As the title states I've got a few questions regarding the tune for my sc setup. First off I got the from trifecta. First thing I have a question about is the misfires I'm getting. They only occur after the engine is up to operating temp and only when I'm not on the throttle (idling or coasting). Vince said it's probably because the injectors need turned down so low to idle that they might not pump enough fuel in every time to get a good idle. Just wondering if anyone has this same issue because I've heard that anyone who goes with hpt doesn't have this problem. Next 2 questions I have are about readings on my interceptor. I'm just wondering what would be a normal reading for ignition advance and knock retard. I know the less knock retard the better but I just want to know if some is unavoidable. I only see 3.something max and it goes away pretty quick. I have no idea what I should read for ignition advance though. At idle it bounces between like 9-11, coasting it's mid to upper 30's, and WOT it's between like 15-17. Any input would be appreciated. Thanks!

 

Bump

 

You should have 0 misfires. 60s can be tuned for no misfires but might have a sloppy idle.

Also should have 0 KR. 3 KR is not normal and should be fixed.

Your timing sounds normal. It always flexes and being that youre boosted 15-17 is normal (im 24.5 at WOT but im NA)

 

Ok thanks. I know my IC pump is working and having a bad one can cause KR but could the tune be the sole cause of the KR?

 

Sure can.

Your AFR good? Could be a couple degrees of too much timing

 

I wish I knew what my AFR is. The wideband for my interceptor quit working after like 2 days and I'm gonna have to send it back for them to check it out so til then I've been trying to take it easy. Last time it was working I was running 10.1 or 10.2 at WOT but vince sent me an update so I have no idea what it's running now.

 

10 anything is RICH

I guess see if you can get the wideband fixed and go from there

 

Yeah I knew it was way too rich and vince said he was gonna work on leaning it out but without being able to monitor it I can't tell if the new tune changed it or not. From what you've said though sounds like it must still be running rich

 

Well first off. I know you can keep an eye on stft and ltft. And can you keep an eye on o2 mv. It's not at all 100% because of hest to the o2 will Skew it. But it can tell you a little. The trims will help you figure out if your Far off enough..

 

True but I have no idea how to read any of those lol

 

Your interceptor has those.perameters in it

 

I meant I don't know what any of those should be reading when I'm driving

 

Do this have it on stft and ltft and let us know what they are under idle and cruise

 

At idle my stft bounces between -0.7 and 3.9, my ltft sits at -2.3. When coasting my stft is either 0.0 or 32.0, it dpeanut bounce it just goes to one or the other. My ltft coasting is 2.3 or 4.6, same thing it dOesnt bounce it just goes to one or the other. Cruising at 65 on the highway my stft bounces between -4 and 4 but it does it so fast it's hard to read and my ltft holds steady at -8.5

 

Yeah it doesn't seem to bad. But there's other things like your injector scaling and ect. But its still off a Lil so keep getting revised

 

im way off on my LTFT cause of winter...like 10%

 

I don't even know what the fuel trims mean but thanks for the help

 

I BELIEVE (maybe James can correct me) a negative percentage means thats how much its correcting for it leaning out. And a positive percentage means thats how much its correcting for richness.

 

What's the difference in long term and short term fuel trims? Tuning is one of the few things that confuses me about working on these cars

 

Ltft save stft is actual instant data that is being recorded to create the commanded sfr. + mean that's how much fuel is added - means its taking away basically

 

I wrote it correctly but hard to understand. Say you have a. + stft ltft. That tells you how far you are off lean so therefor you would add the + to the calibration and that'll give you more fuel.

 

Ok thanks for the info

 

Lol Wikipedia.

Fuel Trim Fuel trim refers to adjustments being made dynamically to the base fuel table to get the proper ratio of fuel to air. Short term fuel trim refers to adjustments being made in response to temporary conditions. Long term fuel trim is used to compensate for issues that seem to be present over a much longer period. Fuel trims are expressed in percentages; positive values indicate lean (add fuel) and negative values indicate rich (subtract fuel). Fuel trim banks refer to the cylinder banks in a V style engine. Cylinder #1 is always in bank 1. Fuel trim is generally calculated by using a wide set of data values, including front O2 sensors, intake air temperature/pressure (or the more elegent air mass sensor), engine (coolant) temp, anti-knock sensors, engine load, throttle position (and change in throttle position),and even battery voltage can effect fuel trim. Long term fuel trim generally should not exceed +- 10

 

I take it that means that in a perfect engine the fuel trims would both be 0?

 

Lol hard to get 0 and. 0...... Every day is different