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Really low timing?

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Kakoriat

20+ Year Contributor
141
1
Sep 5, 2002
Dahlonega, Georgia
Last friday I borrowed Got Grip's datalogger at the track to see how my car is running. Well when I got back he had a look at the logger and said I was running 12 degrees of timing in the high rpm's OMG My question is what could be causing my car to be running such low timing? Tony said when he ran a 13.4 with his T-25 he logged 24 degree's. My best run has been a 14.7@90, this is the run I logged and got 12 degree's. Is it possible that my knock sensor is broken and causing the ECU to retard the timing? Also my CEL has been on for sometime now and with the logger we got the code P3242, where can I find out what code this stands for? I don't have an EGT gauge but I am seriously considering one soon. Please help me.
 
Originally posted by painmaster
What did your knock read on the datalogger?

Oh nuts, I only made one pass with the logger and Tony said it will chunk up if you log more then 3 variables, we did RPM, Timing and O2. We didn't log knock, guess that would have helped.
 
can't log knock on a 2g so it doesn't apply

on mine, I get about 12 deg advance running 10 psi, at 7psi I can see 16 deg advance, and at 15 psi, I can see around 10-12. these are with 02 values anywhere from .90-1.02 The only times I have seen 20+ are a couple of freak runs where my 02s dropped to about .84. the 95's seem to hate timing advance.
 
what does your timing do (if you still have the log)? does it drop down to about 5 and come back up to 12?
does it hit 12 early and stay there (what mine does)
or does it hit say 17 and drop to 12?
 
What other items did you log? Can you post the log up for us to look at? Essentially for you to only be getting 12 deg of timing at WOT you have a crappy tune on your car :)
 
I'll have to wait for Tony to read this, he has the logger. All I know is I pulled 12 degree's of timing on that run, I don't remember what the else the logger said. However I think Tony said my 02 was reading normal.
 
Originally posted by nine5raptor
The only times I have seen 20+ are a couple of freak runs where my 02s dropped to about .84.

ever seen this larryd?
 
Originally posted by Kakoriat
I'll have to wait for Tony to read this, he has the logger. All I know is I pulled 12 degree's of timing on that run, I don't remember what the else the logger said. However I think Tony said my 02 was reading normal.

O2 readings are bogus since they vary based on the temperatures outside (they'll read high on hot days and low on cool nights). Since you can't read knock, it will take awhile to find out if you are indeed encountering knock and timing is being pulled because of it.

But yes, I've heard that the 2Gs are conservative on their timing curve. Also, if you have an SAFC and it's richened up a bit, this would cause a retard in timing too.

-M
 
Originally posted by Phoenyx

But yes, I've heard that the 2Gs are conservative on their timing curve. Also, if you have an SAFC and it's richened up a bit, this would cause a retard in timing too.

-M

I plan on buying Tony's SAFC when he sells it. I know the car runs pig rich, with the SAFC I could turn that down. I'm sure that would help a lot.

Thanks for helping me with this guys, I'm learning a lot.
 
Originally posted by nine5raptor


ever seen this larryd?

No that really doesnt make any sense. According to your o2 you are super lean, like to the point where you would be doing damage. If anything your timing should be null at that point because of the knock/detonation.
 
Originally posted by larryd


No that really doesnt make any sense. According to your o2 you are super lean, like to the point where you would be doing damage. If anything your timing should be null at that point because of the knock/detonation.

You can't go by the O2 voltage reading... it changes with the temperature outside and therefore is bogus since it can read low and have no knock. I"ve seen this on my pocketlogger.

-M
 
Originally posted by larryd
But if the temperature is pretty stable outside and not changing in like 50 degree swings from day to night you can get a good basis off the o2 voltage.

Well over here in the Bay Area, there are at least 30 degree swings. All I'm saying is that you shouldn't base one running lean strictly on the O2 voltage. At night, it will read lower voltage (in the .80s+), but doesn't mean you're actually running lean.

To run lean, you will get knock, that's why it's better to tune based on knock and then fine tune based on timing.

