Zac88 Posted November 12, 2011 Share Posted November 12, 2011 My 05 does. Only on idle, drives just fine, boost comes on fine and everything! I put in new OEM spark plugs as soon as I got it and checked all coilpacks for corrosion and everything looked fine but it was still the same. Checked the blue T vaccum connector beneath the IC and its ok, unplugged a line just to see and it made it worse so that was definetly not the issue. So my next options are replacing the Oil control valves for the AVCS, new injectors and new IM o-rings and TGV gaskets. Anyone else having these problems and how have you fixed them? Link to comment Share on other sites More sharing options...
Wonder_Boy Posted November 12, 2011 Share Posted November 12, 2011 I have it also, I'd like to find a answer too. I noticed it but It only seems to be after the car warms up and the idle RPMs drop down. I've changed the spark plugs and everything seemed clean there. I also used injector cleaner in two tanks of gas so doesn't seem to be the problem. Personally I believe the car needs to idle at a higher RPM Link to comment Share on other sites More sharing options...
Max Capacity Posted November 12, 2011 Share Posted November 12, 2011 Most likely it's the o-rings on the intake manifold. I replaced mine, the car is much better. When you see the old ones next to the new ones you will understand. There is a DIY on here some where. 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...
outahere Posted November 13, 2011 Share Posted November 13, 2011 ...........So my next options are replacing the Oil control valves for the AVCS, new injectors and new IM o-rings and TGV gaskets. Anyone else having these problems and how have you fixed them? IMO if you still have the original injectors, try new injectors first. If that doesn't improve the idle, try new IM gaskets. But it is my understanding that the IM gasket problem manifests as a poor cold idle, that improves as the engine warms up. Oxygen sensor may also be suspect. Link to comment Share on other sites More sharing options...
Max Capacity Posted November 13, 2011 Share Posted November 13, 2011 Mine would stall after driving 15 miles. I replaced the $20.00 o-rings in June and that seem to help the most. Since then I had a CEL for a O2 sensor, I boughta rear sensor and still had the CEL, Then I figured out it was the front sensor. Then I put the VF52 on the car, had it tuned and it was fine but had the little stumble. I took a Q-tip and cleaned the MAF and IAT sensors, I got a CEL for each of those after I started the car, used my Cobb AP to clear them, the car runs great now. 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...
Zac88 Posted November 13, 2011 Author Share Posted November 13, 2011 used MAF cleaner a while ago, didnt make anything better or worse. Link to comment Share on other sites More sharing options...
PearlBlueGT Posted November 13, 2011 Share Posted November 13, 2011 On ours turned out heads were worn out. Link to comment Share on other sites More sharing options...
Zac88 Posted November 13, 2011 Author Share Posted November 13, 2011 cylinder heads? Link to comment Share on other sites More sharing options...
Wonder_Boy Posted November 13, 2011 Share Posted November 13, 2011 I pulled the IAT sensor out and it was pure black on one side, I wiped both it and the MAF with a q-tip and sat in the car while it warmed up and I'll be darned the stumble is gone! Link to comment Share on other sites More sharing options...
Zac88 Posted November 13, 2011 Author Share Posted November 13, 2011 I pulled the IAT sensor out and it was pure black on one side, I wiped both it and the MAF with a q-tip and sat in the car while it warmed up and I'll be darned the stumble is gone! hmm, I still have some electrical contact cleaner, ill try it next weekend! Link to comment Share on other sites More sharing options...
upshiftn Posted December 10, 2011 Share Posted December 10, 2011 Most likely it's the o-rings on the intake manifold. I replaced mine, the car is much better. When you see the old ones next to the new ones you will understand. There is a DIY on here some where. anyone know where this DIY is? haven't been able to locate... Link to comment Share on other sites More sharing options...
slowGT Posted December 10, 2011 Share Posted December 10, 2011 anyone know where this DIY is? haven't been able to locate... http://legacygt.com/forums/showthread.php/diy-rough-idle-cold-start-cold-temps-lgt-07-09-155325.html Link to comment Share on other sites More sharing options...
upshiftn Posted December 12, 2011 Share Posted December 12, 2011 http://legacygt.com/forums/showthread.php/diy-rough-idle-cold-start-cold-temps-lgt-07-09-155325.html my rough idle is not due to cold weather start ups or anything cold temp related. this is a constant rough idle but i should mention that it's not as rough as some describe their's to be. the tachometer on mine doesn't appear to move at all however while sitting and idling (maybe at a stop light or in a parking spot) you feel it in the seats and doesn't feel normal at all. i feel like there's something i can do but don't want to start replacing o-rings or anything else unless i know it's a good bet it might be the problem. FYI my spark plugs are performing properly and the idle doesn't change based on which company fuel i go with... thoughts? Link to comment Share on other sites More sharing options...
