Directscan files collection!

[BM Computer Src]

Spark Advance

Ok,

Now that we have discussed O2's, lets talk about spark advance. How accurate is the commanded Advance (as shown on DS) compared to the actual? Has anyone really compared the two?

 

[bruce]

Re: Spark Advance

Originally posted by BM Computer Src
Ok,

Now that we have discussed O2's, lets talk about spark advance. How accurate is the commanded Advance (as shown on DS) compared to the actual? Has anyone really compared the two?

There have been several threads on this, and when you get all done, they match within the error of the time for the switching delays within the transistors. And were talking usec., here. And DC only reports to the nearest tenth.

Direct Scan is reading the actual RAM location values in the ecm, other then the HP and Torque numbers, I don't think it's actually doing ANY math, other then simple conversions.

If the airflow entry is FF, the ecm is thinking it's passing 255 grams/sec of air. And DS reports 255.

There is a thread about timing in the Trasher chips, and I posted the actual timing code with all the adders and factors.

What you see in DS is what the ecm is doing.
If the numbers aren't what you think then you need to look at the code and see what your missing.

And it's all relative anyway. When tuning your looking for best performance if your at 16 or 18 it really doesn't matter so long as you know that at 16 or 18 gives you best performance.

 

[ijames]

Re: Spark Advance

Originally posted by BM Computer Src
Ok,

Now that we have discussed O2's, lets talk about spark advance. How accurate is the commanded Advance (as shown on DS) compared to the actual? Has anyone really compared the two?

There was a thread on Thrasher timing in the Chips forum where a guy posted that he had made measurements on his ecm bench that were in severe disagreement with the chip tables. I started a thread called bench vs on-the-car timing where I posted measurements I made with a timing light that agreed within 1 deg with what the chip was commanding and what ds was reporting, at all rpms and lv8's that I could access with the car sitting still and the tires on the ground. The difference was constant to less than .25 deg so I think most of it was tolerance stackup in my timing chain, crank sensor placement, and keyways. After this he found a math error in his bench software and then his measurements aligned with mine. This is one case where ds must be doing some math because the Thrasher chips change the base offset for the main table (and others) and ds doesn't correctly handle that so I think it is assuming the stock offset instead of reading it.

 

[BM Computer Src]

I have to agree, but it always seems so odd that some cars you cant put more than 20 degrees timing on, even w/alky or race gas, and others can tolerate 30 degrees. I think those intolerant cars are the variants which may have anomalies, like higher compression or some other unknown changes / problems. It's just hard to look for problems in cars running fast on low timing. My TTA is a prime example. It can only take 20 degrees and 21-22 psi on alky, yet it's fast. I had the same results on race gas. The car is a screamer, and should break into 119-120 mph next time out. I have never run this low of timing and run so fast, it's always been 24+ degrees of timing and same boost.

Conclusion / Bottom line: The actual numbers dont matter, if it's making power.

 

[bruce]

I think it might be alot less confusing to actually talk in the way the ecm does things rather then confuse things with how folks expect things to read.

In the 1227148 the basic timing stuff is

There is Spark Advance.
There is the Spark Reference angle.
There is spark retard, in PE
There is spark retard, not in PE.
timing correction for Coolant Temp.
timing correction for Manifold Air Temp..
Highway Spark
TCC lockup retard

DS reports SA.
Again, I already snipped the code and posted in the Trasher Thread about what it is really there. ie what makes up SA.


Spark retard, in PE or not, is spark retard, ie not to be confused with SA.

If you change the spark reference angle, and displace the SA table accordingly, then those numbers are still the SA. But, they would be applied to the different reference angle.

There is a difference from SA to actually timing in use. Or I should say they can a difference from SA to what you would see with a timing light.

 

[Iceman]

Would someone send in a file(To Bob at BM Computer Src) with lean popping so we can see what it looks like.I am chasing a popping at 21# of boost or higher.At 20#it is ok no popping.
Or you can send me the file at vrice@arn.net

 

[bruce]

Originally posted by Iceman
Would someone send in a file(To Bob at BM Computer Src) with lean popping so we can see what it looks like.I am chasing a popping at 21# of boost or higher.At 20#it is ok no popping.
Or you can send me the file at vrice@arn.net

Why not post one of your's?.
There no guarantee that it's gong to manifest itself the same way from car to car. Might be something else going on that your missing.

 

[striker_29]

Hey Bruce I'm cat2-1, could you look at that one and give me any thoughts? I have been chasing several different problems, some of which started about that time. Also would just like to see what you think, as I'm still a tuning newbie. Thanks...Mark

 

[bruce]

Originally posted by striker_29
Hey Bruce I'm cat2-1, could you look at that one and give me any thoughts? I have been chasing several different problems, some of which started about that time. Also would just like to see what you think, as I'm still a tuning newbie. Thanks...Mark

Commanded AFR is as low as 6.9.
Injector DC is 124%
O2 voltages drop thru out the run.
It would tell alot more, with a WB, but looks like it's going lean as it goes down the track which may or maynot be EGT going up, or intercooler heat saturating, but with the alky inject that shouldn't be as much as of a problem.

