jackal8788 Posted November 4, 2015 Author Share Posted November 4, 2015 ^Yeah, this! I just got off the phone with Cobb and they are also completely stumped. Even a 'soft' misfire or a few shouldn't be dropping my power by 200+ hp. That much drop should have some more severe symptoms presenting like hitching, stuttering, codes being thrown, pet's heads falling off, etc. VF54 to 20G to VF54 to 18G build thread Link to comment Share on other sites More sharing options...
jackal8788 Posted November 5, 2015 Author Share Posted November 5, 2015 You know, as frustrating as this all is, this forum has provided a fantastic sounding board for ideas and discussion so let's keep it going. Know that I appreciate everyone's input, experience, and comments. Now for fuck's sake, let's get the Panda back to it's angry old self! VF54 to 20G to VF54 to 18G build thread Link to comment Share on other sites More sharing options...
GTEASER Posted November 5, 2015 Share Posted November 5, 2015 Have you logged your throttle position sensor at the throttle body and compared it to the load requests and the throttle pedal angle sensor at your foot? I recall that acumen had an issue with is car where the TPS was giving a bad reading and wouldn't open up all the way even tho his foot was pegged to the floor...or something like that. GTEASER's 2012 Legacy GT - Sold GTEASER's 2009 XTeaser - Sold GTEASER's 1992 Legacy SS - Sold Link to comment Share on other sites More sharing options...
FLlegacy Posted November 5, 2015 Share Posted November 5, 2015 I think rechecking the compression with a hot engine would be a good thing to do at this point. There should be a process in the fsm for checking the coil packs. Compression on a hot motor should be 142-171 psi with no more than 7 psi variance. Link to comment Share on other sites More sharing options...
jackal8788 Posted November 5, 2015 Author Share Posted November 5, 2015 I have and I also recall the issue you mentioned. In my case, they are in alignment. 100% accelerator position corresponds to 100% throttle position. VF54 to 20G to VF54 to 18G build thread Link to comment Share on other sites More sharing options...
BBPeik Posted November 5, 2015 Share Posted November 5, 2015 I know this may be a stupid question, but have you checked the throttle body hose and or the bpv hose for small tears or leaks. It seems simple, but the throttle body hose having a leak could be a possibility. The car would still read boost, but you lose it all by the time it gets to the engine. Silly, but maybe? My someday I will be done with it thread. Link to comment Share on other sites More sharing options...
FLlegacy Posted November 5, 2015 Share Posted November 5, 2015 If plugs checked out then that should also rule out a coil pack going bad as you would have heavy build up on that plug. I am thinking the issue is further upstream in the inlet dept. I like fahr-sides suggestion with the TGV. Is that a logable parameter? The valves have a sensor right so the ecu would know if they aren't in position? Link to comment Share on other sites More sharing options...
s2baru Posted November 5, 2015 Share Posted November 5, 2015 Log the roughness for each cylinder too perhaps Link to comment Share on other sites More sharing options...
jackal8788 Posted November 5, 2015 Author Share Posted November 5, 2015 I know this may be a stupid question, but have you checked the throttle body hose and or the bpv hose for small tears or leaks. It seems simple, but the throttle body hose having a leak could be a possibility. The car would still read boost, but you lose it all by the time it gets to the engine. Silly, but maybe? At this point, I'm willing to entertain any thoughts at all! We did smoke-test and no leaks were present though. VF54 to 20G to VF54 to 18G build thread Link to comment Share on other sites More sharing options...
jackal8788 Posted November 5, 2015 Author Share Posted November 5, 2015 Log the roughness for each cylinder too perhaps Thanks S2. That was actually on the docket for today to see if we could isolate what cylinder (or cylinders) are suspect. I may also try flashing a few different old maps that I have just to see if there are any significant differences in performance. Eventually when I exhaust this tank of e85, I might also try running a tank of 93 octane to see how it responds on that tune. VF54 to 20G to VF54 to 18G build thread Link to comment Share on other sites More sharing options...
LatentWagen Posted November 5, 2015 Share Posted November 5, 2015 If it were spark or misfire related, you'd know it. According to your post, your power is off by ~60%, so that'd be like running on one and a half cylinders... which you'd feel, in a big way. To put it in perspective, I had a very easily noticed miss on both 1 and 3 due to a bad HG. The car was still at least 8.5/10 in terms of power. I think your compression is probably fine, as are your plugs and coils. Gotta be somewhere in the plumbing. LW's spec. B / YT / IG Link to comment Share on other sites More sharing options...
jackal8788 Posted November 5, 2015 Author Share Posted November 5, 2015 Yeah, I know it. But I'm sure not finding anything yet that could account for it. If it was plumbing on the intake side I would think it should also show up somewhere in either boost, AFR, or both. VF54 to 20G to VF54 to 18G build thread Link to comment Share on other sites More sharing options...
jojorios Posted November 5, 2015 Share Posted November 5, 2015 Just for general knowledge, any reason you did a compression test and not a leakdown? Link to comment Share on other sites More sharing options...
