Red Hot Cats
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Joined: Mar 2007
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From: Macungie Pa
Red Hot Cats
posted this in C5 Tech last night...
My H/C/I car just had a SD tune on wednesday. It's a big cam on a 346.
Drove home 95 miles with 2 issues. Small stuttering between 1800-2200 rpms in any gear and idling down at a stop will drop to 400-500 rpms then pick back up to 900-950. Nothing else....yesterday I discover after a short cruise that my cats are in meltdown mode plus tons of underhood heat. Car ran great and hammered 1 time and she ran real strong. No current codes, no pinging, and no knocking. Plugs are TR6's gapped at .050 and they look clean.
Will get with the tuner tomorrow but looks like anoher trip to his shop. Wish I knew of any risks of driving this thing unless I just go ahead and gut the cats and then take the follow-up trip....
My H/C/I car just had a SD tune on wednesday. It's a big cam on a 346.
Drove home 95 miles with 2 issues. Small stuttering between 1800-2200 rpms in any gear and idling down at a stop will drop to 400-500 rpms then pick back up to 900-950. Nothing else....yesterday I discover after a short cruise that my cats are in meltdown mode plus tons of underhood heat. Car ran great and hammered 1 time and she ran real strong. No current codes, no pinging, and no knocking. Plugs are TR6's gapped at .050 and they look clean.
Will get with the tuner tomorrow but looks like anoher trip to his shop. Wish I knew of any risks of driving this thing unless I just go ahead and gut the cats and then take the follow-up trip....
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From: Palmdale, Ca----- 2009 Cyber Gray 4LT A6 F55 452 RWHP 422 RWTQ- RIP 1998 C5 734 RWHP & 585 RWTQ-----
When you say H/C/I do you mean for the "I" Inducted, if so what injection are you running Nitrous or SuperCharger?
In my first assesment and best guess at this point, it sure seems that your CATS are melted or plugged up - especially if they are glowing red hot!
They are unable to evacuate all the exhaust and it is backing up! or your plugs are way to cold if your not FI!
Now as far as the TR6's wayyyyyyy to much gap for a Force Induction - it needs to be more on the edge of .032 and "NOT" .050
and if your not FI then you need to get a hotter plug to burn the gases and not the cooler TR6's
Let us know anymore details - You might try taking the cats off and doing an open header drive and see how it acts - just be careful and drive it normal and copy the way you drove it when the cats got really hot! It's worth the try and re-gap those plugs!
I hope this helps some
Thanks,Matt
In my first assesment and best guess at this point, it sure seems that your CATS are melted or plugged up - especially if they are glowing red hot!
They are unable to evacuate all the exhaust and it is backing up! or your plugs are way to cold if your not FI!
Now as far as the TR6's wayyyyyyy to much gap for a Force Induction - it needs to be more on the edge of .032 and "NOT" .050
and if your not FI then you need to get a hotter plug to burn the gases and not the cooler TR6'sLet us know anymore details - You might try taking the cats off and doing an open header drive and see how it acts - just be careful and drive it normal and copy the way you drove it when the cats got really hot! It's worth the try and re-gap those plugs!
I hope this helps some
Thanks,Matt
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Joined: May 2003
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From: ECS : WTF did you break now and HTF did you break it this time
When you say H/C/I do you mean for the "I" Inducted, if so what injection are you running Nitrous or SuperCharger?
In my first assesment and best guess at this point, it sure seems that your CATS are melted or plugged up - especially if they are glowing red hot!
They are unable to evacuate all the exhaust and it is backing up! or your plugs are way to cold if your not FI!
Now as far as the TR6's wayyyyyyy to much gap for a Force Induction - it needs to be more on the edge of .032 and "NOT" .050 and if your not FI then you need to get a hotter plug to burn the gases and not the cooler TR6's
Let us know anymore details - You might try taking the cats off and doing an open header drive and see how it acts - just be careful and drive it normal and copy the way you drove it when the cats got really hot! It's worth the try and re-gap those plugs!
I hope this helps some
Thanks,Matt
In my first assesment and best guess at this point, it sure seems that your CATS are melted or plugged up - especially if they are glowing red hot!
They are unable to evacuate all the exhaust and it is backing up! or your plugs are way to cold if your not FI!
