subydrift Posted December 28, 2018 Share Posted December 28, 2018 Hey guys, I've noticed lately when I am in stop and go traffic each time I hit the brakes as I move up my rpms seem to drop to ~500 and the engine gives a little studder before jumping back up to ~650-700 range. It has never stalled but is annoying as hell. Could this be something to do with the one way valve in the brake booster vacuum line? Bad brake booster maybe? Any ideas? I have an '05 OBXT with the 5EAT trans. Thanks. Link to comment Share on other sites More sharing options...
Dishwasher Posted December 28, 2018 Share Posted December 28, 2018 Probably a vacuum leak somewhere. Brought to you by Pfizer Link to comment Share on other sites More sharing options...
kzr750r1 Posted December 28, 2018 Share Posted December 28, 2018 There are a few things to check. Confirming all vacuum lines are solid is best first stab. Had this issue for a long time years ago around 120K and was fixed by changing the Oil Control Valve Solenoids. The are not hard to do but will start going south around 80 to 100K. IMHO should be part of the belt change maintenance schedule. No more stumble or stalls off idle after the swap. I'm about to do another change soon at 215K. Link to comment Share on other sites More sharing options...
relative4 Posted December 28, 2018 Share Posted December 28, 2018 Easiest diagnostic start is get an OBDLink or a VAG-COM cable and pull the learned values. Link to comment Share on other sites More sharing options...
subydrift Posted December 29, 2018 Author Share Posted December 29, 2018 I’ll check all the vacuum lines I can access most easily. Maybe just buy replacements for them anyways to be safe. Kzr750r1, are you referring to the AVCS solenoids? That sit on the front top of the heads? Link to comment Share on other sites More sharing options...
08SpecB_DE Posted December 29, 2018 Share Posted December 29, 2018 Have you cleaned the throttle body lately? It might be a good idea to clean the maf as well, but be careful. Link to comment Share on other sites More sharing options...
subydrift Posted December 29, 2018 Author Share Posted December 29, 2018 I cleaned the MAF when I changed my air filter back in the summer. But I do need to install my AVO MAF pipe so I’ll give it a quick spray when I’m in there. And I remember when I had the engine apart for the rebuild I cleaned the TB as best I could with a clean cloth. Thanks for all the advice you guys! With regards to the OBDLink cable, has anyone used the OBDLink MX+ Bluetooth unit with the app for diagnostics and monitoring? Link to comment Share on other sites More sharing options...
kzr750r1 Posted December 29, 2018 Share Posted December 29, 2018 I’ll check all the vacuum lines I can access most easily. Maybe just buy replacements for them anyways to be safe. Kzr750r1, are you referring to the AVCS solenoids? That sit on the front top of the heads? Yep. That's what I'm referring to. I literally went through all the same suggestions folks are offering till just finally replacing them. No codes to say point at them being an issue... Just the last thing that made seance to try. Had already done the , Vacuum line check and tie wrapped them all, Replaced the blue T, Cleaned the intake and Throttle body, Cleaned out the head crossover of sludge, PCV replaced, Replaced the intake to TGV seals... It was fixed with the AVCS (OCVS) being replaced. Kinda looking forward to my next replacement. These have 75K on them and showing a little corrosion on the outside. They sat out of the car for two years while I rebuilt the motor. Although mostly submerged in oil it could not have been good for them to remain static for so long. Link to comment Share on other sites More sharing options...
RabidWombat Posted December 29, 2018 Share Posted December 29, 2018 I'm having the exact same issue. Any recommendations on checking for vacuum leaks without a smoke generator. I've pulled out LV using btssm but I'm not sure what I should be looking for? Link to comment Share on other sites More sharing options...
relative4 Posted December 29, 2018 Share Posted December 29, 2018 Post the LV snapshot here. Link to comment Share on other sites More sharing options...
RabidWombat Posted December 30, 2018 Share Posted December 30, 2018 Post the LV snapshot here. I uploaded two files, the more recent is from December, the other is from August. The difference is probably about 1k miles. Link to comment Share on other sites More sharing options...
relative4 Posted December 30, 2018 Share Posted December 30, 2018 Those are fine. When parked, does hitting the brakes cause a stumble? If so, log your fuel correction values while doing that, and listen at the brake booster for hissing. Then turn the car off, wait 30 seconds, and press the pedal to see if the brake booster still operates or if the brake pedal is hard. Link to comment Share on other sites More sharing options...
RabidWombat Posted January 6, 2019 Share Posted January 6, 2019 Just following up. I tried the brake test, and nothing the car runs perfectly. To be honest, I can't make it stumble at all now. There's maybe a slight stumble when the AC compressor kicks on, but that's probably normal. Link to comment Share on other sites More sharing options...
kzr750r1 Posted January 6, 2019 Share Posted January 6, 2019 Swapped the OCVS a few Friday. Car is running much better in town and off idle. When I was fighting this symptom before I could not trigger it. Just decided to act abbey normal on it's own. Seriously if you have not changed these parts in the time you have owned the car your best bet is to change them. Passenger side is the hardest with the coolant tank mounting bracket in the way. Not sure how the 09 layout looks but suspecting it will be a similar PITA. You have to strip a few items out of the way to do the job including pulling the front head breather hoses for clearance. Link to comment Share on other sites More sharing options...
