Even better.you should try some e85 too at some point

I'm in beams territory now aren't I? 
 
What do I need to run e85? It turns out that my previous compression ratio wasn't 10.8 or whatever at all it was about 11.3:1 this ran  pretty well on the factory ecu up to 5000rpm (I hadn't gone higher). The factory knock sensor would be doing its job. I'm going to double check my specs/measurements tomorrow. I've heard of cars getting around with up to 12:1 compression on nothing but 95-98 octane fuel. I'd still carry around a bottle of octane booster just in case!
 
Just as a precaution should I retard my ignition timing a couple of degrees until it is properly tuned?
 
 

I would definitely retard the ignition and wait for the tune. Remember the Beams is VVTi.
Just an insight with the knock sensor. The factory unit on all the 3S engines up to GEN4 are single point frequency. That point is what the ECU is looking at. Once you play around with the engine the frequency is changed. Seen it.
 
The best way is with a wide band knock sensor like a wide band O2 sensor you can then home in the frequency where you can see knock. However you cant do this with an OEM ECU. You need aftermarket like i did and even went one step further with a dedicated knock module.
 



But a good substitute is you want to remain on the factory ECU is to use the failsafe knock detector with the wide band knock sensor.
 
wide band
 

Thanks for your input Mandalay. You wouldn't happen to have a part number for the sensor would you? Is it a plug and play affair?

i also want the part number, looks like there's multiple wires tho, not singular like the factory gen2/3.

Also how far should I retard ignition timing?

NOTE: If you have a OEM ECU you can not use this!

Ok, Here is something interesting for everyone.

There are a few types of ways to monitor knock, the most common way is with a resonant sensor like installed in all 3S and 5S engines. The other is a Flat type Non-Resonant Knock sensor.

The Resonant type has a few disadvantages: It is only tuned to a certain frequency and it basically "rings" like a bell. Meaning at high enough engine speed it could still be ringing while the next Knock occurs. Thus not letting you know about other smaller knock events in the mean time if they happened.

I guess you could almost compare it like a O2 sensor. Think of the difference as wide band and narrow band.

This sensor is rated around 6khz through 15khz!

For those with a larger bore (thus changing the knock frequency) using a wide range flat type sensor can get you back to actually hearing all your knock.

Anyway.... Toyota now practically only uses a single sensor and that is a flat type made by Denso. They use it on almost all engines even through the Lexus line.

Well, if you have a EMS that can use a Non-Resonant knock sensor you are in luck. Toyota just happens to make an adapter. Simply remove your old knock sensor, screw in the stud, slide the new knock sensor on with the connector facing forward and then bolt it down to 15ft/lbs.

As far as wiring and operation I won't get into that. Please figure it out on your own. I think I've shared enough....

BTW: Incase you wonder what this setup was used on, well... I lied.
The ST246 3S-GTE engine uses this setup. So a 3S engine did use this from the factory.

I test installed one today and it fits wonderfully!

Knock Sensor: 89615-20090
Hex Lobular Stud: 90126-08044
Nut: 90179-08153
Connector: 90980-11875
Repair wire (QTY 2): 82998-12780
The knock sensor is a 2 wire with a braid.
 
NO ITS NOT plug and play. You need aftermarket ECU or the J&S safeguard knock control gizmo.
 
Sorry i have no idea what to retard to . My recommendation is to be patient , wait and let your tuner do it.
 
One thing for sure that i 100% recommend is being able to see knock and letting the ECU control it. One thing is that once the engine is modified there is no guarantee the OEM will do its job right. There are a few to prove this unfortunately :(

giggiddy

Just an insight, the racing Japanese cars that use the 3S block also run 2 knock sensors. They tap a thread in the arrowed part which is exactly the same as the OEM taped part for the knock senor
 

The Early 3SGTE engines ran a 6k narrow band knock sensor.
 
Plugging in a different sensor will not work, either not registering knock or throwing a code.
 
An option is an AVO knock block, the earlier model was brilliant, with a 5led bar graph the lit up according to the severity of the knock, which when combined with common sense, is enough to save an engine.
 
If you were to run a link ECU, you can wire a knock block in directly to the ECU, for full knock control. With a Motec you need an SKM, and with haltech's, pro plugins have knock control (but no model available for the MR2, and the platinum series can be set up, tho it is a royal pain in the ass.
 
I personally would not be driving it around untuned, as during run in, mixtures are a vital part of the engine running in properly. When the engine is running rich, the excess fuel washes down the bores, inhibiting the ability of the rings to bed in. Running lean causes combustion temps to get too high, which can lead to scoring of the bores.
 
If you insist on running it in on the standard ecu, get access to a dyno to have the initial engine bed in done, where mixtures can be monitered and listened to for any knock. It will cost you an hour or two of the dyno, but you know the first running of the motor is done and loaded up correctly to get the rings to bed in as best as possible, ensuring your engine will be the best it can be. The correct loads and revs can be held to help the engine break in more effectively, and safer than can be done on the streets.