I know why my times sucked!

[MattysTA]

Well it took me a bit to realize this DOH! but when i bought the car i had to get it through inspection but the engine light was on and i was getting codes for my catalyst 02 sensors(threw my sims on from my old car to get her through and forgot about it). so needless to say my cats are clogging and im losing alot of power, which in turn makes total sense that my front 02 readings were between 8-900 mv's at idle and going as low as.045 under WOT and that would be because the cat is holding back so much backpressure its screwing with the readings. stay tuned for my new times once i get the dealer to replace them this week :)

[deadtrend1]

eh, if you already have simms, just take a broomstick to the cats.


Disclaimer: Doing that will violate current emission laws so in no way do I condone this ...... :)

[MattysTA]

eh, if you already have simms, just take a broomstick to the cats.


Disclaimer: Doing that will violate current emission laws so in no way do I condone this ...... :)


lol yeah i was going to do that but i decided to just let the dealer replace them. besides im in the process of getting a new y-pipe for my lt's that are waiting to go in. and if i ever want to put it back to stock for whatever reason itll have low mile factory cats...

[Mike]

ehhh the times from your second post arent that bad given the time of year and 60'........im sure they will help but probably not that signifigantly

[MattysTA]

that time was the first run of the night,2nd trip to the track. 3 runs after that it went down to 14.1-14.2. went back to the track again fri and same thing14.1-14.2 2.1 60 ft. so how do i go from a 13.8 to a 14.2 when all i lost in the 60ft was a tenth?( ive read other guys pulling 2.1's that are doing low 13's) these cats are gonna make a big difference. i'll put up my new times this coming weekend once this problem is fixed :)

[GP99GT]

which O2's did you put the simulators on? the ones before the cat?

[MattysTA]

which O2's did you put the simulators on? the ones before the cat?



umm yeah why was i not supposed to? LOL of course i put them after the cats.....

[deadtrend1]

don't think the connector would work on the front ones anyways

[MattysTA]

don't think the connector would work on the front ones anyways

you are correct fronts are flat connector, rears are square..

[DevilDougWS6]

you are correct fronts are flat connector, rears are square..

not to hijack but where in TR are you? i think i saw you on 37 last night. we should meet up and hang out sometime!

[MattysTA]

not to hijack but where in TR are you? i think i saw you on 37 last night. we should meet up and hang out sometime!

Yup i was out there, i was also at kmart, you must have been the nbm i saw there when everyone got kicked out.... i live at the border of Tr/Manchester....

[GP99GT]

nevermind, i read it wrong. i thought you were saying the rear O2s were screwing up the reading.

[Mike]

if your cats are messed up enough to slow the car down, you would notice in other driving than just the timeslip

[MattysTA]

if your cats are messed up enough to slow the car down, you would notice in other driving than just the timeslip

well i would if the car was fine when i bought it but it wasnt. it was falling on its face constantly untill i cleaned the maf. then it was much better but it still doesnt pull as hard as it should be...

[SuperSweet]

what was your MPH. I went 13.2 at 106 with a 2.1 60' bone stock. I would have to agree that the cats would be holding you back with that kind of time

[Mike]

whatever makes you feel better

[MattysTA]

ill feel better when the car is doing what it should for now im troubleshooting not making excuses. like yesterday i did some testing with a lazer temp gun and heres my results...
the temp at the manifolds was around 280 and the cats were 260 well after the cats the pipe going into the y pipe 3 inches after the cat was only 200 degrees, how is it possible to lose 60 degress within 3 inches? its not unless there is a clog, also i checked the intermediate pipe going into the muffler and it was 150 yet the outlet pipe right next to it was only 130 again how can pipes that are less than 3 inches aprt lose 20 degrees between them? so that leads me to believe there is also some kind of clog in the muffler....

[MattysTA]

what was your MPH. I went 13.2 at 106 with a 2.1 60' bone stock. I would have to agree that the cats would be holding you back with that kind of time


13.8@101 was the best and now no better than 14.1-14.2 @98 mph

[SuperSweet]

stick/auto? either way there is a problem. try a pass after the cats and see what happens. you might want to change those front O2's as well for the sake of things.

