Lean Spike when Accelerating - 0411 Swapped Pickup

[Obsolete489]

Hello All,

I'm having a strange issue with the tune for my pickup, when accelerating with MAP north of 75 kPa and below 3000 rpm, where I get a lean spike of 17:1 to 18:1 AFR on the wideband and I can feel the loss of power. The injector pw's look fairly steady, MAF frequency is pretty steady, tps looks normal. It is also worth noting that I do not see this condition if I do a WOT pull.

I pulled my injector data from ls1 tech, so I don't think that is the issue. Attachment 75655Attachment 75656
Tune and log attached.
Does anyone have any thoughts?

Engine info:
489 vortec (gen 6)
comp 01-415-8
stock heads and intake
headers
36lb injectors from a gtp
Lean Spike.hpl489 Tune 12-7.hpt

[Oleblu]

Transient issues maybe. Have you played with injection timing. That cam doesnt seem to large for a big block, I wouldn't think eoit would be that far altered but it's possible I guess. It doesn't happen in wot because you have pe enrichment masking the symptoms of the lean condion.

[Obsolete489]

No that cam isn't real big. I wondered about transients, but it happens after being in the throttle for a few seconds.
I suppose PE might mask it, but I figured I would see at least a blip on the wideband.

I haven't messed with the injection timing yet. Any recommendations on what to try?

[Oleblu]

Search eoit tuning there is even injection timing exell spreadsheet to be found. I'm on my phone otherwise I'd post it for ya.

edit found this in my bookmarks on break.

https://www.hptuners.com/forum/showt...A-how-to-guide

Here is the eoit spreadsheet.

EOIT Worksheet.xls

[Obsolete489]

Alright I'll look around and see what I can find.

[Oleblu]

posted eoit worksheet above in previous post

[Obsolete489]

Thanks man! I'll give this a shot and report back.

[Obsolete489]

I supposed I should try shutting down the MAF completely, but I pushed the high rpm disable above where I'm seeing this issue and it still happens.

[Oleblu]

Transient fueling uses the VE table for airflow reference, not the MAF. Shutting down the maf completely will only let you know if the problem was maf related which you now know it is not.

[Obsolete489]

Good to know.

Transient issues can still come up in what seems like a fairly steady state situation though? The lean spike in the log I attached shows up a full 3 seconds after I change from 15% to 40% throttle position. I was under the assumption that transient issues really only showed up during quick throttle changes?

Not trying to question your thought of it being a transient issue, just trying to learn.

[Oleblu]

Do you think this could be a closed loop issue? what headers are you running and where are your o2 sensors located? This could possibly be from the sensors being a little lazy to switch. which is common with long tube headers and setting the sensors farther back from their original location. Have you tried running it SD open loop? I was only thinking transients because iv'e had similar issues with my 5.7 vortec after the intake swap. but this was only after my intake swap, and changing the injectors. Sorry for the rash of questions.

Transients are constantly playing part in any throttle transition and the resulting moments afterwards. For what its worth with my 5.7 vortec I have completely disabled steady state by setting the rpm enable to like 12000 rpm. which did seem to calm the fueling transitions. Have you checked the transient how to thread i posted above your data seems strikingly similar to the data posted in that thread.

Edit must have been pretty fresh up there with an IAT of 12*F is that correct or close to ambient?

[Obsolete489]

I'm pretty sure I had the same issue in open loop, but I will give it a shot tomorrow on my way to work and see what happens. I'm only running shorty headers, but the mid pipes that the o2s are installed in are 3", so it could be an issue with the o2s, they are mounted pretty close to the factory location though.

I have read that thread before, because I was pretty sure the issue was transients as well. I did try adding to the impact factory in the high map area, but all that did was make it spike rich immediately when I hit the throttle. I should probably re-read the thread though and see if there is something I missed.

That was the correct IAT haha it was a bit chilly. Ambient temp was about 6*, windchill was -10*.

