving to the house it was idling rough and backfiring again. Dang it.
Right now I'm sitting at work thinking about it and can't do anything but type this out... That's why we're here! When I get home I plan to tear into it, it could be as simple as my green wire mod pulled off the spade connector and broke the circuit. Fingers crossed.
I had a question for the cruiser heads that I think I know the answer to but here goes, the decel fuel cut vacuum switch it was is used to tell the ECM what to turn the ICS on and off with. So the green wire mod eliminates the need for the vacuum switch altogether, correct?
Meaning I can cap the decel fuel cut port on the carb?
mattressking
10 digits to freedom
Before we jump to conclusions, you have "green wire mod" in quotes. So I assume you grounded the white wire, correct?
Haha yes, but good on you for checking! Remember, it worked perfectly for about 30-40 miles and lots of starts/stops.
I'm guessing its a wiring issue, (probably my crimp) but really wanted to inquire most about the vacuum switch.
I'm guessing its a wiring issue, (probably my crimp) but really wanted to inquire most about the vacuum switch.
Yes, if you ground the ICS to carb body then decel switch is non-functional.
Thank you!
The ICS wire 'mod' grounds the circuit so that whenever the ignition key is turned on, the ICS is energized - allowing fuel to flow to both idle circuits. When the 'mod' is done, the vacuum switch serves no purpose.
Grounding the ICS wire should be only done if the emissions computer is malfunctioning (or missing) or the vacuum switch is dead and you don't want to replace them with used units.
Grounding the ICS wire makes the ICS always stay energized so fuel will always flow through both idle circuits in the carb. This is how the fuel normally flows when your foot is on the gas or the engine is idling.
But the 'mod' is a band-aid for missing or malfunctioning parts. The engine will perform better overall if the deceleration fuel cut system is functional.
When functional, the system prevents backfires when decelerating in gear (especially down long hills) or even during a shift, provides better engine braking down hills while in gear,
prevents exhaust grumbling when coasting in gear down hill, helps improve mpg a little bit and prevents dieseling after engine shutdown.
Disconnecting the system (if it works) provides zero benefits and several negatives.
• Backfire
• Dieseling at shut down
• Overheating the catalytic converter (if there is one) - which just creates more heat under the car... traveling up the exhaust pipe.
Not sure about that. I haven't heard of anyone doing that. Not sure how the fuel flows through the carb next to the valve. Personally I wouldn't do that. But that's just me.
If my emissions computer was toast & vacuum switch a goner (and I couldn't replace them) I'd wire the ICS to the ignition so that it would energize when the key was turned on.
DFCO (Deceleration Fuel Cut Off) is a good thing to have for slight improvement in fuel economy, but without it, and a properly tuned/desmogged/running 2F you'll just get the stink eye from tree huggers and Pious Prius drivers. Possible to get backfire if exhaust is too rich. Generally, DFCO didn't come about until CATs were mandated.
When you let off the gas pedal, as in engine braking, you get a momentary spike (no pun) in manifold vacuum as throttle valve closes. This vacuum spike draws extra fuel through the idle circuit. You can see this clearly if you have an Air/Fuel meter as it goes way rich when you engine brake, even with the ICS functioning properly. The decel switch tries to close off that circuit under those conditions.
Obviously, it's all computer controlled on modern FI vehicles.
When you let off the gas pedal, as in engine braking, you get a momentary spike (no pun) in manifold vacuum as throttle valve closes. This vacuum spike draws extra fuel through the idle circuit. You can see this clearly if you have an Air/Fuel meter as it goes way rich when you engine brake, even with the ICS functioning properly. The decel switch tries to close off that circuit under those conditions.
Obviously, it's all computer controlled on modern FI vehicles.
Land you're right. I mistakenly mixed up the two words "backfire" & "afterfire" (after burn). For some reason I always think of a backfire as an exhaust explosion instead of an intake explosion which it actually is. My boo boo.
