At 33* you are going to run into trouble at stoplights and in summer time heat in my experience the coolant temp will just creep right on up.

You also want to be careful just adding a bunch of timing at part throttle just because its not knocking doesnt mean its best. If you put it on the edge of retard then the transient conditions are what will kick your rear (knock retard). Advance on its own does not make hp or improve anything. There is only one setting that is dead on correct for timing at a given rpm/load point, and it is hard to find outside of the lab. Then again what if your intake air temps go up, or you get a lower quality tank of fuel than you tuned with.

As far as that goes I stay very conservative with my timing. The lt1 pcm is not very graceful with pulling timing. It tends to way overshoot whats required and it also remembers where it has had trouble in the past and will keep on retarding at that point. Generally speaking when the pcm retards timing the car will feel like a complete dog.

Everybody has a different take on timing some tuners at alot and are really aggressive with it. Just one of those things you gotta pick a side on or try both. I havent ever found anything in it. Sometimes though its necessary to adjust timing and smooth the table to eliminate/minimize cam surge.

That is a good website I used that when I started. I have since developed some of my own theories and methods although his are pretty good.

 

So should I back the timing off at Idle even though It raises the kpa reading? I drove the car all day today and had no problems at stoplights and got small cam surge at around 1500rpm, but thats fine with me.

It runs like a raped ape.
and since I only tuned for idle, It should still be using the stock settings everywhere else right? Is that safe?

also, what should I change in the DFCO tables for a little better MPGs.

Thanks for the help and sorry for asking so many questions

 

Wait till its 100+ outside and the pavement will give you 2nd degree burns on bare feet. Your coolant temp will creep right on up with that much idle timing in traffic. I dont doubt that it idles smoother with that extra timing, and I run mine around there when winter has really set in. You'll also want to make sure that the increase in vacuum is seen in closed loop not just open loop. Its possible in open loop mode to adjust idle air fuel mixture and increase vacuum quite a bit. Closed loop doesnt do such a good job of picking out fueling for a cammed engine and vacuum suffers.

Everything else should be ok for part throttle. Your blms will tell you if the tune is good enough in part throttle for sure.

I would not be suprised if your wot fueling and timing needed quite a bit of adjustment. I wont speculate on where you are at now on a/f ratio due to the variations i've seen between other cars.

Never really messed with dfco, havent felt the need to. I manage 17mpg in town and 27mpg at 65-70mph. Get about 22-23mpg on my daily commute.

 

alright I get it now, I backed it off a little at idle. I just got done recording a log with freescan, I'm seeing knock retard at 5 max when I WOT. the MAP readings were not at 100 but I think thats because the tires were spinning and there wasn't enough load.
here is the dattalog If you want to look at it, and tell me if you see anything else wrong.

thanks.

 

Knock retard at wot is because you're trying to run 38* of timing at 2000 rpm under a pretty good load, back it off its too much too soon. I'll leave it to you to figure out where you need to adjust timing as its a good exercise.

You also need blm locker to have any chance of getting your wot fueling nailed down, looks like its going to be rich at a glance.

You may also want to adjust the tps% point at which you get into wot fueling. The stock setup is pretty conservative about when it declairs wot. I like to get into pe mode at much lower throttle positions it helps avoid some knock retard.

Are you at high altitude? your map value before startup looks a little low. This time of year unless you live in the mountains atm pressure should be about 100kpa not 80. Could also be some sort of issue with the map sensor or harness. Although your wot map values kind of backs up the poor atm pressure. airflow looks a little low to me but if the air isnt very dense then its probably correct.

Pretty bad split blms at idle and when you let off the throttle and coast. Takes way more energy and time to troubleshoot/cure this than I care to put out here, search will yield good results for ideas.

Might be some sort of issue with your vss seems to be bouncing around early in the log when you touch the gas cant really tell if you're moving or not but its a pretty quick jump from 0-3 back to 0 again hard to tell but it looks very jumpy.

Also when you go wot, its best not to hesitate and go a few percent and then nail it. If you're going to go wot for logging purposes just commit to it and jam the gas to the floor.

