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PCM sometimes pulls timing but can't for what reason.

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Old 11-05-2013, 08:37 AM
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Default PCM sometimes pulls timing but can't for what reason.

1999 trans am running speed density sometimes the car will pull timing but can't find any reason why it should. I've been told that I should have my low and high octane tables the same. Also have heard there are calculations and tables not seen that affect timing.

Any thoughts?
Old 11-05-2013, 11:55 AM
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It could be tons of things, post the tune I'll check the most common things.
Old 11-05-2013, 11:04 PM
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Burst knock???
Old 11-05-2013, 11:45 PM
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mines doing something similar... it gets burst knock when ever i launch the car, in turn it pulls the same amount of knock retard which pulls timing.
Old 11-05-2013, 11:46 PM
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ive maxed the burst knock enable and zero'd the burst knock retard vs ect but i still pick up burst knock on the scanner
Old 11-06-2013, 07:44 AM
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Originally Posted by boostit5.3
ive maxed the burst knock enable and zero'd the burst knock retard vs ect but i still pick up burst knock on the scanner
don't think it's burst knock, don't see any kr, it's like it's going between unknown tables and calculations doesn't show anything in the datalogs.

Last edited by mike13; 11-06-2013 at 07:55 AM.
Old 11-06-2013, 07:56 AM
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theres other things that factor into over all timing.. check your iat timing tables?
Old 11-06-2013, 08:06 AM
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Originally Posted by boostit5.3
theres other things that factor into over all timing.. check your iat timing tables?
sure did, checked all the visible tables.
Old 11-06-2013, 08:17 AM
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Torque management, traction control, IAT table, ECT table, commanded AFR table... Is it running off just the low octane table?
Old 11-06-2013, 08:20 AM
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Originally Posted by Chevy406
Torque management, traction control, IAT table, ECT table, commanded AFR table... Is it running off just the low octane table?
checked all those, no not just the low octane table. It's like there's calculations going on that aren't seen in the tables.
Old 11-06-2013, 08:23 AM
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Is it an automatic?
When you are able to post the tune and a scan there will be more chance of folks helping you.
Old 11-06-2013, 08:40 AM
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Originally Posted by Chevy406
Is it an automatic?
When you are able to post the tune and a scan there will be more chance of folks helping you.
Yes automatic.
Old 11-06-2013, 11:01 AM
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System > General > System Options > BrakeTqMgt make sure that is a zero

Transmission > Torque Management disable abuse mode and zero out all torque reduction tables

Engine > Torque Management > General of course zero (or max out) tables that have anything to do with limiting torque

That's about all I can come up with off the top of my head without seeing your tune.
Old 11-06-2013, 11:44 PM
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I was tracing this issue on a car once and I made a custom scanner in the hpt that monitored all timing functions. If you do that, you should be able to see where it is coming from.
Old 11-07-2013, 03:36 AM
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Post the tune
Old 11-07-2013, 07:50 AM
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here's the tune. you'll notice how much timing I run in the "drive" table, it's for having the car on the transbrake.
Old 11-07-2013, 09:31 AM
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Post the details on your setup, what are all your mods?
Old 11-07-2013, 09:39 AM
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Originally Posted by LSX Power Tuning
Post the details on your setup, what are all your mods?
1999 Trans Am
390/ 4L80e
billet 83mm turbo
14lbs boost, I run 50% 114 race gas
80lb injectors

4000lb car runs 143mph.
Old 11-07-2013, 10:26 AM
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You still run a MAF? (nevermind I see you don't) VE table looks bonkers. Injector data, Engine Size, Cylinder Vol looks wrong. Injectors will not flow the same volume when intake vacuum changes and it uses the Cylinder Vol to calculate along with your injector data for the VE table. VE table should look like a dyno sheet and not the ocean.

Why is Boost Enrichment Enabled at 110 kPa but is set to 1.00 all the way across? I know it will use your PE EQ ratio table as it's richer.

I know this doesn't help your problem but I wouldn't go into PE until you address those issues. Do you use a wideband? If so go drive around and get a log and post it up.

Try putting the MAF codes to 2 instead of 3. Maybe your car is different but when I put mine to 3 the car will not run right.

Last edited by danieloneil01; 11-07-2013 at 10:47 AM.
Old 11-07-2013, 10:59 AM
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no maf, boost referenced fuel regulator.


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