Cmg393

Hey guys. I asked this in another (not mine) post but thought I might need to make a whole new one.

I have a cam only (sns stage 2 regular 227/234).
It has stock heads and gears, longtubes, exhaust and a lid.
It wants to buck at low rpm and runs shitty with the ac on.
The tuner said he it just wouldn't make power and it was tuned at a respectable late model Chevy shop in NC so it's not like its anything new for them. He also said if I figured out what was wrong with it he would retune for free.
Any help would be nice.

HCI2000SS

iTrader: (2)

It had had no issues at all before the cam? Also was it tuned by the same person before the cam?

Cmg393

It wasn't tuned at all before the cam and it had no issues at all what so ever before the cam.

farmington

iTrader: (14)

you need to figure out where to find a new tuner ASAP

Cmg393

It was supposed to be one of the best in NC I even asked where on this site. That is what weirded me out.

HCI2000SS

iTrader: (2)

If they've done many like yours before then it makes me think something may have gone wrong or was neglected during the cam install

Cmg393

I did it. Even degreeed it (which was still came out to be dot to dot)
I did btr spring kit
Ls2 chain
Melting high pressure pump
Rocker bearing upgrade
Btr Push rods
Arp bolt
And all new gaskets
I'm probably missing something that I installed and just forgot to list but you get the idea.

Darth_V8r

iTrader: (4)

Couple of questions for you. Does the engine even rev? The tick SNS should rev past 6500. Typically, this would cause HP>TQ, not the other way around.

Second - does your engine try to peak torque early (like around 4000), double hump around 5000, then fall off? That could indicate a tooth off

The bucking - if you have a manual, and a 10 degrees overlap cam, it will buck at low speeds

Cmg393

When you ask if it even rev's, do you mean does it spin up evenly and strong? Then yes. It revs up like a champ. If that's not what you meant then could you reword that please. I wanna make sure I give you the right info.
And he left it at 6500 because I didn't plan on spinning it to high since its my daily. I just wanted a little more power. (I guess not though lol)
The dyno graph looks like you would normally expect I suppose except at much lower numbers than it should be.
And well that explains the jumping. Would 4.10 gears fix that?

Mark01Ws6

330 is pretty low. Something is off.
Tuned correctly this cam will give a slight surge at low rpms. (1500) Ac should have very little effect on it if at all.
The tune can be a major issue. Trust me my 1st tune was horrible to say the least. It was so far off I was worried it was more than the tune. It bucked, surged, would shut off at idle, couldn't even rev it without it surging and cutting off etc.
Had Jeremy Formato retune it and now it's an absolute blast to drive. No issues at all.

Take the advice and get a new tuner. Also just a thought but did he dyno it in anything other than 4th gear (assuming it's a M6) or 3rd if an A4?

Cmg393

No I don't think so.
And I guess I'm just out 400 dollars and the next "best" tuner around here is about 570 and everyone is pretty much booked up for a few weeks unless I asked them to retune it because it drives like complete crap. I'm sure they won't give me a refund.

The tuner said it doesn't sound right at idle. But it sounds pretty close to the other videos of the same cam. So idk.

I just figured it would be something else. It kind of acts like it is still untuned but closer to where it's supposed to be. If that makes sense. It doesn't shut off but sometimes it fluxes at idle real bad. Especially when the AC is turned on and it shakes a noticeable about with it on.

Darth_V8r

iTrader: (4)

I was trying to see if there was anything to indicate the cam was not degreed correctly for any reason. Have personal experience with that, and the engine wouldn't go past 5500 due to a 9 degree advance due to the timing set. 4.10 gears would help in that you get out of 1200 rpm sooner Car running really bad with AC on can indicate a vacuum leak.

Where I'm really struggling is why your HP came in below your torque. A cammed car will almost always be the other way around. Especially since they make peak HP at 6300 and peak TQ at 4800. It should be more like 370/350, which is why I asked about it revving. Anything in the graph to indicate under fueling?

Also, the stock LS1 intake doesn't flow well at all. Truck intakes flow better. Now, it's probably not 40 horsepower worth but the air demand on that cam is much higher than stock. If your car came with the ls6 intake, that should be fine.

Darth_V8r

iTrader: (4)

Regarding the tune, in my case the tuner was able to pinpoint the cam as the issue pretty quickly. I would expect a good tuner to be able to do the same in your case. Plenty of stories about tuners finding low fuel pressure, dead cylinders, failed sensors, and once those items are fixed, the car runs great.

I would hate to see you spend another 400-500 on a tune just to find out something like the fuel pump is going bad or the pushrods are too long / too short

tmoney82

Me personally, a turner shouldn't give the car back to a customer without exhausting everything that he can do to get it right. And for them to say that the car doesn't seems to be running right, he should at least refund some of his money back so he can take it elsewhere.

Cmg393

well regarding the pushrods, I asked tick performance and they said they use 7.400 with this cam and so has everyone else who has use it. ( i asked in the sns stage 2 cam thread ) )

It idles fine without the ac on but when it is on you can hear the car idle differently, even when it isn't fluxing. Like it's strained. I'll have to look up where I might have a vacuum leak and chase that.

and heres a pic of the dyno print out he handed me so maybe you can tell me whats up.



this is all he gave me.

HCI2000SS

iTrader: (2)

Actually this happens more often than you may think. My buddy took his ride to a guy who is sort of known as the "go to guy" for ls1 tuning, and the guy told him to pick up his ride, because it starting running lean. So my buddy picked it up, went through a bunch of bs trying to figure it out, and eventually found it to be the fuel regulator

tmoney82

Well I was meaning if everything else was mechanically right! But I can see where this can happen

slogo

When I screw something up, and it was running good before I worked on it, I
go over everything I touched when I did the job, meaning I touch every thing again (not
dissembling again just touching) and usually I put a vacuum line on in the wrong place, didn't plug something in tight enough, forgot the ground, usually its just something simple
but it happens, not saying you did anything wrong, thats just how I usually fix my problems, good luck finding you'r issue

HCI2000SS

iTrader: (2)

Dumb question but are you sure there isn't a fuel issue somewhere?

Jake89

Another thing that has yet to be addressed is the AFR. I believe it should be around 12.8-13.2 (maybe a little to lean not completely sure). I would go back and request the dyne sheet showing the RPM's and AFR on the same sheet instead of the MPH. That is just my two cents. Hopefully it is something really simple.