Joe_G

I can tell you with 100% certainty that it'll be free for anyone with a cord to scan you and email you the scan. Be sure and scan when the car is acting up.

And have them download the tune and email that to you as well. It'll be free to look at, you just can't change it without buying a license to change it. You will be able to see what the tuner changed from stock via the compare tunes feature.

Speeddemon777

Haha thanks man! I appreciate the thought. So I couldnt track down a HPTuners for the time being. I will call around on monday I have a few shops that some of my friends work at that may have one (they specialize in Porsches).

UPDATE:
So today I did the smoke test on the intake. There were no noticeable leaks anywhere. I did have to plug the vacuum line going to the intake plenum to get good pressure. I also checked the cats. They looked really good in my opinion ie no broken parts, blockage, or abnormal discoloration. I was able to get video of one of them Ill put a link below.

I figured while I was under the car I would replace the knock sensor. For 12 dollars and 3min I figured it was a long shot but why not. And as expected no change in the performance or noise of the car. I will try tomorrow to get the tuners drf file. If I am successful I will post it here. Is there any questions or information I should also try and get from the tuner tomorrow? Thanks again.


Cat Video:

schpenxel

Any chance the shop will give you a copy of the tune at least? I would be interested in at least having a look at it to see if i can find anything obvious.

Speeddemon777

Hoping they will. If not I will have an HP Tuners Standard on Tuesday or Wednesday. I took back the scanner I bought and for 100 dollars more I figured it was worth the investment to have the HP Tuners. I can remove the tune from the car and upload it for you guys as well as scan the car then.

schpenxel

Sounds good! I agree... for $100 more you might as well.

kcbc

are u telling me there's not a real auto repair shop in California can diagnose your problem scientifically without throw parts on the wall and saying prayer to hope it stick and hoping your problem can go away?...... tech2 is great machine and factory scan tool ...however it is processed informations ....how do u know the O2 sensor is reporting accurately that your car is really running lean?...is it really running lean ...and if your fuel pressure is within spec ...how do you know if the volume of fuel is deliver appropriate?....fuel pressure is not linear proportional to volume!!!..that is a fact --> look up google....but 9 out of 10 mechanic wanna be didn't know that....they are just guessing!!!...I fixed a simple 91 chevy pickup with bad fuel pump but deliver proper pressure spec at idle and bogged down the minute your floor the pedal ..... that truck came from 3 shops who told me the fuel supply is not a problem because the pressure was check out at idle!!!
idle.....

zali0104

GOD F%#$% BLESS YOU kcbc!
This thread is like palm reading 101. Been two weeks and the car still has not made it to a repair shop. Every guru on here thinks cars are fixed by a tune.
GO SEE A FREAKIN MECHANIC.
OPINIONS DO NOT FIX CARS.

Had to put that out there..............ok I'm calmer now

Joe_G

What are you guys talking about? This gentleman has taken his car to the dealer and several shops, and he's replaced the most common items that would cause these symptoms, and he's followed up on each and every suggestion.

IMHO he is approaching this in a methodical fashion, and since his problem is somewhat esoteric, he is asking yet another source (this well regarded internet forum that has in my years of experience here, suggested the right fix for just about every problem eventually) for additional information to help him solve his problem.

I think Speeddemon777 is doing a great job trying to fix this and I'm confident he will with this forum's help. A scan of the car's sensors in a format that many of us are familiar with will no doubt shed light on this problem and I'm looking forward to seeing this get resolved for him.

zali0104

Tuners and speed shops in general are not mechanics. They can change parts......diagnose...?????
All the places he went to, not one has found the problem. I wonder why?
Listen i feel for the dude, but he needs to google "corvette repair" in his area and spend the $250.

schpenxel

You mad?

kcbc

Look up local ASE qualify but L1 certified in specialize on engine performance and emission repair auto shop....any1 who pass front end,brake job test can call ASE certified mechanic but L1 is the highest level which train and pass real exam to DIAGNOSE an issue not THROWING PARTS!!!.....so far no one here address the test of a lean condition but just throwing parts and changing system...... you be surprise the way a dealership structure that mostly they are set up on installing parts as warranty rather than diagnose.....



