Noob looking for knowledge - C5 Corvette

[jack08520]

This is from my relatively stock 2000 Covette which was tuned by East Coast Supercharging. I changed the injectors and despite the assurances that I was getting the 99/00 specific injectors I received the later ones (for an '01 I believe). What came out were PN 280155890 (23.5 lb/hr) and what went in were PN 280155931 (25.5 lb/hr) - the numbers came from a fellow I spoke with at AUS.

So the difference is 8.5% - I was going to multiply my injector flow rate by .921 (23.5/25,5) but ECS advised multiplying by 25.5/23.5 =1.08 which is what I did.

Attached is cold idle start and trying to understand (among other things) why the O2 sensors have high-frequency oscillations up until "the event" at 1min then after that the rate of change dramatically decreases (my AIR pump kicking in?).

Also have concerns about the STFT - read that if either STFT or LTFT are greater than -10 then there is cause for concern. Seems that B1 is consistently higher than B2 and both are greater than -10.

I have a track day log as well but to be honest don't yet understand enough to make sense of it.

Hoping to improve things aheade of my next event over Labor Day.

Appreciate any and all feedback!

[04silverado6.0]

You will want to use data from a file that came with those injectors. Just adding to what you have is not correct. Also copy voltage offset, short pulse adder and potentially min pw.

[HATEHPTUNERS]

With what those new injectors cost you, is there a reason you did not want to go LARGER? The GM flex fuel injectors-36 lb./hr would leave you room for more upgrades later without having to change the injectors again. Let's say a year from now you want a performance cam...... you WILL be changing those injectors along with the cam swap...

[aaronc7]

Like mentioned above, I would highly recommend copying over all injector table values from 01+ tune and then go from there. If voltage offset or anything else like that is different, fueling could change quite a bit, especially at low load/idle.

Be a lot easier for folks to help if we had a copy of the tune to look over for anything else amiss etc. Once the injector data is correct and fueling is in the ballpark, then you can progress to fine tuning the MAF calibration etc. Going from known injector to another known injector, the fueling should be pretty good, but I've always had to retune the MAF/VE a bit with an injector swap to get it dialed in perfect.

[jack08520]

Thanks all for the replies - will have the tune posted later today. My plan was to keep the same sized injectors and not have to fuss with the tune - but thats not how things went...

[jack08520]

Attached is the tune I was running and the one I am running now (when the idle log was taken) where flow is x1.08. I also attached a log from part of a ride I did yesterday.

[aaronc7]

Give this a shot. I copied over the injector data from a 01-04 file. Quick glance, the injector flow rate is slightly higher than your x1.08 file, and the voltage offset table values are generally 0.1-0.2 lower than what's in your stock table. Both will result in shorter injector pulsewidth = increase your negative fuel trims. So this in itself will get fuel trims closer to 0 and will help.

This might be "good enough" but I'd get a good long datalog to confirm fuel trims are close in all operating regions. Can fine tune if you want to, but might not be needed.

[jack08520]

I also found some '02 tunes in the repository - ones by Scott (20194314228.hpt), Andrew (1221328239.hpt), and FRC Tom (1186583271.hpt) - the first 2 are nearly identical but the 3rd is not - trying to figure that out. Appreciate the suggestions and will give it a try and report back. What is preferred - a scan at idle or a highway driving log?

[aaronc7]

Some of the files in the repository marked at stock files are indeed not stock... just FYI. I looked at several different 01, 02, 03 and 04 tune files and all had basically identical injector values. The 04 values were ever so slightly different probably just rounding errors since 04 is on a slightly new PCM hardware or whatever.

Don't even really need a log.. just glance at fuel trims at idle and normal driving conditions and take a look at LTFT. If it's off by more 5 percent then you may wanna do some MAF tuning.

For MAF tuning, you'll want to get a long datalog with a big variety of RPM and load, basically hit as many of the MAF table cells as possible and aim to get at least 10 hits in each cell, at steady throttle. But, you might not even need to do that.

[jack08520]

Give this a shot. I copied over the injector data from a 01-04 file. Quick glance, the injector flow rate is slightly higher than your x1.08 file, and the voltage offset table values are generally 0.1-0.2 lower than what's in your stock table. Both will result in shorter injector pulsewidth = increase your negative fuel trims. So this in itself will get fuel trims closer to 0 and will help.

This might be "good enough" but I'd get a good long datalog to confirm fuel trims are close in all operating regions. Can fine tune if you want to, but might not be needed.

I'm digging into this now - I have a track day on Monday and will see if this makes an improvement...

[jack08520]

Give this a shot. I copied over the injector data from a 01-04 file. Quick glance, the injector flow rate is slightly higher than your x1.08 file, and the voltage offset table values are generally 0.1-0.2 lower than what's in your stock table. Both will result in shorter injector pulsewidth = increase your negative fuel trims. So this in itself will get fuel trims closer to 0 and will help.

This might be "good enough" but I'd get a good long datalog to confirm fuel trims are close in all operating regions. Can fine tune if you want to, but might not be needed.

I checked your file against mine and saw no differences other than the injector data. I made some changes to your file to try and tune out CAGS and we'll see if that code goes away. This is a warm idle scan and indeed the fuel trims are improved. Will gather some more on-track data tomorrow.

Injectors-before.jpgInjectors-after.jpgInjectors-difference.jpgAfter aaronc7 tune 9-3-23.hpl

[aaronc7]

I checked your file against mine and saw no differences other than the injector data. I made some changes to your file to try and tune out CAGS and we'll see if that code goes away. This is a warm idle scan and indeed the fuel trims are improved. Will gather some more on-track data tomorrow.

Injectors-before.jpgInjectors-after.jpgInjectors-difference.jpgAfter aaronc7 tune 9-3-23.hpl

how'd the event go? any logs from the sessions?