way2tall89 Posted October 30, 2013 Share Posted October 30, 2013 Hey all. Quick question. Have any of you heard about the stock UP on the LGT's causing knock because of the cat? I took my car into the shop and they did a diagnostic run with my car. They ran some logs and saw a couple things. 1) The cat in the up pipe appears to be getting very hot and not getting cool enough on freeway runs. They suspect this is what's causing the knock in my car. 2) The O2 sensor is reporting abnormally and he is wondering why it hasn't actually thrown a CEL with the numbers its pulling. He suspects due to the sustained heat of the cat on the UP that it might have burnt out the O2 sensor and that's where I'm getting bad fuel trims in my LV. I initially took my car in to be looked at for an apparent oil leak I could physically see burning from the DP or turbo. I could smell it in the cabin. After a thorough inspection he concluded that this was a normal occurrence of oil vapor in the inlet seaping and suggested an AOS eventually. He wasn't too concerned. He did mention that octane can get lowered (we only have 91 where I live) and that too much oil in the shaft can cause an imbalance which can decrease the life of the turbo. Though he said the turbo looks amazing for 105k miles. He said the main thing is getting that UP out and replacing the O2 sensor. He said his tuner (who logged the car) said the logs looked great other than these minor things. No major issues to worry about.Then we started talking about stage 2 stuff but I'm not quite ready to make that jump. If need be I can do the work myself when it comes to installing the UP and O2 sensor. I just wanted some opinions on if this information seems logical and sound to the LGT community. I believe this guy makes a very strong case but I don't know enough about engine knock to know if it can be validated. Any takers? Link to comment Share on other sites More sharing options...
Mega Users seabass07 Posted October 30, 2013 Mega Users Share Posted October 30, 2013 There's an egt sensor in the up pipe. Any idea what temps it was showing? I'm pretty sure if it was as bad as stated, it would throw a cel. Replace the up with a catless one and see what happens. That should be replaced anyway. Look for a used sti up. As for the oil dripping on the exhaust, the shop is full of shit and you should find another one. You have an oil leak. You probably also have a vac leak causing your bad fuel trims and knock. Link to comment Share on other sites More sharing options...
way2tall89 Posted October 30, 2013 Author Share Posted October 30, 2013 Yeah the egt was staying above 1000 degrees even after being on the freeway for a while. He said it should have went down to at least 800 Sent from my SCH-I545 using Tapatalk Link to comment Share on other sites More sharing options...
Mega Users seabass07 Posted October 30, 2013 Mega Users Share Posted October 30, 2013 It's a cat. It's supposed to be hot. The stock tune also keeps timing very high at low loads to keep the cats temps up. Link to comment Share on other sites More sharing options...
way2tall89 Posted October 31, 2013 Author Share Posted October 31, 2013 Well if it is a true leak, its very very tiny. After almost 3k miles I'm down a 1/2 quart. This is after about a 1k mile non stop trip. I have 106k miles on the car. The invoice I received stated "There was the usual oil from the PCV system in the intercooler and the throttle body". They said they didn't see any apparent signs of leaking around the turbo.... Link to comment Share on other sites More sharing options...
McDowell Performance Tunin Posted November 4, 2013 Share Posted November 4, 2013 1000 degrees is near the bottom of the egt sensor voltage scaling. That's not very hot for a stock tune, with a cat. www.facebook.com/mcdowelltuning [sIGPIC][/sIGPIC] Click Here for Stage1, Stage2 and Stage3 Tuning and eTuning Info Link to comment Share on other sites More sharing options...
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