GTEASER Posted November 5, 2015 Share Posted November 5, 2015 Are you running stock intake box and piping? pre-turbo. GTEASER's 2012 Legacy GT - Sold GTEASER's 2009 XTeaser - Sold GTEASER's 1992 Legacy SS - Sold Link to comment Share on other sites More sharing options...
jackal8788 Posted November 5, 2015 Author Share Posted November 5, 2015 Just for general knowledge, any reason you did a compression test and not a leakdown? Just didn't have the equipment on hand to do a leakdown test. I figured if the compression test looked bad, I would take it out for the leakdown. Might still be a good idea to do though. VF54 to 20G to VF54 to 18G build thread Link to comment Share on other sites More sharing options...
jackal8788 Posted November 5, 2015 Author Share Posted November 5, 2015 Are you running stock intake box and piping? pre-turbo. Not quite. I have the stock intake box but i have a KStech 73mm intake pipe that my MAF is installed on. We went with this larger MAF housing due to concerns about maxing out the MAF with the stock MAF diameter. The turbo inlet pipe is stock. VF54 to 20G to VF54 to 18G build thread Link to comment Share on other sites More sharing options...
GTEASER Posted November 5, 2015 Share Posted November 5, 2015 And you've inspected the stock intake piping to make certain it's not collapsing under vacuum anywhere? I'd say take the filter out and go for a drive to see if you're still down on power, but I wouldn't want anything to get sucked into your turbo. GTEASER's 2012 Legacy GT - Sold GTEASER's 2009 XTeaser - Sold GTEASER's 1992 Legacy SS - Sold Link to comment Share on other sites More sharing options...
jackal8788 Posted November 5, 2015 Author Share Posted November 5, 2015 Haven't done that yet, thanks for the idea. I will inspect and see if there are any signs of collapse. If the intake pipe was collapsing though, wouldn't it struggle to make the boost targets? VF54 to 20G to VF54 to 18G build thread Link to comment Share on other sites More sharing options...
cww516 Posted November 5, 2015 Share Posted November 5, 2015 That would be my thought, and why I'd think your problem is downstream of the turbo. Come to think of it, if you're hitting your boost target, wouldn't the issue have to be downstream of the MAP sensor and throttle plate, since that's where the signal line leads? I have no idea what you can learn about TGV position with an Accessport, but I think fahr_side may be on to something (no surprise there...). Link to comment Share on other sites More sharing options...
jackal8788 Posted November 5, 2015 Author Share Posted November 5, 2015 Posting one more log that I took with some additional parameters added. This does show some roughness detected in cylinder 4. Thoughts anyone?3rd gear low power.csv VF54 to 20G to VF54 to 18G build thread Link to comment Share on other sites More sharing options...
BBPeik Posted November 6, 2015 Share Posted November 6, 2015 You are right on the high rpm roughness. Interesting. I have no help for you, but it is strange. My someday I will be done with it thread. Link to comment Share on other sites More sharing options...
FLlegacy Posted November 6, 2015 Share Posted November 6, 2015 Posting one more log that I took with some additional parameters added. This does show some roughness detected in cylinder 4. Thoughts anyone? According to the log the roughness is on cylinder 3. Swap coils with another cylinder and log again. Link to comment Share on other sites More sharing options...
Perscitus Posted November 6, 2015 Share Posted November 6, 2015 (edited) Yup. Its actually on Cylinder 3, not 4. And it happens once you've let off toward the end of the log... as your throttle plate closed up and I'm assuming you coasted. This is a typical place to have some transient mis-fires, nothing unusual. Plus its only the last 53 rows worth of data... with really just two mis-fire events (notice how the roughness sum went to 1, and it stays there, then switches to 2 and stays there?). This doesn't mean its mis-firing all the time these last 4-5 seconds... just that the counter increased from 0 to 1 then to 2.... So really just 2 mis-fire events in a 4-5 second time period. Both happened under ~20psi boost though, before you re-entered vacuum. Edited November 6, 2015 by Perscitus Link to comment Share on other sites More sharing options...
brandon.mol Posted November 6, 2015 Share Posted November 6, 2015 Sooo.. have you confirmed the TGV is working properly? If the TGV butterflies were stuck partially closed on one or both banks, you would have one hell of an obstruction that would not prevent boost build up but would certainly cause a 60% power loss at higher RPM/flow, easy. Link to comment Share on other sites More sharing options...
jackal8788 Posted November 6, 2015 Author Share Posted November 6, 2015 (edited) Again, thanks for the feedback. Sorry, yes, the roughness was on cylinder 3, not 4. I agree that it sure isn't much. I'll swap the coil pack and see if the issue follows but its hard to believe that something which doesn't create much of a stir for the ECU is robbing that much power. Brandon to your point, I haven't physically checked the TGVs. I did log the drive and signal voltage to make sure that at least the ECU is attempting to open them but verification still needs to happen. Is there a recommended way to do this? Also, is ~3.7 volts the proper signal for fully opening those things? Seems that a 0-5v signal is common but I don't know jack about this kind of stuff. If it should be 5V though, that could be a possibility as it is only showing about 3.7V. Edited November 6, 2015 by jackal8788 VF54 to 20G to VF54 to 18G build thread Link to comment Share on other sites More sharing options...
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