Misfire, where do i go from here. (Page 8/18)
82-T/A [At Work] FEB 22, 02:26 PM

quote
Originally posted by Dukesterpro:

Its a black wire with a purple stripe. Its sole purpose is to provide 12 volts from the coils 12 volt supply the ICM.

My nearly completed CET degree is making me think that this is simply a form of back-emf protection so you don't hear whining over the radio from the ICM's micros working.

This capacitor doesn't appear to make any connection, since its run in parallel to the plug. All that happens is you have a bit more noise in the electrical system. Further, when I plugged my old radio back in, it makes a whining noise it never used to. I did find a replacement capacitor just in an electrolytic flavor instead of ceramic. Its on the way so I guess I am going to have to put up or shut up.

Can't wait to do a bunch of more work and find out you were right all along. lol.

I ordered a scanner from OBDDiagnostics today. Its time to get serious. In the mean time, I'm am going to try to locate that tach filter. It has to be there, because the tach worked really really well when I first got the car.

I will keep everyone posted. Please keep feeding me ideas and information if you think of anything. This is been very informative and I feel that all these ideas, even if they weren't my solution may be a valuable resource to others in the future. Especially as the popularity of the 84 seems to be on a uptick. At least in my area.




I mean, you've basically replaced everything at this point! Haha...

But I think you said it idles pretty well, minus the slightly high idle? That still confuses me. Did you ever check the EGR? Can't remember if you said that.
Dukesterpro FEB 22, 02:33 PM
Idles strong, just at 1500-1700. Doesn't high idle when cold, only when hot. Like the high idle is reversed. Runs good, under half throttle. The more rpm I have to more throttle pedal I can use. If I push the throttle down to fast it bucks and occasionally pops out the intake. Otherwise runs good. Hell I was cruisin at 85mph for over 200 miles without a hiccup. Unless I pushed the throttle down to far. (Think load related vs throttle position, Low RPM + High Throttle = Misfire. High RPM + High Throttle = Good Running)

Everything thats been replaced so far.

Distributor
Pickup Coil
Ignition Coil
Cap
Rotor
Wires
TPS
ICM
IAC
MAP
EGR
Vacuum Lines
Fuel Pump
Fuel Filter
Coolant Temp Sensor (ECM)

This car is a veritable ship of theseus. Im starting to think fuel now? I havent replaced the injector.

[This message has been edited by Dukesterpro (edited 02-22-2023).]

Patrick FEB 22, 07:18 PM

quote
Originally posted by Dukesterpro:

Everything thats been replaced so far...



And all before you've done a very basic tuning requirement... timing the ignition! Dukester, I'm not trying to be critical, but this makes absolutely no sense to me.

I've contacted a friend of mine who's an electronics wizard, and who had an '84 Fiero for years (and who currently has a Formula). I'm hoping he can supply us with some insight. [EDIT] I just realized (after looking up some ancient posts on a local Fiero club's forum) that my friend had an '86 duke. Heck, they all look basically the same. Anyway, he might still be able to help with identifying that component.

In the meantime, is there no merit in what ArthurPeale found and posted? The actual page for the item (T8349) is Here.

[This message has been edited by Patrick (edited 02-22-2023).]

Dukesterpro FEB 23, 09:43 AM

quote
Originally posted by Patrick:

And all before you've done a very basic tuning requirement... timing the ignition! Dukester, I'm not trying to be critical, but this makes absolutely no sense to me.

I've contacted a friend of mine who's an electronics wizard, and who had an '84 Fiero for years (and who currently has a Formula). I'm hoping he can supply us with some insight. [EDIT] I just realized (after looking up some ancient posts on a local Fiero club's forum) that my friend had an '86 duke. Heck, they all look basically the same. Anyway, he might still be able to help with identifying that component.

In the meantime, is there no merit in what ArthurPeale found and posted? The actual page for the item (T8349) is Here.





And I set the timing! I forgot to mention that dont yell at me, lol. 8 degrees at 1 and 4 and split the dfference.


ArtherPeale information was great, but the problem is no where on the returned google searches does the datasheet or webpage for the actual component does it list T8349. Meaning I can't be sure if its actually a "T8349" or google showing me something close. That's also a polyester capacitor, the one on my distributor was ceramic. Might be a newer version, the actual material type doesn't matter here. But without knowing its actual uF and V ratings for the original I cant put that one on.

[This message has been edited by Dukesterpro (edited 02-23-2023).]

