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86-95 Trucks & 4Runners 2nd/3rd gen pickups, and 1st/2nd gen 4Runners with IFS

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Old 03-31-2008, 04:25 PM   #1
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22re, tuning stock efi

93' 4x4 22re 5speed

I have a couple of questions regarding tuning for stock efi

1. What is the spec for total ignition timing (NOT base timing) for the 22re?

2. What ways are there to check whether or not the knock sensor is detecting knock and retarding the ignition timing? All I could think of is to check the total timing at say 3000rpm but is there any other way?

3. Is there any way to check air/fuel ratio to detect rich/lean conditions? I
want to check air/fuel ratio at WOT and high rpms, while the computer is in
open loop.

4. Does anyone have experience running forged pistons and want to chime in
on whether knock sensor relocation is really necessary?

Some more background as to why I ask. I just built a new 22re engine w/ 94mm forged pistons, about 10.2:1 compression, street rv head, headers, ect. and am running stock efi. I have about 300 miles on the engine and a compression check shows 210psi cranking compression. I just want to check whether or not my knock sensor is retarding the timing due to too high compression and/or forged piston noise and whether my fuel system is able to keep up. The engine runs great and very smooth, but I need to make sure everything is working correctly before putting more miles on it.

Thanks.
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Old 03-31-2008, 04:57 PM   #2
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1) Define "total ignition timing" - do you mean peak timing for the motor?

2) The KS generates an analog signal that's subject to some "interpretation" by the ECU. That is, just because it's generating some noise, it doesn't mean that your ECU identifies that noise as knock. The question becomes - how does the ECU indicate that it's operating under knock... No one can answer that question that I know of... We're in the early dark ages of EFI.

3) You can check rich lean by monitoring 02 sensor output. The 02 sensor produces output regardless of open or closed loop operation. Now, if you want to know HOW rich or lean, you'll have to install a wideband.

4) Yes. I've built two forged motors. I run a factory knock sensor (relocated) and a non-stock ECU. My knock computer (knocksense) is also aftermarket. I have to dial the knocksense down as far down toward insensitive as it can go, even with the sensor relocated... I believe it's necessary. (and not hard to do)


10.2 sounds really high on pump gas. Subjectively, one way to test it would be two dyno runs - both running air/fuel results. One running 93 octane and the other running 100 octane. Compare results... IF you're not triggering knock, both graphs will be about the same.
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Old 03-31-2008, 05:46 PM   #3
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Yes, I mean peak timing for the motor. If I measure peak timing and it is less than it should be am I correct in assuming the ecu is operating under knock?

I thought that the o2 sensor would output no matter whether open or closed loop but I wasn't sure. What is the best way to monitor output while driving? I know there are aftermarket gauges that monitor output via leds but is there a simpler way?

I think I will relocate the knock sensor as it is pretty simple, its just too bad I didn't do it before installing the motor. How does the aftermarket knock computer work (knocksense) and can it be used w/ factory efi or just with aftermarket such as megasquirt?

I wish I could run the truck on a dyno but it just isn't very practical for me. I am basically trying to figure out if my factory efi and ignition system is capable and adequate before I do too much damage.

Thanks a bunch.
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Old 03-31-2008, 09:17 PM   #4
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There is no written (Toyota) documentation on the stock timing curve that I know about. If you wanted an estimate, spin up a mechanical advance 22R to 3-4k RPM and check the timing.. I'd bet that the EFI timing peaks are set to something similiar..

Tuning one of them with an aftermarket ECU (no turbo) I got to 24-26 degrees at peak torque, 87 octane. So you're probably looking at 30 degrees peak timing, maybe you could turn more under no load conditions (cruise).

It'll be hard to check timing under load, where you'll trigger knock.. I think if you're triggering knock all the time (no load) you'll set a code - but that's a guess, not a hard fact.

02 sensor: Either get an 02 gauge (air/fuel) or simply tap into the output of the 02 sensor with a volt meter. You can do it at the ECU (in the cab) if you want... All you need to know is voltage. At one time I built my own air/fuel guage out of simple circuits and some instructions, but at the cost of a basic gauge, it's hardly worth it.

The idea behind a knock sensor is that it "listens" for a specific frequency range that occurs when an engine starts pre-detonation. It's an analog signal, so it's pretty ugly and motors are noisy things... My understanding is that most modern ECUs ignore single knock triggers, they "listen" for several in a row and then start to retard timing.. the number they need to hear in a row and how often those triggers occur are going to be different motor to motor. Some ECUs totally ignore the sensor after a specific (high) rpm due to engine noise.

Search for "knocksense" on google if you want more info - They guy who built it, Boris, is very helpful... I don't think you should use it on the same knock sensor as factory EFI due to the way it intercepts current/signal from the senor, it would impact what the factory ECU "sees". You could use it with a 2nd knock sensor.

I actually don't have it connected to MS to retard timing.. I have it trigger a bright LED in the cab.. It takes a while to learn what is a noisy motor and what's likely a fuel/timing issue.. Never got around to hooking it up to MS, and I prefer to know when I'm pushing my luck on boost and fuel octane.

Note, the way I learned to distinguish true pre-detonation from noise was running the truck on 93 octane vs 100 octane fuel and observe the sensor. You have to dial down the knocksense to ignore noise - dial it down too much and it's worthless.. Don't dial it down enough and you'll get false readings.


One other note - if you're wanting to listen for detonation, search for "det can" on the internet - Honda guys tune timing by ear... There's a simple tool you can build.


I think it's likely that your injectors are up to the task and the ECU is likely to pull too much timing if anything... It may pull so much timing that you're not getting the benefit of your compression increase, but it'll be hard to tell without the right tuning tools.


Interesting questions! Good luck.
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Old 03-31-2008, 09:35 PM   #5
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Thanks, I think you've given me some good ideas to get started testing this motor out.
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Old 03-31-2008, 09:35 PM
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22r, 22re, air, bad, check, computer, detonation, efi, engine, fuel, location, meter, stock, timing, total, toyota, tuned

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