Okay, so if you have read the previous topics I have posted you would know that I have been having unexplainable problems with my car.

After my Headers/Xpipe with no cats and retune I only gained 7rwhp/7rwtq.

Well, I went to a different shop today to get the exhaust moved and tightened up. I had a bad rattle/grinding noise from the pipes touching against the car. Well, I got that all fixed up and I talked with them about my unexplainable problem. They told me they would take a look at the tune on the scanner.

Well, to make a long story short... they came back and told me that my car is running at 19 degrees of timing! This is lower than stock! The owner of the shop told me I should be at about 25-26 degrees of timing.

It seems that the tune is set up to run 19 degrees of timing. Whats the deal? Did my original tuner do this on purpose or is something causing this? I am so confused on what exactly is going on.... But, the fact that I am only at 19 degrees of timing explains my 15-20hp loss.

What should I do? I don't see how bad gas could be the cause of all of this... something else has to be wrong.

Also, I switched out my halltech to a vararam last night before I made the trip to DFW. Hoping the vararam will flow better and not cause as high IATs.

Just for reference here are the two original threads about my original timing problem and my minimal dyno gains.

http://forums.corvetteforum.com/show....php?t=2087356

http://forums.corvetteforum.com/show....php?t=2081715

Let me know what you guys think, thanks!

 

Why don't you ask the person who did the tune these ???

 

I'm going to be making a phone call on monday. But, I am confused on whether this is caused by the tune... or something wrong on my car. I just don't really understand what is up, so I'm looking for suggestions and/or explanations.

I don't want to get mad at the wrong person or over-react to anything...

 

Glad to see you're zeroing in on the problem. Keep us posted, it'd be nice to know the cause. Thanks.

 

Do you happen to have access to your tune file? If it's for HP Tuners and you do, let me know and I can take a look at it for you.

 

I don't have access to it...

What I can tell you from today is that the tune is only commanding 19 degrees of timing. Which does not make sense.

I don't know how much timing is actually being taken out, but it should be commanding more like 25 or 26... correct?

 

Well, that all depends on whether your car will take that much timing without knock. Maybe 19* is all the car wants but, I would talk with your tuner or find one you know is completely competent.

 

It's not a linear thing as the amount of timing is based on a lot of different factors - engine RPM, coolant temp, throttle position etc.

As an example, just one of the spark tables in HP Tuners is a 32x33 grid with 1056 values in it.

 

Subscribing...very interesting.

 

If you were curious to see some screenshots of what I'm talking about, PM your e-mail address and I'll send you some pictures of what my tune looks like inside the HP Tuners program.

 

on timing 19-20 degrees is what a typical stocker runs at. I wouldnt go as far as saying 26 degrees would be correct either. You should do or get some logging done to see how much timing your car needs without getting KR. Things appear to be a mess here and I wouldnt have sany reservations about getting it professionally tuned.

 

Sorry, but that made me laugh!

 

ughhhhhh..... I'm just confused on what to do!!

 

I agree that the timing should be looked at BUT may not be the direct cause for your lower hp. Perhaps your car is getting knock and pulling timing back. In fact alot of times cars will make more power with less timing due to knock creeping in.

 

You said you had a "rattle, grinding noise from the pipes". The knock sensors will see that as a knock and reduce timing. I saw a 20RWHP loss on the Dyno with an exhaust rattle.

Fill the tank with good high octane gas, disconnect the battery overnight and Dyno again.

 

The 19-23 degrees timing is actually close to the stock values for an 06-07 LS2. I doubt that the tuner could put in 5 or 6 degrees in the table without seeing some knock retard. On our automatic car, it will get some knock retard at 21 degrees, on the stick car at about 23 degrees. This is after backing off on the IAT correction. This is also at 3000 feet altitude on 91 octane gas. Yours will be different.

You need to ask the second tuner if he actually cranked your timing up to 25-26 and, if he did, was he able to see this much actual timing in the datalog without knock retard. I bet he didn't. If they dynoed it, did they pick anything up in power as a result of the change? Did they dyno it before and after the change or just after? Did they do it after fixing the header interference problem? Did they offer an opinion on whether or not the low timing was due to false knock retard signals from the header interference?

My response to your other thread was to go back and ask the first tuner if the timing tables and corrections he had to use on your car are typical of what he has seen on similar cars in similar conditions. If it wasn't then perhaps the header interference resulted in some false knock retard.

You have added yet another variable by changing cold air intakes. The tune has yet changed again with the Vararam compared to the other intake.

With the Vararam and the exhaust fixed, check the tune one more time and do it on the dyno. And I bet the first tuner can fix it up now.

 

the exhaust rattling was suggested in one of the previous post on your other threads, being picked up as knock, to the tuner saw that it was KR so he brought back the timing, go back to him, put that timing back in, and redyno....

 

Thanks for the suggestion guys!

Just to clarify, the 2nd shop I was at did not change anything, or touch anything (besides fixing the exhaust rattle).

I had the 2nd shop take a look at my tune, but they did not change anything on it. Thats when they told me that it was only commanding 19 degrees of timing and that, that was off and I should be commanding more.

I'm going to call the original shop of my tune and talk to them about it and hope to get in for retuning/dynoing in the next week. If things are still going erray and they don't see it as a problem... Then I might switch to a new tuner.

 

In response to both of these:

If I was getting knock wouldn't it register with the tuner and wouldn't I throw a check engine light? If I was having KR I believe the tuner would have stated that to me.

The only thing I remember him asking me is if I had changed my plugs lately, which I told him that they were NGK TR55s gapped to 42 and only 2 months old.
He said I was pulling 3 degrees of timing and that it was most likely caused by bad gas.

When going to the 2nd shop, they scanned my tune and said that it was only commanding 19 degrees of timing and that I should go back and talk with the original tuner and find out why its only 19, and that I should check and/or change my plugs/wires, put fresh gas in it, add timing and my problems/low numbers should be fixed... Unless, something serious is wrong.

 

If your tuner had the timing set higher and it was retarding 3 degrees of timing, then that would only make sense that he commanded less timing, so it would not retard. Your knocking sound coming from the exhaust might of been the culprit and made the computer think that there was spark knock all along. The tuner cannot get around that, unless he was to turn off the knock control all together (Not sure if that is possible with HP).