VespaGTS Posted December 11, 2018 Share Posted December 11, 2018 Hi guys, I have been chasing a problem lately that I hope one of you can give feedback. While driving around town if I want to pass someone I will once in a while be WOT for a bit. What happens is this: I go to 100% throttle, the car takes off as usual and is pulling hard, then I hit a point that it feels like a rev limiter is kicking in and I get off the gas. Yesterday I was able to do a log and I think I caught it. I am hoping one of you can take a look at the log and give me some feedback? My IAM dropped to .75 So I will be looking for a vacuum leak next. Here is the log...BtSsm_20181210_152238.csv Link to comment Share on other sites More sharing options...
ehsnils Posted December 11, 2018 Share Posted December 11, 2018 Unfortunately the "csv" format is different depending on country settings so someone else may dig deeper into that. From my experience issues like this can be have many causes. Turbo is going (this is probably the most expensive and has to be fixed right away so try to exclude this first from being the cause)Boost leak - like a hose not being properly in pace.Fuel pump starting to fail.Knock sensor pulling the power.Something in the air intake blocking the air flow. Link to comment Share on other sites More sharing options...
VespaGTS Posted December 11, 2018 Author Share Posted December 11, 2018 I just had he Downpipe off and the turbo had very minimal shaft play. I will check the hoses. Link to comment Share on other sites More sharing options...
relative4 Posted December 11, 2018 Share Posted December 11, 2018 Can you please post another log, adding the following: Knock Sum Fine Knock Learn A/F Learning 1 A/F Learning A A/F Learning B A/F Learning C TD Boost Error Dynamic Advance Multiplier To improve resolution and improve readability, please get rid of the following: Coolant temp Misfire 1-4 Speed Throttle pedal Also, please just post one pull where the problem occurred. Link to comment Share on other sites More sharing options...
VespaGTS Posted December 11, 2018 Author Share Posted December 11, 2018 I can do that. I will have to try to re-create the symptoms. But first I’m going to have a look at all vacuum lines and intake connections. Link to comment Share on other sites More sharing options...
VespaGTS Posted December 11, 2018 Author Share Posted December 11, 2018 So this is the last time I could recreate the problem. I will try to log some more tomorrow. Strange that it is intermittent. The best way to describe how it feels is when I am WOT passing it is hitting a rev limiter. It feels like shit and I get off the gas right away. I plan on pulling the TMIC and doing a good inspection of the vacuum lines etc tonight. Sorry that my numbers are in .CSV format. I do not have a Cobb AP. I have hooked up my Tactrix and PC and will go for a drive once I have a look at all the lines tonight.BtSsm_20181211_105200.csv Link to comment Share on other sites More sharing options...
VespaGTS Posted December 11, 2018 Author Share Posted December 11, 2018 Learning view for extra credit... Link to comment Share on other sites More sharing options...
relative4 Posted December 11, 2018 Share Posted December 11, 2018 LV looks great, are you tuned or running an OTS map? Any chance that snapshot was shortly after an ECU reset? Link to comment Share on other sites More sharing options...
ehsnils Posted December 12, 2018 Share Posted December 12, 2018 So this is the last time I could recreate the problem. I will try to log some more tomorrow. Strange that it is intermittent. Might fall in the case of fuel pump being on its way out. A sticking wastegate might also be a problem that's intermittent. Link to comment Share on other sites More sharing options...
VespaGTS Posted December 12, 2018 Author Share Posted December 12, 2018 LV looks great, are you tuned or running an OTS map? Any chance that snapshot was shortly after an ECU reset? I am tuned by XRT, he is on holidays at the moment so I am troubleshooting. The tune was spot on prior to this issue so I don't think that is it. No the snapshot is after the event and no ecu cleared. I will add to this... One week ago it had the same problem, but the check engine, cruise and S mode all lit up. I checked codes and there were none, which I thought was strange since the check engine light is on. I reset the ECU and all of it went back to normal. Link to comment Share on other sites More sharing options...
VespaGTS Posted December 12, 2018 Author Share Posted December 12, 2018 Is there a way to diagnose a fuel pump problem without just replacing the pump. Numbers to look for on RomRaider? Link to comment Share on other sites More sharing options...
ehsnils Posted December 12, 2018 Share Posted December 12, 2018 More things to check - battery voltage, grounding between engine and frame and system voltage at high rpms. It can also be the a sensor like crank or cam sensor that is having intermittent behavior. Those intermittent problems are hard to capture and you should bring a code reader with you to try to catch the code if it appears. Don't forget to also look at "freeze frame" data. This is data logged when certain problems were detected. Link to comment Share on other sites More sharing options...
chato Posted December 13, 2018 Share Posted December 13, 2018 I had something like this and it ended up being a bad coilpack Link to comment Share on other sites More sharing options...
VespaGTS Posted December 13, 2018 Author Share Posted December 13, 2018 I had something like this and it ended up being a bad coilpack How did you figure it out? Link to comment Share on other sites More sharing options...
VespaGTS Posted December 13, 2018 Author Share Posted December 13, 2018 More things to check - battery voltage, grounding between engine and frame and system voltage at high rpms. It can also be the a sensor like crank or cam sensor that is having intermittent behavior. Those intermittent problems are hard to capture and you should bring a code reader with you to try to catch the code if it appears. Don't forget to also look at "freeze frame" data. This is data logged when certain problems were detected. I am logging every drive looking for it with RomRaider and Tactrix OP. Link to comment Share on other sites More sharing options...
chato Posted December 13, 2018 Share Posted December 13, 2018 How did you figure it out? Basically a process of elimination. I did a ton of searching/reading and logging didn't turn up anything abnormal. Was talking with my tuner and he said to check coilpacks. Then one day when it happened I got a misfire CEL, bought a cheap used coilpack off ebay and replaced the one on the cylinder showing misfire. That fixed it so I went ahead and bought four new coilpack as a precaution. Could also potentially identify by logging cylinder roughness, but not 100% on that, I never got a consistent misfire CEL from it. Link to comment Share on other sites More sharing options...
The Yeti71 Posted December 13, 2018 Share Posted December 13, 2018 Could also potentially identify by logging cylinder roughness, but not 100% on that, I never got a consistent misfire CEL from it. This is exactly how I started to diagnose the misfire problem my wagon was having. I monitored each cylinder with the AccessPort's diagnostic, and it identified roughness on cylinder 3. Link to comment Share on other sites More sharing options...
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