spark knock only when temps are above 80??

[smslyguy]

I have been experiencing spark knock when temps are at 80 or above. it seems to run fine below this temp. any ideas as to why i am having spark knock with higher outside temps?? here is my run on this tune. I did notice they do have a spark iat table but i don't really know what the oz/cylinder {link:gm dynclair_dma} stand for??

[WeathermanShawn]

Warmer temperatures (IAT) will definitely make your car more susceptible to ping or knock.

Most factory tunes will 'automatically' pull spark as IAT's increase, but sometimes pinging or knocking is hard to combat in hot summer heat.

Unless you have great gas, I avoid big WOT's on a hot summer day. I wait till it cools off at night. More fun to run it when it is nice and cool (more air density/O2).

[redhardsupra]

or you could just use a table that's designed to deal with this exact problem, and give it a spark modifier that doesnt make it knock.

[mr.prick]

I did notice they do have a spark iat table but i don't really know what the oz/cylinder {link:gm dynclair_dma} stand for??

Spark tables are linked to the following PIDs: GM.DYNCYLAIR_DMA,GM.CYLAIR_DMA,GM.DYNCYLAIR,CALC.C YLAIR
Refer to the cal.link.txt

CALC.CYLAIR is measured by the MAF
IIRC
GM.DYNCYLAIR_DMA is measured by MAP & RPM

[smslyguy]

or you could just use a table that's designed to deal with this exact problem, and give it a spark modifier that doesnt make it knock.


is that the table i was referring to from above??

[WeathermanShawn]

Yea, B5911 Spark IAT Table is a start.

Nothing replaces good common sense. Flooring it at 100F+..I avoid it. Less air density and to keep it from knocking you have to pull spark, which is not going to gain you any power.

But, yes that table is helpful. You can always make it more conservative, though few do.

[smslyguy]

Spark tables are linked to the following PIDs: GM.DYNCYLAIR_DMA,GM.CYLAIR_DMA,GM.DYNCYLAIR,CALC.C YLAIR
Refer to the cal.link.txt

CALC.CYLAIR is measured by the MAF
IIRC
GM.DYNCYLAIR_DMA is measured by MAP & RPM

how do you go about adjusting your timming accordingly using this table?

[WeathermanShawn]

I take it you don't have a wideband, or did you just not log it on this run?

Did you ever get KR like this on any other run? Have you modified your tune at all?

You could be lean, judging from your overall LTFT's. To see KR at part-throttle where you are looks unusual. Is it when you are downshifting? Do you hear it pinging? If the KR is 'real', you are probably either too lean, or you need to work on your High-Octane Spark Table. Otherwise, you need to go back to basics and figure out your tune.

You need to log the Pid(s) that will get you GM. DYNCLAIR in order to modify Table B5911. Based on your data you are going to have to take a lot of spark out from that table to alleviate your problem.

Can you post up some logs?

[joecar]

Post tune file and more logs.

[smslyguy]

I take it you don't have a wideband, or did you just not log it on this run?

Did you ever get KR like this on any other run? Have you modified your tune at all?

I can not make a lot from your log without an attaching tune or your actual wideband AFR. You could be lean, judging from your overall LTFT's. To see KR at part-throttle where you are..pattern just looks bizarre. Is it when you are downshifting? Do you hear it pinging?

You need to log the Pid(s) that will get you GM. DYNCLAIR that one poster indicated to modify Table B5911. Based on your data you are going to have to take a lot of spark out from that table to alleviate your problem.

If the KR is 'real', you are probably either too lean, or you need to work on your High-Octane Spark Table. Otherwise, you need to go back to basics and figure out your tune.

I am trying to be nice here. I think your tune is messed up to be get getting KR at those Rpm's and light loads, regardless of the temperature.

Can you post up further information? Thanks.

..WeathermanShawn..


are you referring to cylair brams/cyl? Is that the same map? I can't seem to find gmdynaclair anywhere?

[smslyguy]

here is a tune after i adjusted the iat spark table, seemed to help at least. I am experience spark knock only underload at lower rmp. like say shifting from 1st to third then to fith and sometimes if i am at a traffic light for a while i will also get spark knock taking off the line.

[joecar]

Seems to me to be due to heat soak (IAT is 80+, ECT is 205+, airmass jumps up substantially, coincides with KR)... adjust the IAT table further and see what happens...

altho that log file shows very little knock.

[smslyguy]

Seems to me to be due to heat soak (IAT is 80+, ECT is 205+, airmass jumps up substantially, conicides with KR)... adjust the IAT further and see what happens...

altho that log file shows very little knock.

it was worse before i a had adjusted the iat, but i will try to go more. How accurate is the v.e. table on the stock o2 sensors? Is it acurrate at stoich? and if anyone knows the acurracy of them outside of stoich?