CC503 cam
1.6 Pro Mags
Stock heads

In the switches menu, I have the calibrations options table. In that table you can "X" several options. If I "X" the speed density mode, my car will run in speed density mode correct?

I am trying to workout some wicked camsurge at around 1000 rpms. It is the only part of my tune that really has issues. I'm wondering if I can find the problem in speed density mode.

For example, if I pull into a gas station and am driving around waiting for a pump to open, this thing will buck and surge wickedly.....we are talking whiplash/necksnapping type surge. I'm always around 1000 rpms and extremely light throttle(~5%) when this thing goes crazy. I have to constantly clutch in and out just to move around.

I don't know if fueling or timing is the problem. I have advanced the timing with little to no change(I have not tried pulling timing yet).

The funny thing is that I can ease out on the clutch, without any throttle, the car will pull itself without surge @ 800 rpms. When I tip into it from this point, the thing surges something wicked until I get above 1200....then it snaps out of it.

Any ideas and input are welcome!

 

Unplug the o2's to run it in open loop, or get a smaller cam.

Running too big of a cam in a street car is the best example of "bigger is not always better" that I've come across.

 

I wanted to see if anyone else could chime in, but I did not think the CC503 was a "big" cam. I've been told it's the biggest of the small.

 

that is not a "big" cam....

I have installed it in several cars with zero issues as far as streetability....

I am sending you a pm eric

 

Sounds lean. Also sounds like it could be a typical missfire due to low cyl pressure or ignition, but also typical of false 02 lean-ing (due to cam or other problem).

First off:
1) Does it run ok shortly after a PCM reset? If so the 02's are to blame likely from pulling fuel. Timing in this area should not jump at all, it's probably the most sensitive area (will not create bucking but will create an overall degraded driving experience.

2) Do what MikeGyver says and unplug 02's and reset PCM and give it another shot. If it runs better and continues to run better then all you might need is leaving the 02's unplugged and some minor MAF/VE tuning.

3) If that does nothing then UNPLUG MAF and run off only MAP sensor, but this is dependant on VE settings which arent normally used.

4) If that shows no improvement or is much worse fix VE's by running 02's, without MAF, and apply VE MASTER a couple times, once VE Master re-aranges tables see how it runs, keep VE Mastering until no improvments are noticed. Finalyl if no improvement over original then you might want to run OPEN LOOP again and enrich the entire area manually in the VE tables (with CLOSED LOOP DISABLED) so you can read the 02 readings and see if it's lean spiking on you, that would simply mean it's a fuel or VE or MAF problem.

Basically real surge/buck can be the result of either a lean condition or cam, they both feel the same. Rich conditions usually are repetitive and somewhat predictable, bucking/surge/lean is all the same and cannot be distinguished since the result (random weak cylinder pressure) is the same. By running the tune rich in the area of suspected surge you are eliminating the possibility of a fuel lean problem and the last thing to cheack is either too much timing or the actual cam causing the problem.

In the end, if it simply runs worse with 02's and time, and everything else you have done has no real effect such as checking injectors, exhaust leaks, etc check then what's happening is the 02's are leaning out the mixture since the cam messes up 02 calibration. Without the 02's you may be able to optimize the power/smoothness but it will never be perfect and you will likely always have a bit of cam surge, but not as bad as when the 02's take control.