Tuning w/ Tunercat

I have a couple of questions
1. I havent found any PE/ power enrichment tables in my tunercat tables, is it called something else?

2. Fuel trim table are the larger values richer (1.02) and the smaller values leaner (.97)

3. I ve been reading how to adjust the MAF tables so i can add fuel to the Upper rpm range of the car, but am still not sure how to ascociate the rpm with the hertz. I'm :confused:

Any help onthese subjects would be greatly appreciated thanks :)

I'm new at using Tunercat myself, but I might be able to help you out. I think you might have to look at the Main Spark vs. RPM vs. MAP (Ext) for PE mode, but I might be wrong.

This is just a guess since looking at the table it starts @ 4000-7000 and this is of course quite a bit of throttle, possible WOT table...

As for the fuel trim table, I believe those variants represent % of fuel, ex. 1.06 = 106%...

As for the MAF table, I wouldn't know since I own a 93 :)

Goodluck.

Originally posted by CRCDUDE
I have a couple of questions
1. I havent found any PE/ power enrichment tables in my tunercat tables, is it called something else?

% change to fuel/air ratio vs coolant temp @ wot
% change to fuel/air ratio vs rpm @ wot

2. Fuel trim table are the larger values richer (1.02) and the smaller values leaner (.97)

Yep, but why do you want to mess with these tables?

3. I ve been reading how to adjust the MAF tables so i can add fuel to the Upper rpm range of the car, but am still not sure how to ascociate the rpm with the hertz.

You don't associate rpm with hertz. If you look at a datalog you will see that there is a field somewhere that displays air flow in grams per second. Match up the afgs area that you want to add or remove fuel in and look at the right side of the maf tables to find the corresponding area. Lower the numbers to "remove fuel" and raise the numbers to "add fuel".

Right on Dan.

I wasn't looking at my program, but I'm sure I would've said the same thing :p

Told you I was new at tuning:alert:

Dan has it right on all counts..... Ill just add that you dont want to mess with the cylinder trim unless you have a large cam .....then some tweeking of the trims can help eliminate split BLMs.

I have a little split usually somethin like 138/143 or so

the main reason for messin with the fuel trim is that the last time we had the headers off there was 2 pipes were really white cyl3/4 and the rest were normall

Is this the correct way to fix that??

Originally posted by gb95zconv
Dan has it right on all counts..... Ill just add that you dont want to mess with the cylinder trim unless you have a large cam .....then some tweeking of the trims can help eliminate split BLMs.

Would the CC306 cam need this?? Just wondering, I'm looking to go bigger this winter and right now I have the hotcam...

Dan, why would it be a bad idea to use the individual fuel trim cells if you consistantly have split blms. I have considered doing it just in idle where my blms are consistantly split. Off idle its not consistantly split so Iwouldnt touch those.

I didn't say it was a good or bad idea to try the individual trims. I've never done it, so I'm always a little skeptical of something that isn't proven. But the more you guys try it and report good results, the more I want to try it out too. :)

Originally posted by Dan K
I didn't say it was a good or bad idea to try the individual trims. I've never done it, so I'm always a little skeptical of something that isn't proven. But the more you guys try it and report good results, the more I want to try it out too. :)

Not much to prove that GM allready hasnt.....from 95 up GM tweeked the individual cylinder trims. Bigger cam will cause different than stock air flow characteristics within the plume . If your sure you have no other issues such as exhaust or intake leaks then the fuel trim is a good tool to use IMO. Just dont go crazy and make drastic changes.....2 or 3% changes can have more effect than you would think. Get out of the box but dont stray too far;)

If the fuel trims are part of the A/F formula then wouldn't their be different pulsewidth calculation for each injector?? ((If someone tells me thier is then I quit :eek: )) Seems like thier would be since the cylinders up front get more air and less as you go back. I have a custom tune for a 224/230 that has the values ranging from +/-5% from the stock 1.00. Something like 1.05 up front and works down to .95 in the back.


Jeff D

Originally posted by PoorMan
If the fuel trims are part of the A/F formula then wouldn't their be different pulsewidth calculation for each injector?? ((If someone tells me thier is then I quit :eek: )) Seems like thier would be since the cylinders up front get more air and less as you go back. I have a custom tune for a 224/230 that has the values ranging from +/-5% from the stock 1.00. Something like 1.05 up front and works down to .95 in the back.


Jeff D


you are correct, there are cylindar balances that take the pulsewidth and adjust it according to location like you say and maybe even firing order but of course that will never change.

fwiw nobody has ever proven the advantages of messing with individual cylindar balance. if a guys adjustments depend on BLMs then hes going about it all wrong!

Originally posted by turbo_Z
you are correct, there are cylindar balances that take the pulsewidth and adjust it according to location like you say and maybe even firing order but of course that will never change.



Agreed that those things dont change....I never said they did . The fact is different cams have different characteristics that can be compensated for or tuned in part by using the fuel trims....at least it has prven effective for me.

As far as using BLM to tune with....I know that as long as the BLM is in the pcm range of ajustment (108-160) the pcm will do the tuning ....I just try to get things as close to 128 as possible before going to wideband tuning with the A/F tables for WOT. I may not do everything by the book(if there is one)....all I can tell you is what has and is working for me.....