how you doing, Joe ! 41s is spark failure, gross misfire, FROM INSIDE THE DIZZY. set the VR gap to spec, i have the 89 dizzy procs on my main timing page under 89. (or the tacho meter is shorting this wire, It can, is tacho bouncing funny?)
http://www.fixkick.com/IGN_timing/89-timing.html
car is EFI. 1.6L not carb. (41s prove that)
the 89 EFI , can surge, and can be causes by these reasons, (we can do tests to find it)
1: just too lean, (both lean caused surge and many times the ECU will jump in and make it worse by trying to correct it and FAILS, called HUNTING.
2: ISC hunting, unplug it to see if that stops the surge (a PITA on 89s to do that physically, i know) but of the surge stops that means the surge is caused by fooled ECU. (will explain later)
3: Dash pot not retracting. (aka: cold start fast idle vacuum throttle valve CSFITV? nah) i call it a DP, if this thing malf's,
it will surge. ECU does this,. more HUNTING. iS IT RETRACTED HOT? (not touching TV stop by 1/8" inch !)
The ISC (wired) IS A SERVO device, its purpose is to control idle at 800 hot. if it can not , the ECU
may hunt H3LL out of it,
4: bad ISC. (if it sticks the ECU goes , totally NUTS ,.)
5: throttle valve letting in too much air. if too , much the ECU hunts it. it closes, RPM is 1500, so what can a ECU do?,it RESETS. "hunts"
6: air leaks of ANY kind.
The ISC can only close 100%, if idle is above 800 hot then, the ECU hunts it. AIR LEAKS, all illegal leaks.
it can fail on the low side but ill skip that, yours is above.
all that is great theory and fact but , who do you fix it.?
next, physics. (last will be tests)
1: Fix air leaks. to the plenum.
2; a clean working ISC
3: the thermal iAC is 100% closed at idle. hot.
see my too fast idle page explains that.
4: when hot there are only 2 legal air paths, the TV throttle valve (close it more) AND the ISC. there are no other paths, if yes,
FAIL
mind set. the plenum is a hard vacuum of 19inchs of mercury, (big time vac)
nature just hates that, it wants to fail.
ACTIONS AN TESTS:
so, close the throttle plate 100% if the throttle cable is stuck tight, bingo binds TV, the cable must never ever be 100% tight, nor the other 2, A/T tranny, and cruise cables (you have 3sp?)
does it hunt now?
if yes, disable the ISC, (my way is to remove it from TB and plug the holes with mastic putty. (electricians putty, its cool stuff) called monkey poop in the bus'ness (in french )
does it hunt still>?
if the TV is closed and the ISC is blocked,(clay) and idle is still fast, tell me how an engine runs with ZERO AIR, last last poster had .?
you can use a smoke machine to find it, but takes great skill, some leaks are normal others not, and id have to be there to see it.
i never use them. i find the leaks using a running engine, by blocking all sources 1 by 1 until its found. never giving up.
TV is the throttle valve, or butterfly plate in the base of the TB, the throttle body.
ok , does this make any sense>?
i make better sense with my new , thyroid pills, LOL ! (maybe...)
cheers to you, lets fix it. ! Gday
PS: the TB love to crack gasket and the middle gasket loves to crack and form an illegal TB, (leaks)
TP stuck.
TV valve set wrong.
Idle duty cycle set all wrong.
leak. (hoses , gaskets, cracks, etc)
, Ordering one right now 