Bad Cats?

[zquez]

Okay so heres the deal. I just finished my install of the DOB manifold and GT500 blower. Got it tuned yesterday and it made 444/464. Respectable numbers no doubt, but I have a couple issues.

#1 Nearly 15# of boost on a 2.75 inch pulley.

#2 High IATs. 120 at idle.

#3 Extra heat in the cockpit post blower install.

#4 Car stumbles at startup. Hasn't died yet, but it has a very weak start and goes straight to 900 rpm. No settling.

#5 There is the presence of a new smell after driving the car. Can't put my finger on it.

Could I have damaged them by running the car with no tune for a couple days? It obviously ran very rich.

Im thinking right now that they're clogged with unburnt fuel and getting very hot, accounting for the burning smell after a drive and the extra heat in the cabin. Thoughts?

 

[Corpo]

Pull your h/x pipe off and put a light in one end. If you can't see light.. cats.

 

[stkjock]

you realize that those take off blowers are nicked named "heatons"?

 

[zquez]

you realize that those take off blowers are nicked named "heatons"?

Haha yeah. The IATs may be a non issue but the boost is my biggest concern.

 

[JeremyH]

Might need a bigger pulley to drop that boost and those iat's some. You will likely make the same power still.

Based on your description I would say its def worth it to at least inspect the cats, also be careful, boost and cats dont get along and can damage the engine if they are indeed clogged.

 

[zquez]

Might need a bigger pulley to drop that boost and those iat's some. You will likely make the same power still.

Based on your description I would say its def worth it to at least inspect the cats, also be careful, boost and cats dont get along and can damage the engine if they are indeed clogged.

This ^ ive heard horror stories about bad cats so I want to figure this out ASAP. I'll probably put the car on the lift tomorrow and check it. My tuner too said to get a bigger pulley. I asked Jason and he said I shouldnt be making that much boost with the pulley I have and suggested the cats. I may end up doing both just to be safe. We have pretty strict emissions testing here in NC so I'll be making every effort to retain cats rather than just getting an offroad pipe.

 

[JeremyH]

That make senses, boost is a measure of restriction so if your exhuast is clogged it very well could be showing more boost. Yeah man check those cats, and ditch em lol

 

[one eyed willy]

Meow

 

[v6tungsten]

Might need a bigger pulley to drop that boost and those iat's some. You will likely make the same power still.

Based on your description I would say its def worth it to at least inspect the cats, also be careful, boost and cats dont get along and can damage the engine if they are indeed clogged.

I here the boost and cats don't get along weekly on this forum. Why is it that other boosted cars Audi, BMW, Mercedes, new Corvette and GT500's all run cats with out problems?

 

[Alfiedagr8]

I here the boost and cats don't get along weekly on this forum. Why is it that other boosted cars Audi, BMW, Mercedes, new Corvette and GT500's all run cats with out problems?

Tuning has to Do with it. These companies spend alot of time and money to make sure the cats don't get damaged.


Sent from my iPhone using Tapatalk

 

[Jinx]

I here the boost and cats don't get along weekly on this forum. Why is it that other boosted cars Audi, BMW, Mercedes, new Corvette and GT500's all run cats with out problems?

I had the same thoughts, but after being shown on this forum by it's member....I can acknowledge that is possible. Well, even if the chances are small on some cars with certain setups......I like to eliminate the chances altogether by just removing the cats.

From what I here, the 2013 GT500 has a "catalytic converter protection" function in it's tune. It may be just hearsay for all I know.

 

[JeremyH]

Thats what rear o2's sensors are for, to monitor the cat and provide feedback to prevent this. However stoich a/f is much richer when boosted compared to na, as well usualy running upgraded fuel system and modified tunes so the cats will be getting more fuel than the stock tune would allow. Also the increased exhaust gas temperature and pressure with boost dont help either.

 

[zquez]

I did the flashlight trick and I couldn't see a damn thing. I put my shopvac into blower mode and put in the inlet and there was plenty of air coming out the other end. idk. My manual says to do a vacuum test, but I didn't have a tee so it'll have to wait. I haven't gotten any codes from the 02 sensors. If I didn't have to get the damn thing smog inspected here in NC I'd probably just get rid of them to be on the safe side.

 

[lito]

Okay so heres the deal. I just finished my install of the DOB manifold and GT500 blower. Got it tuned yesterday and it made 444/464. Respectable numbers no doubt, but I have a couple issues.

#1 Nearly 15# of boost on a 2.75 inch pulley.

#2 High IATs. 120 at idle.

#3 Extra heat in the cockpit post blower install.

#4 Car stumbles at startup. Hasn't died yet, but it has a very weak start and goes straight to 900 rpm. No settling.

#5 There is the presence of a new smell after driving the car. Can't put my finger on it.

Could I have damaged them by running the car with no tune for a couple days? It obviously ran very rich.

Im thinking right now that they're clogged with unburnt fuel and getting very hot, accounting for the burning smell after a drive and the extra heat in the cabin. Thoughts?

1) No much experience with the swap but does not sound bad for that combo and an stock cammed engine.

2) Heatsoaking of ACT is normal.

4) Tune issue, which injectors are you using? GT500s by chance?

5) Can be anything.

Damage by running rich, basically no.

With clogged cats you would not have gotten those numbers.

Rich does not kill cats.

 

[Swarzkopf]

Clogged or not, I bet you'd drop 1-2 PSI just from deleting the cats. You'd probably pick up a few horsepower, too.

Regarding the 'smell':
Does the new smell smell like rotten eggs? Could be the cats.
Kind of like fried onions mixed with poop? Might be leaking a bit of blower fluid somewhere (snout to case surface usually).

 

[S197gt07]

Have you asked Jason if 15# is normal for a 2.75"?

I've been following the builds closely and that seems real high for that size.

 

[stri8ed]

op, any word on what the problem might be?

 

[JeremyH]

op, any word on what the problem might be?

+1.

 

[S197gt07]

I think I read on another forum that he had a clogged cat. Jason said that was way to much boost for that pulley size so he checked the cats.

 

[sportinawoody]

i thought those numbers were weak for 15 lbs. definitely something going on