trying first SD tune, surging/sputtering horribly...

Reply Subscribe

Thread Tools

Search this Thread

Nov 25, 2005 | 08:01 AM

Bad30th

Thread Starter

12 Second Club

iTrader: (13)

Joined: Nov 2001

Posts: 1,898

Likes: 0

From: San Diego, CA

trying first SD tune, surging/sputtering horribly...

I set the P0103 to set MIL at first instance and walked through the HPTuners wideband tuning help file. The SES light showed on the dash this time (if you read my last post).

I have to pedal the car to even keep it running/idling with the MAF unplugged, and it's fighting for all it's worth sputtering and surging. If I let off the gas it will sputter to keep running and sometimes dies. Is this normal for my mods (or normal at all ?). Should I just drive it in SD and log data and hope the tuning progressively make the idle/drivability better ?

The log was about 10:1 on the wideband at idle startup - I think it's the 1.15x to the VE tables in the HPTuners help instructions that's pushing it so rich, I will try the same steps without that change today.

I am attaching a brief scan of it idling in SD mode.

Any help or tips would be greatly appreciated... This happen to anyone else ?

Thanks !
Rob (Bad30th)

Attached Files

SD-LOG1 BAD30TH.zip (15.0 KB, 20 views)

Nov 25, 2005 | 09:18 AM

BLK02WS6

9 Second Club

iTrader: (2)

Joined: Jul 2002

Posts: 2,583

Likes: 1

From: on the dyno tuning in MD

Try reducing the VE table 1200, 800, and 400rpm columns by 10%, 15%, and 20% respectively - go down to 70 Kpa, and see if that doesn't get you closer so it will run enough to get you some good data.

Nov 25, 2005 | 10:15 AM

foff667

LS1TECH Sponsor

iTrader: (2)

Joined: Jul 2003

Posts: 7,986

Likes: 3

From: Clermont, FL

did you upgrade to the 2 bar or 3 bar pkg?

Nov 25, 2005 | 10:27 AM

TAQuickness

TECH Junkie

iTrader: (28)

Joined: Jan 2004

Posts: 3,250

Likes: 1

From: Houston

You want to work out your idle before you log the rest of the data. Using the steps in the doc your using, let the car idle until you get 50 or so counts at idle. Then take that data and apply it to your VE table. Will be a night and day difference after you apply the data.

Nov 25, 2005 | 01:06 PM

ninobrn99

TECH Addict

iTrader: (8)

Joined: Apr 2003

Posts: 2,513

Likes: 0

From: Honolulu HI

cant he just use 2.0 and create a RAF histogram to get his idle down? Thats what I did, then I did my ve.

Nov 25, 2005 | 01:07 PM

Bad30th

Thread Starter

12 Second Club

iTrader: (13)

Joined: Nov 2001

Posts: 1,898

Likes: 0

From: San Diego, CA

Quote:

Originally Posted by foff667

did you upgrade to the 2 bar or 3 bar pkg?

I have the 2-bar package, haven't gotten to use it yet though, my current tune still has the MAF enabled and it has some surging/stumbling at cruise... I'm now taking a stab at VE and MAF tuning the under 4k rpm range for drivability. (I have had the 'top end' dyno tuned already but want to work on the lower RPM tuning/drivability - made 504rwhp/512rwtq at 5200RPMs / 16 degrees timing, 9psi, trans is slipping and would not hold past 5k which will be getting fixed soon).

Quote:

Originally Posted by BLK02WS6

Try reducing the VE table 1200, 800, and 400rpm columns by 10%, 15%, and 20% respectively - go down to 70 Kpa, and see if that doesn't get you closer so it will run enough to get you some good data.

The HPTuners wideband O2 tuning Help file says to multiply the entire primary and secondary VE tables by 1.15 to make sure there's plenty of fuel. I will go back and reduce the idle range VE tables and hope it helps.

The new 71cc heads are really flowing a lot of air it looks like.

Quote:

Originally Posted by TAQuickness

The HPTuners help file ? The car idles fine with the MAF enabled, so I didn't do anything with the idle. I also have a problem with having P0121, I have the MAP window check disabled on that because of it throwing the code constantly.

I'm beginning to see a correlation between the rough idle in SD mode and the P0121 code. More air than VE thinks should be there ? I do have a 1/4" hole in the TB blade... I will log IAC counts to see where they are.

Thanks for the help guys, keep it comin' !!