87.5ea82txt Posted October 16, 2012 Share Posted October 16, 2012 Lately my 87.5 xt has started running like crap, especially when cold. It seems like I have an air leak, but I can't seem to find a cracked or disconnected vacuum line. Not really sure what to now. Should I pull the spider manifold and look for bad lines under it? Could my maf just be dirty? Maybe some other culprit that I haven't considered? Link to comment Share on other sites More sharing options...
naru Posted October 16, 2012 Share Posted October 16, 2012 Lately my 87.5 xt has started running like crap, especially when cold. It seems like I have an air leak, but I can't seem to find a cracked or disconnected vacuum line. Not really sure what to now. Should I pull the spider manifold and look for bad lines under it? Could my maf just be dirty? Maybe some other culprit that I haven't considered? Poor idle? Installing a vacuum gauge on the manifold would likely be a lot more informative and less labour intensive. I would have a look at the o2 sensor voltage as well. Does idle improve when mixture is enriched w/propane or the return line is pinched? When mixture is leaned w/a controlled vac. leak? Ignition system inspection and compression test may be in order. Could be dirty MAF. Consider the infamous poorly crimped injector? wiring cnnection in the rocker panel too. Link to comment Share on other sites More sharing options...
87.5ea82txt Posted October 16, 2012 Author Share Posted October 16, 2012 I did a compression test not to long ago and all cylinders produced similar pressure. I have a boost gauge attached and does not seem to flutter. Are you suggesting creating a vacuum in the lines? The car starts up right away, but misses badly. It definitely seems to be running rich and I have noticed a decrease in my mileage. I'm not too familiar with the wiring issue you mention. What should my o2 voltage be? Link to comment Share on other sites More sharing options...
87.5ea82txt Posted October 16, 2012 Author Share Posted October 16, 2012 When I fitted the intercooler a few years back, I used crappy rubber hoses at first before cutting expensive nylon ones and sometimes one would pop off under boost and the engine would stutter badly. It's doing the same thing, and that's why I feel that it's not getting the airflow that the maf is saying it is. Link to comment Share on other sites More sharing options...
naru Posted October 16, 2012 Share Posted October 16, 2012 (edited) I did a compression test not to long ago and all cylinders produced similar pressure. I have a boost gauge attached and does not seem to flutter. Are you suggesting creating a vacuum in the lines? The car starts up right away, but misses badly. It definitely seems to be running rich and I have noticed a decrease in my mileage. I'm not too familiar with the wiring issue you mention. What should my o2 voltage be? No.just tee a temporary gauge in to read the vacuum. How much vacuum does your boost gauge read at idle? Check the coolant temperature sender and its connection.They like to corrode. See if you can isolate the miss by removing plug or injector wires one at a time. The wiring thing is specific to XTs,I think.You`ll have to search for that one. O2 sensor voltage should oscillate above and below 0.5volts when warm.Use a digital meter. What happens if you unplug the MAF? I would inspect spark plugs/wires. Edited October 16, 2012 by naru Link to comment Share on other sites More sharing options...
87.5ea82txt Posted October 16, 2012 Author Share Posted October 16, 2012 I disconnected the boost gauge yesterday to rule out a leak from that, and I broke the thin plastic line from it being old and hard. I believe it was at around -3psi....I think. Would less vacuum indicate a leak? I have new plugs that I will put in here as soon as the engine cools down. It did seem like it was just one cylinder that was missing, but wasn't very apparent until I put it in gear and started driving first thing in the morning, then it would start firing once it got warm enough to move the temperature gauge. Once warm, it runs fairly smooth on/off boost while I run though the gears, but lacks power and tends to stumble when cruising at 30mph around 2200rpms. The plug wires are old, but still look ok. I'm going to order some anyways. After I put the plugs in, Ill disconect the wires from the maf and see if that changes anything. If I disconect the maf from the intake pipe it will just die. Link to comment Share on other sites More sharing options...
naru Posted October 17, 2012 Share Posted October 17, 2012 By my reckoning,-3 psi = about 6 inches hg of vacuum. Normal is in the 15-20 range. Reading will be affected by misfire for ANY reason,but,this indicates a vacuum leak to me,if the reading is accurate. Link to comment Share on other sites More sharing options...
