X90 friendly?

[High Arctic Si]

no the TB comes right off, with cable off, and 4 nuts. (and water hoses to IAC)
the IAC is a real pistol, its has 6mm screws that love to seize in the body,
what i do is remove IAC from TB , TB off car. and try hard to get penerating oil down screw case junctures. hard to do but try.
then work the screw ccw/cw back and forth with screw driver or if cant use vise grips to the head to get the screw to jog just the smallest amount and use more PEN oil.

ill do red words now....
So i removed the air intake pipe and had a look into the throttle body, it is sooted up and grimy.
must the intake manifold be remove to get the throttle body off?
could i try and flush out the IAC with it in place? sure, but it is stuck closed, this can be hard fix .. but is a great first start idea, no lie.
ISC sucks air when i remove the pipe and will cause the engine to stall, i guess that means it is not affecting the cold idle rpms, in a bad way.
pinch it to see if it runs slow RPM like 500. removing the hose , causes AFR to vastly lean. (you lied to the MAF) all non metered mAF leaks
cause lean (if ecu can not correct it. via closed loop) and this is a gross air leak. but proves the ISC is not clogged.
If the IAC is blocked,stuck the ISC will open up wider but will not be able to hit you at 1500 rpm cold , as the IAC does. in fact the ISC will just stall or hunt.
The ISC is like good for plus or minus 400rpm (no spec) around 800 hot. what it can do cold ,i dont know. but is moot point if IAC is stuck closed.



I guess i could test the iac by blowing through a hose going in the inlet, with engine cold, air should pass through freely. a very great idea that.
But fitting square to round hose will take a mind twister........???? but yes, a brilliant idea. thanks.
If clogged, it would not. (true for sure if 100% closed, as it seems it is)
Or i could tape it and start engine cold and see if the RPMS are even lower at idle (that too is brilliant, sum of all leaks test, brilliant)
i see you undersand the vacuum and flow issues, you will win.

ON mine car, the IAC was jammed open but fund a whole throttle body for $25 a new IAC was over $200 (so took a chance and won) YMMV

I just ordered the autel you recommended, but have access to a decent obd2 scanner at a local shop. last time i hooked it up it had a hard time connecting and would not operate with engine running, (usual cause is 1: no 12v on DLC pin 16 or your scanned has no comm support for early OBD2(very rare).
It said COMMUNICATIONS FAILURE?
could this (dead ecu:?) be caused by the p0300 (NO), random multiple misfire. no the ECU will log 300s all day , it will keep reporting them or clear them.
the other code indicated coolant temp sensor voltage too high.
ECT too high is just that, or wires cut to it or was stored from pulling wires key on, reset the ECU and see if ECT codes return , if not all is well..

For the last couple of days i have been able to keep the flashing SEL lamp calm by warming up the car with foot on throttle till it reaches operating temps,
yes, the DEAD IAC will in fact confuse the H3LL out of the ECU. it thinks gee , im cold, and the IAC is open, so tries to mix air to match that.
Keep in mind the MAF works at low rpm but is very inaccurate, then. but a cold started engine, there is no closed loop. just IAC and fuel mixed crudely for
about 10 to 30 seconds,dead cold, the closed loop happens, if not the ECU is confused. The IAC is part of the math at cold start.
my guess, is it is a cold IAC air table (ROM). the ECU looks at ECT sees the real temperature and then looks up cold air flow of the IAC in the table and mixes
fuel based on that , dead cold and for sure cranking, : in fact cranking will be way too rich with a stuck closed IAC< no air = rich. it might food too.
so that is why adding 10% throttle helps. you are a virtual IAC< (not fun for sure)
As you can see the ECT is very key here too. reading to low temp, flooding, to high starving.

takes about 10 or 15 minutes at -25c ambient temp.
Now after inspecting the front fender fuse block, this little trick doesn't seem to work anymore. what trick? there is no jumper on 1996 + cars.
the SEL light flashes, iam wondering now if i have a bad wire somewhere causing poor running. (watch all DTCs , any and all)
fender block? the SEL flashes for 1 reason, that reason is gross 300s, P0300s ,it only means the CAT is burning to a crisp,( gross misifre load vast fuel and oxygen to the CAT,it then glows red not and can in fact melt or go DOA. ) all 96 cars in USA do that, most Canada cars do not, its masked,
if you look in the FSM under code 300 there are 2 column on the right side, called A and b, one is USA, other is Canada, true E28 cars.
may errors in canada cars are not reported with CEL glowing. oddly as that is ,its true. but yours I bet is a USA car in Canada.
the sticker under the hold will say USA standards compliant USA< if Canada, it will stated that fact.

I will get the scan tool on the machine today and report back with the results.
thanks for the advice.

if you get Scan tool comm fails, that means the ECU has lost power. or pin 16 fuse is blown.
every time, 96 ECU never go bad, ever. (unless an injector shorts, that is).....


if you put a voltmeter on the CIG lighter you can see loss of DC power there, if that drops out running car, you do have a DC power distribution failures. we can find that easy.

Well I have removed the throttle body and replaced with a known good complete throttle body from my other x90, not much improvement. Then i tore off the old cold start air valve and found that it was clean and seems to let air through quite well, i havent cooked it yet to see if will stop air but its cold start function seems to be OK.

Trouble codes are the persistent P1715, P0340, P0300, the flashing SEL lamp is intermittent. It is dumping loads of fuel and i fear i may have already burned up my new CAT, car still runs though. Would the camshaft position sensor failure cause the random misfire? I thought it was just there to help out the crank position sensor.

Next step will be changing out the distributor with the one from my other car, wondering if the P0340 is the root of the misfire.

Or if my issue is high fuel pressure, no adaptor to check pressure at the rail.

My headlights do get brighter when i apply throttle also the automatic windows only work well when i have the RPMS up. Battery is good. Maybe i have a bad ground or electrical isssue causing the P0340. I fear that all the work I have done will be a big circle of unnecessary repairs right around the real issue which is going to be a real simple one that I could have discovered in minutes of thoughtful, methodical testing with a good multimeter.

I do have the FSM for the X90 and Iam going to run through the the volt and ohms test at the ECM.
I need to solve this problem before I go broke on fuel and fry my CAT!!

Your thoughts are appreciated,

Si