RabidWombat Posted January 10, 2019 Share Posted January 10, 2019 Swapped the OCVS a few Friday. Car is running much better in town and off idle. When I was fighting this symptom before I could not trigger it. Just decided to act abbey normal on it's own. Seriously if you have not changed these parts in the time you have owned the car your best bet is to change them. Passenger side is the hardest with the coolant tank mounting bracket in the way. Not sure how the 09 layout looks but suspecting it will be a similar PITA. You have to strip a few items out of the way to do the job including pulling the front head breather hoses for clearance. What were the part numbers (I know 09 is different, but looking for reference)? Did you find a walkthrough online anywhere? I'm probably going to have to do this myself so I'm trying to get a handle on how bad a job it is. Link to comment Share on other sites More sharing options...
kzr750r1 Posted January 10, 2019 Share Posted January 10, 2019 I go to Heuberger. Looks like 07+ is different than mine on the 06. The mounting tab but probably the same part otherwise. It's all doable just take your time. The thing is rotating it 45 degrees and it dragging just a little jamming it past the bracket. It's a little unnerving but again doable. Hopefully the 09 accommodated for that with this different locking tab and possibly a coolant tank bracket that isn't in the way. Let us know how it goes and drives after... Link to comment Share on other sites More sharing options...
apexi Posted January 10, 2019 Share Posted January 10, 2019 Here's some pictures and stuff.. I think the some of the pics are from 05's, but maybe they could still help.. https://legacygt.com/forums/showpost.php?p=5853683&postcount=19 Link to comment Share on other sites More sharing options...
kzr750r1 Posted January 10, 2019 Share Posted January 10, 2019 What were the part numbers (I know 09 is different, but looking for reference)? Did you find a walkthrough online anywhere? I'm probably going to have to do this myself so I'm trying to get a handle on how bad a job it is. Here is the 09 PN. https://parts.bestbuysubaru.com/p/Subaru__/VALVE-ASSEMBLY-OIL-CONTROL/49223110/10921AA080.html Link to comment Share on other sites More sharing options...
Dishwasher Posted January 10, 2019 Share Posted January 10, 2019 Anyone try the Gates solonoids, or is OEM the only way to go? https://www.rockauto.com/en/moreinfo.php?pk=7998068&cc=1432596&jsn=411&jsn=411&jsn=411 Brought to you by Pfizer Link to comment Share on other sites More sharing options...
xt2005bonbon Posted January 10, 2019 Share Posted January 10, 2019 Before you touch the OCVs, you can always log or view their respective angles on BtSsm (see 'VVT'). They should be in sync at all times. If you find one noticeably lagging behind, then there is definitely something wrong there. Although it might not be OCV. Could be an issue in oil supply (e.g. clogged banjo bolt filter). Link to comment Share on other sites More sharing options...
kzr750r1 Posted January 11, 2019 Share Posted January 11, 2019 I've not done much driving after the last OCV, PCV, Plug change. However the car is no longer doing this same thing when breaking to a stop. Had it stall a few weeks back and this all went away after changing these components. Was not going to go through all the other guess work I did last time going through this issue. That was painful and before I had the AP. On the AP you can log or monitor the AVCS as well. Not sure what the unit of measure is on the monitor but one side was usually an increment off from the other. These new units seem to be 100% in sync with each other. I'm not the only one saying OCV and PCV are good to replace after several thousands of miles or when symptoms arise like this with no other reasonable explanation. Just seems lately we have had a new group of folks buying older cars that have never had these parts replaced. First time I battled it was over five years ago, actually saw the thread where this was discussed recently kinda made me smile...Said it then and say it now. OCV should be replaced at 105K with the belt. Immediately IMHO if the car is a new purchase and you have no history of it's maintenance. Would save alot of head scratching. Link to comment Share on other sites More sharing options...
xt2005bonbon Posted January 11, 2019 Share Posted January 11, 2019 The unit should be in degrees. Mine would peak around 11 or 12 degrees under load and warm engine (yours may vary depending on your tune). When the engine is not under load (and warm), they should be zero. But yeah, they should stay in sync. I think what is important to log is to see how they both transition from zero degree to X degrees. You want to see if they both get to their target angle more or less at the same rate. Link to comment Share on other sites More sharing options...
kzr750r1 Posted January 12, 2019 Share Posted January 12, 2019 Hmm yeah mine has maxed out at like 40 and min is zero... But lately they are dead nuts the same reading. Have been stuck at my home office all week and feel like letting her rip a little well see how it feels this weekend. Link to comment Share on other sites More sharing options...
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