16V cold idle Issues and more

[Darth-Jesus]

New suzuki guy here - first off want to thank fixkick for all the online material -it's been incredibly helpful learning this suzuki stuff!

I took a 95 Sidekick 1.6 16V engine (OBD1), rebuilt it from info on this site, and istalled it into an 87 Samurai.
When cold, it's idling above 2k RPM for over 10minutes when cold out (0 deg) and then eventually drops to 800, and then it runs great. When ambient is 70deg, it isn't much faster to idle stabilize. So far I've:
-Verified NO CEL or codes (only 12)
-Verified timing (~5deg BTDC)
-Verified ECT sensor resistance/voltages
-Verified IAT sensor resistance/voltages
-Verified ISC resistance
-Pull fuel pressure regulator vacuum line and idle changes

Then I checked the ISC air hose pinch test. When motor is cold and I pinch the hose or disconnect the connector, idle drops. When motor is warm - pinching the hose or removing the connector doesnt change idle!
So I've began looking for major air leaks and cant find anything using carb cleaner. Also - the only hose that changes idle at all when pinched is the hose to the evap purge solenoid. (is this correct or also a problem?)

What next? Please help!

[fixkick]

hello new guy and welcome.!
good choice upgrade to any Sammi
the IAC under the throttle body dictates speed of idle drop from cold, and of course #1 is the cooling thermostat most get fully hot fast..
hot ISC pinch ,that is wrong results (done right you did), you've got air leaks.
if hot 180F coolant and the 02 sensors is swinging, then there is an air leak , so block the IAC square port to prove it leaks,
other causes?
or someone unscrewed the idle bleed screw. on top of TB (under black plastic cap)
http://www.fixkick.com/fresh-air/Slide_S...ge_25.html
or throttle cable is too tight holding open the throttle. (or if A/T tranny the kick down cable too tight) im sure you dont have cruise cables.

i think the evap VSV is closed at idle, it opens only moving car, like EGR VSV. id be worried that this thing leaks at idle.

i think the IAC is bad, so block its small rectangle port, use clay or duct tape, the latter , might suck in easy, so clean the bore well with carb cleaner so the tape sticks good.
I like the clay block trick, because i can pack it tight in to that hole (slot)seen below.
my guess, is this
the ISC is closed, hot, because the ECU sees this huge air leak (rpm ) and shuts it down.
the ISC is supposed to be at 50% dutycycle 800rpm hot. yours is NOT. that is for sure, you proved that.
my guess, is the IAC is stuck open and then PO, cranked in on the idle bleed screw to hit 800. this is wrong way to set idle.

one more leak , is some one turned the never touch screw on the throttle valve stop,. the TV must be closed 99.9% in fact its so closed water will not pass thru, off car.
TV closed 99.9% (no touch screw)
IAC closed 100% hot. (test it)
ISC tuned with bleed so ISC is about in the 50% middle of its range. most times if there are no leaks, setting bleed to 800 RPM hot , does in fact let the ISC work in mid range.(correct)
the factory calibrates the ISC for that, to happen. (see side screw on iSC)




my 97 had a stuck IAC (thermal) and did same deal. i found a used one that worked, a hole Throttle body. in fact.

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btw,. this system air density using the MAF works like this. HOT engine only.
all illegal (un-metered) air cause engine to go leak, (closed loop functions can correct small leaks but not big leaks which cause lean and too low RPM)
The ISC will correct it this until about 400rpm worth of leaks are corrected until the ISC closes 100% then hold there.

Legal air leaks all cause normal AFR,. not ever lean, and all cause fast RPM hot. (isc will in fact try to correct all RPM errors, no matter what)
this list is short for (metered legal air)
1: TV (its closed )
2: ISC, its 1/2 open (50% duty modulation) electric
3: iAC thermo valve ,its closed. so is not a factor here. unless its NOT?

take off the front air tube from TB lips and pack that port in clay tight,
the put back the air pipe.
then attempt to set the Bleed to 800 rpm hot. im hoping you can.
4: bleed its set to 800 RPM this bleed rate assures the ISC has lots of range.

all hose leaks are illegal air hot, and drops RPM due to lean state, and ISC will try to correct it.
there is tiny PCV leak
no EGR leaks (all are bad, unless moving fast )
No VSV valves that leak. at hot idle. if the TPS idle switch is wrong, both VSV can get confused, (might)

i think the 16v system is easier to find leaks, than the 8v, the 8v has many ways they can leak inside, very odd ways.
The 16v has this very simple TB, just like all modern cars, (less electric motor on side, throttle by wire)

[Darth-Jesus]

Thanks for the prompt response - I greatly appreciate the help.

Blocked the IAC port (there's two, I only blocked the port you indicated) and NO drop in idle until operating temp was met. No change from before - RPM started above 2k, and eventually hit 800.

Idle screw - I only looked at it, and its pretty deeply set - so unclear if it has ever been touched. Did not adjust because when warm it is idling at 800.
Throttle cable - I've removed it to make sure that it wasnt the problem - there is zero tension at idle.
Throttle valve stop - I've never touched it, doesnt mean PO didnt. But when I cleaned the TB with cleaner, it collected and didnt leak past the TV.
VSV - If i pinch the evap line the idle drops ~100RPM whether the idle is at cold 2k, or warm 800.

