rob-2 Posted April 10, 2013 Share Posted April 10, 2013 I’m getting knock and not sure exactly why. Hoping the data logs below shed some light. Any insights? Car History: Purchased car 59K July 2011 Currently 97K All regular service has been done Went stage 1 91K Went stage 2 (just moments ago) Stage 2: Car is currently running a Invidia Catless downpipe with K&N drop in filter (not intake). The car has a transmission cooler on it, but is otherwise stock. Additional details/observations: The downpipe was installed this AM and car reflashed to stage2 ACN. After making a few runs I noticed the boost was peaking at 13.8psi instead of the targeted 16psi. Upon further inspection I noticed some dead spots in the RPM band where it appeared the car was pulling power. I first suspected bad gas. With half a tank of Safeway gas I purchased Lucas octane booster and filled up the tank with it at chevron. I’ve driven approximately 7 miles on this tank. Last few weeks, while on stage 1, I noticed a slight puff of burnt oil in exhaust on start up from dead cold. I believe my PCV value to be the problem and will be replacing that shortly. Logs: Datalog4.csv is on pure 91 safeway gas Datalog9.csv is on 50% 91 safeway gas + lucas octane booster + 50% 91 oc chevron gas Questions: 1. How do I determine the cause of the knock? 2. If the cause of the knocking is gas have I driven enough (7 miles) to work through the bad gas?datalog9.csvdatalog4.csv Link to comment Share on other sites More sharing options...
rob-2 Posted April 10, 2013 Author Share Posted April 10, 2013 It appears I can force a knock by getting on and off the gas quickly around 2200-2500 rpm. Stayed out of boost and was able to get 33 knock readings in under 5 min of driving. Bad engine mount? Link to comment Share on other sites More sharing options...
ArtClassShank Posted April 10, 2013 Share Posted April 10, 2013 Not sure what the knock sensors are like with Legacy GT's. But on my old Mazdaspeed3, the drive train was rather noisy. Shifting produced lots of knock, and hard acceleration from a low speed set them off. I'm sure someone more familiar with Legacy tuning should have a better answer. Also, what gear were these pulls done in? Link to comment Share on other sites More sharing options...
Gex Posted April 10, 2013 Share Posted April 10, 2013 Drive train noise/stop and go traffic will make knock the counter goes to 38 and resets. If you are seeing learned knock and pulling timing then it could be bad. Standard OTS Cobb tunes are not that great and tend to run rich. Not hitting target boost could be a boost leak? Still have the cat in the uppipe? What is your DAM? If you reset the ECU it can take 30 or so miles to learn the new trims. Link to comment Share on other sites More sharing options...
rob-2 Posted April 10, 2013 Author Share Posted April 10, 2013 Well it appears I have a 'roughness' or misfire in cyl 4. Might have had this from day one as there has been an odd idle lot. Car doesn't throw a code, Cobb AP picks up the problem at low rpms between 1500-2500 but doesn't have the roughness at 4500. Thoughts? Link to comment Share on other sites More sharing options...
rob-2 Posted April 10, 2013 Author Share Posted April 10, 2013 Flipped the coil pack from 4 and 3 around and the roughness disappeared. Not reporting in the cobb AP either. idle smoothed right out. Will monitor, I suspect it's only temporary. Link to comment Share on other sites More sharing options...
rob-2 Posted April 11, 2013 Author Share Posted April 11, 2013 Swapping coils has removed the misfire (roughness) on cyl 4. I am also not getting any knock switch 'on' states or much more than 1.7 negative knock learn. Cobb suggests anything greater than 4 is cause of concern. I do however have oil in the TMIC, which has me set to replace the PCV value. Part ordered. Pictures below incase you have the same problem. Goes without saying plugs will be changed once oil stops building in the TMIC. In my research it seems the cobb stage 2 map doesn't like a K&N drop in filter and so this has been removed. Interestingly peak boost has risen to 14.96psi in third gear. At no point has the car thrown a cel. I Link to comment Share on other sites More sharing options...
rob-2 Posted April 11, 2013 Author Share Posted April 11, 2013 In the AM, prior to the above coil swap, I cleaned the MAF sensor without any change in the cars performance. This is what it looked like after 97K, in theory uncleaned in all those miles. Link to comment Share on other sites More sharing options...
rob-2 Posted April 11, 2013 Author Share Posted April 11, 2013 In an update I found my non-turbo side TMIC connection wasn't very tight. Fixed it and that picked up nearly 1psi. Link to comment Share on other sites More sharing options...
xt2005bonbon Posted April 11, 2013 Share Posted April 11, 2013 In the AM, prior to the above coil swap, I cleaned the MAF sensor without any change in the cars performance. This is what it looked like after 97K, in theory uncleaned in all those miles. You know that the sensor shown above on your picture is the IAT sensor right (shown in green below)? The actual MAF sensor is inside the plastic case (red arrow). Link to comment Share on other sites More sharing options...
rob-2 Posted April 11, 2013 Author Share Posted April 11, 2013 You know that the sensor shown above on your picture is the IAT sensor right (shown in green below)? The actual MAF sensor is inside the plastic case (red arrow). Correctomondo sir. I sprayed both parts Link to comment Share on other sites More sharing options...
xt2005bonbon Posted April 11, 2013 Share Posted April 11, 2013 [ame=http://www.youtube.com/watch?v=0tJGk4ofc18]Alrighty then - YouTube[/ame] I hope the source of your knock is not serious. Good luck. Link to comment Share on other sites More sharing options...
rob-2 Posted April 19, 2013 Author Share Posted April 19, 2013 The problem has completely gone away. For reference I: 1. Replaced K&N filter with stock - no change 2. Clean MAF - no change 3. Swapped coil 4 with 3 - removed misfire. 4. Replaced PCV - smooth idle and no knock I believe so much oil was getting into the intake as to force a knock due to low octane. Link to comment Share on other sites More sharing options...
stuck686 Posted April 19, 2013 Share Posted April 19, 2013 use 93 oct on your 91 map, srs Link to comment Share on other sites More sharing options...
rob-2 Posted April 19, 2013 Author Share Posted April 19, 2013 use 93 oct on your 91 map, srs Wish it was regularly available. It's not. Link to comment Share on other sites More sharing options...
stuck686 Posted April 19, 2013 Share Posted April 19, 2013 are you sure? try a gas station app Link to comment Share on other sites More sharing options...
doobaruGT Posted April 19, 2013 Share Posted April 19, 2013 use 93 oct on your 91 map, srs This helped fix it for me. I had the same issue with the Cobb OTS map. Updated parts list since original part-out here. Original Full part-out of my LGT HERE! Link to comment Share on other sites More sharing options...
rob-2 Posted April 19, 2013 Author Share Posted April 19, 2013 are you sure? try a gas station app It's hard to find regular supply of 93 oc on the west coast. I have no idea why. When I lived out East it was everywhere. My 4500 feet also makes it less important, so I've been told. Link to comment Share on other sites More sharing options...
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