25 Degrees Base Timing...

[AWJ]

What do ya think?

So I have to pull the distributor due to an oil leak there. I've always suspected base timing was changed when the prev owner had the turbo conversion done. So I checked the timing. Let the car head up, jumped t1 and e1, hooked up the light. The mark is way out at like 25 btdc. I moved the pick up to a few spots around the #1 wire and it was the same every time. Checked several times. I expected it would be different but not so much. Here's a pick of blown up fsm shot and actual garage shot. The mark is outside the number range. I take it the farthers counter clockwise the box is 20 and it's about 5 out from there. See for yourself, so I'm not crazy.

That's harder to see than I thought. The yellow is the edge of the box and the 10 (mid box). Purple is around the white timing mark. Guess you'll have to take my word for it. But that's where it is. Here's the full size.

[on_chrome]

I think you should set @ base timing and get your car retuned by justin nenni with tunning concepts @512) 791-4012. He's the man, trust me!!! You have a different computer...don't you, or piggy back. LMK.

[AWJ]

You are the only person to give any input on this directly between two websites. I haven't gone to SF or IS.net yet. I'm thinking about it. My car runs the oem ecu. The only thing affecting timing at this point is the oem control. I do have a haltech f5. But as I understand it is only affecting auxillary injector cut in and operation as a linear function of boost. This puts the fuel there. Timing is taken car of still at oem parameters. So I figure there was some sort of mechanical measure taken at the distributor.

From what I have been able to determine on my own through searching (I went to bed a 4:45 am this morning) - there are several possiblilities.

1. There is something wrong with my ignition system.

I don't think so, because the car really seems to run fine overall. Worst case is the plugs could use replacement.

2. The harmonic balancer has physically moved from its correct position, putting the timing mark where I see at light pulse, because it physically is in the wrong place. I'll check this today if I can determine a method. There is also a way to find tdc in relation to #1 cylinder by manually turning the motor with some sort of indicator throught the #1 spark plug hole. This would show me what I'm dealing physcially on a 360* crank rotation.

3. My timing is set at 25* from the zero on the timing case. This would mean my spark fires at 15 degrees before it would normally. I would expect this to cause preignition or even detonation. Unless I am perceiving this incorrectly and to compress the a/f mixture after firing is !Removed! while compressing before firing is advance.

I really would benefit to figure this out before I change plugs, remove the distributor, or frankly - go anywhere else from here. Where is Tuning Concepts located? Thanks for your input.

[on_chrome]

1. you should repalce your plugs every 3,000-5,000 miles on a turboed car because of over use of the plug. Also, I hope your using NGK 3330's.

2. I don't know about the harmonice balancer moving form it's orig. position, but yes you can take the #1 spark plug out and chack rotation.

3. It sounds like the previous owner did something wrong maybe and you need to fix it. As far as I know everyone (supra's and sc 300's) are all at base 10 and timing is controlled with the computer. For instance, mine is at 10 degrees and the timing is pulled at the computer when under boost. If you adjust the timing at the distributor, you could end up having serious problems in the long run.

How much boost are you running?

Are there any sings of weird things with your car like check engine light or acceleration problems?

If you talk to Justin, he's here in austin and flies worldwide to tune (like japan and england) and he is reasonably priced for the satisfaction of your car being tuned "perfect", he will tell you probably to set it at 10 degrees and drive light and see how it operates from there. You probably don't need to change the distributor if there isn't any signs of damange and if you take the cap off, and look at the posts and they look fine, then more than likely your ok there. Having your timing advanced sometimes doesn't show much signs of something being wrong, the gas mileage won't be good, but a good rule of thumb is that if you know for a fact that something is wrong then start over from what you know it to be right at. LMK.

[jzz30]

i have known some harmonic balancers to move out of place. if the crank mark doesnt match the cam mark i usually but a long screwdriver in to #1cylinder and see about where tdc is.

[AWJ]

Excellent advice fellas. No one else has tuned in on this on any other forums. Maybe I'm presenting it in a cofusing matter or not clearly stating my question. There are way too many variables here. I know the car is not set to OEM timing. The car runs fine. No MIL's, hesitations or mises, preignition/detonation is not a major issue. I have experienced it very few times. I am over due on a spark plug change. That is coming very shortly. The car was set up with a fresh tune by Toyomoto just before I bought it in '02 Due to the fact that the car was running fine, I'm going ahead with my plans noting the crank time position. I will put everything back together after I've finished my additions and maintenance items. Provided the balancer did not move - I will check timing again and see where it is. I would honestly hope it's at the same position so I can go from there. The only thing I will change ignition related is the plugs. Problem is, I have to remove the distributor to fix the oil leak. I'll do my darndest to get it back as close as possible to where it is now. Then I will go tuning. I will update once I get things back together. This issue is going to be deeper than what I can find on the internet I think.

[thombiz]

I took my SC300 in and had the Toyota mechanics check the timing this past October. It was about 5 degrees too advanced. Timing that is too advanced could give an indication by making a knock sound at "cold start" start up. Otherwise it could manifest itself in requiring numerous rotations to start instead of just a couple. Part of the issue is the timing of the spray from the fuel injector coupled with the ignition timing. If the timing of the fuel injector is early, you could get pre-ignition which would be evident by backfiring into the intake manifold and the throttle body during startup. From what I read above, most of this you have already figured out. If it is as you say, everything is running pretty well, then it makes sense the timing marks aren't in the correct position. That is where I would start verification. Hope this helps.

[AWJ]

It does. thanks bro. I'm going to have to go on the assumption that my balancer has moved. And keep my fingers crossed. I'll update once I button everything up.