RobY Posted March 5, 2008 Share Posted March 5, 2008 Lately I have been experiencing some weird boost cut issues. It happens after I drive some distance in 5th gear then downshift into a lower gear. When I punch it the boost dosent go over wastegate pressure or about 9 psi. Its begining to get really irritating. The Boost reverts back to full boost after a few shifts. Or it sometimes suddenly comes back on a few seconds later. I have no idea whats going on. I have a scanmaster and the ECU is showing positive KC during the incident all the time. The boost just randomly cuts at times. Do you think my boost control solnoid is going or do you think its a software issue? I have a COBB OTC Stage II map. I also happened at times with my TDC etune map. Link to comment Share on other sites More sharing options...
qikslvr Posted March 5, 2008 Share Posted March 5, 2008 Start checking vacuum lines and zip-tie them as you go if you haven't already. There is a t-connector under the intercooler that is notorious for coming apart. You might also want to check the intercooler to throttle body hose to see if the clamps are tight. Let's kick this pig! Link to comment Share on other sites More sharing options...
LittleBlueGT Posted March 5, 2008 Share Posted March 5, 2008 Check your IAM. Have you done any mods to the EBCS? Any mods to the wiring of it, could it be a bad connection? Full tune of 68HTA, KSTech 73 MAF, Racer X FMIC and ID1000s................by the DataLog Mafia!!! Link to comment Share on other sites More sharing options...
Infamous1 Posted March 5, 2008 Share Posted March 5, 2008 Yeah that sounds like your IAM is taking a dive and the ecu is reverting to WG spring pressure. Link to comment Share on other sites More sharing options...
RobY Posted March 5, 2008 Author Share Posted March 5, 2008 Vaccum lines under intercooler have been worm drive hose clamped tight and superglued. KC values are positive does that have anything to do with IAM? No mods to EBCS. Link to comment Share on other sites More sharing options...
LittleBlueGT Posted March 5, 2008 Share Posted March 5, 2008 KC values are positive does that have anything to do with IAM? In your tune you (like almost all tunes) have + KC numbers specified for certain load/rpm cells. If your IAM is 1.0 then you will be running the max KC values (assuming there is no knock). If your IAM is 0.5 then you will be running 50% of the max KC value (again assuming there is no knock). You need to log Feedback Correction to see if there is any knock (and check IAM just before and after logging, no need to actually log it). Feedback correction shows if the ECU is pulling timing. As an example showing how you could easily have + KC numbers and be knocking: a particle cell calls for +8 KC, your IAM is at 0.5 and you are pulling 2 degress of timing at that moment due to knock. You will still show (8 * .5 -2) 2 degrees of positive KC, but it is definitely not good. FWIW I blew my engine on the dyno showing 2 degrees of positive KC. Full tune of 68HTA, KSTech 73 MAF, Racer X FMIC and ID1000s................by the DataLog Mafia!!! Link to comment Share on other sites More sharing options...
Infamous1 Posted March 5, 2008 Share Posted March 5, 2008 FWIW I blew my engine on the dyno showing 2 degrees of positive KC. How much DA was the map calling for at that point? Link to comment Share on other sites More sharing options...
LittleBlueGT Posted March 5, 2008 Share Posted March 5, 2008 How much DA was the map calling for at that point? Called for 8 degrees. FBKC went from 0 to -4 to -6 them boom! Full tune of 68HTA, KSTech 73 MAF, Racer X FMIC and ID1000s................by the DataLog Mafia!!! Link to comment Share on other sites More sharing options...
Infamous1 Posted March 5, 2008 Share Posted March 5, 2008 Called for 8 degrees. FBKC went from 0 to -4 to -6 them boom! Ouch that hurts..... Link to comment Share on other sites More sharing options...
mickeyd2005 Posted March 5, 2008 Share Posted March 5, 2008 You need to log Feedback Correction to see if there is any knock (and check IAM just before and after logging, no need to actually log it). Feedback correction shows if the ECU is pulling timing. Technically, you need to log all three: Feedback Correction Fine Learning Knock Correction IAM to determine if there is knock or not or you can log KC and compare it to your DA table. When the knock sensor has a knock signal, the ecu has a choice of three different ways to reduce timing: FBKC, FLKC, or IAM. OP's problem definitely sounds like IAM related since boost is cut down to wastegate spring pressure for short period of time. Link to comment Share on other sites More sharing options...