Not to discredit O2 voltage at all. For example, you could be getting knock and read O2 voltage to be 0.82 (in cool weather). And you might richen up the fuel to get an O2 of 0.84 which could be all you need to eliminate the knock. After tunign to that, on the next day, it could be over 70F outside and your O2 reading could be 0.92 where as the previous night, you set it to 0.84. That's why it's imperative that you tune in the coldest conditions so that you know for a fact that you won't be lean in warmer weather.


-M
 
hmmm. I wouldn't think 02 voltage would vary much with temperature, as the with the stock mas the ecu accounts for temps, or in my case, the air mass is measured directly (hotwire). Also with the heated 02 sensors, they shouldn't vary much either.

When I got these values, it was in a single pull (had it happen several times). Looked about like this (all was at wot).

rpm timing 02
3000 23 .84
3500 21 .84
4000 14 .96
4500 12 .98
5000 12 .98
5500 14 .98
6000 14 .98

now that I think about it, I haven't actually had this happen since I installed the gm mas, now my problem is logs that do this:

1st (wot) run:

3000 12 .98
3500 12 .98
4000 14 .98
4500 14 .98
5000 14 .98
5500 14 .98
6000 14 .98 (by now boost has crept up to 18 from 10 - set low for tuning)

2nd (wot) run - just a couple of minutes later - no change in maft/boost settings

3000 12 .90
3500 12 .92
4000 12 .92
4500 10 .92
5000 12 .90
5500 11 .90 (usually I let up before I get this far as the car feels like a dog).
 
Exactly. As this proves my assumptions - even on consecutive runs, you are getting different O2 values.

Sure the O2 will change from temperature to temperature outside. The mass of air changes so you will get more lean in colder whether and the O2 will show this. That's why it is best to tune in the coldest possible weather for a given situation.

From your chart, and the timing - you are running lean even though your O2s are fine (yet another reason why you can't tune based on O2s). Add some fuel and I bet you won't creep as high as you are now.:D

-M
 
Originally posted by Phoenyx
Exactly. As this proves my assumptions - even on consecutive runs, you are getting different O2 values.

Sure the O2 will change from temperature to temperature outside. The mass of air changes so you will get more lean in colder whether and the O2 will show this. That's why it is best to tune in the coldest possible weather for a given situation.
actually with the stock mas, the air mass is calculated using the temp at the filter (among other things) it doesn't actually measure the mass.

my hotwire mas measures the airmass, density doesn't matter.
From your chart, and the timing - you are running lean even though your O2s are fine (yet another reason why you can't tune based on O2s). Add some fuel and I bet you won't creep as high as you are now.:D

-M

those WERE my thoughts, unfortunately in practice, it didn't work that way. If I lean it out more, my creep goes away and 02s become more steady, although the 02s are lower (.90-.92) and timing is the same (~12-14).

if I richen it up (those I showed were wot at -5% or -10% - makes no difference in timing/o2 voltage) timing goes to 4 and stays there, never moving when I have the go pedal down (I richened in 5% increments up to +20% and they were all the same (.94 02 voltage and 4 deg advance). <<this doesn't make sense does it? but when I lean it out 02s go .94, .94, 1.02, 1.00, .98, .96 I think the 02 the ecu may be mistaking 1.04 for .94

arrgh, so frustrating, this tuning thing is.
 
Originally posted by nine5raptor

actually with the stock mas, the air mass is calculated using the temp at the filter (among other things) it doesn't actually measure the mass.

my hotwire mas measures the airmass, density doesn't matter.

Density is equal to air mass. And the ECU does calculate this air mass some kind of way. It's displayed in the datalogger.



those WERE my thoughts, unfortunately in practice, it didn't work that way. If I lean it out more, my creep goes away and 02s become more steady, although the 02s are lower (.90-.92) and timing is the same (~12-14).

if I richen it up (those I showed were wot at -5% or -10% - makes no difference in timing/o2 voltage) timing goes to 4 and stays there, never moving when I have the go pedal down (I richened in 5% increments up to +20% and they were all the same (.94 02 voltage and 4 deg advance). <<this doesn't make sense does it? but when I lean it out 02s go .94, .94, 1.02, 1.00, .98, .96 I think the 02 the ecu may be mistaking 1.04 for .94

arrgh, so frustrating, this tuning thing is.

