Cool man. Maybe this weekend I will try your strategy of more timing to see if it smooths the car out a little bit but I don't know how well it will work with stock compression... I really need a new motor. It'll happen eventually when I get some time to build it (or if this one blows!)

Every time I asked about cam surge, people say pull timing out. Does a low compression motor allow you to run more timing across the board?

Also, since you seem to have your tune sorted out pretty well, did you have to alter the VE tables or MAF calibration tables at all to get it running right?

 

I'd be suspicious of that claim. What exactly are the true symptoms (RPM range, throttle position, AFR, Open/Closed loop, etc.) of the "surge"? Also, what logic are they employing in ascertaining the problem to be too much timing as the cause. I am curious about the logic employed. It may be correct, from an empirical standpoint, but it seems too simplistic.

I think there would be some advantage in adding more timing with a low-CR engine AT CERTAIN RPM RANGES ONLY!

Note the table below (assuming a 9.0:1 CR):
When you go into boost, your CR starts to equal stock (10.4:1) at about 2.5 PSI, then increase thereafter. Since you probably won't see 2.5 PSI until about 3000 RPM, you could, theoretically, implement stock timing, or slightly advanced, in the <3K range, but you would need to start pulling timing out and adding fuel promptly to avoid detonation.

1.0 PSI 2.0 PSI 3.0 PSI 4.0 PSI 5.0 PSI 6.0 PSI 7.0 PSI 8.0 PSI
9.612 10.224 10.837 11.449 12.061 12.673 13.286 13.898

 

What are your IATs?

 

They don't have any evidence they just say if you have cam surge at cruise (blm cell 6) in closed loop pull some timing out. I did it and noticed a menial change if any at all. I have a feeling I have an eletrical issue or something physical that's causing the surging.

When you say that the CR is about stock at 2.5 psi, what is the term for that? Dynamic CR?? I have heard that term thrown around, don't know exactly what it means though. How do you calculate it??

 

I didn't have to alter the Maf Table at all. The VE Tables I got from Bryan Herter. However, the VE Tables have absolutely no effect on the way my car runs. I could double all the values and it would still run fine.

Moving the MAF to the pressure side made a big difference in the way the car runs overall and made it easier to tune.

I think if you have stock compression you should be able to use stock timing except in the 95-100 KPA areas. Mine runs weak (because of low compression) unless I run more timing in the midranges.

The only major changes I've made to my stock tune was the timing tables, closed throttle timing, and EGR timing(zeroed them out) and PE tables of course.

The stock computer is very adaptive in closed loop. I tried messing with the blm limiting, open loop, speed density and my car just flat out runs better with stock closed loop tuning. Sometimes you have to run the car about 2 weeks to let the computer relearn all its cells before evaluating a change you have made.

Now I know why these dyno tuners make the big bucks.

 

I see. You did pretty much the same thing I did. Other than adjusting constants and stuff (dfco map enable/disable for example). My timing is all stock less the 95-100 kPa range. My VE tables and MAF calibration are untouched.

So tell me, what kind of changes did you make to your closed throttle timing? I'm curious to know how a cam changes the closed throttle timing. This affects idle and decel timing right?

I also moved the MAF to just before the throttle body. I cleaned the resistors when I did that and it really helped a lot but I think it was more the dirty resistor thing... the intake is sealed up pretty tight.

I have a question that's sort of off subject but I have gotten the most answers out of this thread than any other! Did you find it necessary to change the IAC follower table, and if so, what effect did it have? I find that coming to a stop in neutral I get a very subtle surge of about 200 rpms but it's definitely audible. Moreso when cold I believe...

As far as dyno tuning goes... I know a lot of shall we say, mediocre dyno tuners. It seems that people like us start tuning their own cars and then before you know it they are calling themselves dyno tuners while they are still learning on other people's cars. I mean truthfully with a dyno it's really trivial to tune the car at WOT, it's the driveability that requires skill which many of them don't have. There are only a few in the area I'd trust... For example, my friend has a 00 vette with heads, mild blower cam, and a vortech blower w/ aftercooler at 5.5 psi or something like that. The car apparently put down 560 rwhp (didn't see the latest sheet but the last sheet was over 500) but people who have rode in it say it would be a close race with my car and I'm not putting down anywhere close to that much power. We have never had a real race, but on the street if I start pulling a millisecond before him I will keep widening the gap... I don't see how that's possible with that setup. He can drive too its not that... He was tuned by one of those spontaneous dyno tuners. One that I would trust however, is called FFP in roseville... he's tuned cars that speak for themselves.

Now, I have a wideband, tunercat, my garage has been turned into my own little labratory. Once I get a dyno in there Ill be set!!!!

 

Closed TPS Spark Advance Vs. RPM

RPM Deg Spk
0 0.0
400 28.0
800 28.0
1200 24.0
1600 24.0
2000 24.0
2400 30.0
2800 35.0
3200 40.0
3600 40.0
4000 40.0
4400 40.0
4800 40.0


Throttle Follower IAC Offset Vs. MPH

MPH Steps
0 5
4 5
8 5
12 5
16 5
20 5
24 5
28 5
32 5
36 5
40 5
44 5
48 5
52 5
56 5
60 5
64 5

The cam causes it to "coast" so less Throttle follower is needed than stock.

The closed throttle spark advance is very important because it sets your idle timing and your coast down timing. These two tables affect each other so if you change one it will cause you to change the other.

I have to agree. I don't think you can ever learn all there is to know about these computers.