RobY Posted March 6, 2008 Author Share Posted March 6, 2008 AWW damit time for a real protune eh... Link to comment Share on other sites More sharing options...
mickeyd2005 Posted March 6, 2008 Share Posted March 6, 2008 Try the Cobb ACN91 map. Link to comment Share on other sites More sharing options...
RobY Posted March 6, 2008 Author Share Posted March 6, 2008 If it keeps acting up I will... It seems to be behaving today... It may have been bad gas... I hate shared hose terminals... I get a nice hosefull of your previous users puke 87 octane Unfortunately almost every gas station has shared hose terminals... Link to comment Share on other sites More sharing options...
Deer Killer Posted March 6, 2008 Share Posted March 6, 2008 Called for 8 degrees. FBKC went from 0 to -4 to -6 them boom! perhaps off-topic but I've been thinking about: 1. Increasing the FBKC step value to -3 or -4 2. Changing the map switching threshold to .875 IAM 3. Unflattening the DA map. Apparently the higher DA values give it more authority to adjust IAM. I _have_ seem IAM adjust quickly from 1 to .875 and then back again. Of course this was most likely due to the TGV connectors tapping the block before I tied them down 4. Change the rough correction DA threshold to work with #3. Of course in your case the "knock" might have been ringlands banging against the cylinder, and the motor simply let go. Link to comment Share on other sites More sharing options...
Deer Killer Posted March 6, 2008 Share Posted March 6, 2008 If it keeps acting up I will... It seems to be behaving today... It may have been bad gas... I hate shared hose terminals... I get a nice hosefull of your previous users puke 87 octane Unfortunately almost every gas station has shared hose terminals... 87 happens. I have half a mind to tune the car with 87 and make sure it drops everything sharply and noticeably, so you're not under any false impressions of what happened without your laptop. Link to comment Share on other sites More sharing options...
Boostjunkie Posted March 6, 2008 Share Posted March 6, 2008 87 happens. I have half a mind to tune the car with 87 and make sure it drops everything sharply and noticeably, so you're not under any false impressions of what happened without your laptop. Don't do it. I had a 2.5L shortblock swap WRX that I tuned that just wouldn't make any power and was super knock prone. Had me scratching my head for days. The owner of the car came back last week for an oil change and told me that he just realized that he had about a half tank of 87 octane in the car when I tuned it. Made me feel a heck of a lot better. Link to comment Share on other sites More sharing options...
LittleBlueGT Posted March 6, 2008 Share Posted March 6, 2008 perhaps off-topic but I've been thinking about: 1. Increasing the FBKC step value to -3 or -4 2. Changing the map switching threshold to .875 IAM 3. Unflattening the DA map. Apparently the higher DA values give it more authority to adjust IAM. I _have_ seem IAM adjust quickly from 1 to .875 and then back again. Of course this was most likely due to the TGV connectors tapping the block before I tied them down 4. Change the rough correction DA threshold to work with #3. Of course in your case the "knock" might have been ringlands banging against the cylinder, and the motor simply let go. 1) makes "shift knock" or "mash knock" horrible 2) already done 3) I think that is wrong I had never previously had my IAM fall (although with my TDC map it may have fallen before when I was stage 2.5 before I started logging..........lots and lots of pulled timing there) I think my knock was real knock, incorrect alky mixture resulting in 12.8 vs 11.8 AFR will do that. Full tune of 68HTA, KSTech 73 MAF, Racer X FMIC and ID1000s................by the DataLog Mafia!!! Link to comment Share on other sites More sharing options...
Deer Killer Posted March 6, 2008 Share Posted March 6, 2008 1) makes "shift knock" or "mash knock" horrible 2) already done 3) I think that is wrong I had never previously had my IAM fall (although with my TDC map it may have fallen before when I was stage 2.5 before I started logging..........lots and lots of pulled timing there) I think my knock was real knock, incorrect alky mixture resulting in 12.8 vs 11.8 AFR will do that. The stock map has DA's set below the rough correction threshold. They only do rough correction in the most knock prone area. This also supposedly keeps the IAM from flying back up at less knock-prone areas. I don't know if the the rough correction threshold is for all correction or just negative correction. Makes sense for all correction. Link to comment Share on other sites More sharing options...
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