What LT Headers do not give 02 sensor problems?
Drifting
Joined: Jun 2007
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From: Toronto Ontario
LT Streets
My LG streets were installed, and to my understanding the shop had to change the O2 senors from the front to the back and only plugged in the rears, (now fronts) so only 2 senors connected. They did get all four to connect, but apparently that is not the "right way" to do it.
No codes and runs very well....
No codes and runs very well....
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Sorry .... but you misunderstand the issue.
The catalytic converters (cats) are VERY sensitive to temperature ..... they want HOT gases from the engine to assist in the catalytic process. On a cold engine start the cats are too cold to catalyze the gases and take a while to come up to temperature before they start working (light off). Many Corvettes are fitted with "pup" cats that are directly below the stock manifold .... they heat fast and once they are working they reduce pollutants and help heat the main cats to get them to "light off".
Long Tubes are called that because distance the hot exhaust gases have to flow has been "lengthened" over the distance the stock manifold flows the gases. That added distance is enough to affect the performance of the cats, especially in cold start situations. The cats can take longer than the PCM is programmed to allow for "light off", which will set codes. The cats can be working, but not efficiently, which can set codes. The cats need to be VERY hot to work correctly .... usually above 800 degrees.
That's why there are ZERO LTs certified by the CARB as smog legal, and never will be .... the LTs do the opposite of what the cats are designed for and need ... to be as close as possible to the exhaust ports in the heads.
And that's why anyone with LTs is gonna get rear O2 sensor codes at various times with a "stock" PCM ..... and why many people with LTs have the rears "tuned out" of the PCM DTC checks.
The catalytic converters (cats) are VERY sensitive to temperature ..... they want HOT gases from the engine to assist in the catalytic process. On a cold engine start the cats are too cold to catalyze the gases and take a while to come up to temperature before they start working (light off). Many Corvettes are fitted with "pup" cats that are directly below the stock manifold .... they heat fast and once they are working they reduce pollutants and help heat the main cats to get them to "light off".
Long Tubes are called that because distance the hot exhaust gases have to flow has been "lengthened" over the distance the stock manifold flows the gases. That added distance is enough to affect the performance of the cats, especially in cold start situations. The cats can take longer than the PCM is programmed to allow for "light off", which will set codes. The cats can be working, but not efficiently, which can set codes. The cats need to be VERY hot to work correctly .... usually above 800 degrees.
That's why there are ZERO LTs certified by the CARB as smog legal, and never will be .... the LTs do the opposite of what the cats are designed for and need ... to be as close as possible to the exhaust ports in the heads.
And that's why anyone with LTs is gonna get rear O2 sensor codes at various times with a "stock" PCM ..... and why many people with LTs have the rears "tuned out" of the PCM DTC checks.
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Ok let me clear a few things up as we are on different pages.
1. You said you have only found 1 post about codes? You need to search again! I'll gladly give you links to over 50 posts on 02 sensors and codes related to the front sensor banks as the rear banks everybody running headers knows you turn off.
2. You mention 4 02s. and with a stock system yes you have all 4. However when running headers, most manufactures only tell you to run 2. The rear o2's in the front positions. The rear 02 banks are completely turned off so its impossible to get any codes at all from those.
4. Iam not talking of the same codes as you mentioned. The codes Iam referring to are on the front sensor banks and are switching issues due to 02 sensors either heating up too quickly or not quickly enough. This is because of the new location of the 02's in the pipe. Hope this clears things up.
Please anybody having a switching code being thrown (P0153) for example. Chime in.
1. You said you have only found 1 post about codes? You need to search again! I'll gladly give you links to over 50 posts on 02 sensors and codes related to the front sensor banks as the rear banks everybody running headers knows you turn off.
2. You mention 4 02s. and with a stock system yes you have all 4. However when running headers, most manufactures only tell you to run 2. The rear o2's in the front positions. The rear 02 banks are completely turned off so its impossible to get any codes at all from those.
4. Iam not talking of the same codes as you mentioned. The codes Iam referring to are on the front sensor banks and are switching issues due to 02 sensors either heating up too quickly or not quickly enough. This is because of the new location of the 02's in the pipe. Hope this clears things up.
