Increased exhaust emissions after mild cam install

Engine is LS3 stock and tuned good.

About 5 months later, a workshop installed a cam from Texas Speed for our customer. We noticed at idle high exhaust emissions (smells, eye burning exhaust fumes, etc....) and sluggish transient throttle response. Before attempting to re-tune, is this expected or could be a problem with cam installation? Appreciate any suggestions/comments.

G'day Saif.

That sounds reasonably expected. The cam will have changed the VE of the engine (quite drastically if its an aggressive profile with lots of overlap) at the idle RPM, so the fueling will now be incorrect. You'll definitely need a re-tune.

Are you running a Vernier cam gear, or the original fixed position item? Are you still running the original rockers?

Hi Zac, thanks for the feedback.

Fixed cam gear and original rockers is we use.

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To be honest, there isn't too much that could go wrong if you've only changed the cam, but still have the original gear, lifters, push rods and rockers etc. You could do a leakdown test to check your valve sealing, but I think your problem can be sorted with tuning. Have you got the specs of the cam that's been installed? You might have to end up raising the idle speed to get it really happy, the VE might be so low at the original idle speed that it'll just never want to run there.