[MattysTA]

stick/auto? either way there is a problem. try a pass after the cats and see what happens. you might want to change those front O2's as well for the sake of things.

its auto and im def going to change the 02's because they are reading 8-900 mv's at idle and going down to .050 at wot which is ass backwards

[JL8Jeff]

It might not be the cats as much as the O2's are giving bad readings which screw up the computer mixture. The factory cats are made to heat up as much as possible to burn off emission's so the temps don't really tell you too much. That being said, one of my factory cats smelled funny from the day I got the car with 33K miles on it so I'm sure there was some buildup in there. The PCV setup on the LS1 allows the engine to suck in oil and that will cause buildup everywhere which will throw things off over time. I'd try the O2's first and if that doesn't make a difference, then go after the cats or install headers.

[MattysTA]

It might not be the cats as much as the O2's are giving bad readings which screw up the computer mixture. The factory cats are made to heat up as much as possible to burn off emission's so the temps don't really tell you too much. That being said, one of my factory cats smelled funny from the day I got the car with 33K miles on it so I'm sure there was some buildup in there. The PCV setup on the LS1 allows the engine to suck in oil and that will cause buildup everywhere which will throw things off over time. I'd try the O2's first and if that doesn't make a difference, then go after the cats or install headers.

true its possible but i even ran the car locked in open loop taking the front 02's out of the equation and still no difference... i have headers and im waiting for the new ypipe to get here but i want to see the car go the best it can now before i start doing anything major so i have a real baseline to start with .

[ins0mnia24]

what are you using and how are you reading the mV's on your O2's because they don't stay at any specific mV except when you 1st turn the key on then they send a predetermined amount until you are out of open loop..

[MattysTA]

what are you using and how are you reading the mV's on your O2's because they don't stay at any specific mV except when you 1st turn the key on then they send a predetermined amount until you are out of open loop..

yes i know the mv's are supposed to fluctuate at idle and they do i mean at cruising that they are staying closer to the above numbers.... i have efilive...

yes the predetermined amount is from the back up ve table...then they run off the 02's CL which like i said above i locked it in OL so it would run off the back up ve table instead of the 02's.

[ins0mnia24]

Yeh you would be able to see just by how fast the mV readings take place to judge if you are getting lazy readings from the O2's..
And then even if no dash light you would still have a Dtc until it got bad enough to set the dash light off..

You probably have some tuning issue's
Other than that since you have Efi live I would ditch the sim's and cats then..

[sweetbmxrider]

those exhaust temps are worthless. how many miles on the car?

[MattysTA]

Yeh you would be able to see just by how fast the mV readings take place to judge if you are getting lazy readings from the O2's..
And then even if no dash light you would still have a Dtc until it got bad enough to set the dash light off..

You probably have some tuning issue's
Other than that since you have Efi live I would ditch the sim's and cats then..


actually ive had no dtc's without the dashlight off, plenty of them with it on though.

i have the factory tune in it. i only use it for scanning,logging and misc. things like the tm etc. im not going to change a/f around till i get a wideband for both banks.

also i just got done"fixing" the cats and tomorrow after work ill be putting in two new front 02's and all new plugs(took out two for bolt access and found two diff ones lol) then after i drill out the three manifold studs that snapped and put it back together hopefully ill make it to the track if not then fri night......

[ins0mnia24]

wow you didnt even touch the torque management programing?

[MattysTA]

wow you didnt even touch the torque management programing?


yeah its disabled, i said it above letters tm lol

[MattysTA]

those exhaust temps are worthless. how many miles on the car?

what makes you say that? and it is just under 80k

[ins0mnia24]

yeh I didnt recognize the abbreviation with out the .
Keep at with the EFI live you can definitely pull a few more degree's of timing out of your automatic..
Gm gave them 5-7 less than the 6-speed cars

[MattysTA]

yeh I didnt recognize the abbreviation with out the .
Keep at with the EFI live you can definitely pull a few more degree's of timing out of your automatic..
Gm gave them 5-7 less than the 6-speed cars


really more timing? ive seen 40 on the scanner, so your teling me the 6 spds are seeing 47? wow

[sweetbmxrider]

what makes you say that? and it is just under 80k

80k i would deff go over the tune up stuff but like you said you are replacing the plugs. and like it was already said, the cat conv. is supposed to heat up to burn off as much of the emissions as possible. naturally the rest of the exhaust will be cooler. a muffler, by principle, is restrictive so it will be hotter than the tail pipes.

