ECT Sensor
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Joined: Jun 2009
Posts: 417
From: GA
ECT Sensor
I found out why the SES light was coming on and the car would smooth out. I have a bad ect sensor and there is only one wire going to it, I traced it back and can't find the other wire, I think the one wire thats going to it is green, does anyone know what color the other one is? thanks
Registered User
Joined: Dec 1969
Posts: 27,725
From: Little Rock, AR
If it is the one going to the cylinder head, there is only one wire and it is green. It has nothing to do with how the car runs and cannot cause the check engine light to come on. It is only for the gauge. The two wire sensor that is in the water pump has yellow and black wires. It feeds info to the PCM.
I know I have recommended several times for you to visit my Tech Page for a lot of your previous questions (not that you are taking the hint). It will answer all your questions about the ECTs and more.
http://shbox.com/1/4th_gen_tech2.html#ect
I know I have recommended several times for you to visit my Tech Page for a lot of your previous questions (not that you are taking the hint). It will answer all your questions about the ECTs and more.
http://shbox.com/1/4th_gen_tech2.html#ect
Thread Starter
Registered User
Joined: Jun 2009
Posts: 417
From: GA
I changed out some of the spark plugs yesterday and more of them today, when I did I pulled the plugs that I had put in yesterday to make sure they were gapped correctly and they were black with soot telling me that I have been running rich. I did a quick search and found this old thread , here is a quote from it
I pulled the sensor out of the cylinder head and took a ride and the SES light never came on. I got home and plugged it back in and after about 5-10 minutes of driving the light came on again and instantly smoothed out with no stalling or hesitation. Probably the reading from the faulty ECT sensor is making it think it's super cold, which would dump a lot more fuel in, fouling the plugs.
According to my Helms manual it goes into closed loop @ 140*F, so I went to the garage with my scanner with the intention of paying close attention to the Engine Coolant Temp (ECT) in relation to when the problem starts, and also to comparing the Bank 1 & 2 O2 sensors throughout the warm-up cycle.
ECT got above 140* and everything was fine, didn't see any obvious problems with the O2 readings. Then I noticed that as the car was warming up, the ECT on my scanner was reading noticeably lower than what the inst panel gage was reading. Problem seemed to begin when the difference was approx 30* and up. Shut it down, got to looking in my Helms, and sure enough, a bad ECT sensor can cause a hard/no start, rough idle, stalling, and little/no acceleration when increasing throttle.
Picked up an ECT sensor ($12), swapped it out, and went to fire it up and....no start...WTF??? Checked it with the scanner and had a -40*, plugged the connector into the old sensor and still had a -40* reading. Started shaking wires looking for an intermittent break while watching the scanner. narrowed it down to an area of wires covered in electrical tape. WOW.........some jack-@ss at some time in the car's life had to replace the ECT connector and did it by just twisting the wires together!! I CORRECTLY spliced both sensor wires, and the car fired right up. The ECT on the scanner is dead on with the inst panel gage as well. Let the car idle for 20-30 minutes with no issues. Took it out on a 20 minute test drive at full throttle, part throttle, you name it. NO ISSUES AT ALL. Left the Z06 in the garage and drove the Z28 around earlier today as well with no problems, runs like a champ!
I'm guessing that it was running pig rich due to the false low engine temp reading. This in turn was loading up and eventually causing a restriction in the cat......maybe?
....point is it's fixed now
Thanks to the guys who helped me think outside the box
ECT got above 140* and everything was fine, didn't see any obvious problems with the O2 readings. Then I noticed that as the car was warming up, the ECT on my scanner was reading noticeably lower than what the inst panel gage was reading. Problem seemed to begin when the difference was approx 30* and up. Shut it down, got to looking in my Helms, and sure enough, a bad ECT sensor can cause a hard/no start, rough idle, stalling, and little/no acceleration when increasing throttle.
Picked up an ECT sensor ($12), swapped it out, and went to fire it up and....no start...WTF??? Checked it with the scanner and had a -40*, plugged the connector into the old sensor and still had a -40* reading. Started shaking wires looking for an intermittent break while watching the scanner. narrowed it down to an area of wires covered in electrical tape. WOW.........some jack-@ss at some time in the car's life had to replace the ECT connector and did it by just twisting the wires together!! I CORRECTLY spliced both sensor wires, and the car fired right up. The ECT on the scanner is dead on with the inst panel gage as well. Let the car idle for 20-30 minutes with no issues. Took it out on a 20 minute test drive at full throttle, part throttle, you name it. NO ISSUES AT ALL. Left the Z06 in the garage and drove the Z28 around earlier today as well with no problems, runs like a champ!
I'm guessing that it was running pig rich due to the false low engine temp reading. This in turn was loading up and eventually causing a restriction in the cat......maybe?
