Coolant Temp Sensor
Thread Starter
Instructor
Joined: Jan 2005
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From: Hudson FL
Coolant Temp Sensor
Does the Coolant Temperature Sensor mounted in the front of the block send signals to any component that would control engine idle and performance, timing etc.
I notice that this sensor was oose and my digital coolant guage was reading temperature all over the place. From 198 to 140 to 40 to LO. Every time it did while at normal operating temp (198) the engine missed and bucked - like the timing was off. At one point it even stalled, and wouldnt start. Then when I jiggle the wires at the temp sensor connect and was able to stabilze the temp reading to nrmal operating temp. the car started and ran fine.
Its loosened up on a few more occasions and when it does the temp readings go wild and the car runs rough, play with the wires and stabilize it and the car runs fine.
So does that sensor send info to ECM, ICM, Opti or any other engine management system that could produce inefficient operation, missing or stalling?
Please advise
Thanks
Frank
I notice that this sensor was oose and my digital coolant guage was reading temperature all over the place. From 198 to 140 to 40 to LO. Every time it did while at normal operating temp (198) the engine missed and bucked - like the timing was off. At one point it even stalled, and wouldnt start. Then when I jiggle the wires at the temp sensor connect and was able to stabilze the temp reading to nrmal operating temp. the car started and ran fine.
Its loosened up on a few more occasions and when it does the temp readings go wild and the car runs rough, play with the wires and stabilize it and the car runs fine.
So does that sensor send info to ECM, ICM, Opti or any other engine management system that could produce inefficient operation, missing or stalling?
Please advise
Thanks
Frank
Le Mans Master
Joined: Feb 2006
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From: Louisiana
Originally Posted by fjm59vette
So does that sensor send info to ECM, ICM, Opti or any other engine management system that could produce inefficient operation, missing or stalling?
Please advise
Thanks
Frank
Please advise
Thanks
Frank
Team Owner
Joined: Jan 2003
Posts: 20,292
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From: Summerland B.C. Canada
Yes as stated. The ECM uses it to control a crapload of stuff 
But, it has no relationship to the temp gauge, it only feeds the ECM info. I'm not familiar with the 90's and newer vettes , but thats the case for 84-89
But, it has no relationship to the temp gauge, it only feeds the ECM info. I'm not familiar with the 90's and newer vettes , but thats the case for 84-89
Le Mans Master
Joined: May 2005
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From: Queensland, AUSTRALIA
Originally Posted by AGENT 86
Yes as stated. The ECM uses it to control a crapload of stuff
But, it has no relationship to the temp gauge, it only feeds the ECM info. I'm not familiar with the 90's and newer vettes , but thats the case for 84-89
But, it has no relationship to the temp gauge, it only feeds the ECM info. I'm not familiar with the 90's and newer vettes , but thats the case for 84-89
P.S. Fjm59vette, we can always help you much better if we know abit more about your car!!! (i only took a wild guess that is a 92-96)
Last edited by Casethecorvetteman; Sep 20, 2006 at 06:03 AM.
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From: The Top of Utah
In an L98 the ECT sensor is in the front intake manifold. I don't believe any of the C4s have temperature senders in the block, anywhere. Other senders or switches are located in the heads.
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Le Mans Master
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From: Queensland, AUSTRALIA
Originally Posted by CFI-EFI
In an L98 the ECT sensor is in the front intake manifold. I don't believe any of the C4s have temperature senders in the block, anywhere. Other senders or switches are located in the heads.
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Le Mans Master
Joined: Jan 2006
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From: Orlando FL
As stated knowing what kind of car you have would take lots of guess work out of it. But if you do have the sensor in the water pump up front, it does feed you temp gauge and as said, inputs to your ECM. It is a MAJOR player in the A/F mixture calculations that the ECM performs especially in open loop operations.
As the engine temp goes up, the resistance of the sensor goes down hence telling the ECM to go leaner. If the sensor is open, wires broken or connection corroded the resistance will go higher (much higher) and tell the ECM to go real rich because the ECM thinks the engine is cold.
As the engine temp goes up, the resistance of the sensor goes down hence telling the ECM to go leaner. If the sensor is open, wires broken or connection corroded the resistance will go higher (much higher) and tell the ECM to go real rich because the ECM thinks the engine is cold.
Last edited by pcolt94; Sep 20, 2006 at 02:38 PM.
Melting Slicks
Joined: Feb 2006
Posts: 2,753
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From: backwoods upstate ny
MANY of these CTS units are off calibration, even though not fully failed...check yours with a scanner when cold and with the engine at operating temp...many, many minor performance problems are the result of an inaccurate signal from the CTS to the ecm
new CTS units are cheap...both price and quality...MUST check with a VOM vs tables in the fsm prior to install (i've seen several brand new ''junk'' ones)
Last edited by redrose; Sep 20, 2006 at 02:07 PM.
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Race Director
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From: The Top of Utah
Originally Posted by Casethecorvetteman
Its a gamble at what engine he is talking about really isnt it. He doesnt tell us or give us a year model, which makes life hard. Since he says words like "opti" im going to guess he has an LT1 and
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Thread Starter
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From: Hudson FL
definately a C4
Originally Posted by CFI-EFI
And by his user name, fjm59vette, it doesn't even look like it is a C4. Maybe it's a transplant. But if so, what into what?
