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Ted Ritter
Ted Ritter, Toyota Master Tech
Category: Toyota
Satisfied Customers: 4182
Experience:  Toyota Master Tech, ASE Certified
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Toyota Pickup: I have a 91 Toyota pickup with a 3.0 engine,

Customer Question

I have a 91 Toyota pickup with a 3.0 engine, manual trans, 4x4. I replaced the head gaskets along with the knock sensor short harness. everything went great at first until the knock sensor fault 52 came on and will not go away. So far i have replaced the computer with a used one to test, i put a new import direct knock sensor from oreillys mounted externally to the block to test and even went as far to get shielded wire and replace the harness all the way to the computer. The light comes on after i give the engine about three quick revs up to 2000 or so rpms. It comes on quicker when i hook up the old sensor that is still mounted in the correct location, but even the new sensor isn't much better. Any thoughts?
Submitted: 7 months ago.
Category: Toyota
Expert:  Ted Ritter replied 7 months ago.
Hello, is there any unusual noise or vibration from the engine? Have you checked the engine timing using a timing light?
Customer: replied 7 months ago.
No noise or vibration that i can hear. I have not checked the timing yet though. Can that cause symptoms along these lines?
Expert:  Ted Ritter replied 7 months ago.
The knock sensor consists of a vibration sensitive piezo crystal, any mechanical noise also causes a vibration to some degree, too far advanced timing can cause pre ignition or a slight knock, the sensor can compensate for some of this by controlling the timing through the computer( electronic spark advance ) but it's tolerance is kind of narrow so when it goes over the set limit it turns the check engine light on, you've covered just about evrything else that normally cures a stubborn Code 52 on these engines so please check and make sure the initial timing is set to no more than ten degrees advanced with a jumper between terminals TE1 and E1 in the check connector under the hood.
Customer: replied 7 months ago.
I'm checking it now, I'll let you know what i find.
Expert:  Ted Ritter replied 7 months ago.
Sounds good.
Customer: replied 7 months ago.
The timing was at about 14 degrees before... i feel like an idiot. It is working great so far and no light on since i set it to 10 degrees. Im going to button it up and road test it but i think that was it. Thank you for your quick response i really appreciate it.
Expert:  Ted Ritter replied 7 months ago.
You're welcome, I think you've solved the problem, pleas also take a moment to give my answer a rating.
Customer: replied 7 months ago.
Well i went to road test it and the light came back on. I came back and cleared the code by pulling the ecu fuse and then disconnecting the battery just to make sure and it is coming on just like before. I can hear a faint rattle in the engine but nothing that I would think would trip the fault code. I am going to the machine shop to pick up some parts in the morning and am going to have him take a listen to the truck but in the mean time is there anything else you can think of?
Expert:  Ted Ritter replied 7 months ago.
That noise could be the cause, can't think of anything else right now. Let me know tomorrow what they say.
Customer: replied 7 months ago.
Thank you i will.
Expert:  Ted Ritter replied 7 months ago.
Looking forward to hearing back from you.
Customer: replied 6 months ago.
I took the truck to the machine shop and he said it sounds normal to him. I retarded the timing down to 7 degrees before and put chevron 91 octane in it and light stays off a lot better. I was able to drive it for a long ways before i had the light come back on (same code 52).
Expert:  Ted Ritter replied 6 months ago.
Thanks, it's obviously a timing issue, are you sure the crank pulley is in the right position?another way to check TDC is to remove the #1 spark plug and put a long thin rod into the spark plug hole, rotate the engine until the rod comes all the way up, note when it goes up and starts to go back down go back and forth until you find the exact point where it goes up and back down, that is the TDC, check the crank pulley and make sure it's at the zero mark.
Customer: replied 6 months ago.
I just checked it and my timing is right on. I even pulled the distributor cap and i was right on there too. Could i have a problem with the distributor or something else that would cause the computer controlled timing to be incorrect? Do you have any info on what my total advance should be? When i checked it seems to advance itself up to about 25 degrees almost directly off idle then maxes out at about 35 at probably 3500 rpm. I have been testing this all with my remotely mounted sensor by the way. When i reconnect the old sensor it throws the code almost instantly just the same as before.
Expert:  Ted Ritter replied 6 months ago.
The timing should go from eight degrees at idle to about 20-24 at 2000 rpm and increase gradually is the rpms go up.
Customer: replied 6 months ago.
I'm going to check that right now. After i do i think i may opt for the phone call if your available? Would it just cost me an extra $6 on top of the $20 i already owe or an additional $26?
Customer: replied 6 months ago.
The timing is jumping straight to about 45 degrees when i rev it to about 1500-2000. One thing I've noticed is my idle is a little high around 1100 with the vehicle warmed up. Where as yesterday it was closer to 950 which i know is still higher than the spec of 800 but i didn't think much of it until now. I'm thinking that was probably something i should have shared from the beginning.
Expert:  Ted Ritter replied 6 months ago.
A phone call won't really help because I have run out of ideas other than to just start replacing parts like the distributor. You can ask for another expert to get involved by opting out and relisting and requesting a phone call in your post.

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