....point is it's fixed now
Thanks to the guys who helped me think outside the box
Last edited by SmokeyBlaZe; Jul 13, 2009 at 01:20 AM.
Thread Starter
Registered User
Joined: Jun 2009
Posts: 417
From: GA
this is what my old one looks like http://i716.photobucket.com/albums/w...7/IMG_0203.jpg and this is the one I need. http://www.rockauto.com/catalog/rafr...&a=FR316-PT728
They don't even look like the same part.
They don't even look like the same part.
Registered User
Joined: Sep 2004
Posts: 146
From: Northern Calif
I pulled the sensor out of the cylinder head and took a ride and the SES light never came on. I got home and plugged it back in and after about 5-10 minutes of driving the light came on again and instantly smoothed out with no stalling or hesitation. Probably the reading from the faulty ECT sensor is making it think it's super cold, which would dump a lot more fuel in, fouling the plugs.
Here's the picture of the PCM wiring to the ECT.
http://shbox.com/1/1995_pcm1.jpg
Brian
Last edited by briand069; Jul 14, 2009 at 10:09 PM. Reason: Added link to pcm wiring
Registered User
Joined: Dec 1969
Posts: 27,725
From: Little Rock, AR
I changed out some of the spark plugs yesterday and more of them today, when I did I pulled the plugs that I had put in yesterday to make sure they were gapped correctly and they were black with soot telling me that I have been running rich. I did a quick search and found this old thread , here is a quote from it
I pulled the sensor out of the cylinder head and took a ride and the SES light never came on. I got home and plugged it back in and after about 5-10 minutes of driving the light came on again and instantly smoothed out with no stalling or hesitation. Probably the reading from the faulty ECT sensor is making it think it's super cold, which would dump a lot more fuel in, fouling the plugs.
I pulled the sensor out of the cylinder head and took a ride and the SES light never came on. I got home and plugged it back in and after about 5-10 minutes of driving the light came on again and instantly smoothed out with no stalling or hesitation. Probably the reading from the faulty ECT sensor is making it think it's super cold, which would dump a lot more fuel in, fouling the plugs.
You continue to fly blind by not scanning to find out the trouble code indicated by the CEL.
You say you go to my site and read, but it does not look like you are understanding what is in the print.
Registered User
Joined: Dec 1969
Posts: 27,725
From: Little Rock, AR
this is what my old one looks like http://i716.photobucket.com/albums/w...7/IMG_0203.jpg and this is the one I need. http://www.rockauto.com/catalog/rafr...&a=FR316-PT728
They don't even look like the same part.
They don't even look like the same part.
PT728 looks like this and is the correct one for the sensor in the head:
Administrator
Joined: Nov 1998
Posts: 71,094
From: Hell was full so they sent me to NJ
You appear to have a significant number of problems with your car. Several of us are trying hard to help you. You really need to start reading each response in detail, and making sure you understand it. When Rob/Shoebox tells you the coolant temp sensor in the head has NOTHING to do with how the engine runs, he is giving you 100% accurate info. You can't just ignore it, and come up with some theory that the sensor in the head really does have something to do with the way the engine runs.
If you have an SES light on, the only sure way to find out why its on is to have it scanned.
If you want help, you need to respond seriously to the attempts to help you. Otherwise, people are going to start ignoring your posts.
Just trying to help you.
If you have an SES light on, the only sure way to find out why its on is to have it scanned.
If you want help, you need to respond seriously to the attempts to help you. Otherwise, people are going to start ignoring your posts.
Just trying to help you.
Registered User
Joined: Sep 2004
Posts: 146
From: Northern Calif
Registered User
Joined: Dec 1969
Posts: 27,725
From: Little Rock, AR
AZ won't scan it because it is OBD-I. They only scan OBD-II. Investing in a scanner would be your best option.
Administrator
Joined: Nov 1998
Posts: 71,094
From: Hell was full so they sent me to NJ
I told him about Shoebox's 12-pin -> 16-pin jumpers in another thread recently. That's the problem.....
You could borrow an OBD-I scanner from someone.
You could buy an OBD-I scanner. I've seen them for $70.
You could download free software from TTS DataMaster or FreeScan, get a cable from AKM cables and scan the car with a laptop.
You could buy a ScanMaster LT1 and watch the data in the PCM real time.
You could pay a dealer to scan it with a Tech-1
You could find an auto parts store that is willing to listen to you, and help you.
You could borrow an OBD-I scanner from someone.
You could buy an OBD-I scanner. I've seen them for $70.
You could download free software from TTS DataMaster or FreeScan, get a cable from AKM cables and scan the car with a laptop.
You could buy a ScanMaster LT1 and watch the data in the PCM real time.
You could pay a dealer to scan it with a Tech-1
You could find an auto parts store that is willing to listen to you, and help you.
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