3800 Tuning Help Please

[98 TGP TOY]

Hey guys, I just finished installing a DHP 1.0 with rear O2 and EGR codes deleted. It also has the adjustable timing tables programmed in. Right now the timing is set low until i get my fuel figured out. Then I also installed the LS1 maf and my ported TB.

Now the problem, my lfts are pinned at 16.41. I took it out for a quick drive and when I put about 1/4 throttle into it, the O2 would read like 45-55 and i started getting knock. Is it necessary to go to wot to reach the normal O2 range of 900ish? No, i havent taken it to wot nor will take it to wot until i figure it out .

So im obviously running really lean, correct?. I have a mini afc 1.1 to adjust afr. It was at 100% when I started the drive, then i bumped it up to 103% by the time I got back, and there was no change in lfts. Will I need to upgrade to a 2.0? I know they have LS1 maf fuel curves in it.

Let me know guys, thanx.

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[98 TGP TOY]

Also, whats a good IAC?

And is there any other ways to tell if you have a vac leak?


The car will start fine. It will have a bouncy idle like their is a vac leak. Then if I rev it up a little it will stay reved for a couple seconds and slowly back down. Then i rev it again and it comes down quicker. Then it will idle fine.

Just some further info, thanx guys.

 

[Mike K]

Originally posted by 98 gtp toy@Sep 28 2004, 07:32 PM
Also, whats a good IAC?

And is there any other ways to tell if you have a vac leak?


The car will start fine. It will have a bouncy idle like their is a vac leak. Then if I rev it up a little it will stay reved for a couple seconds and slowly back down. Then i rev it again and it comes down quicker. Then it will idle fine.

Just some further info, thanx guys.

That and the pegged LTFTs indicate that you do indeed have a vacuum leak somewhere in the system. Fix this before you begin to tune, otherwise you're tuning around a problem.

 

[98 TGP TOY]

Thats what I figured. I think I've got in at the TB. Will be checking it out tomorrow or thursday. Thanx.

 

[98 TGP TOY]

Ok, well I checked out the TB and its sealed up well, and thats the only thing I messed with. The ltft are still pegged at 16.41, but as soon as I start moving they drop to normal levels. But if I let off the gas they go back up. Could this still be a vac leak?


Oh and I crapped my pants. While I was out for a drive tonight, I half throttled it to see if I had any knock from this vac leak. None showed up, luckily......but at the end of the run i heard a loud pop sound and all of a sudden my car wouldnt boost. I thought I busted the turbo or something serious...i just finished cleaning out my pants. Luckily i just blew the intake pipe out of a rubber coupler. <_< . I must have not tightened it down or soemthing.

 

[BumpinGTP]

add a couple % of fuel and see if the Ltrims go down at all. also, to get the WOT O2 values you only need to go 3/4 throttle.

 

[98 TGP TOY]

Bumped it up another 2%...and nothing. I only have a mini-afc 1.1 or 1.0...is that ok?

I kept watching it, and at idle its pinned, but the second i tap the gas, even slightly, its heads for zero. Could this be anything with the adjustable timing? The iat is set at 158* right now. Thats how it was when i got it. Does that matter at all?


The car idles perfect. I think the rough idle before may have been because I just put the pcm in.


I dont know, let me know guys...Thanx.

 

[98 TGP TOY]

TTT - had the car out today and it runs well. Didnt floor it or anything, but it isnt acting like a vac leak.

 

[98 TGP TOY]

Also, I only have the mini afc 1.0/1.1. So as I just confirmed i can only tune at wot with this, correct?

So me pushing it up a couple % isnt going to do anything at idle. Could these high ltfts be caused simply by the ls1 maf.

Ron?

Thanx guys.

 

[jk99gtp]

I might be wrong on my last post.

I believe the Mini-Afc 1.0/1.1 allows you to set a standard setting across all frequencies of the MAF, the 2.0 in enhanced mode is better for the tuner in mind because it lets you tune each setting individually from each Khz range on the MAF (Idle 1-3Khz, Cruise 4-6Khz, and WOT 7-13Khz)..

So all in all, I believe when you go, lets say +/- 2% for example, on the Mini-AFc 1.0/1.1 its for all frequencies on the MAF (Idle, Cruise , WOT)....

Still learning about this myself also, so excuse any misinformation I might've given...

 

[98 TGP TOY]

Understood, but I still think its something to do with tuning, and not a vac leak.

 

[jk99gtp]

I do think the 2.0 might be beneficial for you, since you do have a LS1 MAF. The 2.0 has built in fuel-curves for this...

http://www.zzperformance.com/zzp/products/...mini_afc_20.htm

Thanks,

Joel

 

[imported_snoop]

do you have a air/fuel gauge. if so, what is that reading. if it is pegged to the lean side, you have a vac leak. if not, your good to go

 

[98 TGP TOY]

Nope, no a/f gauge. All I have is the LS1M.

Besides, i thought the a/f gauge only runs off the O2 sensor, and if thats true then the a/f wont matter unless i go to wot. Right?

 

[98 TGP TOY]

WOOT WOOT....figured this b*tch out. Oh she thought she had me tricked. Solved a lot of problems in one.


Again...the l36 manifold is crap....but this is partially my fault. I wasnt aware that RTV doesnt like boosting. I have a theory that my barbie doll intake manifold flexed, allowed boost to blow some of the rtv aside, and is not leaking. This explains the knock, the fact that I cant boost past 9 psi, and the ltfts. Time to upgrade to something better.