Looks like the Alky might be slow as you get alot of K/R then it pretty much goes away, might be false, but I'd try readjusting the alky trigger and see what happens.

Without knowing the mechanical shape of things, from what you've supplied, looks like better alky injection methology, and or more injector.

BUT, you can hit several walls at once, and curing one doesn't mean you'll instantly go faster. Gets to better intercooler may help, larger injectors, refashioning the alky, might take one or all to get over the hurdle. Again assuming the mechanical stuff is OK, ie O2 sensor is accurately reporting things, good enough fuel pump, fuel filter etc.

 

[striker_29]

Hey Bruce thanks a lot for your help man, I really appreciate it On that particular run though, I had unhooked the alky and my intercooler shroud was missing. I was running c16 and 25 psi. Does that change your outlook on that at all?? Thanks again ...Mark

 

[bruce]

Originally posted by striker_29
Hey Bruce thanks a lot for your help man, I really appreciate it On that particular run though, I had unhooked the alky and my intercooler shroud was missing. I was running c16 and 25 psi. Does that change your outlook on that at all?? Thanks again ...Mark

Anything else to want to tell me?.

I'm glad you said that in a way. I just so happened to notice.
In scope mode, put the Inj PW, right on top of the Knock Retard.

See anything?.

At the first sudden demand of fuel the DC goes over 100%, the injectors are out of fuel and the motor detonates.

AND, this might be an indication of the injectors chattering as they go static, so far I haven't really been able to tell if an injector goes static, is it's chatering longet closed then open, or if it varies. Some have said that the injector just hangs 1/2 way open, that would be lean.

Then as you go further down track the DC disparety increases even more and you get into more detonation.

Adding F/P might help,
But your still trying to run static.

Again, assuming no mechanical ills causing a false knock, or leaving other details out.

 

[striker_29]

Thanks Bruce. The first instance of detonation occured with o2 mv's in the 840 range. I was actually thinking this may be an indication of rich knock. This was an RA106 chip with only 25 lbs of boost, and fp@48 line off if I remember correctly. I was thinking I needed more boost, but I guess thats not the case. There should not have been any reason for any false knock there. Thanks again...Mark

 

[bruce]

Originally posted by striker_29
Thanks Bruce. The first instance of detonation occured with o2 mv's in the 840 range. I was actually thinking this may be an indication of rich knock. This was an RA106 chip with only 25 lbs of boost, and fp@48 line off if I remember correctly. I was thinking I needed more boost, but I guess thats not the case. There should not have been any reason for any false knock there. Thanks again...Mark

I doubt it's false knock.
It might be a injector chattering as it goes to static.
DS just reports what the ecm wants to happen or things is happening. An injector chattering ain't going to show up unless your running an Oscilliscope on the injector. All it takes is one injector chattering, and one cylinder going lean for the Knock sensor to be triggered.

 

[TurboDave]

OK, I submitted my quickest and fastest run ever. It went to BM just moments ago, and was submitted for category 3. Don't know when it'll show up.

 

[BM Computer Src]

It's been updated!

The is great, exactly the type of response and help I was hoping would happen!

I see lots of buick's getting faster because they will learn how to interpret and tune better. Thanks to everyone who participates!!



Bob

 

[BM Computer Src]

I have just added Brian Schauder's 11 second recording.

Thanks Brian.

Bob

 

[Brian Schauder]

No problem Bob. I think it was a great idea,and find it very interesting.

 

[Donald McMullin]

TurboDave:

I looked at your DS file and have one question. Why does your MAF spike to 254 in two different spots?? Looking at shift points and other events at time of the spikes, I could not identify why this is happening.

Any thoughts as to why you are seeing MAF spikes??

P.S. Nice pictures of your new home. Sorry we will not be seeing you in Las Vegas this year.

Deep Enough

Donald McMullin

 

[TurboDave]

Originally posted by Donald McMullin
TurboDave:

I looked at your DS file and have one question. Why does your MAF spike to 254 in two different spots?? Looking at shift points and other events at time of the spikes, I could not identify why this is happening.

Any thoughts as to why you are seeing MAF spikes??

P.S. Nice pictures of your new home. Sorry we will not be seeing you in Las Vegas this year.

Deep Enough

Donald McMullin

Hi Don.

Those spikes I attribute to some noise on the line somewhere. Nothing to do with what was actually happening under the hood. That's the only run that entire weekend that it occured. You'll notice, nothing else was impacted.

I'm going to miss LV something fierce. The track is beautiful, and that run was made at Las Vegas!!
But It would cost me at least a week just to go. Minimum 3 days travel each way, plus race days.

 

[Mr URL]

Originally posted by TurboDave
OK, I submitted my quickest and fastest run ever. It went to BM just moments ago, and was submitted for category 3. Don't know when it'll show up.

Doesn't make sense to me. Top speed was 109.