I again tried carb-cleaner spray method to find leaks and am finding nothing.

You mentioned O2 sensor and TPS. Should that be where I look next? TPS cal?
(Edit - just calibrated TPS - checked out ok for all feeler gauge sizes - needed minor adjustment - zero change regarding idle)


Also - I forgot to mention in my original post that I did put a new 190deg tstat and used the appropriate gasket and weep hole orientation.

[fixkick]

"When motor is warm - pinching the hose or removing the connector doesnt change idle!"
this is wrong, this fact proves the ISC is closed, the if not stuck closed) the ecu has it closed. and means there is no idle speed regulation. (downward)

The tps idle switch must be closed it idle, 50 to about 300ohm (over 500 is trip point and failure,) failure means, idle controls are suspended buy ECU.
the ISC calibration, is best down with a scope on the ISC pins, for 50% duty cycle, adjust the air bleed for 50% on iSC inputs signals. (or use a dutycycle meter on same pins.
i think its a 200 Hz signal. so 50% is symmetrical square wave.
if the bleed is set wrong, say out too much the ISC closes more , and if too much out, the isc closes to 100%, meaning more bleed air , will cause idle to rise above 800rpm hot
as you close the bleed, the ISC starts to open more,and if bleed is 100% closed the ISC opens to max.


THe TPS is the first thing the must be right.
if all other parts are good then only the dutycycle needs to be set if off.
the book shows using a custom tool to set DC, that has its own current source so we dont have that and a scope or DC meter (built in to some DMM's) work best.

sounds complex but is not, all your parts seem to be good. id get the Tps closed.


if the TPS is good. then the bleed is set wrong. only.

high voltage is ISC open, and faster idle, and low voltage ,closed and slow idle. i have the bleed open a tad too much...
scope has ground buster on it.



once correct and in the middle the ECU can control about 400 too much or 400 too little RPM (+-400) so when you put all electric loads on engine it can open wider, then when engine rpm wants to be too high ,say on a day you are have cold dense air and low altitude(more HP), the ISC then closes down.

[Darth-Jesus]

Thanks again! - A friend is going to bring a scope by later tonight. I'll check/adjust and report back.

[fixkick]

i hope its just the bleed set wrong,

a fast test for the TPS
is at pin 2, (to ground) volt meter.
in pin 1 is bottom
pin 2 is idle switch, it will be at 0v, for idle and move throttle a bit and it goes to 5v fast. if at 5vdc all the time its set wrong. (back probing pin 2)
Pin 2 Idle switch out Blue/white (0v when at idle 5v off idle )

here is the lay out for TPS, some GM books show it wrong.

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also , if lucky the DMM set to volts and connected across the ISC pins
6v is the average DC voltage reading for 50% but some meters dont like this square wave (band width issues) and read wrong. or have too slow a sample rate.

[Darth-Jesus]

No scope yet - but an update:

1st: The purge solenoid - I recently replaced a "clicky" one with a junkyard one. Junkyard one doesnt click but as it turns out... it doesnt work either. You can blow right thru it, hence the leak. I replaced the "new" one for the old one that clicks on RPM rise, and no longer does pinching that hose affect idle.

2nd: Went to pull the clay out of the IAC port and dropped a chunk into the IAC - oops!
So I pulled the TB, recovered the clay and bench calibrated the TPS.
Put it all back together and the TPS was reading 5V at pin 2 on idle. By the time I figured out that I just re-installed the throttle cable wrong, TPS now at 0V idle - the engine had warmed and the ISC pinch test and connector removal worked! So - my initial "on car" tps calibration wasn't quite right like I thought it was.

TPS now calibrated for sure - its cooling down now and once the ECT shows truly cold, I'll time the re-start and see if anything changed.

[fixkick]

great discovery, once it all works that sammi will be 90HP monster, very light body and plenty of power.
yes the VSV run backwards, no power open , when you key on the go to default powered up and closed, IIRC.
then when going fast or fast RPM the EVAP opens and sucks fumes from canister. if no canister present, i'd remove the VSV to it and plug the vacuum leak,

Happy days for your sammi

[Darth-Jesus]

great discovery, once it all works that sammi will be 90HP monster, very light body and plenty of power.
yes the VSV run backwards, no power open , when you key on the go to default powered up and closed, IIRC.
then when going fast or fast RPM the EVAP opens and sucks fumes from canister. if no canister present, i'd remove the VSV to it and plug the vacuum leak,

Happy days for your sammi

Well fixkick - I am incredibly greatful for your help - Thank you!
Warm up idle is no longer racing and idle-down duration has dropped to normal duration.

All due to the TPS cal - I hooked up the scope (had a real noisy connection with my quick test setup) for the ISC and it was close to 50% duty cycle so I only made a minor adjustment. Next day I have to work on the car I'll clean up the noisy test connection and dial it in perfectly - but for now I'm calling it fixed!

[fixkick]

that means, 50% no air leaks, and the ISC is still at factory calibration, a very good sign!!!

my full duty page
http://www.fixkick.com/IDLE-AIR/dutycycl...e-air.html

im glad you dont have all the way for this to mess up,. some can be very hard to find air leaks....

what a great engine find for a swap.. cheers !