Now as far as the TR6's wayyyyyyy to much gap for a Force Induction - it needs to be more on the edge of .032 and "NOT" .050
and if your not FI then you need to get a hotter plug to burn the gases and not the cooler TR6'sLet us know anymore details - You might try taking the cats off and doing an open header drive and see how it acts - just be careful and drive it normal and copy the way you drove it when the cats got really hot! It's worth the try and re-gap those plugs!
I hope this helps some
Thanks,Matt
besides the obvious of clogged cats (buddy's truck with clogged cats wouldn't even move, but would idle) I've seen glowing cats in cars with wires crossed (lt1....not the case here) and with massive timing retard (used wrong distributor gear material and it was worn 2/3rds down from where it was meant to be with my 502 when I switched from the GM distributor to a msd billet I had sitting in the garage)
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Joined: Mar 2007
Posts: 507
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From: Macungie Pa
When you say H/C/I do you mean for the "I" Inducted, if so what injection are you running Nitrous or SuperCharger?
In my first assesment and best guess at this point, it sure seems that your CATS are melted or plugged up - especially if they are glowing red hot!
They are unable to evacuate all the exhaust and it is backing up! or your plugs are way to cold if your not FI!
Now as far as the TR6's wayyyyyyy to much gap for a Force Induction - it needs to be more on the edge of .032 and "NOT" .050 and if your not FI then you need to get a hotter plug to burn the gases and not the cooler TR6's
Let us know anymore details - You might try taking the cats off and doing an open header drive and see how it acts - just be careful and drive it normal and copy the way you drove it when the cats got really hot! It's worth the try and re-gap those plugs!
I hope this helps some
Thanks,Matt
In my first assesment and best guess at this point, it sure seems that your CATS are melted or plugged up - especially if they are glowing red hot!
They are unable to evacuate all the exhaust and it is backing up! or your plugs are way to cold if your not FI!
Now as far as the TR6's wayyyyyyy to much gap for a Force Induction - it needs to be more on the edge of .032 and "NOT" .050
and if your not FI then you need to get a hotter plug to burn the gases and not the cooler TR6'sLet us know anymore details - You might try taking the cats off and doing an open header drive and see how it acts - just be careful and drive it normal and copy the way you drove it when the cats got really hot! It's worth the try and re-gap those plugs!
I hope this helps some
Thanks,Matt
I had both sets of plugs, TR55's and the TR6's and while not knowing my a/f ratio, I decided on the colder plug for the drive to the tuner.
My bad....
I will confer with my tuner tomorrow and I might as well drop the exhaust and check the condition of my cats as a precaution.
I'll post any results...
Thanks for the help guys....
Race Director
Joined: Apr 2009
Posts: 10,581
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From: SE TEX
Good luck with everything! I would check the cats because they may be bad now. I was told when headers get red hot it means you are running rich, maybe someone can confirm this?
Not sure what to gap plugs for a N/A car but .050 seems like a lot.
Again, good luck with it all!
Not sure what to gap plugs for a N/A car but .050 seems like a lot.
Again, good luck with it all!
Le Mans Master
Joined: Feb 2007
Posts: 6,674
Likes: 57
From: Mt Pleasant, TN
Good luck with everything! I would check the cats because they may be bad now. I was told when headers get red hot it means you are running rich, maybe someone can confirm this?
Not sure what to gap plugs for a N/A car but .050 seems like a lot.
Again, good luck with it all!
Not sure what to gap plugs for a N/A car but .050 seems like a lot.
Again, good luck with it all!
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Joined: Mar 2007
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From: Macungie Pa
Okay...I changed over to the TR55's, gapped at .050.
Started great as usual and idled smoother for about 20 seconds. Throttle response was crisper too. Was going to let warm up a bit and take quick test ride but the idling started getting rough and choppy.
Looked underneath and drivers cat was aglow and passenger side was starting to light up too. No error codes. Took em off. I thought I'd see them blocked up but they seem to be clear, letting light thru both.
WTF...I know I just saw them lit up...I'd hate to gut them out if I don't need to. My tuner says the a/f ratio was fine. Going to gut out and get the thing back to the tuner.
side note....car had about 150 miles on it with easy driving on the TR6's and another 100 or so with the TR6's after the tune. Only thrashing was on the dyno.
Thanks.......
Started great as usual and idled smoother for about 20 seconds. Throttle response was crisper too. Was going to let warm up a bit and take quick test ride but the idling started getting rough and choppy.
