Correction Maps

[Rickertsen2]

what are your thoughts on correction maps. IE coolant temp, barometric pressure, etc. Most ECUs come with some base maps that look reasonable and we don't usually modify them. Our cars our however sensitive to weather and don't always like to start. What methods do you employ. Is it worth the effort? IMO There are alot of FSAE Cars with bad tunes. There is no reason why these cars shouldn't start and run and idle like the stock bike.

[Rickertsen2]

what are your thoughts on correction maps. IE coolant temp, barometric pressure, etc. Most ECUs come with some base maps that look reasonable and we don't usually modify them. Our cars our however sensitive to weather and don't always like to start. What methods do you employ. Is it worth the effort? IMO There are alot of FSAE Cars with bad tunes. There is no reason why these cars shouldn't start and run and idle like the stock bike.

[JamesWolak]

Intake and engine temp corrections are a good idea at the very least. Not just to make you car run better but in order to save your ass when you're overheating.

At the very least you should be removing timing when your ET/IT are getting too hot. I think ours is something like 1 degree of advance removed per 10 degrees f above 220(et) and something similar for intake temp but started at a much lower temp.

For start up there should be some sort of cranking comp/post start comp that will help you with your start up issues. You can also use engine temp comps to help too.

You should also play with you accel/deccel comps for drivability

[Pete M]

There have been a few threads on this topic and much good advice has been given.

Basic summary is that compensation tables are there for a reason, and the ones like AT and ET are basically compulsory and i don't understand how you could consider you've tuned an engine without them. Bad ET compensation is 90% of the reason FSAE cars don't hot start imho. Many teams tune their base map to start well cold rather than using the ET comp, so when it tries to start hot it's horribly too rich.

[Wesley]

We had our unveiling this year when it was 28 degrees outside this year, and it started on the third crank. It starts that well whether it's hot, cold, snowing, or raining.

A lot of it comes from running an F4i for 6 years, but we don't consider the engine tuned if it can't start. As a matter of fact, I don't even touch the upper load/RPM until it will start hot or cold, idle, and free rev smoothly and tolerate throttle drop without stalling.

It is nice, however, to have a climate that will see both Detroit and California extremes in less than a month. If we're lucky we can tune it for cold weather AND for hot before the frame's even built.

Enrichment tables are critical. Also, a lot of iteration between incrementing idle pulsewidths and enrichments to balance out where the fuel should come from is important.

Air temp is less critical to enrichments than coolant temp by a long shot. I don't have our map in front of me, but it's probably around 6 percent at 40 degrees, whereas engine temp is around 30 percent enriched at 40 degrees. (Fahrenheit)

It HAS to be tuned by trial and error, because you will get terrible 02 readings (plus, tuning idle with an O2 sensor is tough anyways, due to fluctuations at that low of an RPM)

It's so nice to be able to just light off the engine when you hear teams around you cranking furiously. On top of that, proper enrichments allow you to save fuel on endurance by not idling in line - you also make better power than an improperly tuned cool engine.

It's going to be interesting trying to duplicate that with the Aprilia this year, I hear they don't start worth a damn on the bikes, much less an FSAE car.

[JamesWolak]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Pete M:
Bad ET compensation is 90% of the reason FSAE cars don't hot start imho. </div></BLOCKQUOTE>

I wish that was our issue. Instead we eat batteries like no other.

[Type Q]

I am going steal a line from Carrol Smith. When asked to comment about an FSAE car that had a large over-built cooling system/radiator, he said, "A race car that can't cool itself, can't do anything else."

So I'll add that a race car will not start, will not do anything else.

[Pete M]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by JamesWolak:
Instead we eat batteries like no other. </div></BLOCKQUOTE>

I'll admit that I've been spoiled by the CBR's great alternator. We've always had an electrical power surplus in competition trim, with the battery charging both at idle and whilst driving. But we've never really had to do anything special to do that.

Still, i've heard many, many SAE cars cranking off two batteries at way higher rpm than we crank at and still not starting, many of them 4 cyl 600s, including CBRs. Our battery is a cheap conventional VRLA motorcycle battery that weighs 2.2 kg. Engine reliably starts within a couple of revolutions.