87.5ea82txt Posted October 18, 2012 Author Share Posted October 18, 2012 Ok I think I found the problem! I removed the rubber intake pipe that goes between the maf and the turbo inlet and discovered a large crack around where it clamps to the turbo. I've kind of been wanting to replace it with a shorter pipe to make room for the air filter so I remove the 90° elbow I have between the filter and the maf. The only issue I see is going to be able to make the ports for the three small hoses that connect to it in various places. Do you know how I should go about doing this? Link to comment Share on other sites More sharing options...
87.5ea82txt Posted October 18, 2012 Author Share Posted October 18, 2012 I cut some material away on the end of the hose and used a dremel to smooth out the inside so I could slide the hose a little further down on the turbo inlet. I also used a hose clamp instead of the wire one so I could get a wider grip on the hose to help keep it sealed. I guess it will have to do for now... I fired it up and it runs much better now, but still has a slight miss only noticeable at idle. Link to comment Share on other sites More sharing options...
87.5ea82txt Posted October 19, 2012 Author Share Posted October 19, 2012 I also haven't replaced the pcv valve or cleaned the egr valve. Would that have a noticeable impact on performance? Link to comment Share on other sites More sharing options...
AKghandi Posted October 20, 2012 Share Posted October 20, 2012 (edited) i had the same problem with my ea82t the intake pipe was cracked and leaking so it would slowly idle down and down until it would just stall. then i bought a new pipe (newish) put it on sealed it with rtv just to be sure and bought t clamps...then about 2 days later it started again but this time it was my maf that was bad..but alls well and she purrs like a kitten, i hope you can figure yours out.(mine still stumbles a little until the boost kicks in.. i thinks its just the nature of the beast. try some seafoam it might help a little. also if making a new intake pipe is too hard you can move the maf between the IC and TB it will get more accurate readings and wont cause any more problems. Edited October 20, 2012 by AKghandi Link to comment Share on other sites More sharing options...
87.5ea82txt Posted October 20, 2012 Author Share Posted October 20, 2012 I've seen people put the maf right before the throttle body. I've read that the added volume between the two from an intercooler can cause issues with throttle response, but wasn't sure if going from a cool vacuum to hot pressure would have a negative effect on the maf's readings or longevity. I have a thunderbird intercooler connected directly to the turbo and about two feet of 3" piping from its outlet to the throttle body, so it's not a huge volume of air. I did a search for custom intake piping and found a site that had these adapters that you could drill a hole in the side of a pipe and insert a rubber grommet and your barb adapter into it to connect various sized vacuum lines. I'll have to measure the maf and turbo inlet, but I believe the maf is 3" and the turbo 2.25, so I may get a 3" elbow with a 6" leg and use a reducer hose to connect to the turbo. Link to comment Share on other sites More sharing options...
AKghandi Posted October 20, 2012 Share Posted October 20, 2012 im not an expert on the mechanics of the fuel control system, but i do know with the maf right in front of the TB the ECM would be getting a more accurate reading. and when its there the maf wont be sucking in cold air making the ecm think the motor is getting cool air. so the a/f ratio would be better. and from my expirience when its really cold outside the maf gets over worked trying to keep the wire hot. when it was -40 here my maf went all kinds of crazy. heres a thread on it http://www.ultimatesubaru.org/forum/showthread.php?t=64741 Link to comment Share on other sites More sharing options...
87.5ea82txt Posted October 21, 2012 Author Share Posted October 21, 2012 Ah, thanks for the link. Seems to be more reasons to do it than to not. Only thing is, I'll need to figure out where to incorporate a blow off valve. I saw a 2.5" adapter pipe, but it would be silly to have all kinds of different pipe sizes. Maybe I could just weld it to the steel pipe that I'm using now. Link to comment Share on other sites More sharing options...
87.5ea82txt Posted October 22, 2012 Author Share Posted October 22, 2012 This is kind of what I'm working with at the moment. Link to comment Share on other sites More sharing options...
sikend667 Posted October 26, 2012 Share Posted October 26, 2012 sertain BOVs like the turboxs one that i have come with a weld on bung in the box i didnt use mine as im running a WRX intercooler but they are easy to install with a hole saw and a welder Link to comment Share on other sites More sharing options...
87.5ea82txt Posted November 15, 2012 Author Share Posted November 15, 2012 There is a line on the intake that connects to the valve cover. Could I just put a small filter on the valve cover or will it effect performance if it is not connected to intake? Link to comment Share on other sites More sharing options...
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