So Ive been putting this thread off for a few weeks in hopes that Id find the problem. But I cant. I got my car dyno tuned after my LS6 intake manifold swap. The A/F was around 16.5-17.0:1. After tuning it, it seems for some odd reason that it runs best at around 14.0-14.5:1 A/F where most LS1's like to be around a 13ish. My tuner said it was mainly because my MAF is ported and air could be hitting the backside of the sensor and causing a problem (I may have misunderstood that part, but I dont think I did).

Now my tuner said I most likely have a vaccum leak, but cant seem to find, and my rpms seem normal, except a hanging idle once in a while. Now the intake manifold was tightened down in the right pattern, and all hoses plugged back in. Now the fuel injectors popped in, but it doesnt seem as if they are in all the way. Im sure if they werent tho, I wouldnt have made the power I did and there would be fuel all over.

The tune is a somewhat speed density tune, due to the fact that my knock sensors were going nuts and pulling 4-8* timing. I believe its down to 4* now.I changed plugs AFTER the tune, and it seemed to make the car a little snappier.But Ive heard that NGK's have a high tendency to break the ceramic. They are gapped at .054, is that an ok gap for a bolt on car? Now the idle has some issues it seems. It gets a few spots where its rough and then back to normal. But even when its rough the rpms dont jump at all.

What has really got me frustrated is I ran my friends bone stock 02 camaro 6spd from a 45 roll and it was dead even untill the top of 2nd then I barely started to pull. Hes bone stock tho. I know he has the better heads, but that cant make THAT much of a difference. Can it? Whats going on with the tuning?

I throw codes for my front o2's on occasion. So Im assuming the are bad. I replaced them with the old rears that arent in use, and the code went away. But I dont know if it went away like it normally does or if the o2 fixed it. Sometimes when I ease on to the throttle then pound it, the car seems to lag, Maybe I got the cool LS1 V-tec I have no idea whats going on here.

Mods are: XS Stainless LTs,TSP TDs,SLP Lid,P&P TB, P&P MAF, LS6 intake, MSD wires, NGK TR55s gapped at .054, !AIR, !EGR, FRA mod as well.

Any help is appreciated.

 

i don't think you should use rear o2 in the front

 

Put a stock MAF back on it for starters.

 

o2codes are not uncommon on lt cars in cold weather. but it's the last part of june. 16:1 or 17:1 can work on a part throttle lean cruise. is 14.5:1 wot? it'll run like an raped ape at that but only for so long.

quote: 2xls1 Put a stock MAF back on it for starters.


what he said
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It loses power when we drop it below 14.5:1. And yes thats at WOT.

 

 

For starter a lid and LTs are good for 25-35 HP on the own. Now for the hard questios. What is your air/fuel ratio at full throttle? What is you timing? If you get that you can start to answer ur question. PS if it is 14.0 I would not run the car until it is about 13.0

 

I really hate to say this, but if a tuner set your car to 14.5 at WOT, and thats where you make the most power, there are serious problems going on with either the tuner, or his measurement equipment.

If your car is truly see'ing 14.5 at WOT, i highly suggest you immediately stop driving the car and get it to another tuner ASAP.

 

I will try and post a pic of the graph. But the A/F spikes from 2.5k-3.3k and gets as high as 16.25:1 then dumps down to 15:1 by 4.1k then slowly drops to 14.1 by 6000rpms.


I was told the MAF has a big affect on it and the vacuum leak are causing this problem. I changed the maf for an 85mm Delphi maf that isnt ported just descreened. It feels as if that cleaned up the choppy idle a bit. As for the vacuum leak I have no effin idea where it could be. I know that on the 01-02 Air system had a little plug on the back of the manifold, but I cant seem to find it. The only 3 lines I can feel coming off the back of the manifold 1 hose from the driver side, the small plug on the pass side and the pigtail connector on the pass side as well. WTF am I missing?

 

try what my brother did. We both had a simular problem. He disconneted that big manifold lookin thing and all those small lines, runs great. He did this by getting a plastic "T" and connecting the lines from the brake booster,pump and whatever the other one is for. Smog guy never even notices.

 

You mean you disconnected everything from the back of the manifold?

 

Ouch u better get it tuned lean is hot. you run much like that and u will be getting a new engine. You need to tune for your maf. Unless a leak is large it will not make your car that lean.