Wasted Potential Posted December 12, 2017 Share Posted December 12, 2017 2005 LGT 5EAT, getting ready for logging for stage 3 tune so I attempted to block the intake and blow into the vacuum line off the bypass valve off the intercooler. Smoke seemed to slowly accumulate near passenger side intake runners/below manifold. Smoke was not thick enough to pinpoint exactly. My question: If the intake runner was leaking that much wouldn't I have an idle issue? Seeing how the inlet and PCV lines do not see much more than 2-4psi what is the point of checking for any leaks? Seems air escaping would be so negligible that positive pressure from the crankcase would just vent to atmosphere/through the leak. What is the probability the intake is actually leaking versus a local vacuum line? Seems absurdly small.. Is the VF52 turbo inlet shorter/more recessed than a VF40? It seems my inlet is just short, tightening the work clamp works the inlet off the turbo. Debated unbolting it from the manifold. The leak detector does not seem "secure" enough even in mint condition to hold 5psi, but maybe it does? If I just pull the metal tab from the male end and tape it into the sensor, and then just plug the line back into the inlet, all problems there should be resolved correct? I'm not noticing any boost issues, but I assume this methodology should result in a little retained pressure so I must have an issue somewhere. Link to comment Share on other sites More sharing options...
Max Capacity Posted December 12, 2017 Share Posted December 12, 2017 Look to make sure you have the larger orange O-rings between the intake and TGV's. There is not difference in the length of the turbo inlet on the VF52. Try giving that small hose you blew into a short blast of air from a compressor, then put your thumb over the hose. 305,600miles 5/2012 ej257 short block, 8/2011 installed VF52 turbo, @20.8psi, 280whp, 300ftlbs. (SOLD). CHECK your oil, these cars use it. Engine Build - Click Here Link to comment Share on other sites More sharing options...
Wasted Potential Posted December 12, 2017 Author Share Posted December 12, 2017 Is the purpose of this boost leak in this format to make sure the MAF is accounting for all air going into the manifold so the ECU is seeing consistent non variable inflow? Link to comment Share on other sites More sharing options...
Max Capacity Posted December 12, 2017 Share Posted December 12, 2017 Yes. Also to prove you don't have a vacuum leak, which you'll hear as air rushing out somewhere. After a few seconds, when you remove your thumb, air should come out where your thumb was. Makes you feel good when that happens. 305,600miles 5/2012 ej257 short block, 8/2011 installed VF52 turbo, @20.8psi, 280whp, 300ftlbs. (SOLD). CHECK your oil, these cars use it. Engine Build - Click Here Link to comment Share on other sites More sharing options...
Wasted Potential Posted December 12, 2017 Author Share Posted December 12, 2017 How would a vacuum leak necessarily increase boost or induce a spike momentarily in boost? Link to comment Share on other sites More sharing options...
traildogck Posted December 12, 2017 Share Posted December 12, 2017 If you have a vacuum leak, you usually have low boost since the leak is still there when the system pressurizes with boost. If you are overboosting and spiking I would be looking more at the wastegate to make sure that is functioning properly. CKE SSP product information and sales : chris.ckessp@gmail.com Link to comment Share on other sites More sharing options...
Wasted Potential Posted December 12, 2017 Author Share Posted December 12, 2017 I am currently running a Cobb AP stage 2 tune, but later found out I have a VF52 on it. I should not be riding it hard, but I like to make poor choices every now and then... boost will spike to 18.0 +/- 0.5 and ride around 16.5 +/- 0.5 through RPM and have not noticed what it tapers to at redline. I purchased a stage 3 e tune, and am waiting for that and will install my grimmspeed EBCS before trying to really look at existing problems. What is apparent is that if I cover the intake inlet, take off the vacuum line to the bypass valve on the intercooler, and blow into it, no pressure will hold. That is why I feel there is a problem. A redneck friend blew his vape pecker smoke into the tube, and we could see that it was apparent it would come to the passenger area of the intake manifold... I just ordered a new turbo inlet and about $220 worth of hoses and gaskets for the intake so I may get to pull it next week or before Christmas weekend and attempt to resolve this for the e tune logging to commence. Link to comment Share on other sites More sharing options...