Looked underneath and drivers cat was aglow and passenger side was starting to light up too. No error codes. Took em off. I thought I'd see them blocked up but they seem to be clear, letting light thru both.
WTF...I know I just saw them lit up...I'd hate to gut them out if I don't need to. My tuner says the a/f ratio was fine. Going to gut out and get the thing back to the tuner.
side note....car had about 150 miles on it with easy driving on the TR6's and another 100 or so with the TR6's after the tune. Only thrashing was on the dyno.
Thanks.......
Melting Slicks
Joined: Aug 2005
Posts: 3,398
Likes: 2
Whats your water temps like? Could be stuck injectors flowing way too much fuel or emissions system messed up (a.i.r. pump etc.), timing way retarded (coolant temp vs timing tables not right when warmed up, some setting dumping lots of fuel once warmed or very little fuel or SD mode is using wrong octane table if tuner didnt copy the high table over to low table since SD runs on low octane table and you might be too retarded timing if he didnt do that. Man it cold be anything....
Something just aint right somewhere in one of the tuning tables that was changed it sounds like and when car starts warming up it throws settings off with fuel or timing.
Is your MAF still on the car and just unplugged or removed completely? Maybe tuner did not enter something right to fail MAF into SD mode and MAF is still trying to work if its left on car and left plugged in maybe?
Call your tuner and see if he can email you the tune file for someone to look at it before you drive the car back to him and possibly damage it badly.
Or Obama has something to do with it....
Something just aint right somewhere in one of the tuning tables that was changed it sounds like and when car starts warming up it throws settings off with fuel or timing.
Is your MAF still on the car and just unplugged or removed completely? Maybe tuner did not enter something right to fail MAF into SD mode and MAF is still trying to work if its left on car and left plugged in maybe?
Call your tuner and see if he can email you the tune file for someone to look at it before you drive the car back to him and possibly damage it badly.
Or Obama has something to do with it....
Last edited by briann510; Apr 29, 2009 at 04:09 PM.
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From: Macungie Pa
I ran the car today with the headers open. As before, the idling characteristics changed to rougher and choppier with the rise in the coolant temps. Held rpms steady at 1800 and it got rougher, almost like the gurgling sound that some get on de-accel. I shut down. The other thing I noticed is I didn't have the extreme heat under the hood. The intake was actually cold. I know it was only about 10 minutes but I wouldv'e had a ton of heat before. After talking with the tuner, I'm going to gut out the cats and take a short local run and see if I have any driving issues.
The MAF is still on the car but the harness is removed.
To be continued....
The MAF is still on the car but the harness is removed.
To be continued....
Melting Slicks
Joined: Aug 2005
Posts: 3,398
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You do have a remote IAT sensor correct? The later C5's had the IAT sensor built into the MAF so you cant just unplug it when in SD mode.
Even with open exhaust though you still have problems it sounds like.
Even with open exhaust though you still have problems it sounds like.
Last edited by briann510; Apr 30, 2009 at 07:55 AM.
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Joined: Mar 2007
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From: Macungie Pa
Yes I have the remote IAT sensor.
Question. ..severly retarded timing...would cam install be off a tooth at cam sprocket ?? ..was installed dot to dot...cam has a 114 +4 lsa...
car revved right to 7k on the dyno...what else would retard the timing ?? No, I didn't degree the cam. I have pics of dot to dot.
Punched out one cat and the other tomorrow...
The idling and sputtering issues were present from the first time I fired up the car, pre and post tune. TR6's were too.
My tuner is highly respected in the corvette tuning/performance industry and is well known for his knowledge and customer service. He has my complete trust . The part that worries me is not knowing for sure that it IS tune related....
Later....I need a couple of lagers...
Question. ..severly retarded timing...would cam install be off a tooth at cam sprocket ?? ..was installed dot to dot...cam has a 114 +4 lsa...
car revved right to 7k on the dyno...what else would retard the timing ?? No, I didn't degree the cam. I have pics of dot to dot.
Punched out one cat and the other tomorrow...
The idling and sputtering issues were present from the first time I fired up the car, pre and post tune. TR6's were too.
My tuner is highly respected in the corvette tuning/performance industry and is well known for his knowledge and customer service. He has my complete trust . The part that worries me is not knowing for sure that it IS tune related....
Later....I need a couple of lagers...