[Oleblu]

Damn 6 with a -10* windchill yea that's cold man. I noticed the low marker on the gauge seemed to be in or at the - point. lol I can only laugh because my wife was just complaining the other day when it was 26* with a windchill of 17*. Me personally I wish it stayed colder longer in the west Texas area I enjoy those low intake temps. Sure makes my truck feel nice and snappy.

Back on track here I also run my o2 sensors in a 3" ID pipe. I had to alter some of the closed loop proportional (airflow mode and o2 error) tables also made some changes in my closed loop integrator delay tables as well. Ghuggins has an awesome writeup pertaining to o2 sensor tuning after header installs. mostly referencing long tube headers, but i believe you will find some good info pertaining to your particular application. This one you'll have to search for as i don't have it bookmarked.

[Obsolete489]

Well today it's going to be like 45 here haha it's kinda been an odd winter so far, cold then warm. Eventually here it'll just be cold. Haven't had much snow yet either, unfortunately.

Later this evening I'll search for his thread on it. Even if it isn't my issue, I'm sure that there are some worthwhile changes that I can make. Thanks for the direction man.

[Oleblu]

Another thing I noticed in your tune is your still running EGR? if so then im sure its working properly, but if you've deleted your EGR the airflow tables could possibly be causing some of this issue. as they are still populated tables.

[Hutchinson]

OleBlu, thanks for the GHuggins header tip, I did a search for "GHuggins" (looked throughout list), then did an advanced search for "GHuggins" with "headers",...couldn't find reference above. I must be dumb or something at using that search/advanced search page,...wouldn't be the first time I've been dumb,....any tips?

How's that new intake been treating you? Gotter final tuned? I've been out for awhile, started a new power plant Project up in Ohio,...been a little busy.

Thanks Guys.

[Oleblu]

Man honestly I always have better luck using google search instead of hptuners search bar im not sure why it doesn't pull up some stuff and does others. I just got back in the house from dialing in my sons .22 making sure its ready to drill tagets with ease for him at 50 yards. He's gonna have a fun christmas! Anyways ill do some searching for you guys im sure i can find it, but its going to take me some time.

The intake has turned out great. after getting everything dialed in before the cam swap the truck made a couple pulls on the dyno. with intake/exhaust and a 0411 swap tuned by me only. she made 259.9hp at 4800rpm and put out over 300 lb-ft of torque from 1500 to 3600rpm.


Edit i found an attachment of some o2 sensor settings in my bookmarks but am still having trouble finding the particular thread Ghuggins posted the atachment in bare with me and ill keep searching

https://www.hptuners.com/forum/attac...8&d=1471481418


I'll let yall know I tried some of these out and figured out more or less how to manipulate the narrowbands in my favor. its very doubtful these settings in particular will work for the either of you guys but they will give you a reference of what's going to need to be fiddled with to get results.

[Obsolete489]

Pretty sure I have the egr disabled in the general menu, at least I better because I have the actual egr unplugged haha.

I think i found the correct thread, haven't had time to read it yet though.
https://www.hptuners.com/forum/showt...g-with-Headers

Do you know what the truck makes after the cam swap then? Those seem like pretty good numbers for no serious mods.

Should be a great Christmas for your son! Nothing better than getting a gun, in my opinion haha

Thanks for all the help man.

[Oleblu]

Probably be best to zero out the egr airflow tables just for sanity sake. I should have specified those numbers were with the nv3500 trans. Much less drivetrain loss than the 4l80e. If I was to guess through the 80e after the cam swap and pulling roughly 5.5 cc's from the heads. it's probably just at 300 to the wheels. With the nv3500 I'm sure it was closer to 325 at the wheels. Hopefully soon I'll hit the rollers and really see what it's putting down. Overall I'm very happy with the small block. It's probably just at or over 180,000 miles. When I had the heads off each cylinder still had beautiful crosshatch.

[Obsolete489]

Good thinking, I'll do that for tomorrow mornings test. I'm also going to try some o2 changes. If this has no effect I'll try open loop sd on the drive home.

300 to the wheels is pretty good, especially for 180k, I would imagine that motivates the truck quite well.

Some day, I'll get mine on a dyno too.