I fixed a Hyundai last week ,finding the # 2 intake had a broken intake gasket and keep giving me p0302 on # 2 cylinder misfire ....also a p0420 catalytic inefficient code .... guess what.. it came from the dealer and they threw everything on tune up ,switch everything from plugs,injectors,cables ,fuel system service and catalytic converter and the kitchen sink not once but 2 times .... my scan tool live data keep telling me is running rich cause the fuel trim was close to double digits on the negative side ....but it was the computer strategy when it saw high O2 that was sucking in thru the intake as unmetering air and skewed the O2 sensor reading from reality ... so it just kept dumping fuel as a result from a lean condition creating a rich misfire..also flat line the rear O2 sensor causing a cat code....so...tell me about dealership repair !!!!
scan data only good for interpretation if you know the strategy and how the system work ....it is not the BIBLE

kcbc

THANK YOU !!!...


The complete knowledge of internal combustion engine vehicle ,continuous education and certification through sanctioned organization of qualification examination qualify as a technician not some1 just hang a sign take parts out and bypass a problem when they can not fix it the way it was built......




I am so amazed and stunned by reading this forum ,threads after threads repeatedly that owner treating their Z06 like a 1971 chevy pickup truck ..when there's a problem...lets throw parts and hope the problem goes away..... And these are not dumb people in real life...cause if they are ..how can they afford a Z06 ? ....but some how only in auto industry.. people just brain washed by the 'car guy'
mentality.... I'm pretty sure most of them wont let their doctor ,a/c repair man ,electrician or plumber just try parts and service without diagnose and testing ....but only on cars...they are so brave to tear things down and throw parts at a problem.....wish they let their doctor do that to them like what they did to their cars

Joe_G

KCBC you're making a huge stereotype assumption in your assessment of specialty shop technicians, and I can say in the case of at least my shop, you are completely off base. Both of the techs that have worked on my car are ASE certified, dealership trained technicians who chose careers after the dealership with specialty performance shops because they are huge gear heads and they want to specialize their skills modding the cars they love. They know every bolt on our cars and are excellent diagnosticians. They spend their off time at the track

As to consulting with this forum for advice, again, that is a smart move. This is a way to tap into the collective knowledge of people with decades of experience with these cars. Not every post will be of value (case in point) but I've solved many esoteric problems here and I've seen countless others get solved by some of the well meaning and educated folks on this forum.

Speeddemon I hope we, and others smarter than me, can give you some advice on where else to look so that this can be fixed once and for all. The good news is that unlike the 70's cars I worked as a mechanic, our cars have sensors that typically tell us what is wrong (including if the sensor is faulty).

zali0104

Ok..... I took my meds. Attack mode off.
This is the point I'm trying to make, I live in NY. Seems every corner you turn there is a tuner putting out 9 sec cars with ungodly amounts of power. I know quite a few, none of whom have non software based diagnostic tools. Specifically kv probes connected to a scope, smoke machines, ( heard they don't exist in cali), bore scopes, the list can go on and on.
A tuner for the most part assumes your engine is mechanically sound and does what they do best, tune. This is EXACTLY what happened to the OP. The tuner did what tuners do and ignored the possibility of a mechanical issue. OP left with a tune, nothing more.
Over the years I learned, the more I learned the more I realized how much I did not know. No gun slinging tuner is gonna be a ninga engine builder, it's just not possible.
Bottom line is a sensor is not smart, it reads what it can and send information to the pcm hoping it gets there, The pcm assumes the signal it gets is valid and makes adjustments to suit. Alot of assumptions when there can be loose connections, corrosion.
high resistance in circuits, and mechanical issues that can skew sensor readings. A tuner sees the end result of all of the above.
Instead of asking for an opinion, ask for a good mechanic.

Speeddemon777

WOW! I mean wow! is this the internet or what? Listen guys. I am just here for ideas and help. I appreciate anyone who has an opinion with my situation, but there is no need to get hostile over this its my car that has the issue right? Momma always said "if you dont have something nice to say then dont say it at all."