 

OK, I brought down the timing a couple points in the main spark advance table at 1800 thru 2400rpm and 60-75 KPA.......man, I hope I'm doing this right.

I'll load the tune tomorrow and logg it again.

Yes, the altitude here is ~5000.

And yes, my Speedo seems to jump when I rev it up. Is that messing with the PCM?

 

When the pcm detects more than like 1/2 mile an hour it pops out of cell 16 which is the idle cell. Sometimes it can cause a somewhat erratic idle because theres different schemes for the iac etc in cell 18. Generally it will cause the idle to hunt or in some cases create problems returning to idle because it thinks the car is moving to it uses the iac follower program.

 

Hey guys, I'm the one who wrote the page you referenced.

If you're not getting knock at idle with the higher timing, then I'd bump it back up to the place where your MAP is lower. If you check the link I reference on my page about idle timing, Christian also found that increasing timing lowered engine coolant temperature.

I know it sounds strange, but it makes sense if you think it through. You're getting a more efficient combustion, so there is less unburnt fuel igniting in the exhaust or on the way out of the head.

Now, if you increase timing beyond measure, that can certainly cause trouble including overheating (due to pre-ignition). But if you don't have knock, I'd put it back at 33*. I bet your MPG will increase with it there, over 28*.

For DFCO, on most bigger cams, something like 28 for enable and 30 for disable works well. I put the DFCO retard a few degrees over the 1200RPM closed timing value, to get a lot of engine braking.

Have fun! Glad to hear my page is helping people!

 

/\ /\ Hey, where have you been? Looks like we always get some folks needing new tuning help.

FYI, I run my idle at 40* and 1000 rpm but look at the size of my cam. Squeezing out all the vac I can at that timing.

 

Yeah I did my own experiment on the timing, it didnt like it AT ALL during the summer months when it was 100+ in traffic. Knocked it back down to the high 20's and all was fine. Every engine is going to behave differently. I do not accept christians experiment with no questions asked on the basis I have no idea what the engine was or how much modification had been made to the original tune. If he didnt adjust individual cylinder fueling at idle etc then maybe he was just helping the majority of cylinders.

I will not argue with the vacuum increase, that is correct from what I have seen. At the end of the day do whatever your car likes not what me/you anybody else thinks its likes. Just because one engine liked something that does not mean any other one on earth will.

 

WS6T3RROR, when you looked at my log, you said that I was getting knock at around 2k rpm because I was trying to run too much timing too soon. since that was still on the stock part-throttle timing, does that mean that my cam (CC306) needs LESS timing??

 

Hey Blackhawk, nice to see you on here again! I've been around, helping mostly through my website lately. My car recently overheated and it either cracked the block or lifted the heads (coolant in cylinders). :/

ICFT mods can make a noticeable difference at idle (and part-throttle) too, I agree. For the record, Christian's car had a Hotcam and 11.4:1 SCR. So his results are even more amazing considering the high static CR.

With my customers, I like to use their IR thermometer readings of their cylinder exits in open loop in order to tune the ICFT table and get the cylinders running as closely together as possible. That will also help solve split BLMs.

WS6, if your car liked the higher timing until it got hot out, then you should consider using the Spark Coolant Correction table to take timing out at the idle kPa areas at the coolant temp at which you were having trouble. That way you'll still get the better combustion when it's cooler. Same would go for part and wide open throttle.

 

The most timing that gives you the least load (lowest MAP value) and lowest IAC counts will also give you the lowest coolant temps since your using the least amount of fuel and your motor is doing the least amount of work, also the motor will be the quietest at this point (all three will be minimized). It's up to you to decide where you think that point is. If you go to far it will start to run rougher, but it will run the smoothest right before you cross the line of "too far". Easiest demonstrated with a mechanical distributor you can move while running.

I have my idle timing at 35 degrees. It takes forever to heat up but idle is basically free-spinning and it uses the least of everything.. now I wish there was a temp vs idle timing table somewhere so when it's cold I can retard it to make it idle/work harder and warm up faster...

The reason timing is soooooo retarded on stock cars is to get temp up fast and pass emissions... (getting temp up is good for multiple reasons and obviously passing emissions is good too).