cam swap tuning

[mark21742]

I'm swapping my 220/224 .570/.580 112 out for a 236/242 .580/.590 112lsa in my 04 a4 GTO. using Hptuners I tuned in the old cam myself (with help). will this bigger cam be alot harder to tune in or if I go about the whole process the same way as last time be about the same?

just wanted to know what i was up against!

[Frost]

All of the same steps as before... VE and MAF calibration, idle airflow setup; etc

[0rion]

same process but you'll probably have to spend more time in the idle areas.

[mark21742]

ok sounds good, the last one only took a few weeks to get it perfect with 50 million questions answered by you guy lol so I think I know more what I'm doing this time lol
just heard the bigger the cam, the harder they were to to tune

[Frost]

They aren't so much harder the bigger... cams with 228 to 235ish degrees of intake duration and 110-112 LSAs can be bitchy when they want. Not all of them in that range are bad, but I have tuned a lot of grinds from small to large, and that range has the most 'problem children'. I have seen a Trex (110LSA) run relatively well on a stock tune with a properly setup throttle body, and a 228/233 111LSA cam that refused to idle at all on the stock tune in two days back to back. Back then I had originally partly expected it to be the other way around.

[mark21742]

Ok got her fireduo and running. It idles decent at 975rpms. While driving I had some bucking between 1,500-2,000 rpms in drive, drop it down into 3rd and runs fine. Is this a tunning issue, or inherent in a larger cam.

Also I have the VE tuned in pretty good below 4,000 rpms, and using my original PE above 4,000 at W0T its going lean to arout 14.5:1 according to the wideband... Should I fix this by "guess" adjusting the upper VE, or fix it with PE?

Thanks again guys!

[Frost]

Ok got her fireduo and running. It idles decent at 975rpms. While driving I had some bucking between 1,500-2,000 rpms in drive, drop it down into 3rd and runs fine. Is this a tunning issue, or inherent in a larger cam.

Also I have the VE tuned in pretty good below 4,000 rpms, and using my original PE above 4,000 at W0T its going lean to arout 14.5:1 according to the wideband... Should I fix this by "guess" adjusting the upper VE, or fix it with PE?

Thanks again guys!

If you still have a MAF and haven't changed it's crossover point then you are all "on the MAF" by 4K and that is where your error is.

For the bucking, you need to get your VE/MAF tuned firstly, and then your idle airflow. Often times this gets rid of the majority of it. Anything you have leftover can be addressed at that point and is most likely excess airflow from somewhere like the throttle cracker or throttle follower.

[mark21742]

I'm running SD mode, the throttle cracker was 0ed before, but set it back to stock setting because the motor would stall on rev dpown and on the brakes (like when coming to a stop light)... So I should try backing the cracker off some?

For the high rpm lean, I'm street tuning it not dyno, have threshold set up to 8,000rpms... I guess just drive around back roads in 1st gear to get stfts for the higher rpms too?

[0rion]

not really much more to add but had a question.... you say it's bucking in "d" at 1500-2000 rpm's but not when you drop it to 3. What mph are you at in D and what do your lock up settings look like for the converter?

[0rion]

I also think some of your issue is trying to tune using the stft's. Hook a wideband up and tune the ve using afr error and that should help. Frost can probably answer this better than I can but I wouldn't try tuning the upper rpm's by holding first gear....the load on the motor is completely different. Find an open traffic free road and tune by running through the gears normally. I still think the root is using the stft's....afr error would be much better.

[Frost]

Yes, ditch the STFT tuning.... to get good averages out of the transitional garbage can take forever! I can go over a VE table in about in about 10 minutes and have it to the point where I am into fine tuning the last 2-3% error (minus WOT). The second pass gets it most of the way home. After that, you can touch up with STFTs later but it should be good. If it's 14.5 up top, just multiply 90kPa and up to add fuel. Set your OLFA to about 1.02 (14.4ish:1) from 176-up everywhere so that your AFR isn't moving around while you are tuning it. That helps diminish transitional error and wideband lag.

With the bucking though, you need to get this done first so that you can go back to idle airflow tuning. You must have this done first so that you will be able to see what you need in the TC.

The bucking is annoying though... Note the MPH and RPM that you get bucking and reduce the TC by half in those cells and see what you get. You may want to log the TC and TF to see what is going on where the buck occurs too.

[mark21742]

Thanks again guys!

I have the lc-1 hooked up and the a/f error histogram... Was just using the stft to tune by and keeping an eye on the wideband.
How do I use the a/f error, do I copy/paste special its averages like the stft?

Yes the bucking is only in 4th gear between 55-59mph in the 1,500-1,900 range at almost closed throttle cruising, torque converter is set to lock at 35mph (3,800 stall)

[0rion]

yes, the theory is the same for afr error as it is for stft error as far as the copy/paste goes. You should put the car in OLSD and disable dfco though so your trims aren't effecting your fueling. Look in the hptuners help under the user submitted stuff. It'll tell you exactly how to set the car up in open loop to tune using afr error.
I became a big fan of CLSD this summer. I ran OLSD 2 summers ago and didn't like how much the car varied depending on what the outside temp was. I would log going into work during the day and it would be completely different from the log I would have going home at night....I was just chasing my tail. Then I went back to the MAF. Ran that last year and it worked fine and was consistent but had a few quirks here and there. Put the car in SD towards the end of the year but left it in closed loop. Love the way the car drives now. Also by doing that plus a couple other things I picked up .3 at the track.

[mark21742]

yes, the theory is the same for afr error as it is for stft error as far as the copy/paste goes. You should put the car in OLSD and disable dfco though so your trims aren't effecting your fueling. Look in the hptuners help under the user submitted stuff. It'll tell you exactly how to set the car up in open loop to tune using afr error.
I became a big fan of CLSD this summer. I ran OLSD 2 summers ago and didn't like how much the car varied depending on what the outside temp was. I would log going into work during the day and it would be completely different from the log I would have going home at night....I was just chasing my tail. Then I went back to the MAF. Ran that last year and it worked fine and was consistent but had a few quirks here and there. Put the car in SD towards the end of the year but left it in closed loop. Love the way the car drives now. Also by doing that plus a couple other things I picked up .3 at the track.

yup, ive been running CLSD for the last 1 1/2 and love it.

thank you for the info, I'm heading out to do some more logging!