Burning up catylitic convertors???

Sierra3

Sierra3

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Trying to isolate my problem here. I'm getting 3rd set of catylitic convertors installed tonight. I had a problem with my 02 sensor wiring on the pass side when it came down and burnt on the header. Since then I've rewired both sides and put DEI 1200 fehrenheight loom over them and mounted them far away from headers.
What causes the catylitic to burn and plug up? Too rich? or too lean? My last dyno tune with the SCT chip read a perfect ratio on the wideband setup they had. They weleded a removeable bung into my exhaust for it on the dyno pulls. Hopefully it was the burnt wiring that caused the second set to cook, but i am going for another dyno tune ASAP for paranoia sake. I am switching back to the x pipe after cat i originally had before i went with the H pipe after cats.

Also trying to get rid of that "cardboard in the spokes" of a bicycle sound that the exhaust makes when you punch it. Is it because our mufflers are mounted so far back in the stream? i looked at my friends SVT Cobra, and thier mufflers are mounted almost mid stream, that is the only differance between ours. I love the sound of the mustang Cobra exhaust with duals and an X over, and my Mark is actually a Cobra running package now, but it still has that raspy "cardboard in the spokes" sound...?

1995 DK Blue Lincoln Mark VIII
1998 DK Blue Chevrolet 1500 P/U
2004 BLACK/Silver HONDA CBR 600RR
 
RE: Burning up catylitic convertors???

Cats get hot when the mixture is rich. Engines detonate when lean. Back in the carb days, if you let the car fast idle with the choke on for a while, your cats would glow red hot. Something is clearly wrong.

mark
 
RE: Burning up catylitic convertors???

It's going in for a dyno tune again till i Know that this is set right. The guy that did my tune doesnt work for the guys shop anymore. Closest SCT tuner close to zip 32542 is in Panama City. I will call them up today to see if i can get down there on the dyno for a reburn. Heres some pics. Sorry if there crooked, I got off night shift last night and still havent been to sleep yet after picking up car.
Thats the DEI heat resistant loom i was talking about i put all new wiring in for the wiring harness. I know its got some kind of fiberglass in it cause my hands and arms itched for about three days after i got done messing with it. As you can see that ceramic coat isnt worth the extra money i paid to have it put on. The headers are already rusted and in need of a spray can job of 1700 fareinheight manifold paint.

http://www.lincolnsclub.org/forum/user_files/1427.jpg


http://www.lincolnsclub.org/forum/user_files/1428.jpg


http://www.lincolnsclub.org/forum/user_files/1429.jpg
 
RE: Burning up catylitic convertors???

Speculation:
From what I can see in the pics, the O2's are a great deal further downstream than they originally were.

Since the 02 sensors rely on temperature to report accurate data to the PCM they may be the "root of your evils"...

A wide band may show that you have the correct AF ratio but if the 02s are seeing "cooler" temps than they are expecting...

"could be a problem"... dunno for sure.

Might want to compare a stock mark's 02 readings to your 02 readings.. and compare notes
 
RE: Burning up catylitic convertors???

[div class="dcquote"][strong]Quote[/strong]
What causes the catylitic to burn and plug up? Too rich? or too lean?[/div]

Usually "too rich" will plug them up faster than too lean.
too much unburnt fuel will melt the cats, plugging up the TINY orfices
 
RE: Burning up catylitic convertors???

Move them 02's up to the collectors.

the extra time the exhaust gas takes to get back there might screw with the reading also. but that's pure speculation on my part.
 
RE: Burning up catylitic convertors???

Thats what i was originally thinking also seeing how the bungs were made in the headers in the stocker manifold location. Will do. But i was thinking it was something more serious. The car did have sootty tailpipes i kept cleaning and knew it was running a lil rich, but i thought id keep it that way and take the cut in power to be on the safe side of burning a piston. I didnt know it was THAT rich to cause damage.
What is the optimal fule ratio i should be after at the dyno. Thinking of getting a digital wideband gauge to mount up in drivers compartment to keep an eye on it.

