Duraspark issue

[BichoBII]

Hi everyone, im having problems with my durasparked 84 b2, it starts and runs fine, but in traffic it starts idling rough, like missfiring, and if i turn headlights on it gets worse, once i turned both headlights and blower on and it died. If i rev it it goes away, cruises ok, goes back to idle ok, but if it sits too long it comes back. Plugs, cables, cap, rotor and coil have less than 2k miles, checked and tightened every connection on engine bay, installed a relayed connection from battery to coil/module but didin't solve it, im running a bosch red coil with the 0.8 ohms ballast resistor it asked for. Alternator seems fine. I was thinking maybe duraspark module getting hot, at least by hand it just feels warm, i don´t have much money so i don´t want to blindly throw parts, so any ideas or test i can perform would be great.
Thanks in advance!

 

[Twister]

Hi everyone, im having problems with my durasparked 84 b2, it starts and runs fine, but in traffic it starts idling rough, like missfiring, and if i turn headlights on it gets worse, once i turned both headlights and blower on and it died. If i rev it it goes away, cruises ok, goes back to idle ok, but if it sits too long it comes back. Plugs, cables, cap, rotor and coil have less than 2k miles, checked and tightened every connection on engine bay, installed a relayed connection from battery to coil/module but didin't solve it, im running a bosch red coil with the 0.8 ohms ballast resistor it asked for. Alternator seems fine. I was thinking maybe duraspark module getting hot, at least by hand it just feels warm, i don´t have much money so i don´t want to blindly throw parts, so any ideas or test i can perform would be great.
Thanks in advance!

I'd get your alt and dspark box tested. Its free and will only take an hour to get them off, get them tested and then put back on.

Sent from my SPH-L900 using Tapatalk

 

[BichoBII]

hmmm, yeah that would clear things up, but i live in a very isolated place and the b2 is my only vehicle, so if there were some tests i could do with parts on the truck i would rather do that first...

 

[kimcrwbr1]

Put a spark plug in the coil wire and set it on a good ground. Turn the key on run and with a jumper wire short the coil neg terminal to ground quick touches. every time you touch ground the plug should fire. Do you have the old square coil? Remove the ballast resistor and wire the old TFI coil the same. Key on hot coil pos and green wire from module to coil neg. Then with the plug in the coil wire crank on the starter and it should have a nice steady blue snap. GL by the way the module should get hot if you havent add a ground from the module body to engine ground for giggles.

 

[BichoBII]

I don't have the tfi coil, PO did the duraspark, i just cleaned it a bit, i will perform both tests, im guessing i should do it when the engine is hot enough to fail right?

 

[kimcrwbr1]

If it is the module I dont think it matters if the engine is warm or not. You are giving the module battery power correct.

 

[enginepaul]

There is a way to test the module on the car; I don't have it nearby, but a google may help - try pinto or Mustang II or other 70's Fords - all use the same module if they call it DuraSpark II (I think)

If it only fails when additional loads are placed on the circuit, look for a short or connection problem - that includes all grounds. It takes very little power to run these units but it needs clean connections.

 

[BichoBII]

Ok ive found a pdf with instructions to test the whole system, module, coil and pickup coil, will do it as soon as possible and let you guys know how it went, thanks for the answers

 

[BichoBII]

Ok so i tested the whole duraspark system and its good, checked and cleaned every connection, and kinnda narrowed the problem, i think. With engine hot it started with the shaky idle, then bypassed the ballast resistor and idle cleaned, i know for sure the coil asks for a 0.8 ohms ballast resistor, and its working range is 8-10 volts, it never got less than 9.5 volts with ballast resistor so im confused. I was also wondering if it could be a carb issue, leaking down making too rich mixture, needing hotter spark to burn it all... for now i left the resistor bypassed, hopefuly coil won't cook...

 

[kimcrwbr1]

These engines like the idle air mix nice and rich. Preadjust the needles out 3 1/2 turns and bring the engine up to temp and idle it down around 800 rpms the adjust the idle air needles for the highest rpm possible on both needles or use a vacuum pressure guage and set them for the highest vacuum pressure should be 17 hg or above at an idle. If it is low on vacuum pressure focus on finding a vacuum leak.

 

[BichoBII]

Already adjusted them, with vacuum gauge, i get steady 15 hg but im at 10,000 ft so i guess it should be ok. And dont have a tach so i idled it at what feels right. Something weir about idle is sometimes the requirementes from the engine change, after setting it right, next week it starts idling funny, thought it could be the needle springs, but it wants a richer mix, so i loose the needle a bit and idle comes back...

 

[wildbill23c]

Already adjusted them, with vacuum gauge, i get steady 15 hg but im at 10,000 ft so i guess it should be ok. And dont have a tach so i idled it at what feels right. Something weir about idle is sometimes the requirementes from the engine change, after setting it right, next week it starts idling funny, thought it could be the needle springs, but it wants a richer mix, so i loose the needle a bit and idle comes back...

Change the needle springs LOL, I had the same problem with my Bronco 2, turns out those dang idle/air screws were adjusting themselves as the springs had worn out to the point to where they weren't putting any pressure back on the screws to keep them set. These carburetors are pretty touchy, and the smallest vacuum leak you end up with all sorts of adjustment problems.

 

[BichoBII]

They didnt seem worn to me, but if they were, i thougt they could only unscrew the needles, not thigten them, like i said when i needed to readjust them was to loose them a bit. I would replace them but im about to change carb to a holley 2300, hopefully will do it this weekend...

 

[kimcrwbr1]

A easy vacuum leak to miss is on the back of the EGR spacer under the brake booster hose and points straight toward the firewall. It is supposed to go to the vapor cannister by the radiator. If the solenoid is stuck open it is a vacuum leak just put a cap on the nipple and see if your vacuum pressure increases. Mine never did idle very well until I got above 17 hg and has held over 18 for almost two years now. I also change the PCV with spark plugs now as a habit. I get around 15 mpg city and over 18 mpg hwy. Putting in smaller jets helped alot also ever since I put the #41s in.

 

[BichoBII]

I dont have the cannister, and i think i plugged every vacuum port and sprayed around with carb cleaner but will check it anyway. Im running #41 jets, but on a 1.21 venturis carb, and at 10,000 ft, think i should go lower?