Please anybody having a switching code being thrown (P0153) for example. Chime in.
2. I, as many here do, wanted to be as close to smog legal as possible and LG had just started offering there 4 O2 LG Pro systems so I got that one.
3. Why wouldn't you just use the front O2's in the front as the rears are different are they not? LG's come with the front and rear extension harness.
4. I have no idea what you are talking about there, but that may be because I used my fronts on the front. I have had my headers on for 4 years with not a single front O2 code. The only codes I get are from the rear's as I haven't been tuned yet (holding out till I get a cam)
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Millenium Z06 just curious as to what headers your running and did you get extensions to run all 4 o2's? On a side note, you mentioned the codes you were referring to had to do with the rear sensors and that those usually get tuned out. Are you referring to "not to report" or "tuned/turned off"? Cause Iam thinking if you were running all 4 sensors then had codes being thrown off by the rears causing you to turn them off, then you would be running only the front sensors once again and the rears would not be doing anything? Just trying to understand, Iam at desperation right now just trying to get rid of my codes.
What codes are you getting? Why don't you just get extensions and put the front back in? I'm fairly certain they are different and would that not be the cause of your codes?
Like I said earlier, I get absolutely NO codes from anything on my car except the rear O2's and I only get them about every 300-500 miles.
Safety Car
Joined: Aug 2000
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From: San Rafael CA
No I think you misunderstand the question/ issue, the rear O2's are the ones causing the codes, LG and Random Tech both told me it was an efficiency issue with the cats in that they flow too well. Now rather that causes them not to retain the proper heat or not is debatable, they didn't say so I cant argue that. But that dosent make my comment anymore wrong than your comment. Also I believe that 2002 and up do not have pup cats so that would void the many corvettes thought. The fact that my car dosent smell like a gas station tells me that my cats are indeed working.
The cats are "too efficient" ??????????? you are clueless ........
let's see the 2002 and 3 and 4 cars had no pup cats .... that's 3 years ..... the 1997, 1998, 1999, 2000 and 2001 cars (there are exceptions to this) had pup cats .....5 years versus 3 years .... I'll stand by my statement that "MANY" Corvettes have pup cats ..... in fact I'll make that the MAJORITY of C5 Corvettes have pup cats ......
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I really would love to know a tuners point of view
As far as all the posts I have read about this issue. From what I have read, by having the codes not report won't set off any "not readys". I believe that happens when you have a code that you fix but that you don't give the car enough time to fully clear the code. GM states that it is about 40 warm up cycles before a code goes completely away. If you don't complete this cycle the code will show up stored and the result will be a "not ready". Please if any tuner finds this to be incorrect...please by all means correct me as Iam not a tuner.
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LG Pro's and yes, I have the extensions but the rears still weren't long enough so I made my own harness. My car hasn't been tuned so I am still running with 4 O2's. I have not decided what I am going to do with the rears yet because I live in Collin Co in Texas and they test the computer, you can only have 2 "Not Ready's". When I get my inspection report my rear cats/O2's show Ready. My understanding is that turning them off will cause them to show "Not Ready".
What codes are you getting? Why don't you just get extensions and put the front back in? I'm fairly certain they are different and would that not be the cause of your codes?
Like I said earlier, I get absolutely NO codes from anything on my car except the rear O2's and I only get them about every 300-500 miles.
What codes are you getting? Why don't you just get extensions and put the front back in? I'm fairly certain they are different and would that not be the cause of your codes?
Like I said earlier, I get absolutely NO codes from anything on my car except the rear O2's and I only get them about every 300-500 miles.
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um ok, I just noticed what you said. So you too are getting codes. hmmmm interesting. So you would also be forced to turn your rear 02's off. When you got your report, did you have any strikes against you because of the codes or where they completely gone because you drove the car long enough to wipe the codes out of the PCM's memory and thus the inspection didn't pick up on it?
