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96 x90 revival
11-10-2018, 03:07 PM
Post: #1
96 x90 revival
Hey folks, been at it for a while and I'm pretty familiar with the plat form. Picked up a x90 with a fuel pump issue and put in a new pump and filter and got it running. 123000 on the clock 4x4 auto. Had a few code knocked them out. The problem I'm having is that it won't stay in closed loop. I have read the fixkick site quite a bit due to the plentiful info. Thanks,
I have everything checked out and I have this problem. At idle The primary o2 sensor reads .09 and won't toggle as it should. Then the sort term fuel trim tries to correct until it goes of the scale and shuts down and goes into open loop due to incufecient temperature. No engine codes I've checked all sensors related and it's all good , checked fuel pressure 40psi and 50psi with the vacume of the regulator. I can trick it buy creating a vacume leek buy pulling of the evap and get the o2 to toggle and stay in closed loop but it s idling high at that point with a vacume leak. I'm leaning toward a bad ECU as I have ran out of test. I can list a bunch of things I have done and tested. Try me. Thanks again I really aperciate all this knowledge in info your offering..
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11-11-2018, 06:57 AM
Post: #2
RE: 96 x90 revival
welcome X90 that is very cool car, those are. 16valve engine and with MAP sensor and OBD2. sure.
02 front does swing, in fact stuck at or newer zero , (no cracks exhuast flange or exh tunnel #4 crack as is so common that crack. sucking in air and o2 goes to 0vdc and fuel goes full rich.
where did you see the temperature error?
that is good trick, pulling vacuum hose and leaning, the mix.
id say ECU is ok, never heard of any 96 up ecu fail ever (proved)
what is idle fuel pressure.? exactly
is FPR tested fully , from key on to idle and then gunned to WOT for 1 second?
its rich for some reason,
leaking injectors? (do leak down test on them?)
the maf dirty will read low and go lean , never does it go rich, (for sure easy to test with voltmeter to prove not it)
take off the exhaust tin shields yet, exhaust MAN, and gander at it? for cracks.
ever have bad gas in it?
that is it for now, i bet ECU is okay. EFI us rich for 2 reaons , it is rich ! or the O2 sensors caused (0v is no good), and 02 is bad or exhaust leaks doing that.
for sure you are on track, !!!
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11-11-2018, 07:02 AM
Post: #3
RE: 96 x90 revival
i forgot to say, are you sure the 02 front sensor heater element works, but again, the OBD2 reports that if current goes to zero, and is bad 02. or wire fell off it;
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11-11-2018, 08:43 AM
Post: #4
RE: 96 x90 revival
It's a 16v wit ha maf.
O2 gets stuck at .09
The temp error is from a generic obd2 scanner tourque lite
Fuel pressure is 40psi via a fancy barrowed sample on guage.
You had mentioned that an ECU can go bad and fuel out of control in the track fix data
Fuel regulator holds vacume and regulates fuel well , shows 50 psi when pulling vacume source off
New maf and reads ok on the scanner
Have not checked under the heat shields to check for header leak.
New o2
Any pictures of common cracks in manifold?

Thanks for helping me build a better checklist .
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11-12-2018, 10:04 PM (This post was last modified: 11-12-2018 10:21 PM by fixkick.)
Post: #5
RE: 96 x90 revival
50 PSI is too high. (are you at or near sea level)?
keyon pressure and idle PSI? "Snap-on" tools meant? 50 pSI is wrong, and pressure matters big time on all EFI and for sure this year.

Any ECU is bad, if and only if, all inputs are good and 1 or more outputs are bad. (just like any computer really)
The crack.

[Image: 3_12_11_18_6_20_05.jpeg]
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11-12-2018, 10:33 PM
Post: #6
RE: 96 x90 revival
"The temp error is from a generic obd2 scanner tourque lite"

temp = temperature? or temp = temporary? IDK sorry
i keyed off that word TEMP, please tell what is too hot. or too cold, ?
the water temp must reach 180f and old there, if the thermostat is slow it is bad. (or missing or wrong one, this cares termostate uses the rubber right, if missing this ring the
engine temps will be frigid
why is here.... the missing rubber ring here cause the STAT to float. (in that huge 4mm rim) and leak inside.

btw most of this FPR are not NO GOOD, they are too old now. it moves at ever throttle pedal touch of foot . huge wear factor there and the 22year old age.
what is your altitude, this is first first thing, so we can know correct pressures.
and does engine hit 180F, fully and hold and in reasonable time.
the crack and the floating stat are common, to this car only. (a gift from Suzuki)
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11-12-2018, 10:48 PM (This post was last modified: 11-12-2018 11:25 PM by fixkick.)
Post: #7
RE: 96 x90 revival
The ECU is $400, and very expensive
if the engine fails to get hot , quickly and hold 180f or more.

or any ECU input pins reads wrong, no ECU can NOT cure that. (in fact all ECU it one input is wrong it , then emulates that dead sensor but does dump a DTC)
we already know the O2 reads wrong and no ECU can tolerate that not one. but in truth only wastes fuel and overheats the CAT if fuel rich
(even 100 new 02 sensors can read wrong for 4+ reasons.)
1: exhaust header cracks ( any that are near ) near is cat front flange to exhaust ports. see photo above, vast G16B owners, seen this. fail. 16v only. 8v never fails.
2: injection is way to rich to start, (FPR runs too high 50 is high)
2b: leaking injectors (do the leak down test , just like done on all MPI engine)
3: ECU struck in limphome mode. (RUNS RICH ALL THE TIME) if NO DTCs set then its not in LIMP.
4: water not at 180f. , or ECT reads wrong, say reads 150f and water is actually 180f,. easy test type ECT in my search box. (or shows 180f and is really 150f) the ECT is the most easy sensor to test.

