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Discussion Starter #1
I recently purchased an 02 z and its bone stock. 30 days after owning it ended up having to replace the clutch no big deal. The car still ran fine, a short time after that the car started having a bit more of a rough idle so I figured maybe it needed some maintenance. Did an oil change and cleared the maf sensor and air filter. The car still was the same. A few days later i noticed the car has lost power when at partial-wot. All top end is gone. I have replaced spark plugs and wires added sea foam to the crank case and tank. Still having somewhat rough idle and no mid to top end power. The other night the cel came on and pulled that 91416 code which i cleared off but dont think that has anything to do with the power loss. Any ideas guys?
 

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Confusing as you state no DTCs but then say it has tripped the P1416 which says

Possible causes
- Faulty Secondary Air Injection (AIR) pump
- Secondary Air Injection check valve bank 2 ( right side)
- Secondary Air Injection (AIR) pump electrical circuit fault
- Blocked Secondary Air Injection (AIR) system

Or possible the front O2 sensors are too old or an exhaust leak

If the right check valve is stuck open then it would force right head to be much leaner then left head and engine would run badly at low RPMs.

Using a full GM enhanced OBD-II scanner would say what the problem(s) are
 

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Discussion Starter #3
Confusing as you state no DTCs but then say it has tripped the P1416 which says

Possible causes
- Faulty Secondary Air Injection (AIR) pump
- Secondary Air Injection check valve bank 2 ( right side)
- Secondary Air Injection (AIR) pump electrical circuit fault
- Blocked Secondary Air Injection (AIR) system

Or possible the front O2 sensors are too old or an exhaust leak

If the right check valve is stuck open then it would force right head to be much leaner then left head and engine would run badly at low RPMs.

Using a full GM enhanced OBD-II scanner would say what the problem(s) are
Thank you for the information RacingV. Yeah I can see how that is confusing I contradict myself. I guess i had just assumed that since it was running bad already for a week prior to the code throwing that they didnt go hand in hand. Also I only found that the P1416 was related to the passenger check valve but it appears there could be various additional issues as you had mentioned.

As it could be several issues I may need to check out this GM scanner you are referring to. Is this someting a local Autozone might have or is it GM Dealer specific?
 

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On-board tests are done at certain times and engine temps so it is easy to think a problem exists of not just by when a DTC trips.
Also DTCs can be in a history state ( happened before) or current which mean very recent so reason a full OBD-II scanner is needed

No auto parts stores do not sell full OBD-II scanners, they tend to sell DTC code readers only and you have to buy from vendors on the internet.

Right AIR checkvalve is a bit of a bitch as it is located right side back of engine
Taking the right valve cover off might make it easier to get to hose checkvalve is connected to
You MIGHT be able fix a checkvalve that is stuck open by soaking it in a carbon cleaner
Valve allows air to go one direction but not from exhaust side back to smog pump

I'd clean both and assure they are the problem
 

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Discussion Starter #5
On-board tests are done at certain times and engine temps so it is easy to think a problem exists of not just by when a DTC trips.
Also DTCs can be in a history state ( happened before) or current which mean very recent so reason a full OBD-II scanner is needed

No auto parts stores do not sell full OBD-II scanners, they tend to sell DTC code readers only and you have to buy from vendors on the internet.

Right AIR checkvalve is a bit of a bitch as it is located right side back of engine
Taking the right valve cover off might make it easier to get to hose checkvalve is connected to
You MIGHT be able fix a checkvalve that is stuck open by soaking it in a carbon cleaner
Valve allows air to go one direction but not from exhaust side back to smog pump

I'd clean both and assure they are the problem
I havent had a chance to mess with the check valve just yet. But I thought they really only come into play on a cold start and only effect emissions?

In any case a few other things i noticed, i hear somewhat of a whine when wot and in 6th gear at about 1000rpm wot/max load i could hear pinging. Im starting to think that maybe I just need to change out the fuel filter as maybe not enough fuel is getting through. Others have said it could be i have a broken valve spring as around 2002 models are notorious for issues with broken valve springs.
 

