Verifying ignition timing

HighPSI

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May 24, 2001
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timing bouncing around at idle sounds like a sloppy timing chain .
I would guess it's idle timing trim trying to keep the idle smooth. A sloppy timing chain shouldn't effect the timing on a Buick since they have a crank trigger. When a timing chain is about to let go or a cam sensor gear is wearing out you will see the cam sync moving around.
 
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turbota440

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Apr 13, 2007
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Yes. The reluctor is set at ten degrees on a stock balancer. BHJ is usually around six
Yes thank you but again why not 0 deg ?
I will be using a BHJ soon with factory ECM and extender chip. Should I use it as is or ? And why they chose 6 instead of 10 deg ?
Answers are much appreciated.
 

turbota440

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Apr 13, 2007
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Question on the crank sensor connector wires. A pin B pin C pin
I have seen schematic on here somewhere where A is 12 volt B is signal and C is ground. But the wires I have on a cut off pig tail are green wire for A, black wire for B, and forgot but maybe grey wire with stripe for C.
You would think blk wire would ground at B and grey might be signal at C.
What is correct on 87 GN ?
 

TurboBob

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May 24, 2001
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Yes thank you but again why not 0 deg ?
I will be using a BHJ soon with factory ECM and extender chip. Should I use it as is or ? And why they chose 6 instead of 10 deg ?
Answers are much appreciated.
The factory timing is set that way because of the stock ignition control strategy. During engine cranking, before the ECM takes over timing, the 10 degree signal edge is used for timing.

I believe you can order BHJ's set to stock timing.

Bob
 

turbota440

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Apr 13, 2007
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The factory timing is set that way because of the stock ignition control strategy. During engine cranking, before the ECM takes over timing, the 10 degree signal edge is used for timing.

I believe you can order BHJ's set to stock timing.

Bob
Ok so at cranking it's 10 or 6 but once computer takes over it still using that reference and adjust timing in addition to that. So if trigger wheel is wrong then all the timing is wrong or off by that amount. That's why in aftermarket stuff you guys change the reference angle. But I have a Gen 2 and Extender Chip. Any way to adjust that ?
 

TurboBob

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the chip can be adjusted if your balancer is off. or the balancer can be fixed.

the other thought is that as long as you know the timing is off, you can adjust your WOT timing with the Gen-2 (assuming you are using the Extender Extreme G chip), the timing at part throttle is not going to affect you much.

Bob
 

turbota440

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Well looks like BHJ must have corrected their fixture. Timing comes right about 10 deg. Did it very slowly in both directions since only thing in the block is the crank and one piston with no rings.
One other point of interest that threw me for a loop is that you have to put the negative lead of the volt meter to signal lead to see the voltage drop.
Thanks to all that replied.
 
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Otto J

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May 31, 2001
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Well looks like BHJ must have corrected their fixture. Timing comes right about 10 deg. Did it very slowly in both directions since only thing in the block is the crank and one piston with no rings.
One other point of interest that threw me for a loop is that you have to put the negative lead of the volt meter to signal lead to see the voltage drop.
Thanks to all that replied.
You better verify this with a timing light once the engine is running.
 

Flyin Brian

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Jun 18, 2011
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Houston
Ok, I know I am a few years late on this but I have been trying to verify my ignition timing today and am not having much luck.
I have read this thread several times and think I understand it.
I have a BHJ balancer and have mechanically verified that the timing mark is right on.
So I have been trying to follow the procedures in this thread but am having the following problem.
When I jumper the A and B pins in the ALDL the check engine light flashes but the timing does not fix at 15 deg. It just stays around 28 degrees. Is this an issue with my chip? I am using the old TT SD chip.
So I figured that I would just see what I could do with the relatively steady 28 degrees I have at idle.
I am using an old Snap on digital dial back timing light. That is all I have laying around. It does not like the wasted spark so it reads twice the RPM.
I use the dial back feature to get the timing mark to be at zero on the timing tab and it takes 52 degrees to do this. If I am thinking about this correctly, and I am probably not, would I divide this number by 2 to get 26 degrees of actual timing? And if this is approximately correct would that mean my reluctor is off by 2 degrees and that the computer thinks it is getting 28 degrees but it is only actually getting 26 degrees? And this would mean that my reluctor is at 8 degrees instead of 10? I know I really need to figure out how to get my car to fix the timing in diagnostic mode as well as get a more modern timing light but I am trying to work with what I have here today. I hate to dig up a 3 year old thread on Easter Sunday but this is the day I chose to work on this issue. Thanks in advance for any input.
 

Flyin Brian

Member
Jun 18, 2011
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Houston
Thanks Cal.
I think I got it figured out. Got the ECM in diagnostic mode with timing fixed at 15 deg. It was in diagnostic mode before but I was looking at the laptop screen and it does not show the 15 degrees, it shows what the chip is calling for.
So, with it fixed at 15 degrees the timing light shows 12 degrees meaning that the reluctor is at 7.
So does this mean that at WOT when my chip is calling for 20 degrees advance I am only really getting 17 degrees advance?
 
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