Can anyone diagnose a possibly tune related issue?

[nitehawkjcb]

Hey everyone. I am new to this site, but not new to the 3800 world. I'm a member of a few different W-body/3800 forums, but none of them seem to have an active PCM / tuning section, so here I am, trying this one. I have a Powrtuner FWIW.

My issue comes on a cold start. The car will run slightly rough, with vacuum on my Aeroforce gauge being between 8.4 and 9.2 in PARK, depending on how it wants to act(which I know is between ~17 in hg and 18.5 in hg). When the car warms up, after roughly 2-4 minutes of running, the idle becomes great and the car runs like it's supposed to. Vacuum at idle on the Aeroforce is 9.8-10 (close to 20 in hg). I've already changed the MAF sensor, twice. I had this same issue while running a ZZP PCM, now it has started happening with my other PCM (from Milzy, if anyone here knows of him). The only tuning I have done is reduce WOT timing. The check engine codes I'm getting aren't related (EGR delete, AC removed, brake switch (could be a wiring harness issue), and evap - which is bypassed)

No vacuum leaks, newish crank sensor, cam sensor, MAF, TPS. I have 60# injectors, but haven't needed to install them yet. I'm on a 3.1 pulley on a Gen III blower. Tonight I'm going to disconnect the battery so the PCM has to relearn everything, but I doubt I'll see any results with doing that.

Basically, I'm just hoping somebody here knows about tuning and possible problems that can be read with a Powrtuner. I hope someone here can help.

Thanks!


John

[ADrugDealer]

Few things, might help to post your tune file so we can take a look.
Did you do a CASE learn after changing the crank/cam sensor?
Do you have a wideband? If so what is your AFR as idle?
How much timing at idle?

[nitehawkjcb]

I haven't scanned it yet, the issue has just developed (again), I don't have my laptop with me but will bring it tomorrow and scan the car.

I did perform a CASE relearn, which was a process involving turning the key on a few times and leaving it on for ten minutes or so each time. But yes, I have done that.

I do have a wideband, but have not installed it, as I have headers I'm installing when I get the motor pulled to install them. (gotta beat out the firewall, 96 Monte Carlo)

My timing at idle is ~20, will have to double check what it is when the car is cold. But I'll get a UVscan or a Powrtuner scan done and get it posted. It is very nice to know there is somewhere to go where people still help with tuning.

I have a spare IAC laying around too, I may swap that out and see if that's the issue...but like I said, when the car warms up, it runs fine... I will also be getting a 98-99 Z34 wiring harness so I can get rid of this modded GTP harness.

[ADrugDealer]

That is not a CASE relearn, that is a security relearn. Your aeroforce can do a CASE, its under controls in the menu. It involves revving to 6k in neutral or park. It'll give directions. Do that and tell me if it gets better.
You are running a 3.1 with no wideband... my heavens...you are a brave person. get that wideband in.

[nitehawkjcb]

Will do. Thank you for that info.

Never revved to 6k in park, pretty sure the PCM limits me to 4k. But I'll check with my Aeroforce.

lol, you may say I'm brave, but I haven't gone WOT with this pulley for more than a second. Always do keep an eye on KR though.

[ADrugDealer]

Try the CASE learn and report back with your tune file if you have it.

[nitehawkjcb]

Sorry, my Aeroforce must be running old firmware. It doesn't have anything about "Controls". I'm doing some research as to what I can do, or if my Powrtuner can do it.

edit: I'll just get home to my laptop when I get off work and use the Powrtuner to do the relearn. Thanks already, you've been a tremendous help.

[ADrugDealer]

It should be in the main menu tward the bottom.

[nitehawkjcb]

Definitely not there man, I did buy this Aeroforce in like 2007, so it wouldn't surprise me if it was just old firmware, but I'd rather not ship it back to them to update it, when my tuner can do it.

[ADrugDealer]

alright lol

[nitehawkjcb]

I can upload it as a .bin file, is that okay or do I need to find a way to change it to Excel?

Here's a bin.

https://onedrive.live.com/redir?resi...int=file%2cbin

[Scottydoggs]

are these pcm's tuned for the 60 injectors? if they are and your not using them that could be the issue.

[nitehawkjcb]

No sir, these are for my current stock injectors. I have a 60# tune ready to upload, but don't need it yet. I'm toying with the idea of putting the new injectors in when I do all the work for the headers...

[Scottydoggs]

i dont see headers or a ic. that pulleys way to small. unless its on e85. its got to be a knocking even if you have headers.

what brand maf did you use? they engines hate aftermarket mafs. used junk yard oem delco mafs do rather well.

[nitehawkjcb]

I have a Dorman MAF and an ACDelco MAF which I thought was going bad, and I have a modded MAF that I bought with this ported throttle body, but I don't run that one.

I have almost/if not enough mods to run a 3.1. Here's my mod list.
-Ported Heads
-Full size IC
-Ported blower & TB
-Gasket matched LIM
-PLOG, full 3" exhaust
-AL 103's, 180 tstat
-Walbro
-SSAC's waiting to go on, gotta pull the motor and mod the firewall, this should be PLENTY to run the 3.1 pulley.

[Scottydoggs]

ok, that list sounds better lol id use the delco maf. or find a used one from a JY.

try 104 plugs. never know car may just like em better. gap em to like 0.50 see how that feels. if you've not played the plug and gap change game its time to do that.

if you got a air hammer, or even a 5 lb sledge you can push the fire wall in pretty easy with the rear manifold off. lots of room back there.

[nitehawkjcb]

Gotcha. My plugs are gapped at .053 I believe. Gonna be tough to beat that firewall with the motor in the car, but I'ma try to beat it out before I pull the engine...planning on pulling it though lol

[Scottydoggs]

if you put the rear header in place, use two bolts. then mark where the o2 s gonna hit the wall, then take the rear header back out, theres room to swing. your dropping the rear of the sub frame too.

[darkhorizon]

Vac leak via intercooler is common.

[nitehawkjcb]

Had this same issue before the IC install, but the issue went away when I switched PCMs, now it's back of course... But I sealed up the IC very well on both sides of the core, so I don't think that's it... Granted it could be, but I doubt it. Thank you for your input though, I've seen your name around different 3800 forums.