Mine is predominantly at very light throttle in cells 17 and 18. I have tried numerous things in the tuning to get around it but no luck. Cam is relatively mild @ .050 220I/226E/112lsa/.544w1.6/.544w1.6/+.06 so I wouldn't think the surge is undefeatable.

Anyway, please post what worked for you if you were able to beat yours, thanks.

 

I would like to see someone tune out my cam surge... 245/254 112lsa

lol

 

I've read that many have gotten around cam surge with timing changes.

 

Programming out your EGR is the first thing.

A few degrees of additional timing will often help as well.

 

EGR is blocked with blockoff plate and turned off, I have increased timing to 45 degrees in the areas where I see surge with minimal effect. Thanks for the response though. I guess I should run down what I've already tried:

- manipulated BLM matrix (N/A really because the surge is in cells 17 and 18 only, especially 18)

- Leaned and richened MAF to the point of being under 108 and over 128 on block learns, acts the same way lean or rich ...probably worse rich.

- Leaned and richened VE tables, also zero effect.

- Checked the CCP lines and solenoid, seem to be fine. I have yet to try disabling it in the programming to see if that helps. It seems like the surge is worse when CCP activity goes to 0.00

- Checked for vacuum leaks a bit and didn't find any. If vacuum leaks were the problem wouldn't the needle flutter up and down on the boost gauge during surge?

- It has nothing to do with my blower. The surge exists with the blower pulled off of the car and running N/A as I have it right now ....actually seems worse without the blower there putting some load on the engine.

- It's more of a bumpy kind of surge that feels more like a miss than surge.

- It only happens at steady/light throttle under 2K ...the way I like to drive most of the time when I'm not running it hard.

- It's the type of surge you can "drive around" by adjusting your driving habits to drive more erratically on purpose. I hate having to do that though.

- That's about all I've tried and observed.

- I haven't thoroughly checked for leaks around the O2 sensors but doubt that's an issue.

 

It's odd that you mention it in Cells 17 and 18, because cell 18 is normally used for PE mode (WOT running) and I can't remember when cell 17 is normally used. At any rate, they're not cells that are normally used during normal cruising. Are you running an open loop tune? Maybe a PE-idle tune?

 

Surge coming in at around ~2000rpm, or when you are trying to hold steady on the throttle, or cruising at light throttle. Surge goes away if you gas it slightly more through that point or don't hold the light throttle steady so that you have to either accelerate or decelerate a little, or else drop to neutral when coasting.

All (95%) is gone now!!! Even though the surge was small, It feels great driving without the surge!

What worked the most on my car was actually dropping the timing not increasing it. I also adjusted the close throttle spark advance as well. Dropping the timing took maybe 70% of my suge away. Initial timing around 2000rpm was around 38-42 then I dropped it by 4-6 to around 34-37 in the lower Kpa up to 60Kpa and smooth the graph out. During testing I had dropped and added some cells as much as 8-11. Some car like more timing some car doesn't need more timing, just make sure to test with a large enough range to see if there is any benefit.

The next 25% of the surge went away (unexpectedly) when I installed a better bypass valve. I can definintely tell if I switch back and forth the different bypass valves and BOV I had used. The one the works great is http://web.camaross.com/forums/showthread.php?t=405931

Even with the new bypass valve, if I increase my timing back up, my surge will come all back as well.

 

Same experience here...

 

Hmmm, I thought I posted in response to this ..isn't here. Anyway, thanks for the info ....would have never guessed to try dropping the timing. Did you all notice a considerable drop in MPG after dropping the timing down that far?

This is good info but I admit I don't understand it. With a cam you have less VE at low loads/low rpm so it seems like you'd need more timing and fuel to bring up cylinder pressure ...and that that would beat the surge.

I'm not driving the car much this time of year but I will try dropping the timing and let you all know how it worked. I'm keeping my fingers crossed, would be great to be rid of it.

 

i got rid of mine with a open loop tune.
im running cam a little bigger then the 306, with 600 lift
after i installed it car wouldnt make any power until 4k. it really felt like it was struggling to pull its own weight and surging bad
hooked up a wide band to my car and it was showing 17-18 afr when it surged... but my blm were perfect.

got my part throttle afr to aroung 14.5- 15.0 and it ran great... cam surge is basicly gone
also i put the really low rpms to a 13.7-14.0 and gain a bunch of vacume... brakes work alot better now. if i remember my map sesnor reads 45-50 at idle

 

Well I've done significant timing reduction in the lower KPA's <2K and no change that I can tell. I have noticed that it is worse in closed loop, a good bit worse. My block learns are always trying to hit 108-115 in those lower load cells so this tells me that .......the O2 sensors are probably seeing extra O2 from cylinder scavenging and the computer's assuming there is lots of fuel to go along with it, so it lowers fuel integration to compensate for what it "thinks" is a rich condition when in fact there isn't a rich condition, causing a lean condition. I've altered the MAF table before to get the BLM's up to 128+ and still had the surge. Looks like a wideband open loop tune may be the only salvation, and I've never done that .....

 

The above is contradictory to each other. It doesn't make sense. The PCM will react to info O2s send it. The PCM is not able to rationalize or 'think' on it's own.

 

I'm not literally saying it's thinking on it's own lol, just that the limited data it receives causes it to integrate fuel incorrectly. Remember, the O2 sensors can only measure oxygen, they can't measure fuel. At low loads/rpm when they read an excessive amount of oxygen due to overlap and cylinder scavenging it reads say ....... ~.900mv and it subtracts fuel, as that is above the ~.450mv stoich target. The reality is that the ~.900mv reading isn't really rich, it's just creating a high voltage due to the excess O2 being pushed/sucked out of the cylinders. This theory is shared by others as well.

 

As you said, it recognizes O2 not (raw) fuel. High O2... High voltage? Someone has it backwards, or at least is confused.

 

You're not quite with me yet. The computer is confused in a sense because it doesn't have enough information (it has no data to tell it there actually isn't all that much fuel present along with that high O2 reading). I know it sounds backwards, it is working the opposite of how it's supposed to, that's why it's a false lean condition. This is just a theory but I'd bet it's true since my block learns are always low in the surge areas. Honestly I learned this theory from others including dyno tuners who have a lot of experience with tuning these things.