AKSSS Posted August 5, 2009 Report Share Posted August 5, 2009 I am having some conflicting issues with my wideband placement with my rear mount turbo. I am slowly learning more and more about my hptuners and logging. I have my wideband currently placed on my drivers side down pipe before my cat. I had it originally 12 inches after the turbo (as suggested by sts). I was having some conflicting readings with my logs and my wideband. With my sensor up front now, I am having lean numbers on my narrowband sensors, where my actual wideband is WAY rich. I have been told that having the sensor before the cats is important because of the way that the cats skew the readings of the sensor. Sts is telling me that I am getting such screwed up readings because of the backpressure from the turbo. That is why they say to put the sensory behind the turbo. The more that I think about it, isn't that the same thing that a muffler would do to the sensor also, put backpressure on the sensor? So, where should I put my sensor? I am at a loss. I am looking at doing some more mods but I want to be able to get it tuned in properly when I do them. Quote Link to comment Share on other sites More sharing options...
8 UR HMI Posted August 5, 2009 Report Share Posted August 5, 2009 justin i was having the same issues. mine was making it rich cause my tune was off and my cats were clogged. i would ditch the cats man. get them cutout and tuned out. i wouldnt mess with them anymore if ur having issues. i would also upgrade to a 44mm wastegate while ur at it. Quote Link to comment Share on other sites More sharing options...
AKSSS Posted August 5, 2009 Author Report Share Posted August 5, 2009 justin i was having the same issues. mine was making it rich cause my tune was off and my cats were clogged. i would ditch the cats man. get them cutout and tuned out. i wouldnt mess with them anymore if ur having issues. i would also upgrade to a 44mm wastegate while ur at it. I have to have my cats for emissions testing up here. I don't know if I could pass the computer test with one set of narrowbands turned off could I? I can put the fake cats in to pass visual. I'm not sure what size my wastegate is, but right now my wastegate is working fine. Why the larger w/g? Quote Link to comment Share on other sites More sharing options...
8 UR HMI Posted August 5, 2009 Report Share Posted August 5, 2009 with it being cold up there a lot of the time, the 38mm wastegate that comes from sts wont react as fast or let enough excess out and that causes boost creep. thats how u can go lean Quote Link to comment Share on other sites More sharing options...
chpspecial Posted August 5, 2009 Report Share Posted August 5, 2009 (edited) If your cats are clogged up, you will definatly have a reading problem... However, since our truck dont have air pumps to heat up the cats, it is ok to put the sensor pre cats or post cats... the difference in A/F reading will be about .1afr leanner if you do not have any exhaust leaks. I have done this test numerous times on my truck, LC1 pre cats, LM1 post cat and turbo and everytime i saw the same difference. I also run the STS kit. As far as wastegates go, only upgrade if you have boost problems, i.e. you are getting boost creep past your boost settings. I have run up to 15psi on my kit with the standard wg that sts sent out to me, although i believe it is the 38mm, and have not had a boost creep issue. Edited August 5, 2009 by chpspecial (see edit history) Quote Link to comment Share on other sites More sharing options...
AKSSS Posted August 6, 2009 Author Report Share Posted August 6, 2009 If your cats are clogged up, you will definatly have a reading problem... Well I guess I could have a clogged cat, but I'm not sure. I did stop by the emission shop and inquired about the rear o2 sensors being shut off(the shop is ran by a friend of mine). He said that the emissions computer reads the first o2 and then looks for a diffrent reading from the second sensor and that is how they determine if the cats are functioning properly. So with that being said. Maybe go to a set of magnaflow cats or something would help? My narrowbands are showing numbers in the ranges of 850-875 under boost. Where my wideband is showing in the middle to low 11's. So somewhere there is definitly a problem. I understand I should have the narrowbands around 900 to 920 under boost. Meaning I am running lean according to the narrowbands, right? Quote Link to comment Share on other sites More sharing options...
chpspecial Posted August 7, 2009 Report Share Posted August 7, 2009 If the cats are plugged, the rear o2 sensors do not always catch it, they didn't on my GMC. the biggest way to now is if the truck has anypower, and can it get up to speed... if no, you cats are mostlikely plugged. another way is to monitor your front o2 sensors if they are not fluctuating between ~200 and high 800, it is another good indication that the cats are plugged. If the o2 alternate like they should, then it will be something else the problem Quote Link to comment Share on other sites More sharing options...
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