#230 Goes to Dealer for Major GM Testing!!

[redjewel]

Originally Posted by rpepka

Scott, that just sounds a little strange to me, well maybe they got a bad bach of cats? Just no torque. I still am wondering why it shifts at 5500 from 1st to 2nd?

Ok I don't drive it everyday but the wife has the Tahoe up in Dallas this weekend so I get to have some fun. I have thought that mine is a little slow but it is hot and humid down here. But after looking and Scott and Randy's and Rpeka problems I think I am in the slower category. My car shifts around 5500 1st to 2nd also and I am seeing more than 6 seconds 0-60.

[PQ]

Originally Posted by aircooled

Why couldn't the exhaust be holding it back? if ya can't get he spent fuel out how do ya expect to cram fresh fuel in

Originally Posted by LabRat

Too True

Too True

Suck Squeeze Bang Blow

Mess up any of the four, and you are FUBAR


LabRat

That's fine. I'm familiar with the way a motor breathes. But as the picture above shows. It is soooooo much more likely that the problem is closer to the beggining of the breathing process. If it was in the exhaust it would have to be a seriously bad defect on the ones with a problem. Again. No way it's in the exhaust.

[bono83]

I would expect there might be some MINOR variations in performance from exhaust system to exhaust system, but Scott's is way off. I don't buy the exhaust excuse. You shouldn't have to purchase new exhaust parts to meet the published performance specs.

[1camaro70]

timing and air fuel ratio, L99 before tune 305/ 300, after optimising air fuel ratio to 13:1 and adding a little timing 327/ 342, nothing radical, so is computer the problem? Do the computers and their sensors cause the performance issue, look at dyno's air fuel varies even run to run, is that normal? Does it happen the same way with tuned car? same sensors, or is it the timing, but then there are knock sensors too.
Don't know how it all works, we need an engineer to explain.

[Duke]

Originally Posted by Scott@Bjorn3D

Ok latest update.

They want the car Monday or Tuesday. Have to see how busy the shop is. GM wants all kinds of reading off the exhaust in different places. Then they said go ahead and put the GMMP axle back on and take the readings again and do 0-60 runs.

Guess they are thinking the exhaust my be causing issues and holding the thing back.

What kind of readings? Perhaps, % Oxygen to confirm the air to fuel ratio or to indicate incomplete combustion. When controlling a boiler, the air to fuel ratio is set and then trimmed based on the % oxygen to optimize combustion efficiency. An engine should work the same way.

And what do you mean, in different places? Could be measuring pressure at different points in the exhaust system to locate a restriction.

I have been following this thread and some others about the slow L99's, since that is what I plan to get. At least they are collecting data. The troubleshooting process is like anyother experiment, make an hypothesis, gather data, evaluate, make a new hypothesis, gather data, etc. It takes time to do it right.

Hang in there Bro.

[PQ]

Originally Posted by Duke

What kind of readings? Perhaps, % Oxygen to confirm the air to fuel ratio or to indicate incomplete combustion. When controlling a boiler, the air to fuel ratio is set and then trimmed based on the % oxygen to optimize combustion efficiency. An engine should work the same way.

And what do you mean, in different places? Could be measuring pressure at different points in the exhaust system to locate a restriction.

I have been following this thread and some others about the slow L99's, since that is what I plan to get. At least they are collecting data. The troubleshooting process is like anyother experiment, make an hypothesis, gather data, evaluate, make a new hypothesis, gather data, etc. It takes time to do it right.

Hang in there Bro.

They want to make sure an exhaust line for a V6 wasn't put on by mistake.

[rpepka]

Originally Posted by irpq11

They want to make sure an exhaust line for a V6 wasn't put on by mistake.

Funny!

[PQ]

Originally Posted by rpepka

Funny!

Wish I WERE joking.

[67 GTO]

Originally Posted by irpq11

They want to make sure an exhaust line for a V6 wasn't put on by mistake.

You never know, I'm sure you guys have seen the NOWEEDS comparison between the exhausts. Maybe time to check? Far fetched, I know.

http://www.camaro5.com/forums/showpo...&postcount=289

[PQ]

Originally Posted by 67 GTO

You never know, I'm sure you guys have seen the NOWEEDS comparison between the exhausts. Maybe time to check? Far fetched, I know.

http://www.camaro5.com/forums/showpo...&postcount=289

Well, that aught to be easy to check for.

[67 GTO]

Originally Posted by irpq11

Well, that aught to be easy to check for.

Like I said, far fetched for sure. I should have made the post with a little more humor.

Just hope you guys get it worked out.

[PQ]

Originally Posted by 67 GTO

Like I said, far fetched for sure. I should have made the post with a little more humor.

Just hope you guys get it worked out.

I like humor.

[Supermans]

Originally Posted by camaro1

exhaust is not holding the car back,, look at the inside of the factory muffler, it is just a straight pipe,, no power to be gained from just a muffler swap on these cars


even the resonator on the L99 cars is straight through,, when i cut mine off for the x-pipe you could see right straight through it!

What is that fuzzy stuff in the inside? Looks like a gerbil got in there, grabbed itself onto the pipe and got roasted onto it..

Originally Posted by irpq11

I like humor.

Hence my never ending pursuit to create it.

[Scott@Bjorn3D]

Yep dealer told me today they are to measure the exhaust in a bunch of different places to make sure restrictive V-6 exhaust parts did not get on the car. It seems this has happened before and the car L99 acted just like mine does. Replacing the exhaust with the correct V-8 exhaust fixed the issue.