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Tuning Timing... [Archive] - Toyota MR2 Message Board

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Tuning Timing... [Archive] - Toyota MR2 Message Board Toyota MR2 Message Board > Toyota MR2 Generations > MK 2 MR2 - SW20 > MK2 Stand-Alone EMS and Nitrous Discussion > Tuning Timing... PDA

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MR2TuRbZ06-05-2008, 11:57 AMI have tuned my car a little bit on the stock turbo and slowly advanced timing.

Now, i have a CT27, HKS 264 cams (degree'd), 1kcc injectors, and a trunk mount IC.

I can do fuel, thats the easy one :D

What is the best way to tune ignition timing? I will be doing a little bit of street tuning then finishing it up on the dyno.

Oh yea, its on a AEM EMS.

Thanks!
-Damon Enthalpy06-13-2008, 02:38 PMStreet tuning the spark timing is asking for trouble. You are trying to pick out a torque regression in a sea of noise coming from wind and all sorts of other sources. You use accelerometers and do opposing direction runs, but you still have a ton of signal noise. Doing this is like trying to hear your elderly grandma from across the room at a frat party. And no, you can't just tune for detonation.

To do it right, use a dyno. To get close, but not guaranteed optimal, street tune it and hope you don't hit a semi or get a ticket. MR2TuRbZ06-13-2008, 04:46 PMI plan on doing it on a dyno... what i'm asking is what is your technique.... say you have a good pull and no knock is shown.... what is your next step in advancing the timing? How much, and where on the map?

Thanks! Enthalpy06-13-2008, 05:41 PMAt a high level, you set the fuel with known-conservative spark, then advance the timing. Initially do it by a few degrees, then as you approach optimal, slow down. You know you are approaching optimal by keeping old runs on the dyno screen and doing a "power vs. advance" estimate. Do each run at the same temps (can't stress this enough). This is when I LOVE the huge cooling I have on my dyno! I can properly tune much faster than a shop that has no cooling. I have a blower that pumps 45 mph outside air through a 3' X 3' hole straight onto the intercooler and radiator. I have a separate blower for side-mounted MR2s.

You will either hit knock or a spot where torque flattens out and further timing advances don't produce more torque. Obviously, set the timing just shy of this limit. If you hit mild detonation, stop and back off a few degrees. Do this using runs at full throttle, and load-holding at part throttle.

Reset the fuel if your indicated AFR changes. That usually means you started with excessively conservative timing to begin with, and timing changes are actually changing the chemistry of the exhaust or the temp of the probe.

This can also happen if you don't know how to set an air temp offset curve, or if your IAT isn't placed in the correct spot. I flat out refuse to tune a car with the IAT placed pre-turbo. Even clever algorithms like what Autronics use can't completely compensate.

For expected hill racing (I live in the mountains), I will load-hold and purposely heat soak everything then set the temp offsets to keep things safe. I usually like to see EGT data when doing this.

If 1/4 mile racing ONLY, don't worry about part-throttle at all. It's wasting the client's cash. If road-driven or course-racing, set the part throttle spark and fuel.

I personally charge more if the customer wants ABSOLUTE perfect drivability. This requires multiple days to get right (cold mornings and warm afternoons). In one day, I can deliver good drivability, but to perfectly dial in things like cold start, you have to have it multiple days. MR2TuRbZ06-13-2008, 05:50 PMhaha, i see you made the same post on the other board :D

When you advance timing, do you do it across the whole rev band? or just in patches? Enthalpy06-13-2008, 11:12 PMIt depends. I'll usually note where the dips first appear as I advance. I will also watch the tach if I start hearing trace knock splats. Engines usually want a fairly smooth spark curve unless you expect certain air pressure resonances to set themselves up. The only engines with really strong resonances are racing engines designed to do so. Powered by vBulletin® Version 4.2.5 Copyright © 2026 vBulletin Solutions Inc. All rights reserved.

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