A4 cam swap reprog
01-29-2002, 04:38 AM
#1
Staging Lane
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A4 cam swap reprog Why do autos need to be reprogrammed after a cam swap? How does a cam set off the SES light? I've been thinking about doing a cam lately and would like to get by without programming if possible. I am looking at going with a small cam but would still like to get just under the stock computers thresh hold. I remember when Brooke did his heads and cam a couple years ago, he had the idle speed set and either had the MAP removed or altered in some way. Does a cam cause a big enough difference in vacuum to confuse the comp? What about the cam causes the need for programming, is it just the LSA or does the duration effect it?
01-29-2002, 09:40 AM
#2
Re: A4 cam swap reprog Hey Lawrence, good to see you post and glad you are modding the new car again.
The A4 computer programming is mostly for drivability issues, not performance issues. The MAP sensor is sensitive to overlap, either from less LSA or increased duration. Running a 114 LSA and something less than a 220/220 cam might be okay with the stock MAP settings. The SES lights are mostly P0300 random misfire codes and are caused by lopey, lower rpm idling. Raise that idle to 900 rpm in drive and that usually takes care of the issue. The other nice custom programming features for an A4 are raised stock shift points. The way MTI was having them done before, you had new elevated "stock" shiftpoints and could still use the HPP3 to move up and down from those newer raised values. Worked great!
You can also delete your rear O2 sensors, delete EGR and AIR crap, delete certain pesky SES codes, raise your rpm limiter, adjust for gearing ratio, etc... all at the same time.
Tony
The A4 computer programming is mostly for drivability issues, not performance issues. The MAP sensor is sensitive to overlap, either from less LSA or increased duration. Running a 114 LSA and something less than a 220/220 cam might be okay with the stock MAP settings. The SES lights are mostly P0300 random misfire codes and are caused by lopey, lower rpm idling. Raise that idle to 900 rpm in drive and that usually takes care of the issue. The other nice custom programming features for an A4 are raised stock shift points. The way MTI was having them done before, you had new elevated "stock" shiftpoints and could still use the HPP3 to move up and down from those newer raised values. Worked great!
You can also delete your rear O2 sensors, delete EGR and AIR crap, delete certain pesky SES codes, raise your rpm limiter, adjust for gearing ratio, etc... all at the same time.
Tony
01-30-2002, 05:25 AM
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Re: A4 cam swap reprog So in theory if I used less duration I could run a tighter lsa and to get more duration I would need to use a wider angle? Something like 216/112, 218/114, and 221/115 could possibly all work without tripping a code? Would the off the shelf MTI cams work with stock tuning if the tb were drilled slightly to raise idle? But if you were to drill the tb hole to much it could set its own code right? In new territory with an auto and just trying to figure it out.
[ January 30, 2002: Message edited by: laZy ]</p>
[ January 30, 2002: Message edited by: laZy ]</p>