daniel0213

I have a plug that i dont know where it goes. It is coming out of the harness on the drivers side. Its the same harness that has all the ground connections in it. It looks like the plug for the knock sensor, but i know that goes on the other side. (just a rference as to what it looks like). Does anyone know what this is and where it might go? The exhaust i bought from summit has a bung welded in the pipe right at the manifold/pipe connection. It looks like it is for an O2 sensor, but someone told me i don't have 02's cuz its speed density and not mass air! I'm a little lost!!

byebyeL98

Stop listening to the person that said you don't have O2 sensor(s) because it is speed density!!

You most certainly DO (or should) have an O2 sensor on that side (though I forget which year started running two).

This is a great book if you'd like to learn about how the fuel management system works:

http://www.amazon.com/Corvette-Injec...7953555&sr=1-1

Z~max

All Corvettes frome AT LEAST 1985 have O2 sensors, some have multiple. The speed density system does not have a Mass air flow sensor to calculate the amount of incoming air. What year and /or motor is in your car?

BADDUCK

You didn't say if this plug is toward the firewall, in the middle, or more toward the front. How many contacts? One or more. If it is toward the center, and has one contact, it may go the the coolant temperature switch/sensor between plugs 1 and 3 that controls a fan.

Wheelman

Badduck is correct. The plug that is identical to the knock sensor on the drivers side harness goes to the coolant temp sensor that controls the boost fan in between cylinders 1 and 3.

Bob CTS

I believe mine is green w/ a white stripe. At least for an 86.

daniel0213

so i do have an o2 sensor? the plug has one connection. if thats to the fan what does the 02 sensor plug look like and which harness is it in?

Wheelman

Your 02 sensor will be threaded into your drivers side front y pipe if your car is stock. Follow the wire from it to the connector, and to the harness from there, it should be easy to spot.

CFI-EFI

Not if it is a speed density car, he isn't. Why won't people post a year with their problems/questions? The speed density 1984 and the MAF 1985, have the fan switch on the right side of the car, in the head, between the #6 and #8 spark plugs. The 1986 - 1989 cars have the switch where Badduck says, but they are MAF cars. The 1990 went back to speed density, but the ECM took over the management of the auxiliary fan, and consequently no fan switch. I can only guess this is an early '90s car with a speed density system, no aux fan switch, but two knock sensors, and that the mystery connection goes to the left side knock sensor. Maybe???

RACE ON!!!

daniel0213

sorry, it is a 1990 convertible. I don't know how it would go to another knock sensor! It doesn't plug into a knock sensor. It has one contact. I'm gonna take a picture and post it!

Thanks

Wheelman

I assumed it was not an 84 / 85 from the picture. 90 and up has two knock sensors? I learn something new here every day....

daniel0213

i don't see where the second knock sensor goes?? the corresponding hole that the knock sensor goes in on the passenger side has a hose barb for the oil cooler coming out of it!! Where might this sensor go?

Does the O2 sensor have a 1 contact plug just like the knock sensor?

mikey whipreck

The o2 sensor has a non-removable pigtail. It clips into the wiring away from the sensor itself.

daniel0213

That answers my question! i don't see a plug like that on the drivers side. I need to find out which harness it is part of and see if its hiding somewhere!!

CFI-EFI

In your opening post, you said, "It looks like the plug for the knock sensor, but i know that goes on the other side. (just a rference as to what it looks like).". Are you now telling us that isn't true? What gives???



I honestly don't know what year they went to two knock sensors. Mostly, I was trying to play Sherlock Holmes with the lack of information provided. Now it appears even the little we were give, is in doubt. It makes one wonder...

The knock sensors install into the block drain plug holes.

RACE ON!!!

CorvAdel

If it is the same harness that has all of the grounds, my money would be on it being the oil temp. sender lead and plug. This plugs in just above the oil filter onto a brass blade, and is not easy visible.
To my knowledge ALL L98s have one knock sensor, above the starter.
The drain plug location on the other side of the block is where the oil cooler hose goes.

daniel0213

It looks like the same plug as the knock sensor, but the contact is to small to plug into it! I doubt its the oil temp plug, as my guages are reading oil temp. I really think it goes into the 02, but i'm not sure. there is nothing else there! Was there ever a year where the o2 had a 1 contact plug?

CFI-EFI

If the car goes into closed loop, then the O2, where ever it may be, is hooked up and working.RACE ON!!!

daniel0213

well, i'm not sure what closed loop is, but...i do know that i don't have the 02 sensor installed!!! I need to go buy one!! How dangerous is it to run the car without?

byebyeL98

It will tell you all about closed loop