Max Capacity Posted December 12, 2011 Share Posted December 12, 2011 my rough idle is not due to cold weather start ups or anything cold temp related. this is a constant rough idle but i should mention that it's not as rough as some describe their's to be. the tachometer on mine doesn't appear to move at all however while sitting and idling (maybe at a stop light or in a parking spot) you feel it in the seats and doesn't feel normal at all. i feel like there's something i can do but don't want to start replacing o-rings or anything else unless i know it's a good bet it might be the problem. FYI my spark plugs are performing properly and the idle doesn't change based on which company fuel i go with... thoughts? I would clean the MAF and IAT sensors first. Then see if it's any better. That's cheap and easy. I replaced the o-rings in my 05 back in May when the car was on jacks for almost 4 months. I had the rough idle when cold and it stalled a couple of times in traffic. I have also replaced the both O2 sensors, because of a CEL for one. I replaced the turbo with a vf52 had it tuned and had the Tuner turn up the idle a bit. The car still had a rough idle when cold weather set in for a couple of day's in Oct. I cleaned the MAF and IAT and the car has run a lot better cold, today it was 17F and the car starts and runs great. 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...
bmx045 Posted December 12, 2011 Share Posted December 12, 2011 I replaced my plugs a couple weeks ago and the idle is firmer, not exactly rough but more pronounced. This only started after the plugs were replaced with oem. learning view shows perfect fuel trims and no knocking, also logging shows no misfiring at all. It's almost like the motor mounts are blocks of wood, lol. Link to comment Share on other sites More sharing options...
Max Capacity Posted December 12, 2011 Share Posted December 12, 2011 Not to keep beating a dead horse, but have you cleaned the MAF and IAT senosrs ? I'm sure your air filter is clean, right ? I don't know if its makes any real difference, but my 05 does have new 02 sensors. It also has one step colder plugs that were installed over 2 years ago. You could have a new plug that is only 80% healthy. Not everything is alway perfect when new. I hope you used NGK plugs ? I'm sure you did, you seem to know your way around these things. 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...
bmx045 Posted December 12, 2011 Share Posted December 12, 2011 oem = ngk. fuel trims are fine, no misfires. it's not the maf Link to comment Share on other sites More sharing options...
Max Capacity Posted December 12, 2011 Share Posted December 12, 2011 oem = ngk. fuel trims are fine, no misfires. it's not the maf Well you know what's next...a bad valve ? Compression test and leak down test. 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...
bmx045 Posted December 12, 2011 Share Posted December 12, 2011 no misfires. no knocking. Link to comment Share on other sites More sharing options...
Max Capacity Posted December 12, 2011 Share Posted December 12, 2011 So your just hearing a noise or feeling a vibration? Does it drive ok ? I wonder if your getting a exhaust leak at the DP to Mid pipe ? 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...
bmx045 Posted December 12, 2011 Share Posted December 12, 2011 it's fine diagnostically and drivability wise, though yes i have a couple exhaust leaks, lol. Link to comment Share on other sites More sharing options...
Max Capacity Posted December 12, 2011 Share Posted December 12, 2011 Oh see I knew I'd get to it if I just asked the right questions, fix your exhaust leaks 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...
dga Posted December 12, 2011 Share Posted December 12, 2011 Mine just started doing the same thing, rough idle, but my mileage has gone down too...from around 21-22 of mixed driving to 18-19. It's an '08 with about 35,000 on her. Link to comment Share on other sites More sharing options...
YN-TGL Posted December 12, 2011 Share Posted December 12, 2011 Sounds like an intake leak... Do and intake system pressure check with compressed air. Link to comment Share on other sites More sharing options...
dga Posted December 12, 2011 Share Posted December 12, 2011 Yeah, I was just reading up on it. I'm surprised I'd loose 2-4 MPG because of it though, since it only idles rough when it's cold out. Link to comment Share on other sites More sharing options...
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