High HCs on Emissions - Page 3 - ZR-1 Net Registry Forums

04-03-2008

Quote:

Originally Posted by XfireZ51

Arctic,

The trace shows that HC is moving up during decel. Maybe you need to cutoff fuel faster on decel. Could be a calibration change.

And that is masking an issue. Not recomended. This car in good running condition should pass easily.

Arctic91 · 04-03-2008

Hey Jeff...

thanks for asking. Here's a quick update:

A couple weeks back, I made the mistake of bringing it into a local shop that has a good rep for diagnosing emissions problems. A week and $300 later, they were scratching their heads and claimed "internal mechanical problem" as the root cause. Still not throwing codes and everything seems normal. No mods to the car- bone stock - so it shouldn't be this difficult. Lesson learned: stick to those who own a Z to diagnose a Z.

Nitrous Junkie took a look at it for me and ran a leak down test with no issues noted, so I concluded that the other shop was grasping at straws (pretty hard to disprove that diagnosis). Next, I started changing the easy things. New fuel filter and O2s haven't made much of a difference - still running rich, partial throttle "stumbling" and what seems like an intermittent miss at idle. I have new injectors (accel) and ignition wires (MSD) ready to go, but won't be able to get to that until the 12th (with a little help/teaching on the finer points of under-plenum plumbing from Nitrous Junkie and Zr1 Destroyer).

I really hope that the new injectors will do the trick and that the cats haven't been wrecked from it running rich. I'm not sure how long the problem existed before I bought the car... could have had 4 or 40k miles worth of unburned crap filtering through there. I'm thinking that new cats would be the next move if the injectors don't solve the problem. Does that sound logical?

Scott

guinnessdood · 04-03-2008

Scott...if you don't get it to pass with the new injectors I'll be really surprised...but if it doesn't...borrow Ry's "emission exhaust" that is propped up to his fence next to his garage. After you pass...remove his exhaust and install a Corsa...or a B&B (with some aftermarket cats) if you prefer and a set of headers (I think Rod has a used set layin around)....now you'll sound like a ZR-1!!! :-)

cope05 · 04-03-2008

headers laying around..........PM me please with the info if that is the case.

Arctic91 · 04-03-2008

Uly,

I've had the same thought a couple of times... wish me luck once the injectors are in.

04-03-2008	#22
Arctic91 Join Date: Nov 2007 Location: Sykesville, MD Posts: 377	Re: High HCs on Emissions Hey Jeff... thanks for asking. Here's a quick update: A couple weeks back, I made the mistake of bringing it into a local shop that has a good rep for diagnosing emissions problems. A week and $300 later, they were scratching their heads and claimed "internal mechanical problem" as the root cause. Still not throwing codes and everything seems normal. No mods to the car- bone stock - so it shouldn't be this difficult. Lesson learned: stick to those who own a Z to diagnose a Z. Nitrous Junkie took a look at it for me and ran a leak down test with no issues noted, so I concluded that the other shop was grasping at straws (pretty hard to disprove that diagnosis). Next, I started changing the easy things. New fuel filter and O2s haven't made much of a difference - still running rich, partial throttle "stumbling" and what seems like an intermittent miss at idle. I have new injectors (accel) and ignition wires (MSD) ready to go, but won't be able to get to that until the 12th (with a little help/teaching on the finer points of under-plenum plumbing from Nitrous Junkie and Zr1 Destroyer). I really hope that the new injectors will do the trick and that the cats haven't been wrecked from it running rich. I'm not sure how long the problem existed before I bought the car... could have had 4 or 40k miles worth of unburned crap filtering through there. I'm thinking that new cats would be the next move if the injectors don't solve the problem. Does that sound logical? Scott __________________ WAZOO Member '95 Callaway SNAT 450 Aerobody Coupe - Black/Black '92 Callaway SNAT 400 Convertible - Polo Green/Beige '91 ZR-1 #1231 - Arctic White/Saddle (SOLD) '90 ZR-1 #2547 - Turquoise Metallic/Black '89 Callaway Twin Turbo Aerobody Coupe #027 - Black/Black '85 Corvette 454 Coupe - White/Red

04-03-2008	#23
guinnessdood Join Date: Oct 2004 Location: Woods Cross, UT Posts: 389	Re: High HCs on Emissions Scott...if you don't get it to pass with the new injectors I'll be really surprised...but if it doesn't...borrow Ry's "emission exhaust" that is propped up to his fence next to his garage. After you pass...remove his exhaust and install a Corsa...or a B&B (with some aftermarket cats) if you prefer and a set of headers (I think Rod has a used set layin around)....now you'll sound like a ZR-1!!! :-) __________________ Uly Past OWNER 90 ZR-1 #0120 Red/Saddle UT Plate: EZR1DER

04-03-2008	#24
cope05 Join Date: Mar 2008 Location: San Antonio Texas Posts: 16	Re: High HCs on Emissions headers laying around..........PM me please with the info if that is the case.

04-03-2008	#25
Arctic91 Join Date: Nov 2007 Location: Sykesville, MD Posts: 377	Re: High HCs on Emissions Uly, I've had the same thought a couple of times... wish me luck once the injectors are in. __________________ WAZOO Member '95 Callaway SNAT 450 Aerobody Coupe - Black/Black '92 Callaway SNAT 400 Convertible - Polo Green/Beige '91 ZR-1 #1231 - Arctic White/Saddle (SOLD) '90 ZR-1 #2547 - Turquoise Metallic/Black '89 Callaway Twin Turbo Aerobody Coupe #027 - Black/Black '85 Corvette 454 Coupe - White/Red