FAQ: How to tune the PCM? (Series II SC)

Abaddon wrote:

However, you may find that the "smooth" version doesn't necessarily work out. Tune to what it needs, not how pretty the column looks.

I don't want it to be a perfect curve like the stock table is, but something smoother would be nice. It is a bit noticeable under acceleration when it hits one of the lumps.

I export the table into Excel and graph it there, then manually smooth it if needed. Generally the areas that need smoothing are places that just got skipped over during tuning runs. It's important to take a lot of scans when you are making your tuning drives, go over the same areas again and again so you get more than one sample.

After a while you get to know the numbers.

Also, what Abaddon is saying has a lot of merit - the actual end result may need to have some spikes or dips in small areas for special reasons.

Still a n00b HPtuner, please help me understand this if you can..


I have my power enrichment tables set up in a way that it is giving me exactly what I want to see for commanded AFR in PE mode.

But I am actually getting super rich AFRs low 10s! yuck.

Do I need to use the AFR error % histogram to tweak my MAF table? Is that how i get the actual AFRs to match the commanded AFRs? Thank you

I thought E85 was supposed to run super rich.....?

you need to run ~30% more e85 so more fuel inherently means a greater rich afr by roughly 30% I have known a guy making 500+ whp on corn and runs high 9s for afr for certain areas

matt270avian wrote:

I thought E85 was supposed to run super rich.....?

gojo83 wrote:

you need to run ~30% more e85 so more fuel inherently means a greater rich afr by roughly 30% I have known a guy making 500+ whp on corn and runs high 9s for afr for certain areas

not quite, guys.

charlieRobinson wrote:

matt270avian wrote:

I thought E85 was supposed to run super rich.....?

gojo83 wrote:

you need to run ~30% more e85 so more fuel inherently means a greater rich afr by roughly 30% I have known a guy making 500+ whp on corn and runs high 9s for afr for certain areas

not quite, guys.

well he made 608 whp at 5280 ft altitude so he knows a little bit. It may not work for all people but for him it works.

gojo83 wrote:

charlieRobinson wrote:

matt270avian wrote:

I thought E85 was supposed to run super rich.....?

gojo83 wrote:

you need to run ~30% more e85 so more fuel inherently means a greater rich afr by roughly 30% I have known a guy making 500+ whp on corn and runs high 9s for afr for certain areas

not quite, guys.

well he made 608 whp at 5280 ft altitude so he knows a little bit. It may not work for all people but for him it works.

He may know a lil bit, but you do not..

Yes, you must use 30% more fuel when running e85 but it is not rich. It just takes 30% more fuel with corn to reach stoich. Running rich on e85 would be like 35-40%, if you want to talk percentages.

I see a lot of mention of "if you have a 96" and "if you have a 98-99" but what about those of us with a '97? Can we tune our car with HPTuners, or do we have to re-write the PCM of another car (say, one of these ?

I can's say for HPT, but the rare DHP works on '96-'05 (or so) 3800's. The only 3800 I'm yet to find it will not tune is the '99 Riv. It's locked out for some reason.

I can 100% confirm HPT works for a 97 Riviera. I did it twenty minutes ago lol.

Deekster, were you the one who posted a link to a bunch of tuning resources? PDFs and things.. I thought it was in this thread but I cannot find it. Thank you.

Thinking of getting HP Tuners, is there a need for the pro version?

My PCM is on the way back from intense. I'd rather leave it to somebody who knows what he was doing then my learning curve on hptuners.