Max Capacity Posted December 12, 2017 Share Posted December 12, 2017 Yea, you need to fix all the leaks before you pay for the e-tune. But I guess you know that. 305,600miles 5/2012 ej257 short block, 8/2011 installed VF52 turbo, @20.8psi, 280whp, 300ftlbs. (SOLD). CHECK your oil, these cars use it. Engine Build - Click Here Link to comment Share on other sites More sharing options...
Gex Posted December 13, 2017 Share Posted December 13, 2017 Definitely sounds like you have a boost leak. If the ol smoke test showed something. Make a tester or buy one https://www.siliconeintakes.com/intake-leak-pressure-tester/?osCsid=ee51c54e3a91f9a1748e3c8bcedbfcb5. Vf52s (and pretty much every vf39,43,48) all boost creep. The 3 port will exacerbate the problem and not work if not tuned for. You need an external wastegate to solve the issue or a good port and polish with a catted downpipe to merely reduce the creep. A vf40 Stage 2 map won’t be that bad on a vf52. Their pretty safe tunes. Your just not getting all the potential from that vf52. Link to comment Share on other sites More sharing options...
Wasted Potential Posted December 13, 2017 Author Share Posted December 13, 2017 Yea, you need to fix all the leaks before you pay for the e-tune. But I guess you know that. Ironically, did the opposite! But luckily the tuner offers a lot of time for revisions. Definitely sounds like you have a boost leak. If the ol smoke test showed something. Make a tester or buy one https://www.siliconeintakes.com/intake-leak-pressure-tester/?osCsid=ee51c54e3a91f9a1748e3c8bcedbfcb5. Vf52s (and pretty much every vf39,43,48) all boost creep. The 3 port will exacerbate the problem and not work if not tuned for. You need an external wastegate to solve the issue or a good port and polish with a catted downpipe to merely reduce the creep. A vf40 Stage 2 map won’t be that bad on a vf52. Their pretty safe tunes. Your just not getting all the potential from that vf52. The creep doesn't seem horrible, and in regards to the EBCS I will wait for the base map before install of it. I am unfamiliar with an external wastegate in regards to the 5EAT. Hopefully the tuner can make the fueling work with the boost creep if it resides after the leak is fixed with my catted downpipe; but I guess we will see! All those testers are "out of stock." I will look into piecing one together tomorrow! Link to comment Share on other sites More sharing options...
DaveWaters Posted December 13, 2017 Share Posted December 13, 2017 My 17.9psi “creep” looks more like a spike when logged on the AP. It only takes up 1 cell at about the point of shifting. If you haven’t logged it yet and are going by the peak on the AP gauge, I’d log it. Also I don’t recall what intercooler you have but the first time I hit over 17 my oem intercooler opened at the side pinches near the turbo.. I immediately did the bulletproof Home Depot fix and it seems to be holding up now Link to comment Share on other sites More sharing options...
Wasted Potential Posted December 13, 2017 Author Share Posted December 13, 2017 My 17.9psi “creep” looks more like a spike when logged on the AP. It only takes up 1 cell at about the point of shifting. If you haven’t logged it yet and are going by the peak on the AP gauge, I’d log it. Also I don’t recall what intercooler you have but the first time I hit over 17 my oem intercooler opened at the side pinches near the turbo.. I immediately did the bulletproof Home Depot fix and it seems to be holding up now A point worth mentioning, I blew my OE intercooler apart on an 18.x spike and bought a mishimoto replacement. I noticed my spikes only occur during building of boost at 2.8-3.2k rpm, not during shift Link to comment Share on other sites More sharing options...
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