lean area around 2500ish rpms-2014 ctsv

[sgod1100]

Did you ever figure this out. Having the exact same issue with 13 CTS-V and id1050cc injectors. Only thing thats somewhat helped is spike the vve table in that area. Still has a slight spike but at least it doesnt fall on its face when cruising.

Nope, I actually just got some 1050s as well. Wanted to have a little bit more head room....I'm assuming I'll still have the same problem though. Yeah, can't really adjust the maf in that area because you will hit those same Hz values at different rpms and end up being super rich in those areas. The VVE (I feel) is the only way to attempt to try and correct it. I'm almost wondering if messing with the prediction coefficients would help any. It would be just shooting in the dark for me since no one knows how to actually tune them and most just zero them out

[JayRolla]

Nope, I actually just got some 1050s as well. Wanted to have a little bit more head room....I'm assuming I'll still have the same problem though. Yeah, can't really adjust the maf in that area because you will hit those same Hz values at different rpms and end up being super rich in those areas. The VVE (I feel) is the only way to attempt to try and correct it. I'm almost wondering if messing with the prediction coefficients would help any. It would be just shooting in the dark for me since no one knows how to actually tune them and most just zero them out

Man it does suck no one has a good answer. I feel most dyno tuners probably just leave it be as most people dont have a wbo2 and probably dont notice the hesitation/stumble like us self tuners. Seems throwing fuel at it with vve works a little and feel less hesitation but I still see a spike and sometimes still can feel it especially in high gear on the highway. What is very strange is its literally only at 2500rpms and goes away immediately. Maybe its during a transition between the vve zones. Mine does it on SD or blended.

[sgod1100]

Man it does suck no one has a good answer. I feel most dyno tuners probably just leave it be as most people dont have a wbo2 and probably dont notice the hesitation/stumble like us self tuners. Seems throwing fuel at it with vve works a little and feel less hesitation but I still see a spike and sometimes still can feel it especially in high gear on the highway. What is very strange is its literally only at 2500rpms and goes away immediately. Maybe its during a transition between the vve zones. Mine does it on SD or blended.

I moved my VVE zones to where that 2600 rpms area is in the middle of the zone and it really didn't help any. This whole thing started when I changed injectors and added test pipes. It may very well be a combination of both. With my car being an m6 I actually feel it even more than an A6 since with the A6 you have the torque converter to dampen things a little bit.

You by chance have a log of it happening? I'd like to see what yours looks like compared to what I'm seeing

[JayRolla]

I added headers, 3" xpipe with no cats and didnt notice it. I also didnt notice it right after the injectors until I dialed in the maf and then VVE table. My car is also m6. And usually it stumbles more in open loop and then when warmed up its not as bad but I still see spikes on the wbo2. I am sure I have tons of logs when it happens. I can try to post one later tonight.

[PGA2B]

I too have changed my zone boundaries to make the issue fall in the middle of the zone which helped a slight bit through VVE tuning. It is most noticeable when I am in TUTD as it is mimicking a manual transmission. I get a slight stumble but no misfires or KR when it occurs.

[blindsquirrel]

This isn't the 'air calc mode' error/bug/glitch whatever, right? You've been dealing with this long enough I'm sure that must have come up somewhere and been dismissed. I don't know the details (I am not a tuner, just a home-gamer), I just remember seeing it drive other people crazy.

[GHuggins]

If you guys have cams you might want to look into the transient tables - if this is happening with decent pedal transitions and not just holding the throttle in these areas.

The problem is caused by the injectors being in that blower - they no longer spray on the intake valves like they originally did and you wind up with some hefty fuel delays. I've almost had to increase the 100kpa row by 300% for the impact and evap tables for tip in issues with these then interpolate down to 80kpa. The exhaust won't help as it'll increase back pressure slightly, but the new spray pattern is the main problem.

[JayRolla]

If you guys have cams you might want to look into the transient tables - if this is happening with decent pedal transitions and not just holding the throttle in these areas.

The problem is caused by the injectors being in that blower - they no longer spray on the intake valves like they originally did and you wind up with some hefty fuel delays. I've almost had to increase the 100kpa row by 300% for the impact and evap tables for tip in issues with these then interpolate down to 80kpa. The exhaust won't help as it'll increase back pressure slightly, but the new spray pattern is the main problem.

No cam here. Mine happens with a constant steady throttle and as its revving and hits 2500rpm its an immediate lean spike, very slight stumble and as soon as we are at say 2600rpm it goes away. I have a slight tip in lean but nothing major that worries me. The faster I am revving past 2500rpm the less chance it happens. I believe the OP tried all the transient tables without much success. I will look into this and see if it helps. Thanks for the info.

[PGA2B]

Stock cam here too. Same as above. If it is a slow steady increase I see/feel it more.

