coolant sensor help 88 190e 2.3
 

well i got the 91 engine in my 88. all hooked up but will not start. almost starts when i let go of the key.
i had a problem with the 4 wire coolant sensor. seem it plugs in 4 ways. there is no key or pin for fitting the plug one way only.
i can put it on any of the four ways(round 4 pin plug)
if not put in right will it cause no start?
i am used to jap cars that all plugs are differant and only go in one way.
cranks alot, has some spark,reversed plug wires make it pop.
gives a stange firing sound when key is let go, like it wants to .but not to often. needed to sleep on it tonight. so my question is about the round plug. this is a california car also.
88 190e 2.3 thanks rich

The engine coolant temp sensor provides feedback to the ECU.

The ECU richens the mixture on a cold engine to assist startup.

If it's screwed (no pun intended), you will have difficulty starting coz the mixture will be too lean.

To test the sensor, pull the connector off and use a multimeter (set to test resistance) on the diagonally opposite pins.

You should approximately get the following resistance values corresponding to the temp just for your info :

6000 ohm - 0deg Celcius
3000 ohm - 20deg C
1300 ohm - 40deg
600 ohm - 60deg
300 ohm - 80deg
200ohm - 100deg

The pin assignments are :

1 Distributor ignition temp sensor
2 CFI temp sensor
3 Engine ground at intake manifold for distributor ignition system
4 CFI control module ground

At this point in time, you should check the resistance since the engine doesn't start and is cold. You should get a value "big" value corresponding to the ambient temp in your area.

Mine checks out at around 2000 ohms and it's very warm/humid where I live (around 30deg).

Hope it helps.
:)

Oh, yeah. If your sensor is screwed (read : faulty - no pun intended, again :p ), it's a cheap replacement - like 20 bucks or so.

Just unscrew the old one out and screw the new one in with an adjustable wrench.

Cheers.:D

The 4 prong sensor is actually 2 sensors in one case .
As Az explained , the diagonally opposed pins will get a resistance reading for each sensor, but because both sensors have the same values and declining resistance/temp curves , the plug can be installed in any of the 4 positions and it will always be correct, circuit wise.. [ providing each sensors thermistor is good]
That is why there is no orientation key/tab...

thank you very much for the info
 

with no lock tab, i ASSUMED the plug went any which way.
had a spare plug also.
will not start, has compression and enough spark to jump plug gap.
this car was bought dead. over heated till death.
bleed the fuel body, put in new fuel.put a temporary jumper on fuel pump. it does come on when key is turned on, but used jumper to bleed injector lines.
not happy with spark but i would think this car should try to start.one or two fires with a lot of cranking.don't want to kill starter.
spray into intake makes no differance .
well i am going to verify these temp sensor wires, pull out some more hair, and then stare the car down.
what is strange is it won't really fire but if i put the plug wires 180 off it back fires.
maybe a weak spark.
thank you
old and in the way
rich

pictures
 

azhari, i was wondering if you have any more picture's of the 88 190 engine. maybe one with no air cleaner or the coil side of motor. just need to verify my installation
thanks rich