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Hot/Cold Resistance of ECU Coolant Temp Sensor?

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(ed note posted 2 days later) :)' UH WAIT, WAIT. It's the "air bypass" solenoid I unplugged. I couldn't see in the dark. Totally different issue. Still runs much better with it unplugged. Totally different issue,

 

I hope this gets buried. Thanks NIpper, I saw the charat in the Haynes. Thats plug on the temp sensor is impossible to get to. Cracked some small hoses trying.

 

Slinking away hoping not to be noticed.

 

(end ed.)

 

I think I want to play around with the collant temp sensor feedback to the ECU.

 

I read that that a cold CTSensor has 2.8k ohms. Does anyone know what the hot is supposed to be?

 

If I put a fairly large reisistor in parallel with the circuit, it will lower the cold resistance proportionally more than it lowers the hot resistance, kind of compressing the curve. Would this lean out the cold mix?

 

The 97 2.2 Legato 153k runs too rich when cold, but perfectly when warm, except for a kind of hard idle.

I've checked all other things. My feeling is that at this engine at 153k has lowered compresssion and doesn't need all that gas when cold. I assume the cold start mix is a baseline and not mixed from the MAF, because there is no air flow when stopped.

 

Anybody have a done deal to share on this?

 

 

(ed note

 

---------

 

mpergielelmhurstil97legato99forester

212F 176 ohms

194 240

176 332

158 458

140 668

122 672

112 1182

104 1458

95 1800

86 2238

76 2795

68 3520

58 4450

50 5670

40 7280

32 6420

 

28 move to florida.

  • Author
212F 176 ohms

194 240

176 332

158 458

140 668

122 672

112 1182

104 1458

95 1800

86 2238

76 2795

68 3520

58 4450

50 5670

40 7280

32 6420

 

28 move to florida.

 

Har. Thanks much. I can work from there.

(ed.: next day) This morning it was snowing (about 32F) so I decided to take the Legato and didn't want to smell that rich gas at all so I put a jumper across the Coolantempsensor and it started and ran great, idled easily (used to rumble). At the first stop, it threw a CEL, so more fix is required.

 

I charted the numbers and got a curve, so I think I may be able to tune this with that parallel resistor, but first I have to measure the sensor hot, when I get home, and the last thing I want to do immediately is dig under a hot hood.

Thanks for the reference Nipper. I noticed that the resistance readings for 40 and 32 degrees seem to be transposed. Are they really correct?

Thanks for the reference Nipper. I noticed that the resistance readings for 40 and 32 degrees seem to be transposed. Are they really correct?

 

Get the book and find out

 

(yes they are, my oops)

 

nipper

  • Author
Get the book and find out

 

(yes they are, my oops)

 

nipper

 

UH WAIT, WAIT. It's the "air bypass" solenoid I unplugged. I couldn't see in the dark. Totally different issue. Still runs much better with it unplugged. Totally different issue,

 

I hope this gets buried. Thanks NIpper, I saw the charat in the Haynes. Thats plug on the temp sensor is impossible to get to. Cracked some small hoses trying.

 

Slinking away hoping not to be noticed.

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