I've been testing ICs and ran into an issue.. Timing retard. FWIW, I run MTH, and some other suff, but I thought it interesting that the car is running in timing retard whenever I floor it. Not too good. This graph is knock window vs individual cylinder timing as logged via BiM-COM beta.... I'll add some G-Tech Data in a bit... Also, I ran to the rev limiter, so I don't know if the timing retard at the end of the graph means anything in real world driving....

Matt


R9 is the 100 octane, and R2 is the 91. You can also see that some cylinders are worse than others....

 

That looks like what I see between 91 and octaine booster. Full throttle at 3000rpm will drop to the mid to high teens then work up to the high 20's. Thats with a 15% pulley.

 

Are you running 100 octane gas from the pump or are you using an octane booster to increase the number?

 

Do you think similar #s would be created from someone using a Unichip with the map set for 100 octane?

 

I'm pretty sure he's running the 100 octane from the pump. Lucky guy.

 

probably, as long as you are running 100 octane gas as well. otherwise you'd be in trouble, running too lean.

 

but I was just doing it for testing. Too expensive to run every day. I was just shocked that with the 91, I was in timing retard ALL THE TIME!

Matt

 

Just think where I'm at with my timing on my t/c'd car. I'm wanting to go in and get a custom ECU tune. That would be sweet.

 

I'm not sure how you got that.

I use to live in lafayette too, I think I've meet you before. I have the ds/w mcs.

 

It is not called pisswater for no reason....

 

 

Dr,

I can offer a seat of the pants observation between 93 and 100 at the track - I noticed zero difference...no wait...I was short $80.00 that afternoon . Perhaps 93 is the threshold??? I use 93 daily.

 

First off, I looked at some data someone else sent me, and it looks like a stock ECU map for an S with a pully and a CAI still gets timing retard when floored, just a bit less than I got with this measurement. Mine is up to 11 degrees retard, the other data showed up to about 8 degrees. Interestingly, without the pully, it wasn't pulling much timing at all.

Also talked to someone who did some ECU tuning optimization, and he found that about half CA pisswater and half 100 gave the best power. Maybe 100 octane needs even more advance to get all it has to give!

When I've tracked, I put some of the sweet in, and I think I got about 5 more MPH at the end of the front straight at Thunderhill, but that wasn't on an empty tank, so I wasn't driving exactly 100 octane, more like 95-97.

And lastly, after driving a tank full of the 100, I can say for sure that the car is more lively at lower RPM, and the pull is surprising! But peak, I don't really feel that much of a difference.

Overall, I'm just surprised that it's pulling so much timing, and wondering if dropping yet another temp range on the plugs will help....

Matt

 

How are you determining what the timing "should" be? The timing is adaptive and I have not read anything that says it starts at a fixed point.

You might be better off lowering coolant/cylinder head temps with a cooler thermostat to get more timing. Cooalnt temp is one the main inputs for timing and fuel richness.

 

By looking at the knock window and timing. If you look at the first graph in the thread, using 100 octane prevented any energy from going into the knock window, hence the ECU wouldn't retard the timing, hence the timing is at the advance curve that's in the ECU before any timing retard is employed.It HAS to have a base map, or a limit of advance, otherwise it could just keep advancing, and advance too far. OR it would advance until knock is detected, and if you look at the first graph (and others I've taken or seen that haven't been posted), the knock window energy is zero, so it hasn't just advanced until knock onset. I think the adaptive you're refering to is knock sensor mediated timing.
Yep it is, but too cool and it starts getting even more rich, which would be counter productive. There may be a bit lower temp that I can run, but just lowering the thermostat value doesn't garantee that the car will run cooler, it may just warm up slower. The thermostat is wide open during normal operation, and a cooler thermostat won't improve the flow at all in this case. I read in one of the earlier MTH threads that they do get cooler operating temps by turning on the fans at a lower temp, to suck more heat out of the radiator. But to be sure, this is an area that needs some work. I'll probably try it, but I think I'll start with cooler plugs first.... But I don't want more timing. The car can't use all the timing it's got now!

Matt

 

"It HAS to have a base map, or a limit of advance, otherwise it could just keep advancing, and advance too far. OR it would advance until knock is detected" -dr obnxs

That is how it works. It is constantly advancing until knock and then back 3 degrees, then back up 2, and so on. You just can't hear the knock. Are you saying that you know what maximum timing is because you have seen the table or because that was the most you got with 100 octane?

