Verifying ignition timing

JDEstill

Turboliscious!
#21
Jerryl knows this method for verifying the actual timing vs commanded, but I thought I would stick it in this thread for others reference. I copied it from a post I made 5-6 years ago.

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 Direct Scan or the later scan tools)

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. Check that with a piston stop if need be. I use an old timing light that clips onto the #1 wire instead of a dial back light.

John
 
#22
Jerryl knows this method for verifying the actual timing vs commanded, but I thought I would stick it in this thread for others reference. I copied it from a post I made 5-6 years ago.

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 Direct Scan or the later scan tools)

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. Check that with a piston stop if need be. I use an old timing light that clips onto the #1 wire instead of a dial back light.

John
so when do you remove the a-b jumper ,do you reset the ecm after all this?
 

trbojo

'Stang Stinger
#24
Jerryl knows this method for verifying the actual timing vs commanded, but I thought I would stick it in this thread for others reference. I copied it from a post I made 5-6 years ago.

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 Direct Scan or the later scan tools)

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. Check that with a piston stop if need be. I use an old timing light that clips onto the #1 wire instead of a dial back light.

John
just noticed something in this post...it says "there is a single mark to the RIGHT side of the tab"....wouldn't this then be 15* AFTER TDC? i need to verify this myself, and want to make sure i'm looking for the right thing...
 

RmvBfrFlght

Well-Known Member
#25
That 15* mark is BTDC. By "to the right side of the tab" he means toward to the engine side. Normally you are standing at the driver side of the car, with your right side toward the rear of the car. So the pointy mark at 15* BTDC is on the right hand side of the timing tab window.

The regular timing tab marks are on the left side of the window.

RemoveBeforeFlight
 

TurboBuRick

Moderator
Staff member
#26
The aftermarkets have the ability to verify the timing also.

With an XFI (1.540 or newer software): Hit the [F5] key which will take you to the Global Parameters screen. Select "Fixed Timing" and then put a value beside it that you want the timing locked to. Then hit "Apply" at the bottom of the screen. I usually select a value that you have a known, good mark on the balancer to shoot. On BHJ balancers, I usually select 30 degrees. You willl need to adjust the Crank referance angle up or down until the timing on the balancer matches the timing you are locked to.

With a BS3 System: Select "Configuration", then "Operating Parameters Configuration". Select "Enable Timing Test" in the Static Test Timing box. Then put a value below it that you want the timing locked to. Then hit "OK" at the bottom of the screen. Once again, I usually select a value that you have a known, good mark on the balancer to shoot. On BHJ balancers, I usually select 30 degrees. You willl need to adjust the Crank referance angle up or down until the timing on the balancer matches the timing you are locked to.

With the timing set and locked, rev the engine up and verify the timing doesn't move. If it does you will need to adjust the Inductive Delay.
Cal, how about on a fast classic v1.02. Is there a way to lock timing? I don't see a selection for fixed timing in the global parameters.

TIA

Rick
 

DR BOOST

Technical advisor
#27
i didnt see anyone answer the question of the bouncing timing mark at idle.....this happens when the idle speed is irratic. raise the idle speed to 1200-1500 and its much more stable.
 

HighPSI

Moderator
Staff member
#28
Cal, how about on a fast classic v1.02. Is there a way to lock timing? I don't see a selection for fixed timing in the global parameters.

TIA

Rick
No. Just Save your tune, then highlight the entire timing table and set it to the value you are checking. You will also need to zero out the idle timing trim table. Like Dr Boost posted above, it is better to raise the idle up to smooth things out. Once this is done, you can then rev the motor up and adjust your inductive delay.
When everything is finished reload your old program and change the Crank Referance Angle and Inductive Delay to your new values
 

HighPSI

Moderator
Staff member
#33
You adjust the crank reference angle in your computer program to compensate for any variances in the reluctor location

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we4Mateo

Double you eee what?
#34
so if I check my timing and it's off what then?

A machine shop can move the reluctor wheel on the balancer. Or you can just adjust the timing settings accordingly for whatever variance you have. You'll just need to remember how far off it is.

Cal is referring to an adjustment in the XFI that takes care of this variance.
 

HighPSI

Moderator
Staff member
#35
Not just the XFI. BS3, Classic FAST, Accel DFI, MOTEC, etc.. All the aftermarket ecu's do this (this is the aftermarket ecu section).

If you are running a distributor or CNP, if prefer to move the factory reluctor to 50° and use a different ignition strategy.

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HighPSI

Moderator
Staff member
#39
Would the spark display correctly on a scan tool once you fixed it?

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we4Mateo

Double you eee what?
#40
Would the spark display correctly on a scan tool once you fixed it?

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I don't think so, but I've only ever looked at my car through the SM which doesn't show timing. I just mean that the variance is linear with rpm and can be compensated for with the settings in the chip. The scantool should just show whatever the ECM is commanding at the time.