82-T/A [At Work] FEB 23, 11:31 AM

quote
Originally posted by Patrick:

And all before you've done a very basic tuning requirement... timing the ignition! Dukester, I'm not trying to be critical, but this makes absolutely no sense to me.

I've contacted a friend of mine who's an electronics wizard, and who had an '84 Fiero for years (and who currently has a Formula). I'm hoping he can supply us with some insight. [EDIT] I just realized (after looking up some ancient posts on a local Fiero club's forum) that my friend had an '86 duke. Heck, they all look basically the same. Anyway, he might still be able to help with identifying that component.

In the meantime, is there no merit in what ArthurPeale found and posted? The actual page for the item (T8349) is Here.




Oh man, he hasn't timed it yet? Yeah, you definitely want to do that.

By the way... this thread is killing me. All of these pictures and looking up stuff about 84s... I'm like... very close to buying a 2nd Fiero, that's an L4... for my daughter. My wife thinks it's a horrible idea, but my daughter absolutely loves the look of the car. I showed her a picture of it and she was like... OMG, this car is amazing, and it has pop-up headlights. Plus, she wants to learn to drive stick for her first car.

She's 14, and for some insane reason, they let 15 year olds drive here in Florida... so she'll be driving in less than a year... I figured this could be a daughter-father bonding moment.

I'm such an idiot...
Dukesterpro FEB 23, 12:48 PM
After all this pain and suffering, I still would recommend this car.

Its never run perfectly, but it always runs.

Its never not delivered me to work, nor failed to shuttle me home.

As long you and her have the patience to deal with these quirks. Go for it. She will never forget it.

Just teach her good defensive driving. Stay away from everyone always.

As an added bonus the iron dukes guarantees[i] that she will never get a speeding ticket.
ArthurPeale FEB 23, 01:40 PM

quote
Originally posted by Dukesterpro:

ArthurPeale information was great, but the problem is no where on the returned google searches does the datasheet or webpage for the actual component does it list T8349. Meaning I can't be sure if its actually a "T8349" or google showing me something close. That's also a polyester capacitor, the one on my distributor was ceramic. Might be a newer version, the actual material type doesn't matter here. But without knowing its actual uF and V ratings for the original I cant put that one on.




It was also the -only- result I could find for that number. I wasn't even sure if that was the actual component, despite the obvious physical similarity
Patrick FEB 23, 05:06 PM

quote
Originally posted by Dukesterpro:

And I set the timing! I forgot to mention that dont yell at me, lol. 8 degrees at 1 and 4 and split the dfference.



And that was with the ALDL jumper in place? Hey, I've got to ask!


quote
Originally posted by Dukesterpro:

ArtherPeale information was great, but the problem is no where on the returned google searches does the datasheet or webpage for the actual component does it list T8349. Meaning I can't be sure if its actually a "T8349" or google showing me something close.



It's interesting to note, that if a Search is run at the site itself for "T8349", that this capacitor shows up... so it's not just Google that indicates this item is there. However, it is odd that the number "T8349" is not actually indicated anywhere in the part's literature.




quote
Originally posted by Dukesterpro:

But without knowing its actual uF and V ratings for the original I cant put that one on.



And we've hit a snag in regards to that... as even if I can locate this capacitor at my end, I have no way of determining it's specs. I asked my friend who's familiar with electronics if my multimeter has the capacity of doing these measurements (I sent him a photo of my multimeter)... and it doesn't. (And he's currently a thousand miles away from here, so it's not like I can use his multimeter.) So... we're back to square one. I'm of the opinion that this capacitor is only there to smooth things out for the tach, but also fully admit that this is above my pay grade.

[This message has been edited by Patrick (edited 02-24-2023).]

Patrick FEB 23, 05:17 PM

quote
Originally posted by 82-T/A [At Work]:

By the way... this thread is killing me. All of these pictures and looking up stuff about 84s...



And I bet you still haven't found an image of an "older" style '84 duke distributor... despite the fact that 136,840 1984 Fieros were produced and sold.


quote
Originally posted by 82-T/A [At Work]:

...to be perfectly clear... no Fiero ever "came from the factory" with the distributor that has the star of David pattern. They all came with the one that looks like little points sticking up. But the "star of David" design is a NEWER design.


PhatMax FEB 23, 05:31 PM
If the cap is just for filtering you could put any cap in there as long as the minimum spec is the same or a higher value is used. The voltage can be higher as well as the uF…….just have to find the right size to fit.