Engine Coolant Temperature Sensor (ECM)

[cabriogal11]

Hi everyone just replaced my Engine coolant temperature sensor by simply taking the old one out clips and all and replacing it - My question or worry is that is it this simple? Plug and drive - or did I miss a step -


Reason why this was changed was a series of events that went aw-all - fuel pumps - in-tank and out replaced fuel filter as well - car still not starting dies right after start - ????

[CajunSpike]

Take a minute to put the make and model of your cabby in your personal profile.

Assuming you're talking about a 90's cabby..yep..its thats simple.

Can't help with part 2 of that question without knowing car year.

[cabriogal11]

My apologies its a 1990 Vw cabriolet 1.8

[CajunSpike]

for any cabby to run right, it needs three things.
air
spark
gas

air is plentiful..so thats not the problem.

spark - you must have that because the car does start for a minute at least.

That leaves gas.
There's three parts to the fuel system.
Both fuel pumps count as 1 part in this explanation.

fuel pumps
injectors
fuel pressure regulator.

You said you replaced both fuel pumps. I'll take you at your word.
injectors - the fact it starts should mean those are working.
fuel pressure regulator. hmmm...no words about this yet.

Digifant cars(90-93) need about 40 to 45 psi of fuel pressure to run right.
The fuel pump makes more pressure than that.
The purpose of the fuel pressure regulator is to let excess pressure drain off so there isn't too much pressure in the fuel system.

Ok..so much for class.

This is the fuel pressure regulator, in the circle.


The test way to test the fuel system is to buy/borrow/rent a fuel pressure gauge.
You attach it to a barb on the end of the fuel rail. Must be tightly clamped so you don't have gas leaking all over the engine.


Once the gauge is clamped down, turn on the key. Gauge should show about 45psi, engine not running. Pressure should pretty much stay the same for a couple of minutes without dropping down. If it DOES drop down pretty quick, the pressure regulator is bad and should be replaced.

If the gauge shows below..umm...30psi, or no pressure..your high pressure fuel pump isn't pumping enough gas, or dead.

Start the car with gauge attached. Pressure will jump from about 35 to 45 psi, engine running. Thats normal.

In a nutshell you need to make sure the pressure gets to about 45psi(or somewhere close to that) key on, motor off and stays there for a couple minutes.

[tolusina]

.....- car still not starting dies right after start - ????

Well, which is it? Not starting, or starting, not idling? Starting and idling (or not) are two very different things.
---
Oh, and please do put the year, make and model of your car in your profile, it's also often important to know if the car has a manual or automatic transmission.

[cabriogal11]

My apologies here at work and trying to type fast - Its manual 90 1.8

It starts and immediately dies - start it again dies - only way it holds the start if i press the gas pedal and rev it till it stabilizes ?


Will do this profile thing soon - Thanks

[tolusina]

In this pic from Cajun........


Where he has circled, just outside the circle at about 2:00 o'clock, the cylindrical thing is the Idle Stabilizer Valve (sometimes known as as the Idle Air Controller or IAC).
With the key on, engine not running, you should be able to hear, for sure feel, the IAC humming. Can you?

Timing must be spot on, throttle switches or throttle position sensor must be working and properly adjusted. Whether your car has switches or a sensor depends on whether the car has DigiFant I or DigiFant II, see this thread.......
http://forums.vwvortex.com/showthrea...gi-1-or-Digi-2
Ignore the photos, you car looks nothing like that (or shouldn't), see my post #17.
---

My apologies here at work and trying to type fast...

Does your boss know you are futzing around here on his/her dime? lol!

[cabriogal11]

Nope boss dosnt not a VW fan - North American - lol

I will do the listen for after work - I do hear something and I believe its the fuel pump?

[tolusina]

......I will do the listen for after work - I do hear something and I believe its the fuel pump?

The 'hum' is subtle to hear, real obvious when you put a hand on it to feel it.

[cabriogal11]

Will do the hand test then so if I hear it - then step two or diagnosis is ?

[Beetle.freak]

I thought after you changed the blue CTS you were supposed to start the engine and disconnect the blue coolant temperature sensor. Rev the engine through 3,000*rpm three times, each time allowing the throttle to close completely. As this clears the Digifant ECM fault memory ???

[cabriogal11]

Is this true? maybe why not working?

[CajunSpike]

I thought after you changed the blue CTS you were supposed to start the engine and disconnect the blue coolant temperature sensor. Rev the engine through 3,000*rpm three times, each time allowing the throttle to close completely. As this clears the Digifant ECM fault memory ???

I always thought the procedure you're describing...is how you prep to check the timing.

quote from cabby-info.com

Take your timing light (if you have one) and point it into the gearbox hole where the flywheel is. If you have a Digifant
motor, unplug the blue coolant temp sensor and rev the engine 3 times over 3k to clear the ECU memory. Have someone
hold the engine at 2250 RPM and observe the mark in the hole as the engine turns and the light flashes.

unquote

[cabriogal11]

My apologies if my post was confusing - My question was - how simple was it to replace the sensor - and if i missed anything since i simply plugged in and that was it?????

[tolusina]

I thought after you changed the blue CTS you were supposed to start the engine and disconnect the blue coolant temperature sensor. Rev the engine through 3,000*rpm three times, each time allowing the throttle to close completely. As this clears the Digifant ECM fault memory ???

You left out the part about clicking your heels three times while saying "There's No Place Like Home, There's No Place Like Home, There's No Place Like Home"

[Beetle.freak]

I'm mowing grass....the heels are up at the other house !

[Robeuro03]

my new sensor comes on Tuesday. I did the ECU reset, did nothing other than getting rid of a hesitation at 3K when driving. Cold days are hell for me, cant wait to get this sensor installed. Other than that the car drives amazing at any speed

[briano1234]

my new sensor comes on Tuesday. I did the ECU reset, did nothing other than getting rid of a hesitation at 3K when driving. Cold days are hell for me, cant wait to get this sensor installed. Other than that the car drives amazing at any speed

Only remove it with the engine cold. or you'll be sorry
Remove the radiator on the res jug, Suck most of the coolant out with a turkey baster and store in a jug.
Rag off the Distributor.

[cabriogal11]

Only remove it with the engine cold. or you'll be sorry
Remove the radiator on the res jug, Suck most of the coolant out with a turkey baster and store in a jug.
Rag off the Distributor.

Hi I am still getting the no start issue even after I replaced the sensor - this step you mentioned can you explain in a little more detail how its done and is it too late at this point?

[briano1234]

Do the Fuel pressure tests, as it sounds like a fuel pressure issue. I know you replaced the pumps, but there is more to it.

Replace all your vacuum hoses.
Replace your Battery to Frame Ground as well as the Frame to engine/tranny ground.
Did you feel the ISV to see if it was buzzing?

[cabriogal11]

Do the Fuel pressure tests, as it sounds like a fuel pressure issue. I know you replaced the pumps, but there is more to it.

Replace all your vacuum hoses.
Replace your Battery to Frame Ground as well as the Frame to engine/tranny ground.
Did you feel the ISV to see if it was buzzing?

Hi Brianno - will be checking that this morning - I assume in my 90 its in the same location as the Picture?

How complicated is it to replace the grounds?

[briano1234]

Not hard at all, 1 nut, one bolt and nut, and a batter clamp.
See my signature link.