(12-09-2017, 12:57 PM)Rapom Wrote: so today ive noticed on 2 occasions while the kick was cold (sat for more than 10 hours at 15*F) during cold idle i CAN NOT reproduce the surge buy means. this is new to me.
the ECU on all cars have many modes, (a short list)
1: crank mode
2: cold start run. (15f the IAC is fully open) and engine must race fast, do to that fact, ECU has idle controls cold until magic 150F happen and aBOVE.
this ISC is dead, cold , due to actions of IAC. (IAC always wins) http://fixkick.com/engine/96-98%2016v%20...motor1.pdf
3; Warm running, iSC is (ECU slave) runs all idle speeds, and in closed loop AFR and 02 sensor trims MAF errors.
4: acceleration mode, enrich (closed loop ends, MAF runs the shows here 100% (matches fuel to air from MAF data)
5: deceleration mode, cut fuel.
6: Limphome mode. (or far worse failsafe(bad ecu is this)
we dont know what causes the surge, hot yet, its only hot, surge, not cold, so can be lot of things, lacking scan tool it can be very hard to pin down.
but there tests and actions to take, ISC cleaning is a 50k service point in my book. (the horror of the egr/PCV gas cloud, gums it up is why)
but at 1900 rpm the ISC is not used foot in to the throttle pedal, so seems you have at least 2 problems here.
i never put thought to it about hot or cold effecting the surge. apparently it only does it after warmed up. does that bit of info help or hurt us?
helps, sure, it does, most engines do not surge cold due to the very rich AFR, cold,
what matters is , just one thing, is it just lean mixture causing this or is the ECU surging the ISC, there are many tricks of the trade to pin this down lacking a scan tool. (unplug the ISC, hold throttle at 1900 rpm hot, by hand?) surge now.
and /or, (add propane gas during the surge, does this end the surge, (smacks of lien running) with scan tool you'd see, LTFT going nuts of lean.
and another thing..
this ISC needs fixed asap! tonight i had to use headlights, radio, and defrost (ac on)... with all this load.. (even at high cold idle) when i shifted to drive... the poor little guy was idling at 200 rpm.
Why not clean it the ISC it just unbolts from the plenum, if this happens and the idle switch is closed and the EGR main is closed, then the ISC is dead,.
if the ECU tries to open the stuck valve, RPM goes to 200. this is what can happen, stacking up all loads on any engine (even new cars) and a dead ISC.
headlights were very dim (due to low rpm alt output) but i feel if i had to run one more thing, example... if it were raining. the engine would stall. + lugging at 200 rpm has to be bad. im thinking i need to address the ISC first... where is this located? can i remove it without damaging a gasket? clean or replace?
new is $200 + money, cleaning is 1buck.
sure the gasket will be damage, most do 22 years old, but some come out ok but are now like petrified , old hard and brittle. and useless.
a good shop has gasket stock and and xacto knife to make one.... Napa sells, raw gasket material over the counter.
ISC photos here.: lots
http://fixkick.com/find-parts.html
ISC (one line is coolant !!!) other is air.
http://fixkick.com/sensors/16v-engine93w.jpg
ISC
http://fixkick.com/sensors/93-mpi-smog1.JPG
http://fixkick.com/my96-16v/engine2.jpg
and then after we get ALLLLL of the engine sorted... its then time to tackle the slush pump. (tcc not locking up/delay then la la land from 1st to 2nd) another day... another day (kick down cable not calibrated, see my 3speed page)
my surge page covers this. (in all cases the idle switch is closed = 0 vdc) the engine hot, and for sure never below 150F(magic temp rule#1)
http://www.fixkick.com/surge.html
http://www.fixkick.com