freaknbigpanda

Hey Guys,

I recently purchased a 2005 z51 Corvette and it is not passing emissions. Apparently 3 sensors (Heated Catalyst, Evaporative System, & Oxygen Sensor) are 'not ready'. It isn't a failure, the monitors are just not active according the guys at the shop I brought it to.

The corvette has an aftermarket exhaust and an ECU tune.

The shop said that I just have to drive the car more to get the monitors to 'reset' but I am worried that the ECU tune and or aftermarket exhaust has something to do with it. I've driven the car for almost 800km since getting it (mostly highway) so I don't think that is the problem.

Does anybody have info that can help me pass emissions?? Do I have to put the stock exhaust back on & possibly get a new tune?

Thanks!

0Dasilvamotorsports

If the battery has been off then it will need to complete the drive cycles to get information to the monitors .
If you want you can bring it to us and we can guarantee it will passed.

freaknbigpanda

So the exhaust has nothing to do with it? If I complete the drive cycles listed here:

http://www.obdii.com/drivecycle.html

It will pass the test? And thanks for the offer, if it doesn't pass again I will definitely drive it out to you guys.

Cheers

LS7 BUD

Trust Manny at DaSilva Motorsports when he says he can garauntee it will pass... I have a huge cam in my car and tons of work done... It passed without any issues thanks to Manny...

0Dasilvamotorsports

Thanks brother , ya know we get it done @ Dasilva Motorsports

FordPrefect

I also had work done at Manny's, nothing dramatic just headers, high flow cats, x pipe and Borla Stingers along with a Vararam. Passed emissions test with no problems at all.

They know what they are doing, plus you might get a blueberry muffin as well. It's all good.

HiVoltge

My superchargered LS1 has passed emissions with no issues twice since it was installed and tuned by Manny

lionelhutz

PM me your email and I'll send you pdf files listing the drive cycle test info for those 3 monitors.

Out of curiosity, is it a catback exhaust or a full header system?

The biggest problem it appears you have is that you pretty much need a scanner to know it has set the monitors.

FYI, the evaporative and O2 tests really should pass no problem. You can pass with 1 not complete. Also, my understanding is that the monitor changing to "ready" actually means the test was performed. At that point, if there is an issue with the car you should get a code otherwise no codes and ready state means you pass emissions.

freaknbigpanda

So I just did both the O2 and Cat drive cycles and the scanner is still reading 'not ready' for those two tests (evap is ready now randomly). Does anybody have any idea as to why that would be happening? I did the drive cycles exactly as specified in the manual.

0Dasilvamotorsports

Sometimes it takes more than just doing the drive cycles .

If you can out to my shop this week I can help you put this issue behind you .

lionelhutz

I take it you mean the Evap system just turned to ready without doing any special driving?

You've got headers so do you even have catalytic converters? Do you have the rear O2 sensors? Did you find any DTC's with the scanner? It could just never go ready if the tuner didn't disable the relevant DTC codes correctly.

One other thing - is it possible you have a weak battery that has been randomly resetting the monitors every now and then when you start it?

I turned-off a bunch of DTC's on my C5 and it took very little driving for the monitors to come-up ready, maybe 15-20km or so. But, I've seen other newer stock vehicles take 300km+ to set the monitors to ready. Some of them just take time to run the tests.

freaknbigpanda

Yes I do have catalytic converters, no dtcs at all with the scanner. It is possible I have a weak battery, not sure how I would check that though. And yes the evap system just turned ready without any special driving at all.

Arun@Dasilvamotorsports

Your tune could have a lot do with it. Regardless it should be a simple fix to get you to pass.

Caddyboy

There are 2 ways of disabling DTCs, one will pass emissions and the other will not if that's the issue here.

Best heed advice in this thread and take it to a shop that can flash calibrations onto your ECU. GM dealer won't help you in this matter.

lionelhutz

Yes, you can improperly disable the DTC, hence why I posted it could be done wrong. But, I'd expect the rear O2's to still be installed behind the cats and it should still show ready for the O2 monitor if they are all installed. But, it's possible the rear O2's are missing and the tune was done wrong and that's why the O2 and catalyst monitors are not showing ready.

WildWilly55

Take it to Manny!!---Just etested my 01 that would not pass the old test wiith the sniffer attached--headers and very little left of the CATS!!---new test hooked up to the ECM---no problems!!! The infamous wisdom of governments--its not about clean air anymore --it will and always will be about $$$$$$$$$$$$$$$---gotta make up for shutting down all those gas plants somehow!!! Just say'n!!!

RedZ4me

^^^^

100% true, it's about money only. Todays vehicles run cleaner than ever.