Engine Flooding and misfiring after rain

[Akull]

Hello Fixkick,

I've been driving my 16v powered samurai for a couple years now, and recently has become undrivable any time it rains.

Engine is out of a 1994 suzuki sidekick, CA car. EGR has been blocked off with resistor spoofing the ECU. Alternator has been replaced with GM CS130. No catalytic convertor. (engine had previously run fine with these modifications)

Recently, with any hint of rain (drizzle), the engine tries to flood itself and misfires on all cylinders. Spark plugs are black and wet from overfueling.
cold start rpm is 2000rpm only after tapping the gas pedal, then falls on its face below 1000rpm and nearly stalls. This continues even after engine has warmed up, nearly stalling when under 2000rpm unless holding the pedal open.

There is no CEL, and flashes code 12 when I check codes.

I replaced the cap, rotor, plugs, and wires and air filter when the issue started. No fix.
Additionally replaced the coil as it had over 200k miles on it, still no improvement.
I replaced the o2 sensor, which improved hot idle when not raining, but rains have started again and back to the same overfueling issue.

I assuming compression is good as the engine runs great when it is dry outside (strong 800rpm hot idle).

I am suspecting sensor issues as the issue is intermittent with rain...
I'd appreciate any help with this, and what I should start with checking as I will have some time to work on it this weekend.

Thanks.

[fixkick]

Hard questions, for sure engine and EFI swaps
no photo of engine presented , our gallery does work.

I'D say bad spark wire sets. (but are new)
get NGK mag wire.  wire sets. they will not fail. (mag wire ups the spark power  and all these cars need that)
or bad MAF (or just dirty)
is the MAF connected to stock air cleaner, I bet not and the one there is no good. damp, so called cold air intake , loves to fail, as the Air filter is exposed to rain
as it splashes up to non stock air cleaner fitment.

MAF dead or just dirty,  clean it first. the hot wire must be cleaned,
the spark plugs are not queer right,  just J- plugs not 2J or 3J or some crazy bad surface fire spark plugs and gapped to spec, under hood sticker lost tells this.
gap is 0.028"  not wider. ever.

the maf on the new car 1994 , had a nice air cleaner box.
this box keeps the filter dry, and also keeps gross humid air from landing on the hot wire.MAF elements
humid air there will make it read too high and over inject.
the MAF things air is 2 times normal like that.  Stock works best. (air flows ,)
most swaps like this use those silly cone filters.  sitting in space and some seen are bouncing like mad that will wreck any MAF fast.

all maf tests by me shown here Exel plotted, I even used lawn leaf blower to test a maf, to full output, (look ma' no car!)
http://fixkick.com/sensors/92-95MAF/EXCEL-ECHO1.jpg


if the ECT pins are rusty it will read wrong mostly in rain. (humidity)
here is one poster that nails this best, cold air bull it is called.
sucking hot air of the back side of the radiator and full of rain water too.

https://www.youtube.com/shorts/K6MwriNXPX4


good luck to you!!

[fixkick]

the best cold air mod is a custom air box and the huge hose to the cut up fire wall, that is under air pressure moving fast.
the cowl gets pressurized air off the front of the windshield.
the cowl left and right sides have 2 huge water drains, preventing water there.

i have one more idea forgot above 1st post
the 16v has spark plug wells x4. and those wells love to fill up with water or bad VC gaskets that let the wells fill up with engine oil and spark fails hard.

one more...
thermostat works and reaches and holds 180f or more?


that 2000 RPM statement, is on hot engine?
seems your ISC/IAC are not working at all .

the 16v has 2, idle air devices
the ISC is electric and must e kept clean, or it gums up with PCV dirty could in the plenum.
the IAC is thermal only and this old love to fail, they love to fail leaking, and idle can not ever reach 800 again.

the IAC is here.

http://fixkick.com/IDLE-AIR/Slide_Show/i...Body1w.jpg

just removed

and here

http://fixkick.com/IDLE-AIR/Slide_Show/i...d-back.jpg

the IAC is just like thermostat, it has a wax pellet in side the closes 100% at 150f, temp and stays closed not.
if not it sucks air like mad and the ISC is rendered useless.

[fixkick]

this ECU is not smart
it only knows dead maf, not weak or reading too high.
it reports DTC for stuck fully high or full dead. only.

http://fixkick.com/sensors/92-95MAF/92-9...sting.html

my maf tests are simple.

voltage key on, no start is 1.0–1.6 volts , if not MAF may be bad.

idle voltage is. 1.7–2.0 volts. at 800 RPM, if not MAF is bad, or RPM is wrong.

if you gun the throttle hard wot fast the maf can reach 4vdc.
for sure flooding the car up any hill the maf can get near 4vdc. (max air is now) but if engine is weak we can not to that.

[fixkick]

do not drown the maf "water"
if the maf reads high all the time it will over inject.
lies into the computer gets you lies out. (GIGO)
maf lies, like this , make injector pulses way way to long.

the stock cars air cleaner was designed to run at 15,000 feet or sea level and all temperatures and all humidifies.

clean the maf with maf cleaner from 8inches afar, not close sprayed as that can wreck the hot wire element.
I soak it with cleaner, for short spray wait 1min. for this solvent to soak, then repeat 3 times. this will get it clean.
as you drive the hot wire wants to coke up, from road dirt/ and engines in cars from front of you driving (nasty stuff)\

IAC must work
ISC not gummed up
thermostat not dead. (stuck low or missing or installed backwards or bleed hold not up, means up hill) engines slant and the bleed goes to high end on all cars made.
spark wells not full of junk, water or oil or anything but clean air.
K/N junk cone filters wrong.

[Akull]

Hi Fixkick,

Thanks for the response. I worked a bit on it today, turns out my FPR had failed. It was stuck open on static test, (Fuel Pressure dropping to 0 with engine off). Swapped that out with another one, Fuel pressure no longer dropping.

Another issue I found was the TPS was out of calibration, causing high rpm cold start.

Optimistically I think the issue with the rain was the Fuel pressure, but only time will tell.

[Akull]

Regarding the MAF, I will go back this next weekend to see if it is reading incorrect. 
The swap uses the factory 1994 sidekick airbox, however is just open to the engine bay so I'm sure it is reading incorrect when the engine gets hot. I'll attach some photos tomorrow when there is light outside again.

Thanks again,
your website and forum is keeping the suzuki dream alive.