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It didn't show any codes, I get the 0420 and 0430 but clear them thru the DIC and continue on. It also showed the rears as ready so I guess it may be that the car was driven enough to not list the codes. Now about 2 years ago, when my ebcm went out, GM replaced that computer and reset the other. When I went for an inspection about a month later, I got 3 not readys and one was the rear O2's. It took about 500 miles before they were ready and the GM drive test thing didn't fix it. My concern is that they (the State) will tighten the smog laws and that a not ready will cause you to not pass; so if I get a tune and have them tuned out and the law changes, I screwed.
Right now Iam getting the P0153 and P1153 codes and like you I just delete them with my DIC. You said that your rears are showing "ready". How do you check for that? or was that at the inspection place and that is what it showed.
Last edited by XtremeVette; Jul 8, 2008 at 11:20 PM.
Team Owner
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From: S.W. Ohio. . . . . . NRA Life Member
But lets not get sidetracked by bad facts.
there were no pupcats on 1997 and 1998 C5's
1999 and 2000 saw a small number of C5's with pupcats; based on where they were to be shipped (mainly Kalifornia and the Pacific Northwest).
In 2001, all C5's were built with pupcats; and that includes the 01 Z06.
Starting 2002; pupcats continued being factory installed on alll C5's... except for the Z06. And this continued through the 2004 model year.
.
.
Last edited by Mike Mercury; Jul 8, 2008 at 11:50 PM.
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From: Fort St John B.C
Ive got headers,hi flow cats (dynatech) for almost 2 years, with all 4
O2 sensors. I get the P0430 code. I delete it , it comes back pretty quick (quick=usually about 20mins).
I dont remember seeing any pup cats on my 99 when I installed headers.
O2 sensors. I get the P0430 code. I delete it , it comes back pretty quick (quick=usually about 20mins).
I dont remember seeing any pup cats on my 99 when I installed headers.
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ok but how do you get pass emissions with codes? I think in BC you only need emissions what every 10 years?
Team Owner
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I know exactly what you mean.
When I went with aftermarket valve covers (also relocating the coils) I had many ask why I went through all the trouble of duplicating the plumbing of the crankcase ventillation system.
I simply said that I had been driving that Corvette for five years... completely error free; and I wanted it to continue that way.
And I don't even have a catch-can - and don't need one either.
So; I'm like you in that I don't want to mess with any codes or intermittant problems. I guess it's my age. In my earlier years the first thing I ripped off was that funky air pump, removed the cats, and pry'd out that filler neck restrictor that was forcing me to use unleaded gasoline.
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Pretty sure the only city in BC you need to pass "Air Care" or emissions..etc is in Vancouver, actually, there may be other places but Van is the only one I know of. So Im good.
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I hear ya man, thats my biggest fear. I don't want to go through any crap with a "not ready" cause of 02's and thus fail.
Right now Iam getting the P0153 and P1153 codes and like you I just delete them with my DIC. You said that your rears are showing "ready". How do you check for that? or was that at the inspection place and that is what it showed.
Right now Iam getting the P0153 and P1153 codes and like you I just delete them with my DIC. You said that your rears are showing "ready". How do you check for that? or was that at the inspection place and that is what it showed.
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His quote: "Thats one of the biggest issues with the long primaries.The sensors dont get as warm and tend to have problems switching. You could try using a new sensor and they should be good long enough to get you to pass..."
Melting Slicks
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From: Cedarburg, WI
Actually this apparently is a very common problem with long tubes, I just got a PM reply from Chris@EastCoastSupercharging and he agrees.
His quote: "Thats one of the biggest issues with the long primaries.The sensors dont get as warm and tend to have problems switching. You could try using a new sensor and they should be good long enough to get you to pass..."
His quote: "Thats one of the biggest issues with the long primaries.The sensors dont get as warm and tend to have problems switching. You could try using a new sensor and they should be good long enough to get you to pass..."
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The sensors on the C5's are heated. They have 4 wires. They cost considerable amounts of money. They because they are heated are suppose to reach full operating temperature within 30-60 seconds of startup! Thats way not enough time for your car to hit its operating temperature. So why is this heat thing even an issue? I really don't understand it at all! If the sensors are heated by themselves to work so quickly what difference does an exhaust header vs stock manifold have?