Here's a good explanation of afterburning vs backfire.
My vacuum switch died in the past, so I was driving the 60 for several months without the decel fuel cut system working. I definitely did notice more exhaust grumble/sputter while engine braking down long hills (if that's technically afterburning/afterfire I don't know). It was that exhaust sound that alerted me that something had changed.
I never got a gun-shot-loud explosive afterfire in the exhaust except when I set the spark advance a wee bit too retarded when I was fiddling with the timing. Then after flooring it up a long hill & shifting, it went BANG! Thought someone shot a gun at me.
I never personally experienced dieseling at shutdown because my ICS was still functioning. There is a thread here somewhere where a guy was having shut off dieseling problems, & when he got the ICS working again, that problem stopped. But his engine may not have been running great in the first place & the ICS masked other problems.
This is the official word from the FSM for the rare soul (none of the members above obviously) who haven't taken a peek at the emissions FSM.
Here's a good explanation of afterburning vs backfire.
My vacuum switch died in the past, so I was driving the 60 for several months without the decel fuel cut system working. I definitely did notice more exhaust grumble/sputter while engine braking down long hills (if that's technically afterburning/afterfire I don't know). It was that exhaust sound that alerted me that something had changed.
I never got a gun-shot-loud explosive afterfire in the exhaust except when I set the spark advance a wee bit too retarded when I was fiddling with the timing. Then after flooring it up a long hill & shifting, it went BANG! Thought someone shot a gun at me.
I never personally experienced dieseling at shutdown because my ICS was still functioning. There is a thread here somewhere where a guy was having shut off dieseling problems, & when he got the ICS working again, that problem stopped. But his engine may not have been running great in the first place & the ICS masked other problems.
This is the official word from the FSM for the rare soul (none of the members above obviously) who haven't taken a peek at the emissions FSM.
I have a report back. My ECM is definitely faulty. My ground was still holding so I hard wired the ICS to 12V and test drive it. All good. I started chasing wiring and it turns out the 12V supply from the harness had bad continuity and is what was causing the intermittentcy.
I'd like to send the ECM to someone who can repair it and have the system function as intended. For time being I have spliced the ICS into a switched 12V supply and grounded to the chassis. Runs like a champ, no backfire (afterfire) smooth idle and smooth pull through the RPM range.
While I have you all here, any idea what I'm missing under the ECM?
I'd like to send the ECM to someone who can repair it and have the system function as intended. For time being I have spliced the ICS into a switched 12V supply and grounded to the chassis. Runs like a champ, no backfire (afterfire) smooth idle and smooth pull through the RPM range.
While I have you all here, any idea what I'm missing under the ECM?
NeverGiveUpYota
Dare me.
I believe it may only need to have the lead connections in the board checked for cracks and reflowed. Supposedly it's very easy. I'm blanking on who's done it but hopefully someone will pipe in.I have a report back. My ECM is definitely faulty. My ground was still holding so I hard wired the ICS to 12V and test drive it. All good. I started chasing wiring and it turns out the 12V supply from the harness had bad continuity and is what was causing the intermittentcy.
I'd like to send the ECM to someone who can repair it and have the system function as intended. For time being I have spliced the ICS into a switched 12V supply and grounded to the chassis. Runs like a champ, no backfire (afterfire) smooth idle and smooth pull through the RPM range.
While I have you all here, any idea what I'm missing under the ECM?
I've read you can send to Cardone World Class Service | CARDONE but it's spendy, something like $400 or so. You're best bet is to find someone local who repairs old skool Hi-Fi or Radio or TV ... It's just a simple old skool circuit board and anyone with the tools knowledge should be able to test and repair.
Don't remember what was under the ICM, if anything.
Don't remember what was under the ICM, if anything.
Had similar issues, get a magnifying glass and look for cracks in the "computer" solder connections, I found two small cracks in mine, resoldered, all good! Didn't really need to add solder, just needed to melt and reflow the connection. Hope this helps.
