Using a timing light?
- Thread starter 2 QK 4 U
- Start date
Dual spark...............
what's this mean and how does it answer my question?
Our system is waste-spark which means every cylinder fires at the top of the compression stroke and at the top of the exhaust stroke so the light will flash twice as often as on a distributor engine. However, both flashes will show the timing mark in the correct place so it all still works. If you have a simple timing light you need to see which number on the timing tab is even with the timing mark on the balancer when it fires. If you have a fancy delay timing light where you can turn a dial to move the mark back to the zero on the tab then do that and then divide the indicated advance by two (because it gets fooled by the waste spark - I guess some might have a waste spark setting but I've not seen one like that). So long as you are not using a Thrasher chip, the timing light and DirectScan and/or PowerLogger all should agree. The Thrasher chips fool DS into thinking the timing is different than it actually is, but I am pretty sure that no other aftermarket chip does that.
The motor spins clockwise so the right-most arrow on the tab is zero or TDC, and as you go to the left on the tab that is more and more advanced. There is another arrow that is bigger than the rest, and that is 10 deg. Do a search for John Estill, he has posted some on checking all this and there is a way to put the ecm into a test mode that fixes the timing at 10 deg which makes it easy to check (I think you just jumper the right top two pins in the aldl connector but I'm not positive - try it, it won't hurt anything). Sounds like you have already found the problem, though.
The motor spins clockwise so the right-most arrow on the tab is zero or TDC, and as you go to the left on the tab that is more and more advanced. There is another arrow that is bigger than the rest, and that is 10 deg. Do a search for John Estill, he has posted some on checking all this and there is a way to put the ecm into a test mode that fixes the timing at 10 deg which makes it easy to check (I think you just jumper the right top two pins in the aldl connector but I'm not positive - try it, it won't hurt anything). Sounds like you have already found the problem, though.
With the car running jumper the A and B pins in the ALDL plug, just like you would do if you were manually pulling trouble codes. When you do this with the car running the idle speed is normal and the timing is fixed at 15 deg. This is "diagnostic mode". (This is different than ALDL mode, which fixes the idle at 1000 rpm and adds 8 deg to the normal timing. I seem to remember that TurboLink could put the car in ALDL mode if needed, but I don't seem to remember that capability in DS?)
Look on the timing tab (guess you should do this before you start the car ), notice that all but one of the marks runs down the left side. There is a single mark on the right side. That mark is, coincidentally, at 15 deg.
So, with the car idling in diagnostic mode, use the timing light to see if the mark on the balancer lines up with that single mark on the right side of the timing tab. The difference will show you how much off the timing ring on the balancer is (if at all). That's assuming, of course, that the balancer 0 deg mark really is at TDC. Which it should be.
Like Carl said, using an old fashioned timing light works just fine. The fancy dial back lights are probably tougher to use than the old fashioned kind
John
Look on the timing tab (guess you should do this before you start the car
), notice that all but one of the marks runs down the left side. There is a single mark on the right side. That mark is, coincidentally, at 15 deg.So, with the car idling in diagnostic mode, use the timing light to see if the mark on the balancer lines up with that single mark on the right side of the timing tab. The difference will show you how much off the timing ring on the balancer is (if at all). That's assuming, of course, that the balancer 0 deg mark really is at TDC. Which it should be.
Like Carl said, using an old fashioned timing light works just fine. The fancy dial back lights are probably tougher to use than the old fashioned kind
John
I'm not sure about how much it affects tq/hp, but I can see how it would have a big effect on cylinder pressure, detonation, and tendency to blow head gaskets. A tuning guru would have to say for sure, but the talk about "high timing" and "low timing" chips tells me that a few degrees can make a difference. If your timing ring was 4 deg off, and your chip guy set the WOT timing at 20 deg, you might actually have 24 deg (or you might actually have 16 deg, depending on which way the ring was off). How much that ultimately affects performance, someone else would have to say.
This could be part of the reason why some guys say they can run 20 psi on pump gas, while others can't get over 15.