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Guys Sorry - Yes imine is a 1994 LT1 6 Spd Polo w/Greenwood Kit. And most definately the Coolant Temperature Sensor does send info to a system component that affects engine operation, believe me it does, because the thing is loose and and when the temp gauge goes wild the car operates erratically !!! will even stall !!!!
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From: Hudson FL
Reply
Originally Posted by Casethecorvetteman
Yep, its the same on the later ones, but there is 2 sensors(92-96). One for the analog dash guage, and the one in the water pump is the important one
P.S. Fjm59vette, we can always help you much better if we know abit more about your car!!! (i only took a wild guess that is a 92-96)
P.S. Fjm59vette, we can always help you much better if we know abit more about your car!!! (i only took a wild guess that is a 92-96)
Sorry - 1994 LT1 6Spd
Thread Starter
Instructor
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From: Hudson FL
Its gotta be the sensor in the Water Pump
Originally Posted by Casethecorvetteman
Yep, its the same on the later ones, but there is 2 sensors(92-96). One for the analog dash guage, and the one in the water pump is the important one
P.S. Fjm59vette, we can always help you much better if we know abit more about your car!!! (i only took a wild guess that is a 92-96)
P.S. Fjm59vette, we can always help you much better if we know abit more about your car!!! (i only took a wild guess that is a 92-96)
I have to replace it !!!! Do I have to worry about coolant draining all over the place when I do ?
Le Mans Master
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From: Louisiana
Originally Posted by fjm59vette
Guys Sorry - Yes imine is a 1994 LT1 6 Spd Polo w/Greenwood Kit. And most definately the Coolant Temperature Sensor does send info to a system component that affects engine operation, believe me it does, because the thing is loose and and when the temp gauge goes wild the car operates erratically !!! will even stall !!!!
All an overview of what has already been stated.
Le Mans Master
Joined: May 2005
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From: Queensland, AUSTRALIA
Originally Posted by fjm59vette
I said front of block - sorry I didnt realize it was mounted in the water pump. But thats the one. It definately send the info to the digital coolant temp guage cause thats the guage that goes wild, not the analogue one.
I have to replace it !!!! Do I have to worry about coolant draining all over the place when I do ?
I have to replace it !!!! Do I have to worry about coolant draining all over the place when I do ?
Drifting
Joined: Jul 2005
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From: Baltimore MD
Originally Posted by RRT vette
Yes, the ECM. The ECM uses this sensor to contol engine idle on startup and fuel trims, ect.. If the connector is loose or the sensor is faulty it will cause all sorts of drivabilty problems. Apparently there are two different sensors for the LT1 as is for the L98. In the L98 (not certain of the 84 and 85), there is a Coolant temperature sensor in the front of the intake manifold that sends engine temperature to the ECM due to changes in sensor resistance and there is a Coolant temperature sender in the right cylinder head that sends engine temperature to to the dash guage. On the LT1 the Coolant temperaure sensor for the ECM is on the waterpump. Not sure where the guage sensor is, but is should be in one of the heads.
All an overview of what has already been stated.
All an overview of what has already been stated.
For you LT-1 owners - where exactly are these 2 sensors located? Anbody have a good picture?
Le Mans Master
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From: Orlando FL
FYI:
94 & up is a PCM
93 and down is a ECM
Your analog sending unit is on the drivers side between the last two cylinders (5 & 7) in the head. It only drives your analog gauge.
JFM - Just update your profile with your car info, its easy.
94 & up is a PCM
93 and down is a ECM
Your analog sending unit is on the drivers side between the last two cylinders (5 & 7) in the head. It only drives your analog gauge.
JFM - Just update your profile with your car info, its easy.
Last edited by pcolt94; Sep 22, 2006 at 06:31 PM.
Thread Starter
Instructor
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From: Hudson FL
That sensor does send to digital guage
Originally Posted by kittmaster
And digital display data gauge
The sensor on the water pump definately does send the temp to the digital temparature guage on the dash. The only reason I knew the sensor was faulty was due to the crazy temp reading given to me by the digital coolant guage.
Melting Slicks
Joined: Mar 1999
Posts: 3,027
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From: Nashville TN area
FYI, if your gauge on your '94 is changing temp reading erratically, then it is likely the wiring or connector. An open circuit will cause it to read LO.. I had this same problem on my '94, but luckily the bad portion of the harness was near the connector so I just had to replace the end of that pigtail..
The temp reading shown on the digital readout is the same one the ECM is using and it controls fuel.. when it thinks it is cold, it'll dump a lot more fuel, causing your "misfire" feeling..
Email me if you have any more questions, I don't check these boards that often..
Hope this helps,
Mikey
The temp reading shown on the digital readout is the same one the ECM is using and it controls fuel.. when it thinks it is cold, it'll dump a lot more fuel, causing your "misfire" feeling..
Email me if you have any more questions, I don't check these boards that often..
Hope this helps,
Mikey
Instructor
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From: Kaw Lake Oklahoma
2021 C4 of the Year - Unmodified Finalist
Thanks for this post. It answered my question that some mechanics could NOT answer. I went to a car show on Saturday. Car ran fine, but on the way home the digital coolant was bouncing all over the place. Pulled into a parking lot and the engine died. Few minutes later it fired up like nothing was wrong. Read your post, was going to pull the sensor out and check for corrosion, BUT as soon as I touched it half of it fell out in my hand.
Thanks again...... 1996 LT1
Thanks again...... 1996 LT1
