Siriya Posted December 21, 2017 Share Posted December 21, 2017 All, I have an issue thats driving me nuts. Under load (ie 2600+ RPM) the turbo will spool and the engine begins to stutter and pop and the car sounds like it is back firing. If I am on the highway and ease the throttle pedal down it responds better but the stuttering is still there at a higher rpm range. Coils and plugs have both been changed to no avail. Idle is also normal. Any ideas would be appreciated. I have the btssm app if it can help produce an kind of logs to assist. Link to comment Share on other sites More sharing options...
relative4 Posted December 21, 2017 Share Posted December 21, 2017 A good place to start is to use BtSsm to monitor misfires. Throw all 4 misfire counters on your live data screen and see if the problem is specific to a cylinder. Assuming no CEL, check codes anyway in case any are pending. Link to comment Share on other sites More sharing options...
Wasted Potential Posted December 21, 2017 Share Posted December 21, 2017 BtSsm is very worth it if you are not sure as relative4 mentioned. If you are going to spend any money to start diagnosing, please start there! Link to comment Share on other sites More sharing options...
Siriya Posted December 21, 2017 Author Share Posted December 21, 2017 Yes, btssm has saved me in the past. I've tried running it with all four cylinders on but no misfires picked up. Any suggested values i should have it collect so i can create a log for looking at? Link to comment Share on other sites More sharing options...
xt2005bonbon Posted December 21, 2017 Share Posted December 21, 2017 how are you long term fuel trims looking? maybe you have a major boost or vacuum leak? Pull an LV. Link to comment Share on other sites More sharing options...
Siriya Posted December 21, 2017 Author Share Posted December 21, 2017 We did a reset last night to clear the low maf warning after changing the plugs and starting it up without the maf connected. I've attached the data accumulated so far. At times there's very little power and the car crawls as well. I mean really crawls as though no power. Link to comment Share on other sites More sharing options...
JazzAvi8r Posted December 21, 2017 Share Posted December 21, 2017 5EAT or MT? Link to comment Share on other sites More sharing options...
Siriya Posted December 21, 2017 Author Share Posted December 21, 2017 This is 5EAT Link to comment Share on other sites More sharing options...
xt2005bonbon Posted December 21, 2017 Share Posted December 21, 2017 well, looks like you are running lean. Look at your fuel trims. One is at 15%. So it is adding 15% of fuel because it noticed that unmetered air got into the combustion chamber. Probably from a vacuum leak somewhere after the MAF and before the turbo. Time for a smoke test and avoid going into boost until you get that taken care of. Link to comment Share on other sites More sharing options...
xt2005bonbon Posted December 21, 2017 Share Posted December 21, 2017 Actually, I should also ask: are you completely stock? stock tune too? Link to comment Share on other sites More sharing options...
FJuan Posted December 21, 2017 Share Posted December 21, 2017 Check your timing belt, you might have jumped a tooth or two. My wife's balls are delicious. Link to comment Share on other sites More sharing options...
Siriya Posted December 21, 2017 Author Share Posted December 21, 2017 Actually, I should also ask: are you completely stock? stock tune too? I've Decatted and tuned near a year Link to comment Share on other sites More sharing options...
Siriya Posted December 21, 2017 Author Share Posted December 21, 2017 Check your timing belt, you might have jumped a tooth or two. Will check this as well, ty. Link to comment Share on other sites More sharing options...
xt2005bonbon Posted December 21, 2017 Share Posted December 21, 2017 ok. then definitely check for leaks. Link to comment Share on other sites More sharing options...
Siriya Posted December 21, 2017 Author Share Posted December 21, 2017 ok. then definitely check for leaks. Will get on it and report back, thanks much Link to comment Share on other sites More sharing options...
xt2005bonbon Posted December 21, 2017 Share Posted December 21, 2017 I should also add that 15% is the max that most of our ECU can correct for. So it may be needing even more fuel but it can't really correct for it, thus the stutter. In other words, the leak may be pretty obvious. Link to comment Share on other sites More sharing options...
Wasted Potential Posted December 21, 2017 Share Posted December 21, 2017 I don't have much expertise on it but that sounds like the golden goose egg right there! Link to comment Share on other sites More sharing options...
relative4 Posted December 21, 2017 Share Posted December 21, 2017 That's not a vacuum leak, it's fuel supply. Could be pump, regulator. Link to comment Share on other sites More sharing options...
Siriya Posted December 21, 2017 Author Share Posted December 21, 2017 Would this also contribute to a somewhat hard start ? This is somewhat confusing as one in every 10 or so swings I get a normal start...after that it's dragging to turn over. Weve tested the vacuum but no signs of a leak. Any other ideas Link to comment Share on other sites More sharing options...
relative4 Posted December 21, 2017 Share Posted December 21, 2017 Would this also contribute to a somewhat hard start ? Yes, and so would 100 other things. I would test fuel pressure against spec, see the vacay pics for the procedure. Unfortunately, the Harbor Freight fuel pressure tester is garbage. You can get a decent one from standard auto parts stores for like $50. Link to comment Share on other sites More sharing options...
xt2005bonbon Posted December 22, 2017 Share Posted December 22, 2017 How did you check for vacuum leak?Do check timing to make sure you can rule that out.And yeah, there is a chance that there could be some issue with fuel pressure. You could log your injector duty cycle too and see how it behaves. Link to comment Share on other sites More sharing options...
xt2005bonbon Posted December 22, 2017 Share Posted December 22, 2017 There's also 'fuel pump DC' parameter you could log. Link to comment Share on other sites More sharing options...
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