Anyone have issues with decelerating surges on a 230+/230+ cam? Was out with my friend's Torquer v.2 this weekend and he had some pretty nasty surging when off the gas below 1700rpms. Fuel trims were -3~+1, so I knew it wasn't fuel. So, we experimented with spark. I upped the spark advance to one number (42 degrees) in the 'base spark in gear' table and high/low octane tables for the cells he was hitting during the surging (~.14 grams/cyl) and 95% of it went away. No more jumping around. I was just curious if anyone else noticed a problem/solution like this and where their timing is at??? Is 42 degrees too much??? Can I/should I go more to get the remaining 5%???

 

Id like to know as well... Im running 35- 37 in the top 5 rows at 1600 rpm. Ive also tuned for 14.0 AFR (open loop) in the areas where it bucks heavily. Richening it up has certainly helped out a bit, but im not sure how much timing to add either. How far have some of the others gone?

 

TTT. I am dealing with the same phenomena and would like to cure it. Mine surges at varying times from 1,000 to 1,800 rpm. It is really never at any set point. I can sometimes cruise in town in 3rd gear at 1500 rpm just fine, then sometimes it will surge and buck severely.

Oh by the way I have the Comp 232/234 .595/.598 112+2

Dave

 

Is this when you're off the gas (0% TPS)? If so, try to log it when it happens. Then, for the rpm and grams/cyl it happens in...add some timing to that cell and see if that helps. Just remember, high/low octane tables are when you're on the gas above a certain mph. Off the gas (below that certain mph), you need to change the base spark tables (ie base spark in gear). It really helped my friend's car. I wonder if it doesn't happen all of the time for you because of DFCO and it kicking you into open-loop?

 

I am currently running Open loop SD. I am not using a custom OS just the 2000 stock OS. I get it letting off and also tipping into the gas. My current idle timing is set to 32*. The High & Low Octane tables are stock for now. I am getting some Knock Retard above 4000 rpm I have to address first.

I will try logging when it happens. I have DFCO enable speed set to 40mph. I would love to get this solved but if I have to live with it I will.

Dave

 

I ran into this same problem with my 98 w/ 228 cam. From my logs I determined that the cam's higher idle actually bumped up the base table so it was strattling between two very different cells. Notice on the Stock 98 base spark cal I uploaded that the area around 1600 to 2000 is 28, 32. On my newer spark cal you can see I smoothed that over and bingo, no more annoying ocillations btw those cells on deacceleration.

 

Well, I guess the situation I noticed was a little different. His timing wasn't jumping around...just the car.

 

Have you tried using the spark smoothing table? It's specifically for manual cars to control surging at low rpms.

 

He's got an A4

 

I see enabled/disabled, but no table to speak of. Min has always been enabled and I still get plenty of bucking. Throwing tons of fuel and timing and more fuel has helped settle it down a little bit, but its not perfect.

 

I use the absolute timing control in the scanner to help find a good timing range. One car literally had to have 25 degree's of timing or it would surge and buck like you guys are describing. On another car I used over 40 degree's of base timing at low RPM, low load (thanks to Russ K. for the tip/info) to help with other minor issues. If you're running a lot of timing like that, pay attention to how the engine is running and the data your getting back on your scanner to make sure the car likes it.

Just make sure you use common sense if you use the absolute timing, it locks your timing to one value for the entire operating range until you unclick it.

 

230 ish cams seem to do fine at around 28* at idle and just make sure your A/F is dead on..not rich not lean...
and really as long as you get your A/F dead on(with a wideband-not with fuel trims) it should be able to hold a wide range of spark...(I've held idle with as litttle as 20* and as much as 38*
many times the problem is that the IAC motor is not fast enough to keep up with the demands of the cam...
you have to mess with the adaptive idle stuff sometimes to get the surging to stop..
also your throttle cracker can cause issues with bucking while driving..
making sure you have enough air coming in thru holes in the TB blade can help reduse idle issues...get you IAC counts down to around 60ish with AC off and fans off at hot(190-210ish ECT) Idle..
by doing this teh IAC pintle motor is making smaller amounts of airflow changes with every step and can keep up with the needs of idle
you also need to adjust your Base Running Airflow tables to show the pcm how much air it really should have...which will help with idle...

also make your Idle spark maps and High/Low Octane Idle regions match....
the closer they are the less changes they have when transitioning from drive to idle conditions...
the steadier you can make the spark in those tables the more stable idle usually is...even if adaptive idle does some spark movement its all good...it just wont be as jumpy..

you can also mess with the underspeed/overspeed tables(I usually lessen the values and give them less power)

I've made some pretty dam large cams (way more than normal guys put in their cars) idle perfect with just the things mentioned above...
buddy with a beast 259/263 .630/.625 110lsa cam...Idles perfect at 1000rpm's

 

Sweet...I've done a lot of that already and the car's cam'd behavior seems to be pretty close to stock. Just wanted to make sure I wasn't crossing some threshold that may affect the car long-term.

 

great thread, I'm facing the same issues and have the 232/234 Torquer 2 cam. I have a lot of timing, just wondering what to play with next?

 

Can the throttle cracker really make that much difference. Because I had everything you have said setup perfectly but I never touched the throttle crack on my old camaro. And it would always surge right off the throttle mostly around 1500rpm but sometime 1400-1900.

 

 

Moment of enlightenment or frustration?

 

I'd like to here more about how the throttle cracker would help. Mine is much better than it was but it still there enough that I know that it isn't right yet. With all of these damn tables and some of the stories of the gigantic cams running "buck-free", Someone please share the magic.

 

All of this is pointless if you don't have your Desired Airflow and IAC counts in line. So, take care of that first.

Throttle cracker is RPM & MPH dependent. Look at where you're experiencing the problems and then look at those cells in the cracker table. After that, it's just a matter of experimenting to see what your car likes. If your surging is kicking you between a cell that doesn't have any throttle cracker and a cell that does, it's like the IAC is pulsing the gas for you. One number is what you need for those cells (just like spark) so you don't bounce between cells....whether that one number is 0 or .9 or whatever. I think it's when that number is changing/different between cells that you'll notice surging.

Throttle follower is a little different. There, you could probably cut the follower airflow 25~50% after working on the cracker table to see if it cures any remaining issues. Since this table follows throttle movement and cam'd cars typically are more responsive to less pedal vs. stock, this table is probably set too high for the aftermarket cam.

That's my theory. I've yet to put this to practice.

 

My bucking has never been an IAC issue. Ive zero'd out my cracker table, Ive used scanner controls to freeze the IAC, and ive even unplugged the IAC motor. My bucking remains. So far ive cut it back but really jacking up the timing in the low rpm low load section, particularly in the base timing tables. While 800 rpm is set around 28* spark, 1200 rpm ramps up to 42* and it still feels like it needs more. Im scared to be this high as it is, and I dont want to push it any further. On the plus side, looking at the high timing the 5.3L motors come with stock is a bit of a relief.