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sounds like springs
zteve06
blk 02 z06
 

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Im starting to think that maybe I just need to change out the fuel filter as maybe not enough fuel is getting through. Others have said it could be i have a broken valve spring as around 2002 models are notorious for issues with broken valve springs.
No way fuel is your problem. If you're going lean on fuel just revving the motor in neutral, you wouldn't have enough to be able to drive at all under load.

You're hearing funny noises, it's mechanical. But these motors and the driveline can make all sorts of noises. You're a new owner. It may not be anything. A compression check would tell you if you have a valve problem. Or if you're more motivated, the valve covers are not that tough to remove and you could inspect the springs directly.

Air Injection occurs in the exhaust, it doesn't directly effect the engine operation. But I think on the LS6 the intake for the pump is filtered airbox air. If the check valve is bad and exhaust is being driven in to the intake, that could be causing a problem. But I know from experience, throwing a P1416 does not put the engine in to reduced power mode. This may be a problem, but I doubt it's the real problem.

But bottom line, you bought a 12 year old performance car (I own an 02, too). C5s are, in my experience, really well built cars. But they're generally abused by their owners (it's what we buy them for, isn't it?). It may be in need of some tender loving care. Parts that haven't already been replaced are almost certainly worn out if the car has any significant mileage on it (mine's at 110K. I've recently done plugs/wires/senors, and a new clutch, and am gearing up to do the suspension. But the motor still runs like new, idles smooth and gives me close to 30MPG at 70MPH).

As far as reading codes is concerned, the DIC is as good as a scanner. But with a real scanner you can see sensors and get a much better idea of what the engine is doing and this should help you diagnose any problem. So to start, buy yourself some scanning software, HPTuners, EFILive, LS1Edit, something you can hook to the OBD-2 to see what's going on.

Otherwise, without the right tools, you're going to be stuck with guesses.
 

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Discussion Starter #8
No way fuel is your problem. If you're going lean on fuel just revving the motor in neutral, you wouldn't have enough to be able to drive at all under load.

You're hearing funny noises, it's mechanical. But these motors and the driveline can make all sorts of noises. You're a new owner. It may not be anything. A compression check would tell you if you have a valve problem. Or if you're more motivated, the valve covers are not that tough to remove and you could inspect the springs directly.

Air Injection occurs in the exhaust, it doesn't directly effect the engine operation. But I think on the LS6 the intake for the pump is filtered airbox air. If the check valve is bad and exhaust is being driven in to the intake, that could be causing a problem. But I know from experience, throwing a P1416 does not put the engine in to reduced power mode. This may be a problem, but I doubt it's the real problem.

But bottom line, you bought a 12 year old performance car (I own an 02, too). C5s are, in my experience, really well built cars. But they're generally abused by their owners (it's what we buy them for, isn't it?). It may be in need of some tender loving care. Parts that haven't already been replaced are almost certainly worn out if the car has any significant mileage on it (mine's at 110K. I've recently done plugs/wires/senors, and a new clutch, and am gearing up to do the suspension. But the motor still runs like new, idles smooth and gives me close to 30MPG at 70MPH).

As far as reading codes is concerned, the DIC is as good as a scanner. But with a real scanner you can see sensors and get a much better idea of what the engine is doing and this should help you diagnose any problem. So to start, buy yourself some scanning software, HPTuners, EFILive, LS1Edit, something you can hook to the OBD-2 to see what's going on.

Otherwise, without the right tools, you're going to be stuck with guesses.
Thanks, all the information helps. I dont think the car was abused, the previous owner had the car for the last 7 years and only put about 2,700 miles on it, meaning it sat in the garage most of the time. The car ran great when I first got it. The car definitely has a lot of creaks and sounds throughout which sometimes makes it hard to determine if something is wrong or if its normal. Ive factored out valves, only code still is the p1416. Ive recently fueled up with shell ( i ususally use cheap arco gas, shame on me) the car is running a bit better now. I think the whistle/whine like noise i hear from the front is from the check valve as its stuck and like you said the intake does suck air from here. I have paper filters with no oil, the tb had some exhaust like smelling film on it so i believe a mixture of bad gas and the intake sucking in exhaust fumes is the the culprit.

Cant wait to get her running great again so i can start investing in some mods, i was already starting to get use to the power :eek2:
 
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