Surging Idle......and then not.

[geoflyer]

I have a '86 Samurai with a transplanted '96 1.6L 16v. OBD2, No check engine lights. I even got the evap system operable. 4000 miles since swap.

Engine runs great open loop. No Issues.

In closed loop, after coming to a stop, engine idle drops/surges low 100 to 200 rpm. However, upon "blipping" the throttle, the engine smooths right out at 800 rpm. Next stop, rinse and repeat. 

Any ideas?

I have cleaned the ISC IAW the directions on Fixkick. Plunger moved under power. No change in idle issue.

The No check engine light didn't come cheap. TPS was bad. EGR sys had to have a lot of love with a total clog at the back of the throttle body. New distributor, original had an electrical "tick" with an accompanying engine shudder at idle. Two downstream O2 sensors to no avail and then suddenly the exhaust note changed one day and that code and the EGR P400 codes just went away. I occasionally will get a P400 when dirt road riding at slow speed/rpm. Daily drive the snot out of it (65/70mph) and it is happy as a clam and doesn't throw any codes. 

   

[jwunsch]

With such a FrankenSamurai I would encourage you to specify as much as you can, like MT/AT(which AT if there are multiple choices) and on.. as he is usually asking that + 2WD/4WD + door count for Sidekick / Vitara. Scrolling the forum I have made a conclusion that it may affect the electronics a lot. Fixkick seems to be busy with other stuff and sometimes takes some time to respond, so mean while drop as much specs as you can.

ps. GJ with such a swap, sounds work some,

[fixkick]

x2 post all things on car (for sure engine/efi ) things not stock, nobody can ever guess what you drive. we are blind.
is this a help me post are just story and solve is it solve please say so.?
yes EGR loves to fail on all cars with EGR, my jeep has none 1995 zero EGR> (it uses dynamic tuning to avoid EGR junk for NOX)
to prove EGR is it,
just remove the EGR vacuum hose at EGR main (rear of intake man) 96 G16B
and put a GOLF tee in the hose so it can not suck air
the #50 ID EGR tube both SST gaskets not missing or cracked sucking air. same with EGR base gasket not sucking air.
Then make sure the EGR is new or make it 100% clean so it can not stuck open, even cleaned some stick still, I put those all in the ground fill, dumps.
SOME EGR mains even the silly body cracks and sucks air.
do not allow any vacuum , hoses or EGR parts or any parts from MAF to TB to suck air ever. from the atomosphere or it goes lean lean lean and stalls or 200rpm

egr sticks open 200 to 400rpm or stalls in fact the EGR test is to see it stall.
vacuum leaks are unmetered air, means you are fooling the MAF> the air must all be metered by the MAF at all times.


if comes back consider this.
make a profile and add that is best.
200 rpm to 400 is most times EGR stuck open and the engine shakes like a wet dog.
or is flooding or vacuum leaks max.
or the IAC is dead as most are this old. (has 2 IAC/ISC , IAC is thermal below TB, ISC is fast 200Hz solenoid idle speed controller. both must work the IAC works only cold until 150 f hits and IAC goes 100%closed hot. ISC then runs the show (idle modulated by ECM)
is the engine hot or cold or both not told. and is key fact. I bet hot as hot = closed loop idle and light cruising.
closed loop is HOT, 180f hot, and a a real scan tool shows the ECT is 180f to 200f is it does PID scan ECT show correct temp or is the thermostat dead.>?>?????
best is post all PID data, and trim. a real scan tool allows you to do all that and matters huge to lower or end all guessing and replacing good things, or putting in new parts that are in fact the wrong parts, making this super hard to diagnose.
P400 can not be ignored.
only cured. The theromo sensor on the EGR main must be clean too, or it lies and P400 hit.