2008 150 txrg starts and shuts off constantly

[arctic 1]

ok rodbolt tks

I will prob have to read this 100 times to figure it out but I will give it a try so you suspect it is the ISC?

[rodbolt17]

the ISC is a stepper motor.
a 4 wire is a single speed the 6 wire are multi speed.
the ECU monitors TPS and MAP and CPS signals.
based on these signals it determines engine speed.
at idle speeds the idle air is "trimmed" by the ISC.
if the idle speed is high or low the ECU "requests" that the motor spin the pintle in or out to allow more or less idle air.
if the valves sticks all the ECU sees is the idle speed did not change so it keeps applying the ground(request) and this causes and excessive current draw in the ECU which can overheat both the ECU and the ISC making the ECU heat stroke and become delirious and hallucinate.

next time the engine runs,even if it dies, turn the key off and listen for the rattle.
that rattle at key off is the ISC resetting to 100% in anticipation of the NEXT restart.

if it does not rattle either its stuck or you have wireing issues.
it can rattle and still be stuck.

you can also use YDS to manually move the ISC statically.
do it about 5 times and see if the ISC heats up.

do you have command link gauges?

[arctic 1]

ok that helps a little better and no I don't have command link.

The ISC def don't rattle after every key cycle
but do sometimes


I have tested it with the yds and it do move and also gets hot

[twirk_twirk]

where are you guys located just curious

I am in Canada's high arctic Iqaluit ,Nunavut

Cool! I am in Nuuk, Greenland. Just across the Strait! And I've been to Iqaluit several times

[arctic 1]

I am getting 3.5v on both the intake pressure and the isc so where does this leave me

[arctic 1]

that's a lie I have .325 and if I pug in the ISC I loose it as it starts to get hot and have 0

[arctic 1]

cool we have a flight between here and there if you are ever coming through this way let me know would be nice to meet up

[arctic 1]

rodbolt

looks like I have .325 v on the black and orange on the intake sensor and the same on the tps when I plug in the Isc the little voltage I have drops

also when I plug them back in my intake pressure goes from 7inhg to 4 and my atmosphere stays the same at 19

[arctic 1]

which other sensors would have a 5 v ref as I unplugged all three and voltage is only at .325v

[rodbolt17]

now we are onto sumptin.

the ISC is 12 V. not 5.
however if you are testing ORANGE to BLACK and getting less than about 4.8V.
you have an issue with a sensor,wiring or the ECU got smoked.
goes back to why I wont SWAP SHEET.

to easy to end up wit TWO 1500 dollar pieces and still no answer.

[arctic 1]

you are right rodbolt

that's why I always try the bad ecm on a good motor and not good the ecm on a bad motor

anyway all I have to say is that life couldn't of went on without out you guys!!!!

I found the problem

It was a cooked water sensor
as soon as i un plugged it I had five volts on the intake pressure sensor and the pressures went back to normal.
I guess without rodbolt and twirks help the only other option here was to put wings on the thing and get it up to 22 0000 feet then it would have fired right up!!!

on the bright side I have become very familiar with my motor!!

I had it out tonight and work great idling a little high anywhere from 1100 to 1400 not sure if it is from messing with the TPS or if the ISC is sticking a bit or just a bad cable?What do you think?

it has been a pleasue guys and much appreciated with a hunting way of life here in the arctic I cant live without my boat


thanks

[boscoe99]

What is a cooked water sensor?

[arctic 1]

that is a good question as not all 150's have it
and the strange thing is I cant even find it on the parts fiche

On the water jacket on my 150 I have a sensor that is the exact same sensor as the oil pressure sensor after I found the problem today I went to rob it off a busted 150 to find it doesn't have it.but has the cut out in the block but a bolt instead of the sensor so I took the oil pressure sensor and works perfect

Can you tell me

is it a water pressure?
water temp?

[twirk_twirk]

I'll have to pop by next time I'm in Iqaluit It won't be in the foreseeable future though.

Great you at least got it running.

Can you snap a photo of your "water sensor"? Perhaps it is the engine temperature sensor you are referring to. Hard to know though.

Your engine is still having problems if, as you say idle rpm is at 1100 or higher and does not drop to 650-750rpm. Your engine has a fail-safe function which increases the idle rpm to 900 if you have electrical components that are malfunctioning.

Can you take readings of your intake and atmospheric pressure now. Both at KEY ON and then also with engine running at IDLE?

Just wondering. Did you look at your battery?

[rodbolt17]

the water pressure, speed and oil pressure sensors all look alike.
however they wont directly interchange.
and some water and speed sensors fail.