With the colder t-stat the car should still warm up to 180* at the same rate, but beyond that the 180 should keep the head cooler while moving. While with the stock t-stat there is no way (without fans) it is getting any cooler than what it is set at. Like I mention before, bmw uses this temperature for its performance maps ( which are adjusted in real time according to load) so that's why I'm focusing on that way of reducing temps.

Do you plan on data logging different heat ranges? NGK's faq says that the difference between heat ranges is the potential to remove 70 to 100*c. I'm curious to see how cold of a range can be used before plug fouling becomes a problem and what the real world relationship is between coolant/cylinder head temp, timing and horse power is.

There was about 15hp difference between dyno runs with 195* and 215* the last time I dyno'd.

Keep us posted on your findings.

 

I'm using BiM-COM to log knock window energy with the timing data. You can see the back off and advance with the 91 octane, and the non-zero knock window values.

With the 100 octane, the knock window value is zero, and there's no evidence of the retard-advance behaviour. It's never detecting knock (until I hit the rev limiter....).

I've seen other listings that show 75 C difference between heat ranges as well. The IK22s still look fine, no fouling. Maybe another range lower will still be fine.. We'll see.

And in general, I like to log data. It's in my blood! So eventually you'll see other data for it.....

I'll keep you all posted.

Matt

 

That's interesting about the knock window. I was taught that the dme is always pushing timing foward, but my information is for servicing so we don't go that deep into programming.

Can you post some screen shots of the knock window so that I can gain better perspective.

 

The knock window isn't physical. The knock sensor always puts out some voltage, so there's a threshold (RPM dependant, I think) amount of noise that is "ignored". Also, knock sensing is by individual cylinder, so only a certain amount of rotational crank angle is "looked at" to see if one cylinder or another is having knock onset. Then the ECU can retard each cylinder, to keep each one at the best timing. The "knock window energy" is what is plotted in the first two thick lines in the first post, and it has some funky units, and the axis is on the left hand side of the graph. When I finish with my IC testing, I spend some more time logging knock voltage, noise and window to see if I can figure out how they're all related...

Matt

 

matt,

thank you for posting these quantitative results.

i run 93-94 octane in my supertrapped carnation hai mcs. i've gone back and forth to 91 octane several times to check my seat of the pants results: i've always experienced slightly stronger running, slightly more pronounced in low to mid range, with the higher octane.

looking forward to more of your number crunching!

 

ok, you were talking about signal threshold. I was getting the impression that you had a table for base ignition timing.

After re-reading my references, they do imply that there is a base map for igniton timing. So if your not getting any knock signal out of range then I guess that 100 is more than enough for the base map. Now, are you using stock sofware or an aftermarket flash? I'd like to see how it differs with mth or other flashes.

Can you hear the knock when the signal brakes the threashold?

Can you configure your data to have rpm in the x axis?

I tried to log timing at different coolant temps last night, but I over wrote the 180* log and could not get the temp back down once it reached 195*, and this was at 40* ambient. I'll try again today.

Excuse all the questions, I get excited when some else has the same interest in seemingly boring topics.

 

So, at the outset, I'll simply state, I'm an idiot when it comes to this stuff. I'm putting an Motec M48 in my track car and was counciled by a fairly well known engine builder to go with the pro version for its wide band lambda feature. Ah..okay yeah... another $500...ahhh... so I figured I'd do a little research and found an interesting article that some of you might find interesting as it pertains to achieving an ideal burn. Gets pretty technical, but I found a lot of the concepts enlightening.

http://www.megasquirt.info/PWC/LSU4.htm

 

Have you had the opportunity to run this diaognostic on a stock JCW car too? I'm curious.

 

I've only got an '02 S. Sorry, nothing on a base JCW, but if anyone wants to lend me one......

I may be able to convert to RPM. We'll see. Or I'll just measure it again.

Can't hear any knock when this is happening, but it's been cool. I think that when it's hotter, I can hear some slight ping in some situations. The knock sensor is more sensitive than I am.

Matt

 

If you're in the northeast on any given weekend between april and november, you take it on a track. LRP, Watkins glen, New Hampshire...Pocono...dunno about that one.