VS L67 Idle spark issue

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hoosedamoose
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Joined: Thu Nov 14, 2013 9:44 pm
cars: vs statesman

VS L67 Idle spark issue

Post by hoosedamoose »

Hey guys, I think I posted in thr wrong forum before. Anyway,


got a vs l67 running enhanced bin. ive installed a xp hotcam into my l67 last weekend and its running great. Except one thing. For some reason Idle spark in park and neutral isnt running whats commanded in the idle spark tables. When in drive, it runs perfectly with 25deg of spark. Once it goes out of gear it runs 3 degrees, causing it to idle like crap. ive played with the IDLE spark advance in gear vs mg/cyl table. Changing values in this table also seem to offset this 3 deg of spark in park. Im not sure where to look to be honest. im stumped as to why its running so low. The spark map itself also has 25deg commanded in that region. Any ideas will be helpful. Cheers
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Holden202T
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Re: VS L67 Idle spark issue

Post by Holden202T »

its not something like knock sensor retarding it or similar ?
immortality
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Re: VS L67 Idle spark issue

Post by immortality »

I've noticed something similar, our L67 seems to idle with about 14° of timing even though in the table it commands 25°.

I remember someone saying that the PCM uses the timing to control the idle speed.

There are tables that alter timing depending on Intake air temp and coolant temps. If you have fitted a MAT sensor you will need to adjust the Spark - Intake Air temp table to suit.
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The1
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Re: VS L67 Idle spark issue

Post by The1 »

you want this table to stop the retard between P/N and Drive, though 3 degress is more than what's commanded something else isn't right like knock sensors going off due to the cam, can you post a log?

Spark - Retard Vs Reference Pulses After Shift to P/N
hoosedamoose
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Re: VS L67 Idle spark issue

Post by hoosedamoose »

Hi guys! thanks for the reply. Ill Definitely check the knock sensors, that slipped my mind. I do have them disabled though as i have solid mounts and running e85.

There is a MAT sensor fitted into the number 1 runner, there is no spark correction in the table for idle. All set to 0 in that region

Ill post a log shortly :)

Edit: attached log. No knock retard that i can see

the first 10 seconds is basically what happens. low spark in park, commanded spark in gear. In this instance park advance was 9 deg. I did just realise though, lowering the spark in gear table, also lowers the p/n spark as well by the same offset. e.g If i had 29 deg commanded before the cam, my park spark was around 15 deg. After lowering the in gear spark to 25 (-5 deg) the same offset also applied to the p/n spark, lowering it to 9-10 deg.
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hoosedamoose
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cars: vs statesman

Re: VS L67 Idle spark issue

Post by hoosedamoose »

Hey fellas, turns out cylinder 3 had a chipped piston lol.
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The1
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Re: VS L67 Idle spark issue

Post by The1 »

ouch mate. :wtf: Doing a full rebuild?
hoosedamoose
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Re: VS L67 Idle spark issue

Post by hoosedamoose »

The1 wrote:ouch mate. :wtf: Doing a full rebuild?
Yeah, it's all done. Back on the road now. Atleast I learned that if something isn't tunable no matter what you try, then it's probably best to
Start looking for mechanical issues.
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The1
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Re: VS L67 Idle spark issue

Post by The1 »

yep your only using data to see what the engine is doing, then changing the recipe to let it do it's job.
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krusty
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Re: VS L67 Idle spark issue

Post by krusty »

XP cam always triggers knock sensors at idle and below 2000rpm. Will need to dull off the knock sensors or match all possible spark tables to match desired timing in those areas which is less than desirable as plenty of damage can also occur on lean cruise spark adding
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