How do you combat a bucking issue around 1500rpm after a cam install? I have read many threads but no one addresses the bucking problem. I can tap the brakes and it goes away for a while or give it gas. Is it spark or fuel or both? When it bucks does it need more air or fuel or what? I have even put the car in 3rd to get the rpms up a little.

Thanks,
Bill

 

If it hasn't been done already, VE tuning smooths out alot of that, then moving a few degrees of timing in the problem rpm area (2-3 degrees at a time) can clean some of it up. Raising Base RAFs helps the bucking during idle transition to drive in gear. You may still have a little buck, but the smoother the VE is in the problem area, the less you will get. And also, having MAF airflow dialed in correctly assists in lessening the bucking as well.

Everytime I played with one of these parameters I smoothed away alot of my initial bucking! Hope this helps!

 

Which way should you move the timing? What is the Base RAF's?

Thanks for your help.

Bill

 

i really don't think you can clean the bucking all the way with a cam your size...i have had my car tuned and it still bucks...although i'm having second thoughts on how well it was tuned...

 

I have pretty much eliminated bucking unless i'm under 1400 rpm with light throttle. The worst area for me is just trying to idle around in first. It bucks really bad sometimes. Raising the timing in the problem areas seemed to help me.

 

Like has already been said, a good VE table will help alot. What made the most difference for me was advancing the timing in the offending cells. I'm running approx. 35* between 1000 and 1500 in the low load cells, and I've almost completely eliminated the bucking. It'll sometimes start in if I let the rpm's drop to around 1000. You'll never completely get rid of it, but you should be able to minimize it to a fairly good extent.

 

What are the low load cells?

Bill

 

I tweaked my first two cells of the IFR after someone mentioned that it helped with a rich start-up. Cold starts and even hot starts are much better now and I noticed much less bucking, so much so that I can hardly feel it. I added 4% to the IFR to lean the mixture a bit. I'm running a TR230 cam and I've tuned my VE table with a WB. Hope this helps.

 

They would be the cells with the lesser g/cyl (Advance) or MAP (VE) for a given RPM. In other words, the ones closer to the top of the VE and Advance tables in HPTuner. Log a run in HPTuner, and do some driving around at 1500 so the bucking starts up. Afterwards, isolate the cells that you are falling into under those conditions. First, look at your LTFT's and STFT's so you can verify that your VE table and fueling is in line. Then look at your advance. In those cells, add some timing. Then relog, and see if the problem gets better or worse.

Also, you can try disabling Idle Proportional fueling. It didn't help for me, but it does for some people.

If you would like, you can send me a log of the bucking and your current tune to bluetorp@yahoo.com . I should be able to help you minimize the bucking to a large extent.

 

Now that my fueling is right I was able to re-enable Proprtional fueling. The worst I get now is where you can feel that slight surge every once in awhile, but nothing I would really call bucking anymore.

 

Thanks for the offer but I am using FlashScan.

Bill

 

i would suggest the ve tuning & adjust your tc lockup tables to unlock at the point where you'd start to get it so you dont have to deal with it

 

I am planing on VE tuning this week and this weekend. I am just looking over all the info on how to do it.

Do you know what TC table I need to modify in FlashScan. I was wondering if changing the TC would help.
Thanks.

Bill

 

Mine did that a lot, until I tuned it. (about 150 miles ago)The tune helped, but I have noticed that the more I drive it the less it happens. I still have some fine tuning to go, but it is pretty tolerable now.