Rweaver Posted December 13, 2013 Posted December 13, 2013 A few months ago the car started missing a bit. I had my plugs changed and now when taking off from a redlight the car feels laggy. Takes more throttle to move it off the line. So I found a good place an floored it from deadstop multiple times. At around 55 mph the RPM will drop about 600 rpm WithOUT changing gears an then the car just takes off a lot faster.. very odd any input would be greatly appreciated.
Rweaver Posted December 13, 2013 Author Posted December 13, 2013 The first thing I did after this occured was check the gap on every plug.. no engine lights
samuroid Posted December 14, 2013 Posted December 14, 2013 I've been working and researching this problem now for quite some time, Rweaver... I have the same year, same model car you do. After a full 60k maintenance (where they also changed spark plugs btw - idk if this makes any difference) my car became sluggish with RPM lag from a stoplight or when waiting/idling. That was several months ago. It now stalls and dies - generally dropping about 500-600rpm. After reading several forum notes and taking it to no less than 3 shops, including 1 dealership and calling 4, the most helpful shop felt it was a dirty blow off valve, which LGT's are sensitive to. That helped but only for a bit. I'm back to stalling out. Forum msgs and an old reliable shop indicate it may be related to the MAF sensor not working properly. I called the Subie stealorship in the Seattle area where I'm located and noted I would need to rob 3 citizens and a bank before I could pay. I took my car in and they hadn't even ordered the part - demanding they analyze it first. So be warned. However, as forum notes mention, this is a very hard to diagnose issue. All 3 shops that had my car for full days could NOT find any problem. In the end, I may have to take a shot in the dark and just find a place that will replace the MAF completely untested. Forum notes also mention the O2 sensor but those would be secondary. I have no CEL's because I'm running the COBB Accessport and most local shops refuse to service my car because of it. So the good news, you're not alone. The bad news? It may be on it's way to getting worse. I've stalled out in busy traffic. It always starts right back up, but it's nerve racking, it sucks and it's dangerous.
Rweaver Posted December 15, 2013 Author Posted December 15, 2013 I appreciate the info I am getting my car on a dyno real soon at fast tech in Knoxville so hopefully they will be able to figure it out. I will let you know what is found out. I wonder if the spark plugs have to be indexed this is the only other thing I could possible think of that could cause it to do that. because it really did seem like it occurred when the plugs were changed. just not the same car power wise.
bmoreblackonblack Posted December 16, 2013 Posted December 16, 2013 Does your car stall out completely or stall and re-engage, like a blink of an eye? I just sold my 08 5sp because of an intermittent electrical short which caused the engine to cut in and out at various speeds. my performance shop couldn't pin point the issue and the dealer wanted to throw a new harness at it for 1500 bucks. They said that was a good place to "start". I finally hit my boiling point and sold it back to Carmax where I bought it from. Pulled a VIN status and the previous owner had attempted to fix the same issue, but clearly was unsuccessful.
samuroid Posted December 16, 2013 Posted December 16, 2013 Rweaver - keep me posted what the dyno finds out. My shop said I couldn't dyno until they fix all the problems here. Bmoreblackonblack - my car lags and then catches itself and also lags then stalls completely. So both cases really. It's odd. It seems worse when it's on hills if that makes any sense at all both uphill and downhills. I take it reseating the spark plugs which is my next thing, along with replacing the MAF may not do it. If not, my third and last place choice is to sell my pride and joy a lot like you did. :-( I wonder why these problems are just now coming out with this model car? Sent from my iPhone using Tapatalk
samuroid Posted December 16, 2013 Posted December 16, 2013 Thinking about it more carefully... My car doesn't cut out at various speeds like yours. It's always from a stop and when I press the gas, THEN it fails to rev up and either catches itself or dies. No shop in the Northwest can figure this out. Sent from my iPhone using Tapatalk
Rweaver Posted December 16, 2013 Author Posted December 16, 2013 I will keep you posted. I talked to the guy that's going to be tuning my car an his thoughts over the phone which don't explain the miss but he felt like the rpm drop when under load is possibly transmission related. is a very good shop they work on tons of subys and they build the piss out of them. But we are going to dyno it an keep an eye on boost pressures an all numbers to see if the change in power is really with in the engine.. after this issues fixed then tuning it.
Rweaver Posted December 16, 2013 Author Posted December 16, 2013 He mentioned trq converter an vavle body for the drop in rpm when under load. and that the dyno really wouldn't tell us if that's whats wrong but it can help by eliminating a few vitals like turbo fuel pressures ect. I am also having a leak down test done at that time so I am hopeful for a verdict.
Rweaver Posted December 16, 2013 Author Posted December 16, 2013 I could see that being trans related with having a laggy feel an then catches an takes off but with how yours stalls out an how both of ours have misses..my car hates hills too now. whats crazy is mine doesn't do it all the time.. but sometimes it misses up to 4000 rpm in park the next day running fine. I guess what I am saying is I understand this guys thoughts on the catching an taking off part maybe being trans relate, but that doesn't explain the poor running conditions. He hasn't seen this car yet though either an I asked him more about the drop in rpm than the missing really. If the catching is trans realted I know I also have another issue of why is it running bad.
Max Capacity Posted December 16, 2013 Posted December 16, 2013 Your sure you don't have a vacuum leak, could it be a small crack in a hose ? I wouldn't spend money on the dyno until the car 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
Rweaver Posted December 17, 2013 Author Posted December 17, 2013 I have checked all the vacuum lines that I know of that is. And four pulls on the dyno for 70 bucks I figured it would be worth that just for the peace of mind to know that the engine vitals are ok really. He wont be tuning the car until its fixed. Its been to a few shops now an none have any ideas. They tell me to drive till an engine light comes on. I just want to see what someone with tuning experience thinks of how the cars rpm drops under load. When they see that in numbers I am hoping it will point me in a direction. sometimes its so laggy it don't feel safe on the engine really. Its odd
Rweaver Posted December 17, 2013 Author Posted December 17, 2013 its almost like when you take off from a dead stop an floor it its like its running on pure engine until 55mph an then it feels like the turbo just kicks in an the car just takes off. if that makes sense.
Rweaver Posted December 17, 2013 Author Posted December 17, 2013 pretty much it lags to 55 mph then an 600rpm drop will occur with no gear change an the car takes off with what then feels like normal power.
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