[JL8Jeff]

I've seen 42-44 degrees of timing on my stock automatic and I always thought it was a bit much. I always had some pinging and I think it was because of some carbon buildup because of the oil being pulled through the pcv. Even after tuning and headers I still get some ping so I think something else isn't quite right. But the car runs great with 45K miles so I'm leaving it as is for now. I think you're on track running some new 02's for baseline but give it a good Seafoam cleaning as well before the new O2's since it may damage them anyway.

[ins0mnia24]

40 is around what these cars would see at part throttle or just cruising around on the street because there is less air going into the engine so it is ignited earlier..
W.o.t. or during your peak hp and tq rpms it will be alot lower like 19-24 depending on the year of the car

[MattysTA]

well the cats are back on but i have yet to do seafoam,plugs(also have msd wires on the way),and 02's but aside from that i took her for a ride and allready feel a difference im also going to pick up a fuel filter after work and then if its done early then off to etown i go....

[SuperSweet]

ill be there. hope to see you run a better time

[JL8Jeff]

I wouldn't put the new O2's in until after you run Seafoam through it. It could ruin the new O2s. If you haven't checked all the plugs, I wouldn't be surprised to see a couple of them missing the platinum pucks and having a huge gap, that happens with the lousy Delco plugs. Switch to NGK for sure.

[MattysTA]

I wouldn't put the new O2's in until after you run Seafoam through it. It could ruin the new O2s. If you haven't checked all the plugs, I wouldn't be surprised to see a couple of them missing the platinum pucks and having a huge gap, that happens with the lousy Delco plugs. Switch to NGK for sure.


yeah thats what i did, it was weird i did seafoam twice and barley any smoke came out ive done it before on my 97) so afterwards i did the 02's( bought ac delcos off ebay) and then the plugs. put everything in and man what a difference, now my 02's were reading more properly, well atleast till i got to the track....

my bank one s1 went back to readings of .0xx under wot while the bank2 s1 was reading .820


ill post of one of my logs. i think its because ithe 02's the guy sent me are both for the one side as both the new ones had the same length wire with ac98 on them and the ones i took out of the car one had ac98 and the other ac97 on it. the right side one has a shorter wire but right now it has one with the longer wire. the one i took out that i replaced with a long wire like the one that was in there is the side that is not reading right. also im getting some exhaust smoke now(even before the seafoam) probably my pvc sucking oil. im going to switch the 02s from one side to the other and see if it follows...

oh and i also didnt get lower than a 13.9 at the track while the best being a 13.7@101 with a 2.1 60ft(turns out my 17's also spun on the rim a bit after i felt something strange and marked them sure enough one spun on the rim a bit lol)

[ins0mnia24]

The 97's are right side for the front and rear.
And the 98's are Left side front and rear, Not that it really matters because the actual sensors are all the same the only difference is the length of the wires..

[MattysTA]

The 97's are right side for the front and rear.
And the 98's are Left side front and rear, Not that it really matters because the actual sensors are all the same the only difference is the length of the wires..

true the only diff is the length of wire but because of that it also changes how fast the sensor heats and responds so right now my b1 is off by3-5% compared to b2

[ins0mnia24]

The legnth of the wire has no affect on how they read they are there just for proper fitment if you prob them with DVM you will see that.
Both banks arent going to read exactly the same either..

While there is different paremeters that can you do tuning wise to make them switch a little bit faster you arent going to see them as perfectly as you want them to be or think they should be..
As long as you arent getting any codes you are fine..

You could always try the rear Vette sensors like some people do but alot of times it is still going to be the same thing..

[MattysTA]

yeah they arent too bad, ill be borrowing my buddys wideband next weekend to see where im really at so i can do some tuning