I had just spent 15min making this thread and CF lost it, so let's try again.

After getting my car tuned, I've been having some driveability issues and wanted to get the opinion of the masses before I start giving the tuner bad reviews.

Basic setup:
PRC Stage 1 243 heads
Torque V2
LG Longtubes
LS2 Throttle
FAST 92
FAST 36lb injectors

Car made 421whp/376wtrq which to me seemed a little low (not a lot, maybe 20hp) but after seeing other cars run at their dyno day, their dyno is definitley a heartbreaker.

After getting the car tuned the first time, I was having problems with the RPMs missing idle and stalling out. So a week later, I took it back and left it for a few days for them to adjust it.

I get it back and it's better. It's not stalling as often, but the rpms still dip to 400rpm, especially with extra load on the engine from the a/c, power steering or brake booster.

I take it back again. This time I don't leave it and the tuner rides with me. I get it to nearly stall and he gives me a look like "wtf did you just do?". He makes adjustments to WHOLE TABLES which isn't very confidence inspiring. He told me to try it out for a couple days and bring it back if I'm not happy with it.

After driving it for a couple days, not only does it drop under 500rpm on occasion but now if you do a quick off-throttle, on-clutch, the engine will race up to 2000rpm. I took it back yet again. First, I called them asking for an update and they told me the car was ready. This already pissed me off that they didn't call me when it was ready. Next, he told me 3 people drove it and didn't find any issues so they couldn't make any adjustments. He gave me the runaround telling me it's an aggressive cam and I need to drive it differently. I think that's just a bullshit excuse.

I'm sick of taking it back and being told that there's no issues. Am I expecting too much from the setup or am I just dealing with a shitty tuner? They had good reviews but so far, I'm not happy. I really don't want to blow another $500 to have someone else fix their issues.

 

Your cam has a bit more lift and 3/4 more degrees of duration. It isn't that big to be giving you these problems. Should be tuned better. Sounds like you took it to a shop that's good on WOT tuning but not so much on drivability.

 

Don't shoot the tuner just yet, yes it can be a poor tune, but it can also be the injectors you used. The FAST injectors are drilled out stocker's, they are very low quality IMHO, we will not use them here.

 

It's too bad that's what they recommended.

 

Issue with most dyno tuners is that their experience deals strictly with max HP and TQ at WOT only----However they have less experience in P/T and drive ability issues
Good thing is that all your issues are very common on a eng with heads/cam/LT headers
and can be corrected with proper tuning with someone who is willing to take the time to fix all the issues
----Even wrongly scaled injectors can be corrected with wideband tuning for WOT
Now at P/T you have to realize that no matter what your combination is the front 02's rule all your P/T fueling--and that can be corrected with MAF adjustments--Try to get all your LTFT fuel trims to read "0" or slightly negative
The most common tables that need addressing with LT's and a cam are:
adding 3-4 * of timing to both the base idle timing in P/T and in gear
adding apprx 25% to the desired airflow table both in P/T and in gear
raising the desired idle to about 750 again in P/T and in gear
If your car is dying when coming to a stop subtract 20% to the throttle follower decay rate in gear
same goes for P/N if it tries to die subtract 20% in the decay rate
With LT headers the front 02 bungs are moved sometimes as much as 3' further back this makes your 02's read in correctly and all your P/T fuel is messed up because the 02's do not heat up correctly and read wrong--they are only designed to work in the stock location--Why shorty headrs are legal
LOWERING the 02's switching points will help the front 02's but they will never work as stock again but you can get them close ( that's why LT headrs are illegal in most states as they make your 02's read overly rich so far back

 

As already stated above, it is likely tuning issues.

I have had similarly poor experiences with a local tuning shop and gave up. I used to tune a little on the side so I took that up again, it has taken an extreme amount of time to tune everything else beyond WOT - WOT only took a few weeks via some HP Tuner guides.

I would either see if you can work with your current tuner somehow or find a very well known tuner that can do more than just WOT.

 

Assuming it's not a mechanical problem (such as the injectors as mentioned above) that setup should be plenty driveable. My last Corvette had ls6 head and the same cam and drove plenty well.

Do you have a copy of the tune file you could send or does only the tuner have it?

 

I do not. I guess I could request it. They said they didn't lock it so someone could pull it off but that would cost me, I'm sure.

 

Many ppl run the Fast injectors without issue, not saying it is impossible they are the issue, but likely its just not tuned well yet.

What I have learned after 100s of hours tuning is that you can't just take a tune from another car with the same setup, every engine is unique. So it is very much on the tuner to figure out each engine.

Try talking with the tuner and express how your not happy but you want to get it figure out, they may take the chance to work with you and learn how to fix it so their future tunes are even better.