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Discussion Starter #1
I put in a new BTR stage II cam in my GT. I love the sound and understood that on a stock converter it might be pushing through it. My only concern is the idle. The company that tunes it said he tries to find the lowest RPM before it dies and then tunes it up a bit higher than that. He said that once it gets to optimal temperature it’ll idle better but other than that the RPMs drop low and then come back up and it doesn’t sound right to me. Even after a spirited highway drive, going to turn it back on it falls into that weird mode. Maybe I’m over thinking it but I can take it back to be retuned. Seems they forgot to replace the engine cover as well.
 

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I would give your tuner one more chance to make things right and by " making it right" I mean he will street tune it with you in the car and not charge you a dime. Good, reputable tuners will do this and should do this off the bat. If you get any kick-back from the tuner, find a new one.
 

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Discussion Starter #3
They’ve been good to me, and the tuner even said he’d touch it up if need be just didn’t know if I was overreacting. I’ll be sure to get it done.

In love with it all over again but it’s definitely a bit aggressive for a passenger.

Thanks for the reply.
 

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I just installed the same cam in my GT with stock converter. What RPM did he end up getting it down to? Mine idles great now at 750 but it took a good amount of tweaking and logging to get drivability to where it is at! The brakes pushing is only noticeable when the car is first started, maybe for a minute or 2 at most.

Biggest things were getting the idle airflow, spark, and adaptives happy together for all modes... park, drive, ac on and off. It should not be jumping around like crazy, bogging, lurching, acting like it will stall coming to a stop or downshifting.

And another thing i learned is that if you are having a "random" rough idle after cruising highway and then coming down to idle for a minute... it isn't random, its your Catalyst monitor running and it commands a 15.8ish AFR which my engine did not like. It would start shaking hard and surging until it finished or you started moving.

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Discussion Starter #5
Pretty much described how it can be sometimes. Been wanting to take it out the garage but it’s been nothing but cold rain here in Chicago. I’ll call to set up another tuning appointment because I forgot what RPM he said he got it to, but the way he described it to me was he’d get it right to the point where it would die. Go a little higher than that and mark it there. He also said once warmed up, especially after a long drive on the highway it would smooth out but it lunged a little getting out the driveway.

I’ll be sure to bring this stuff up to him
 

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Should be an easy fix. A stage 2 cam shouldn't be that much of a hassle to tune.
 

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Thats really odd, maybe he didn't change all of the tables, and the engine is correcting. Or maybe they didn't switch to speed density tune and run both. (I believe you have to chose one, either speed density or maf otherwise it'll run like crap.)

Funny enough is that there is a Tune in the tune repository on HP tuners site where they got PatG's tune for that cam. Idle I believe is around 800.

I JUST installed the same cam, so I've been studying HP tuners to do the changes myself. Sounds like something is missing in that tune they did.

I've also read somewhere that there is a lean-out protection mode (I cannot remember the name of it for the life of me.) that L76 engines need to have disabled otherwise they'll act weird when you start messing with fuel trims. That isn't a big issue for most LSs but L76 is really sensitive to that mode.
 

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Discussion Starter #8
I’m supposed to take it back sometime next week. He said he’s willing to play around with it more but yeah we smelled it running a bitch richer than before as well, bringing it back into the garage. I also mentioned the lunging which he said could do that after sitting so long because of the stock converter, that’s in the works for next years project as well as a new bumper (GXP) and suspension mods. I took a screenshot of it and I’ll mention it to the tuner. Thanks
 

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Im not sure i did anything about a lean out protection mode, be curious to see what it is. Like i said my biggest thing was the catalyst monitor, i disabled it the day i passed emissions in MD! That thing reslly made the car angry after stopping at a light. Im running mine in MAF mode only, ran out of extra free time recently so VE tuning has been on back burner.

If anyone wanted to see my tune or let the tuner compare things i could share it. I did a lot of reading, research and testing to get it where it is but i do not do it professionally.

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Disabled the rear O2? Or did you set them to not report errors? I think if you disable it does effect the tune slightly. You should set them to not report, I don’t remember anything there that you should straight up disable. Try that
 

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Disabled the rear O2? Or did you set them to not report errors? I think if you disable it does effect the tune slightly. You should set them to not report, I don’t remember anything there that you should straight up disable. Try that
Nope, in the tune there is a box that says "catalyst test", i selected disabled. I still have cats with my longtubes, rear o2's and o2 test on.

There are other threads about stock g8's and random shaking at idle. They found that the catalyst test was commanding almost 16:1 afr at the start of test and it was the source of the shakes. Throw in a decent cam and shakes became surging and rough idling.

So my car passes obd emissions without any changes to MIL error reporting... but once i passed its much more pleasurable without the catalyst test

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