top causes. all, i never saw your full obd2 sensor scan data posted. showing all sensor data.
and All dtc set
nor if there are Pending DTCs, you do know that some DTC do not set fully until 3 or more driving cycles, so we never fail to push the Pending button now.

like 99% of folks say i took it to Autozoned and the free scan shows nothing (no DTCs)
but non know that many top serious, TDCs are hidden until 3 driving cycles. dang, and the AZ guy is clueless about pending codes.
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11-12-2018, 11:21 PM (This post was last modified: 11-12-2018 11:27 PM by fixkick.)
Post: #8
RE: 96 x90 revival
In school the instructor would say , first do basics, know that EFI can no hide a bad engine, (minor wear yes )
so the easy one is 180f, the scan tool tells you it is 180f live data. I also use my $15 IR gun pointed at the thermostat housing after 10 mile drive, to see if they are close.
the gun best reading are after long drive, 10 miles not just around the block or idling for 1/2hr.
next basics are,
Engine vacuum, 19 inches HG hot 800 idle. engine must be 180F or with 192F stat. like mine.
Basics 2, is vacuum does not bounce. (as shown in the gauges boxed sheet inside (ask I have one)
basics 3; engine compression. 1996-98
My 97' pulls 185 PSI min. dead cold. (a new head) later and hot it does 195 PSI. at sea level and less for each 1000 feet higher, tell me yours altitude, or see my table (search"compression")
ok engines is good, and water temperature is 180f or more, good we can now

do fuel pressure next, again sealevel , so 50 PSI is near shut reading, and wrong. and 36 is high altitude, (the FPR does 2 jobs altitude and throttle vacuum)
Static: 36-43 PSI, keyon, not started ( you may have to key on 3 times to build enough pressure, pump runs on 3 seconds)
Running: 30-37 PSI , idling. (these numbers are in the 96FSM) hot engine, 800 rpm for sure.
the MPI injector leakdown test is done now.
make sure engine does get hot and holds 800rpm with AC off. heater off.
scan the PCM, 0bd2.
NO DTC's set
then make sure no Pending DTCs set ( be real sure)
look at all sensors, make sure all are reading correctly. for your conditions
if the 02 sensor fails to swing you have a problem , even at idle 800 RPM hot idle.
if the 02 reads wrong, or is dead, other test are ABORTED on this ECU, for sure the CAT test is never done. now. failing in this way
there are other errors, for slow 02 or and such that can not completed (called Monitors)

The maf sensor can get dirty, and we just clean it. from 8inch distance, with maf cleaner or the like, plastics safe cleaners.
if dirty the maf reads low not too high and that means engine goes way lean, but the 02 front sees that and ECU then sets long term trim higher, to compensate until it gets worse.
hot engine, the maf reads, this, at idle, if I log data and drive one can see full load maf output on this car. 1996

1.7–2.0 volts. at 800 RPM, if not MAF is bad, or RPM is wrong.
see my sick thermostat, it was so slow to close it was pathetic.
see maf hit 55 grams? that is me with 5speed, shifting and flogging it real hard , trying to use all 95HP if the engine. TP is throttle angle sensor. (TPS)

the ECT steps are not ECT caused, that is the scan tools delays scanning, (time delay) no scan tool is instant
bad thermostat here. seen using scan tool , logging data to a laptop.
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11-12-2018, 11:43 PM
Post: #9
RE: 96 x90 revival
lets talk FPR, now.
its 22 years old vast ones are dead now, huge.
what I do is check its whole dynamic range,
i first call my local radio station or use google earth or USGS, and find my altitude , this is always first. know where you are first. so readings , can be expected.
then check the full range,
old FPR can stick so easy inside, and even stick intermittently after it wears a grove inside, the valve after 10,000 + throttle pedal pushes for 22 years.
make sure its vacuum nipple is not leaking fuel if yes FPR= DOA, bad diaphragm.
i run the throttle up and down, see if FPR tracks 1 to 1 each time, if not the FPR is no GOOD
I then like you did use vacuum hand pump (all shops have one) and pump the FPR to all points of its range, to see that it is linear (no sticking) and goes end to end for pressure fuel.
this is KEY EFI device here, just like ECT, MAF are.
is say 50 is wrong, off the bat, but if the guage is from china (nonNamed) its a junk too, I think you used SNAP-on tool, and for sure IS NOT JUNK.
seen tools like this at harbor fright with needle fell off, siting new in box. pure junk but the hoses giving with the gauge fit suzuki, so, are good.
for sure the fuel pressure gauges used need to be good quality. 5% accuracy, good 20% or higher are toy grade, IMO.
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Yesterday, 03:07 AM
Post: #10
RE: 96 x90 revival
Sorry the snap on fuel pressure guage reads 40 psi and then when you pull of the the vacume it reads 50psi

The coolant temperature is reading correctly via my obd2 scanner.

If the header was cracked I would think the o2 sensor would read on the lower end and not stuck at 0.9 volts and I can watch the short term fuel try to minus fuel while in closed loo till it gets past 20-25% and then go into open loop. At that time the scanner message says open loop due to insufficient temp.

I have a used ECU coming tomorrow wish me luck and if not I will be prepared for more testing.
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