1995 DK Blue Lincoln Mark VIII
1998 DK Blue Chevrolet 1500 P/U
2004 BLACK/Silver HONDA CBR 600RR
 
RE: Burning up catylitic convertors???

[div class="dcquote"][strong]Quote[/strong]
Thats what i was originally thinking also seeing how the bungs were made in the headers in the stocker manifold location. Will do. But i was thinking it was something more serious. The car did have sootty tailpipes i kept cleaning and knew it was running a lil rich, but i thought id keep it that way and take the cut in power to be on the safe side of burning a piston. I didnt know it was THAT rich to cause damage. What is the optimal fule ratio i should be after at the dyno. Thinking of getting a digital wideband gauge to mount up in drivers compartment to keep an eye on it. 1995 DK Blue Lincoln Mark VIII1998 DK Blue Chevrolet 1500 P/U 2004 BLACK/Silver HONDA CBR 600RR
[/div]

If you are running rich or lean after a dyno tune, then they didn't tune it right.

Optimum power and minimal emissions can be had with a proper tune. Of course what was said earlier about O2 sensors running at the right temperature applies as well.
 
RE: Burning up catylitic convertors???

[div class="dcquote"][strong]Quote[/strong]
What kinda headers are those? mark
[/div]

They are the ART longtubes.

1995 DK Blue Lincoln Mark VIII
1998 DK Blue Chevrolet 1500 P/U
2004 BLACK/Silver HONDA CBR 600RR
 
RE: Burning up catylitic convertors???

[div class="dcquote"][strong]Quote[/strong]
Heres a pic of my dynotune when it was running last.1995 DK Blue Lincoln Mark VIII1998 DK Blue Chevrolet 1500 P/U 2004 BLACK/Silver HONDA CBR 600RRhttp://www.lincolnsclub.org/forum/user_files/1431.jpg
[/div]

I'm not an expert, but those charts look suspicious. The curves should be much smoother than they are. Maybe some folks who know about tuning can comment.
 
RE: Burning up catylitic convertors???

When you tune on the dyno you're adjusting the mixture at WOT.

Most tuners won't even look at the a/f ratio during normal driving, because it's closed loop. the oxygen sensors will tell the computer if the a/f is off, and the computer will make adjustments. I believe that the changes the tuner makes when checking a/f at WOT have some bearing on the initial tune during closed loop, but the computer will correct a/f based on o2 sensor readings during normal driving.

Now, in your situation, with the o2's too far downstream, they were likely giving a bad reading, causing the computer to think the car was running lean, and thus making it run richer.
 
RE: Burning up catylitic convertors???

Got a spot setup with Lonnie this weekend at Blue Oval. I'm bringing my slicks with me so maybee ill get to hit their track if all goes well.

1995 DK Blue Lincoln Mark VIII
1998 DK Blue Chevrolet 1500 P/U
2004 BLACK/Silver HONDA CBR 600RR
 
RE: Burning up catylitic convertors???

All set for now with the new tune from Lonnie. Car runs fantastic. i know ill be breaking my 8:60 this weekend especially with the new slicks.
Found out from local tranny place that the upper breather vent for tranny is causing the leak. I was told there are two different kinds, a paper kind and a carbon kind. Mine is leaking or venting from there and trickling down side of tranny.
If it doesnt stop, ill have tranny yanked and tore down and find out what really is inside there for what i paid. Also an upgraded TC will be swapped in with higher stall if i go that route.
No sense in starting a campfire without gasoline. "Now that's a fire!" lol

1995 DK Blue Lincoln Mark VIII
1998 DK Blue Chevrolet 1500 P/U
 
RE: Burning up catylitic convertors???

[div class="dcquote"][strong]Quote[/strong]
i know ill be breaking my 8:60 this weekend

Didn't happen, :-(.... But there is always next week. Still got some things to sort out and order for the rearend to tighten it up. Its walking sideways. It is more pronounced now with the slicks. I never noticed it cause it was sliding all over the place. My rear connecting arm bushings will be yanked for some poly units and some nice bracing i saw on Supercoupe Performance webpage.

1995 DK Blue Lincoln Mark VIII
1998 DK Blue Chevrolet 1500 P/U
 
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