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 Post subject: Erratic Spark Timing
PostPosted: Sat Jan 03, 2015 6:13 am 
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Joined: Tue Jul 12, 2011 11:09 am
Posts: 9
Location: E.S. MD
I have a 92 Colt that I am attempting to get timed correctly. When I set the timing to 5 deg, as per the Chiltons manual, the car pings like crazy. Last spring, when I first put this car on the road, it was doing the same thing so I just backed the timing off until the pings went away. Recently I had to replace the distributor so I again attempted to get it timed and again pinging like crazy, even with 93 fuel. I have checked the timing belt and it is on correctly. I even removed it and re-installed it just to make sure. I have tried a couple of ecus and both produce the exact same results. The one thing I have noticed is when the timing adjustment is grounded, the timing still advances if the rpms go up. I was under the impression the timing was locked down by the ecu with it grounded so that an accurate adjustment can be made. It seems like something is mechanically throwing the timing off as the car revs. Ideas?


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 Post subject: Re: Erratic Spark Timing
PostPosted: Sat Jan 03, 2015 1:11 pm 
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The Silent Administrator
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Joined: Wed Dec 24, 2003 3:32 pm
Posts: 9428
Location: Ottawa, ON, Canada
Grounded wire, check.
Engine at operating temp minimum 75 degrees, maybe more, check?
Find physical TDC and confirm your pulley is not separating.

If things look good, double check that your distributor is in phase.
Tiny tab indent to mate up on that style right?

Does the engine timing stabilize right as the ground strap is attached?
Confirmed with the gun aimed and ready?

Just want to make sure it's getting into base timing mode.

There aren't two wires to ground on a 1.5L setup, is/are there?


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 Post subject: Re: Erratic Spark Timing
PostPosted: Sun Jan 04, 2015 6:56 pm 
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Location: E.S. MD
Quote:
Grounded wire, check.
Engine at operating temp minimum 75 degrees, maybe more, check?
Find physical TDC and confirm your pulley is not separating.


Yes fully warmed up and I did a double check on the pulley when I re-installed the timing belt.
Quote:
If things look good, double check that your distributor is in phase.
Tiny tab indent to mate up on that style right?
I'm not sure about the tab but the distributor is indexed correctly, at least according to the manual.
Quote:
Does the engine timing stabilize right as the ground strap is attached?
Confirmed with the gun aimed and ready?

Just want to make sure it's getting into base timing mode.


Sort of. The timing seems to pull back some and slow down but when I rev the engine it advances but does not not jump around like when it's not grounded.
Quote:
There aren't two wires to ground on a 1.5L setup, is/are there?
Not according to the manual.


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 Post subject: Re: Erratic Spark Timing
PostPosted: Mon Jan 05, 2015 1:22 am 
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The Silent Administrator
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Joined: Wed Dec 24, 2003 3:32 pm
Posts: 9428
Location: Ottawa, ON, Canada
Hmmm, seems like everything is normal.

Yes, timing should dial back to base, and hold.

When the ECU is out of base timing mode, it will be compensating with increasing the spark BTDC.

So, if base it like 5-7, actual would be up in the 10-12 range.

Revving won't give any sort of relevance in this regard.
Timing will advance, likely not properly due to being in base timing mode?
Hard to say, never revved a motor and checked while setting base.

What style distributor do you have?

Passenger side of the head?


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 Post subject: Re: Erratic Spark Timing
PostPosted: Mon Jan 05, 2015 5:02 am 
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Joined: Tue Jul 12, 2011 11:09 am
Posts: 9
Location: E.S. MD
I'm not sure what style of distributor I have but it does come out over the transmission on the passenger side.


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 Post subject: Re: Erratic Spark Timing
PostPosted: Mon Jan 12, 2015 7:54 am 
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Posts: 9
Location: E.S. MD
I've managed to trace the issue back some wiring I had done a while back. I’m running a Megasquirt, fuel only, using the crank speed sensor for the tach in. I tweaked the way I grab the signal and it seems to be working now. It must not have liked sharing the signal with another ecu.


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 Post subject: Re: Erratic Spark Timing
PostPosted: Mon Jan 12, 2015 7:33 pm 
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The Silent Administrator
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Joined: Wed Dec 24, 2003 3:32 pm
Posts: 9428
Location: Ottawa, ON, Canada
You would definitely skew the signal if you tap into it. Best to run individual signals from individual sensors to each component.

There should be no other way to do this. Most of the time. 8)

Glad you found the issue.

Didn't know things were "tapped into".


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