[sgod1100]

If you guys have cams you might want to look into the transient tables - if this is happening with decent pedal transitions and not just holding the throttle in these areas.

The problem is caused by the injectors being in that blower - they no longer spray on the intake valves like they originally did and you wind up with some hefty fuel delays. I've almost had to increase the 100kpa row by 300% for the impact and evap tables for tip in issues with these then interpolate down to 80kpa. The exhaust won't help as it'll increase back pressure slightly, but the new spray pattern is the main problem.

Stock cam here too. Mine happens anywhere from 50-80 kpa-ish and it's not on any throttle snaps. I might have mentioned previously in this thread, as I can't remember. If I'm accelerating "normally" and I go through that 2500-2600rpm band it will very slightly surge and at that point my wideband will read anywhere from 15.5-16.0 for a very short period of time. Then right back to normal. This also happens in PE as well so this rules out a bad o2 sensor. Yeah, regarding the spray pattern I read the "thru-hole" is on an angle with respect to the body of the injector to allow to spray directly on the intake valve. I've messed with the transient tables, but I never increased them THAT much. At this point though I'm willing to try ANYTHING...lol. I'm also very surprised that there isn't a "ok this is the fix" solution considering there are so many of these cars tuned with smaller pulleys, heads, cam etc. Unless tuners don't want to give away their secrets....I'm not sure

[sgod1100]

This isn't the 'air calc mode' error/bug/glitch whatever, right? You've been dealing with this long enough I'm sure that must have come up somewhere and been dismissed. I don't know the details (I am not a tuner, just a home-gamer), I just remember seeing it drive other people crazy.

I haven't even heard of that....lol. So I'm not sure.

[sgod1100]

I added headers, 3" xpipe with no cats and didnt notice it. I also didnt notice it right after the injectors until I dialed in the maf and then VVE table. My car is also m6. And usually it stumbles more in open loop and then when warmed up its not as bad but I still see spikes on the wbo2. I am sure I have tons of logs when it happens. I can try to post one later tonight.

Since it stumbles in OL you should look at adding fuel to the IVT table. I added 5% to my whole table to get the car to be much more manageable while cold. I don't bother if commanded matches actual fuel since its in OL for such a short period of time. I just make sure it's somewhat close

[sgod1100]

No cam here. Mine happens with a constant steady throttle and as its revving and hits 2500rpm its an immediate lean spike, very slight stumble and as soon as we are at say 2600rpm it goes away. I have a slight tip in lean but nothing major that worries me. The faster I am revving past 2500rpm the less chance it happens. I believe the OP tried all the transient tables without much success. I will look into this and see if it helps. Thanks for the info.

Yeah i tried messing with the transient tables, but I never increased them by 3x the OEM amount...like I mentioned previously not really gonna to try it I guess

[GHuggins]

Transient tables won't help if it's just regular driving where it's happening. At least not the main tables. Accel/decel maybe. I was wondering if the issue wasn't in the torque model since it has a downward slope to 2800 where it jumps back up. Personally haven't had one do this, but nearly everyone does the 850's with just the pulley upgrades.

[sgod1100]

Transient tables won't help if it's just regular driving where it's happening. At least not the main tables. Accel/decel maybe. I was wondering if the issue wasn't in the torque model since it has a downward slope to 2800 where it jumps back up. Personally haven't had one do this, but nearly everyone does the 850's with just the pulley upgrades.

and that's what I was thinking too since it doesn't happen during throttle snaps. I haven't touched my torque model at all...it's all stock. I just took my 850s out and in process of putting the 1050s in. But seems like I'll have the exact same problem with those...lol. It would be really ironic though that all of us have the same common problem....well I guess we all do...we all can't figure it out...lmao

[sgod1100]

Transient tables won't help if it's just regular driving where it's happening. At least not the main tables. Accel/decel maybe. I was wondering if the issue wasn't in the torque model since it has a downward slope to 2800 where it jumps back up. Personally haven't had one do this, but nearly everyone does the 850's with just the pulley upgrades.

the torque model in mine are all "1s" in the 1.00 eq column....not sure if that is the table you are referring to or not

[GHuggins]

No. shoot me an email and I'll swap it out for a test.

[sgod1100]

No. shoot me an email and I'll swap it out for a test.

Ok, my car is down right now though...waiting on the big thick orange lid gasket. Should be here by thursday so I'll have everything back together then

[sgod1100]

No. shoot me an email and I'll swap it out for a test.

maybe one of the other guys can try what you are wanting to try

[GHuggins]

This is your latest tune that you posted over in the injector thread with the changes. Should report correct torque with the multipliers. I also changed fuel from wall stabilization to 2. Only changes I made. Let us know if it makes any difference at all. If it doesn't work then no loss.