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sudden voltage drop problem
Posted: Sun Apr 05, 2015 7:17 pm
by alper
hi
I've been having
sudden voltage drops in my own car.
when the ignition is on, there's no problem.
when the car is running, problem starts :
https://www.youtube.com/watch?v=430whKcu4aw
I changed the coils, crank sensor, ecu.
no solution.
I made new cables for coils, ecu power, and ecu ground, power ground,
no solution.
I disabled everything but the crank sensor, coils and injectors,
no solution.
I changed the fuel pump, also fed the fuel pump from another battery, no solution.
what is the problem, do you think ?
Re: sudden voltage drop problem
Posted: Sun Apr 05, 2015 11:24 pm
by Jan32
Did you test it without alternator? Maybe there is the problem.
Re: sudden voltage drop problem
Posted: Mon Apr 06, 2015 12:24 am
by alper
I tried it already - no difference..
Re: sudden voltage drop problem
Posted: Mon Apr 06, 2015 7:33 am
by Jean Niemi
I used to see similar happening, but it was only with older SW/FW.
What Software/Firmware are you using?
Re: sudden voltage drop problem
Posted: Mon Apr 06, 2015 9:19 am
by Jan32
Did you measure the same with an Multimeter or better an oszilloscope?
Re: sudden voltage drop problem
Posted: Mon Apr 06, 2015 10:03 am
by alper
I dont have an oscilloscope, but I measured it with some multimeters, the multimeters dont show any voltage drop, however, they are not as sensitive as an oscilloscope.
Re: sudden voltage drop problem
Posted: Mon Apr 06, 2015 11:22 pm
by Urosch89
Maybe try to mount a capacitor on the line of the coils, tell me if there are news.
Bye
Re: sudden voltage drop problem
Posted: Mon Apr 06, 2015 11:34 pm
by astra vxr
could be battery ,alternator , or just a crap ground its not dropping enough to cause much problems so it will be something simple
Re: sudden voltage drop problem
Posted: Tue Apr 07, 2015 10:34 am
by alper
I think I've found the problem.
I have another car (sierra dohc turbo) with the same setup, with the same problem.
both are wasted spark operated.
the other cars with sequential firing don't have the same stuff.
soo...
can it be because of wasted spark ?
Re: sudden voltage drop problem
Posted: Tue Apr 07, 2015 6:33 pm
by Jadzwin
It is rather connected to bad grounding. The coils draw lots of current and if they share ground with EMU it can make such problems.
Is the battery realocated from the hood ?
Re: sudden voltage drop problem
Posted: Tue Apr 07, 2015 6:41 pm
by alper
they dont share the grounding with emu. but I will check all the grounds again and report
Re: sudden voltage drop problem
Posted: Tue Apr 07, 2015 6:58 pm
by astra vxr
are you useing brand new loom or useing adapter ?
Re: sudden voltage drop problem
Posted: Tue Apr 07, 2015 7:08 pm
by alper
two different fresh looms on two different cars.
Re: sudden voltage drop problem
Posted: Tue Apr 07, 2015 7:27 pm
by Jadzwin
Try to draw the schematic with ALL of your car grounds.
Re: sudden voltage drop problem
Posted: Wed Apr 08, 2015 1:53 am
by alper
ok I will..
the voltage drops are more likely like parasites - not drops like heavy load as a fan turns on.