I first heard of timing ring slippage from a guy that used to work at Conley's, they found that to be the root cause on a car that detonated once they got it up to 15 psi, no matter what they did to it.
John
This could be part of the reason why some guys say they can run 20 psi on pump gas, while others can't get over 15.
I first heard of timing ring slippage from a guy that used to work at Conley's, they found that to be the root cause on a car that detonated once they got it up to 15 psi, no matter what they did to it.
John
Timing ring??
yeah the Reluctor ring pressed on the backside of the balancer.....sometimes called interupter ring....it's purpose is to tell the ecm when the #1 is ready to fire.n IF it slips on the balancer it can change your timing.
I guess this would be obvious if one was to look at it :smile:
Jerryl
Tall Unvaccinated Chinese Guy
- Joined
- Dec 14, 2004
JD is a pretty sharp guy, along with amny others on this baord.
Here is a post on the same subject.
http://www.turbobuick.com/forums/general-turbo-buick-tech/194487-ignition-timing-variance.html
Here is a post on the same subject.
http://www.turbobuick.com/forums/general-turbo-buick-tech/194487-ignition-timing-variance.html
Ok, well I might as well go through that too just to make sure I have them squirting fuel when they are supposed to.
What controls spark timing then?
2 QK, did you check the timing with the timing light as per the method I described? Or is the car down and that isn't possible yet?
The crank sensor controls when the injectors squirt as well, as I understand it the cam sensor just tells the ecm which cylinder is #1. So if you get it installed 180deg out, the car will still start and run: the waste spark setup fires #1 and its opposite (I forget which one that is) at the same time, so it still gets spark, and the fuel injector gets squirted anyway so there is fuel sitting there waiting for the valve to open. And so it runs. The cam sensor tends to be either right or wrong, no in-between that should really affect how the car runs. Though the car does run better when it is installed properly instead of 180deg out. But that's it - with the cam sensor adjustment you'll get no start, starts and runs pretty well, or starts and runs perfect. Not really the place to look for missing power. Unless the guts inside it have come loose I suppose, there have been guys that has happened to, but I thought the result of that was bad popping and such as the ecm suddenly thinks a different cylinder is #1 and changes the timing accordingly.
John
The crank sensor controls when the injectors squirt as well, as I understand it the cam sensor just tells the ecm which cylinder is #1. So if you get it installed 180deg out, the car will still start and run: the waste spark setup fires #1 and its opposite (I forget which one that is) at the same time, so it still gets spark, and the fuel injector gets squirted anyway so there is fuel sitting there waiting for the valve to open. And so it runs. The cam sensor tends to be either right or wrong, no in-between that should really affect how the car runs. Though the car does run better when it is installed properly instead of 180deg out. But that's it - with the cam sensor adjustment you'll get no start, starts and runs pretty well, or starts and runs perfect. Not really the place to look for missing power. Unless the guts inside it have come loose I suppose, there have been guys that has happened to, but I thought the result of that was bad popping and such as the ecm suddenly thinks a different cylinder is #1 and changes the timing accordingly.
John
darkred87T
Active Member
- Joined
- Oct 27, 2003
Sorry to jack an old thread but...
I checked my timing for the heck of it becuase Iv'e had an idle problem ever since Iv'e owned the car. I paper clipped the "A" and "B" connectors on the ALDL and used an old style timing light, (it's the kind with the clamp for #1 Cylinder).
With the car idling, I can see the timing mark from the balancer lining up with that tab on the right of the indicator. However, it's jumping around. Is this normal because of the dual spark? Iv'e used a timing light on other cars and the mark is usually pretty steady with the light. Just curious.
Thanks,
Mike
I checked my timing for the heck of it becuase Iv'e had an idle problem ever since Iv'e owned the car. I paper clipped the "A" and "B" connectors on the ALDL and used an old style timing light, (it's the kind with the clamp for #1 Cylinder).
With the car idling, I can see the timing mark from the balancer lining up with that tab on the right of the indicator. However, it's jumping around. Is this normal because of the dual spark? Iv'e used a timing light on other cars and the mark is usually pretty steady with the light. Just curious.
Thanks,
Mike
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