phorensic

A while back I posted a thread with experimental ignition timing changes without a timing light. I concluded that rotating the distributer clockwise about 1/8" produced more power. Well... I finally borrowed a timing light.

I advanced the distributer about another 1/8" clockwise and ran around town for a few days. I was so excited about how much more power I had, and how it woke the motor up so much, that I decided to go borrow my fabricators timing light. Turns out I'm at 15 degrees BTDC with TE1 and E1 jumped. Stock, I believe, is recommended to be at 10 degrees BTDC.

Per my fabricators recommendations, and my guesses, we decided not to advance it any further. I am running 87 octane right now and I plan on switching over to midgrade for the fact that I have no idea if it is pinging or not. I would rather not overwork the knock sensor. I would rather have just that extra bit of safety, just in case. I wish I knew if the knock sensor was detecting knock and if the ECU is intervening. Oh well, Megasquirt is on its way.

Now, is there anyone out there who can tell me if 15 BTDC plus any additional advance is safe on 87 octane? I have no idea what the total advance is, so for now I'm going to run midgrade just for safety.

Hope you guys can benefit from this mod. Get to advancing already!

Toysrme

I've always told 3vz-fe owners to run 17*btdc base timing, lean the engine via the AFM cog, and run 87. The 3vz-fe get's away with it because Toyota detuned it 15 horsepower farther than it should have been via retarded ignition timing & running very rich.

The 3vz-e - from what BumpingYota has told me, is not as safe to add ignition timing on.

The easyest/cheapest way is to build yourself an engine stethescope & listen to it run. Electronic ones are very, very pimp. Just don't drive in traffic with earphones, you'll get in trouble & it's illegal in most states. Otherwise, you have to invest in electronics that can read engine RPM, and knock sensors - even then you're not reading what the ECU is changing, or what it considers engine knock.
I like hearing knock better.

phorensic

17* on the 3vz-fe - less safe for 3vze = 15* btdc should work for me.

I've already leaned the AFM out two clicks. However, I have a massive exhaust leak, and I believe my O2 sensor is reading lean because of it, therefore richening the mixture WAY too much. Wish I had the willpower to fix that before Megasquirt/turbo. Meh.

BTW, how many clicks do you 3vz-fe guys lean out the AFM?

suprathepeg

SO if you advance the timing without leaning the mixture then what happens? Where do you cross the line between performance and dependability?

suprathepeg

Can you just advance the timing on the 3vz-Fe without leaning out the mixture? What will happen? The only reason I ask is my parents have a 92 Camry.

phorensic

If you advance the timing without leaning the mixture you are just staying on the safer side of things. Richer = safer.

Let me put it this way. Advance timing too far = knock. Lean too far = knock. You can do either, but both put you closer to the edge of knock. So leaving the AFM alone will keep you on the safe side of things.

suprathepeg

Yea I'm just wondering if you would get the power. The other thing I was wondering is if you get the better milage without leaning out the mixture?

Toysrme

suprathepeg you can do so safely on a 3vz-fe. Toyota de-tuned the daylights out of 92-93 to keep them from competing with the i6's found in higher end cars. Freebie mods make a 185bhp 3vz-fe a 200bhp 3vz-fe pretty quick.
You can go a long way on a 3vz-fe. One guy set his base timing to 22*btdc (Off the stock scale by 2*) leaned it 6 clicks & did a 1/4 mile run. No detonation, but he did slow down from running too much timing.


They got detuned so much, there is a lot of room for play.


I digress. On the 3vz-e, ya 15* sounds like a good starting place, but be mindful of pinging.

FastCat

I agree that advancing the timing too much leads to knock, but I can't believe you can create a permanent too lean condition.

Don't the OBDI Toyota ECM's use long and short term fuel trims? If they do, then you can't make permanent closed-loop fuel changes like that, so I'd be surprised if Toyota didn't use fuel trims.

On GM vehicles I've experience with (OBDI and OBDII), the fuel trims are how the PCM adjusts the fuel to correct for lean or rich conditions normally caused by changing weather conditions by up to 25%. The PCM makes these adjustments based on the O2 sensor readings, so even if you make a change that leans out the AFR, the PCM recognizes this and increases the fuel trims until the AFR is back close to stoich. This is done completely automatically.

If a fuel injection system didn't "learn" how to trim fuel for changing weather conditions then it would really be no better than a carbureted motor.

Toysrme

No, OBD-I does not have long, or short term fuel trims. It only has one fuel trim that is applied during closed loop conditions. Like I said, the only people that have reported any increase are the smaller i4's. Especially the M/T's as they tend to lug in gears.

suprathepeg

So to bring this back to my 3.0 if I remove the EGR I will be running leaner, and if I advance the timing I'll be getting close to predetonation. What are the dangers of removing the EGR and advancing the timing together on the 3vze?

suprathepeg

Bumpa bump bump.

Toysrme

Nothing unless you go insanely too far. The knock sensors will catch any bad knocking. EGR only functions at low throttle, mid throttle & transitions. It doesn't cause a problem @ wot as it would normally be shut off.


If it pings a little, reduce the timing a hair. It's that easy!