Factory PCM knock control discussion
#27
For the positive RPM delta values, I think it is there to reduce detonation during transition from cruise to acceleration.
OTOH, I think the Yamamoto books says that this type of detonation isn't problematic for rotaries.
For negative RPM deltas, more advance increases engine braking.
I have run with these tables zeroed, and I didn't have major problems. Still, caveat emptor.
At light loads - as are used in normal everyday cruise conditions - an ignition advance of 40 degrees or more will improve responsiveness and economy. This advance can be used successfully on many engines - even those with an 11:1 compression ratio, if they are being run on high octane fuel. One factor limiting the cruise ignition advance that can be used is the maximum ignition timing attack rate provided by the ECU - that is, how fast the timing can change. If very advanced timing is being used with light loads and the attack rate is not high, there may be slight detonation when the engine load suddenly increases. link
For negative RPM deltas, more advance increases engine braking.
I have run with these tables zeroed, and I didn't have major problems. Still, caveat emptor.
Last edited by oltmann; 12-19-2011 at 03:20 PM. Reason: also
#31
Because your question makes no sense -- Fazda never asserted that it does need to be messed with. He merely asked a question.
It seems that in turbo applications it might actually be useful to retard the timing somewhat during deceleration, which seems to be the opposite of how things are set up in the OE calibration.
So, it must be there for a reason, should I leave it or have it pull less timing?
This feature is useful for engine braking under ecology limitations.
In order to avoid rich spices under throttle off it is useful to provide some additional air that is counterproductive for engine braking. Retarded ignition fills the bill.
Secondary, ignition retarded provides inti-lag feature for turbo application if you wish to accelerate sharply after breaking or gear switching. link
In order to avoid rich spices under throttle off it is useful to provide some additional air that is counterproductive for engine braking. Retarded ignition fills the bill.
Secondary, ignition retarded provides inti-lag feature for turbo application if you wish to accelerate sharply after breaking or gear switching. link
#32
Well it all started looking at 3gear wot logs, right around 5950rpm the car decides its not going any higher, standing on the throttle. Afrs look good, but timming is 5. So I am thinking that having this timming to small that it stalls the cycle, and it cant recover. To early a spark and you loss all power. All my other logs I have seen like to have 9 - 10 on the leading, through that boosted range with out timing pulled. So thats what I am shooting for. I have already adjusted my timing for boost, do I really need another? Maybe this is a rear occurance.
#33
This is what those tables ought to look like:
![](https://www.rx8club.com/attachments/series-i-engine-tuning-forum-63/179781d1324410863-factory-pcm-knock-control-discussion-delta.png)
So, if you are seeing timing that is 3-8 degrees retarded on the leading and 8 degrees retarded trailing, I think there is a good chance these tables are the cause.
Whether or not it should be "fixed" is really a judgement call.
![](https://www.rx8club.com/attachments/series-i-engine-tuning-forum-63/179781d1324410863-factory-pcm-knock-control-discussion-delta.png)
So, if you are seeing timing that is 3-8 degrees retarded on the leading and 8 degrees retarded trailing, I think there is a good chance these tables are the cause.
Whether or not it should be "fixed" is really a judgement call.
#35
#38
#43
Open excel, click file, open. select all files open text file. Text import wizard opens. Click next. Under delimiters checkbox comma, click next, then finish.
Rx8club does not let .csv or .exel files to be attached
Rx8club does not let .csv or .exel files to be attached
#45
thinking out type
I am hoping its obvious,
the problem is me
you don't have enough info to help me
dannobre looked at my logs and noticed
Throttle Position = 67 (did a search this is the normal max)
Accel. Pedal Pos. =100
I am hoping its obvious,
the problem is me
you don't have enough info to help me
dannobre looked at my logs and noticed
Throttle Position = 67 (did a search this is the normal max)
Accel. Pedal Pos. =100
Last edited by FazdaRX_8; 12-29-2011 at 12:26 PM.