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missing knock sensor


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knocksensor
New User

Jun 8, 2015, 6:31 PM

Post #1 of 7 (974 views)
missing knock sensor Sign In

I have a 85 Toyota Supra. I purchased a while ago with a bad engine. I replaced the engine from a junk yard. The engine came from a if I recall correct a 83, perhaps a 82. The junk yard told me the engine would work for my 85. They closed down in a short time after I purchased the entire car.

I put that engine in my 85 and I have had problems with the car running like crap. I put in new plugs and wires. I had the timing checked. I was told the timing was originally off by a jumped timing belt and it was then set to specs. They said it had good vacuum and that the check engine light was specifically on for the knock sensor.

Depending on the mood of the car, or perhaps the day of the week, it will sometimes start and idle so so, some days like crap. I have to rev it up to get it started down the road. It has a hard time getting up and moving. Some times when I go down the road, if I do not put the pedal to the floor it will help. The max I can get is perhaps 60mph.

I did try to rig up a spot for it. I took out a motor mount bolt, took a piece of steel, drilled out a hole all the way through and one half ways through. I tapped out the half way hole. Then bolting the piece of metal to the block where the motor mount bolt was. Screwed in the knock sensor and plugged it in. It did not help any. This spot is a bit far from where it is supposed to be.

What are you diagnosis? Do you think it would be the knock sensor giving problems or something else? I have pondered taking off the intake and either drilling and tapping a spot where it is supposed to be, or taking JB weld and sticking a piece of metal to the block and then putting the knock sensor in that. How exact to the factory spot does it need to be? a inch or 2 off factory spot ok?


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Jun 8, 2015, 6:38 PM

Post #2 of 7 (970 views)
Re: missing knock sensor Sign In

When you put the wrong motor in a car, there is no limit to the things that can go wrong when the operating system doesn't match the engine.



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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



knocksensor
New User

Jun 8, 2015, 7:00 PM

Post #3 of 7 (965 views)
Re: missing knock sensor Sign In

Everything else with the engine is 100% the same. Only the knock sensor is missing. Everything else matched up.


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Jun 9, 2015, 2:04 AM

Post #4 of 7 (957 views)
Re: missing knock sensor Sign In

That means the operating system is different. Just because plugs match up with sensors doesn't mean the computer programming is the same.

In 82 some of the engines were carbureted. These engine could be very different internally even if it was fuel injected originally.

The fact that it runs that bad and the computer is not recognizing that with a trouble code is suspect.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



Discretesignals
Ultimate Carjunky / Moderator
Discretesignals profile image

Jun 9, 2015, 4:31 AM

Post #5 of 7 (949 views)
Re: missing knock sensor Sign In

The knock sensor missing is not causing your issue. The knock sensor is used by the engine computer to retard the ignition timing if it detects a knock signal. If the sensor is missing, there is no signal, so the computer doesn't retard timing. I personally never ran into a vehicle that a knock sensor itself caused a drive-ability issue. I have seen the knock sensor system retard the ignition timing and make the engine run bad, but that was because the engine was noisy and the knock sensor was picking it up.

Maybe you should start off by doing a compression test. Write down the numbers.





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(This post was edited by Discretesignals on Jun 9, 2015, 4:38 AM)


knocksensor
New User

Jun 9, 2015, 5:30 AM

Post #6 of 7 (942 views)
Re: missing knock sensor Sign In

I will do a compression test this week. I was thinking of changing the fuel filter also. Thank you.


knocksensor
New User

Jun 9, 2015, 5:33 AM

Post #7 of 7 (941 views)
Re: missing knock sensor Sign In

The engine I got was not a carburetor. It was the same set up as the original. What would you do first? I am going to do a compression test and maybe change fuel filter.






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