I purposely didnt name the shops that I dealt with, because they did nothing wrong in my opinion. They have worked hard to try and help me. I have been in contact with them on possible ideas and trouble shooting techniques FREE OF CHARGE. I will say this, they are not parts changers, they are listed as repair shops specifically for corvettes! I did however branch out to other "Mechanics" if you will. The look on their face when I show them the list of tests and parts I have tried....Lets just say I have had many pats on the back and rejection, because I had eliminated most of what they would of tried to fix the car. They were very considerate and offered up any helpful advice as well as access to diagnostics scanners such as the tech 2 to which I am very greatful of. I am also very grateful for those on the forum trying to help me.

I do agree in the beginning I did replace parts in the most logical and orderly fashion, because they are typical GM parts that go bad. Well you live in learn I guess. I have learned alot in this experience, so at least there is that. Either way it is the past now...


UPDATE:
Back to the problem at hand. The tuner was nice enough to give me his cell number and we have been countering back and forth with ideas to the problem. I did notice today that my alternator was spiking down from 14v to 12.5v under WOT. It wasnt every time at WOT but it was something seemingly random to be noted. I do have the first gen alternator. So could be a viable issue.

Also, I talked to the tuner more about the tune and was able to get more information as to what was done to the car. First off the dyno sheet had some confusing info. The timing was originally high and the car was running pig rich causing detonation. The tuner removed timing and ended up at 17 degrees of timing at 12:1 A/F for the resulting Hp I noted above. The hesitation was removed but the detonation was not.

I do have the HP tuners file that the tuner was nice enough to give me. Please PM if you would like to take a look. Thanks to anyone who had an idea thus far! I really do appreciate it.

Speeddemon777

If you have ever heard of or know of a good mechanic in the SoCal area that is willing to take this on. I am all ears. I have been rejected by 3 mechanics thus far that have some of the best reviews in the online forums and on yelp that I could find. The people here on the forum and at the speed/repair shop are the best I got.

96GS#007

The point that some including myself are trying to make is that it's not a tune issue. On a stock engine, the stock tune should be fine. After all, how many thousands of cars did GM deliver with the stock tune?!? Screwing with the tune is doing nothing more than masking the real problem.....sort of.

Hence, that's why people are saying that some real diagnostics need to be done and that includes looking at some of the mechanical components. An alternator isn't going to cause detonation or hesitation. There is something else mechanically going on.

zali0104

Dude........I have friends on a few tech forums, wats your zip? I'll see what I can do.

Speeddemon777

I agree, I didnt really want to do the tune. Stock car plus stock tune should always be fine. These are the events leading up to the dyno decision. I had one shop turn me down because the problem existed at an rpm and in turn speed that they deemed unsafe. So they said dyno was the only way they would look at it. Another shop looked at the tech2 and all the things I tried and was convinced it need to be on the dyno for more diagnostics. The last shop I went to, suggested a dyno for further diagnosis. So I did the dyno.

The dealer who I will not name revved my engine like they were in a race car as they took it to the back to have the computer replaced. I do not trust them. They have been nothing but grief for many years. They immediately wanted to keep the car for a week to "diagnose". I called another dealer they said they dont really deal with vettes that the dealer who I do not trust was the best option for my area. Just some back story. I really did fight going to the dyno till everyone ran out of ideas.

Speeddemon777

FINAL VERDICT

So after throwing ideas back and forth with my tuner all day today as to what it could be. The conclusion we came too was the alternator. Basically at high rpm the voltage would become sporadic for some unknown reason. The theory is that the fan blades hit the windings causing the car lose voltage intermittently. This sporadic voltage was too fast for the car DIC to pick up except for a few times. So I tracked down a gen II alternator and put it in as per the request from the tuner. Now she back to her usual old self and this nightmare is finally over. NOW TIME FOR A RETUNE!!!!

I really gotta hand it to you guys though. The ideas kept the juices flowing and allowed me to both learn a lot about advanced troubleshooting and about the car itself. You all inspired me to keep going. I cant thank you all enough.