Only thing I can think of is that MAS (or O2) isn't doing something right. What is your knock sum? At what rpm?

-M
 
Originally posted by Phoenyx


Density is equal to air mass. And the ECU does calculate this air mass some kind of way. It's displayed in the datalogger.

density = airmass/volume

the stocker uses the temp/baro pressure/input from the vortex sensor/others to calculate the amount of airflow each cylinder gets per rotation, the important thing here for our discussion is that the ecu does actually acount for variations in temperature by itself.

Only thing I can think of is that MAS (or O2) isn't doing something right. What is your knock sum? At what rpm?

-M

unfortunately, I can't read knock sum as I have a 2g.
 
Originally posted by nine5raptor

density = airmass/volume

the stocker uses the temp/baro pressure/input from the vortex sensor/others to calculate the amount of airflow each cylinder gets per rotation, the important thing here for our discussion is that the ecu does actually acount for variations in temperature by itself.

Not when its being fooled by a piggyback.;) Since this is the case, you'll have to go by timing or knock instead of any other readings.



unfortunately, I can't read knock sum as I have a 2g.

Hmm...then you will have to go by timing. Lean it out some more till you get about 15-17 timing at the upper rpms. This would be ideal. Richening it is causing the timing to drop (which makes sense). You won't be able to get more timing out of it unless you have some timing controller.

-M
 
Well you guys are whoring Kakoriat's thread, but I will try to answer some of the questions.

Sorry I didn't see this sooner, I rarely read the tuning forum.

I don't have the log anymore but I remember the trend.

The car started timing low but normal, just as mine does and it was starting to rise, it got to 14 and immediatly dropped to 13 then 12 and held steady at 12 to where ever he shifted. That means the knock sensor was sensing something to me, whether its knock or phantom knock, I don't know.

O2's were constant around .94 but I don't put much faith in that. He was running reltatively low boost (15 psi I believe) which should be more than possible on pump gas.

Like he said, I was able to get 24 degrees on my 13.4 run with the T25, but I was able to lean the car out enough to get on a better timing map. His is pulling timing for some reason on this timing map and I am not sure why.

Have any suggestions, Larry or anyone else?
 
Gotgrip touched on a tuning tip above; even though 2G's can't read knock, you can watch the timing to see how it changes, and that will tell you if you are getting knock, and at what rpm it happens, but it won't exactly tell how much knock. A normal timing curve won't have any sudden changes, it should only change by one or two degrees at a time.
 
Nine5raptor, your two runs are a good example of what to look for. Run #1 is a good baseline, run #2 shows the timing being pulled at two points, that's knock. I'm willing to bet that the intercooler and intake tract wasn't cooled enough from the first run. Next time stop the car, go over to the intercooler and feel it's temperature. If it's still warm, just drive around without boosting for a few more minutes.

Kakoriat's timing might just be from running 15 psi with no AFC. The ECU was seeing a lot of air coming in, maybe saw a little knock, and that put the ECU on the poor timing map. This might be a case where 13 or 14 psi would be faster.

Even at these early stages of modding a logger helps tremendously. I'm thinking that a logger should be one of the first mods.
 
Originally posted by pneumo
Even at these early stages of modding a logger helps tremendously. I'm thinking that a logger should be one of the first mods.

I agree completly, I can't believe I ran my car without the logger now, I wish I would have had one from day one.

The thing about your theory of too much boost, putting him on a different timing map... I don't think that is the case because of the way it dips down. The only reason it would dip would be knock right? I think the main thing here is trying to figure out why he is seeing knock or phantom knock.
 
Originally posted by pneumo
Nine5raptor, your two runs are a good example of what to look for. Run #1 is a good baseline, run #2 shows the timing being pulled at two points, that's knock. I'm willing to bet that the intercooler and intake tract wasn't cooled enough from the first run. Next time stop the car, go over to the intercooler and feel it's temperature. If it's still warm, just drive around without boosting for a few more minutes.


I shouldn't be having issues with heat soak. Mine runs are done while driving to/from work. I usually go for about 3 runs during my 45 min drive on the highway. My bumper is ported all to hell to increase flow as well.
 
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