gathermewool Posted May 20, 2009 Share Posted May 20, 2009 This has pretty much been the issue since I bought the car 18 months ago. The exhaust smells pretty strongly of fuel (mostly when cold) I also have the infamous P0400 EGR Flow Malfunction code. The EGR system works perfectly, but I've heard from some people that this code can be an indicator that the cats are starting to plug up. Any thoughts? Car runs pretty well and starts every single time no issues. '15 FB25 Magnatec 0W-20 + FU filter (70,517 miles) RSB, Fr. Strut Bar, Tint, STI BBS, LED er'where Link to comment Share on other sites More sharing options...
Platinum_Racing Posted May 20, 2009 Share Posted May 20, 2009 It's either the cats, or there really is a problem with the EGR system... I'd give the EGR system a thorough once over, even if you think it's okay. Other than that, I'm sure you know the drill..... Spark plugs and wires. Link to comment Share on other sites More sharing options...
gathermewool Posted May 20, 2009 Author Share Posted May 20, 2009 EGR system has gotten the dozen-over It works as well as any human being can determine Plugs and wires are all < 30k old. I believe the plugs are platinum, but I could be wrong. I'll pull them some time next week if I get the chance : ) '15 FB25 Magnatec 0W-20 + FU filter (70,517 miles) RSB, Fr. Strut Bar, Tint, STI BBS, LED er'where Link to comment Share on other sites More sharing options...
Platinum_Racing Posted May 20, 2009 Share Posted May 20, 2009 Hmmm.... It's kinda hard to tell if a cat is clogged. The best way to check it out is to take it out and see if the engine runs better. Does it hesitate at all? It's too bad it's against the law to buy a used cat at a junkyard.... Fortunatly not all junkyards care about this law... I'd check a couple and play ignorant... Just ask if they have any catalytic converters for your car. If they say they can't do it, try telling them you're just use it to see if your catalytic converter is clogged. If they say no you're probably just gonna have to stick your neck out there and buy a new cat. Like I said, there really is no way to check a clogged cat except seeing how the car runs without it, but in your case the car seems to run fine, so you're kinda in a bind. Maybe check the MAF/TPS/O2 sensors and see if they need good cleaning/replacing... It's worth a go before you go spending copious amounts of money. Link to comment Share on other sites More sharing options...
gathermewool Posted May 20, 2009 Author Share Posted May 20, 2009 There is a hesitation from time to time when I first get on the accelerator. Also seems like it runs better when it's fully warmed up (meaning she's been driven 10+ miles.) I just chalked (is the saying chocked or chalked???) it up to the 195k miles and comparing it to my sti... I may pull the plugs first, and if they seem fine or replacing doesn't seem to do anything I'll see what I can do about the cats. It seems like new cats will cost many hundreds of dollars. : ( I'm up for inspection this November, and if this P0400 code IS being caused by high exhaust gas back pressure, then what that certain some one told me is correct and the only real fix would be to replace the cats : ( '15 FB25 Magnatec 0W-20 + FU filter (70,517 miles) RSB, Fr. Strut Bar, Tint, STI BBS, LED er'where Link to comment Share on other sites More sharing options...
gathermewool Posted May 20, 2009 Author Share Posted May 20, 2009 Hey, maybe I'll just Seafoam fog the hell out of it and see if that helps things out at all haha! '15 FB25 Magnatec 0W-20 + FU filter (70,517 miles) RSB, Fr. Strut Bar, Tint, STI BBS, LED er'where Link to comment Share on other sites More sharing options...
Platinum_Racing Posted May 20, 2009 Share Posted May 20, 2009 Seafoam works best in the gas, but in the oil/vacuum lines it's been known to cause problems, or make existing ones worse. For example, if you've got worn piston rings, and you use the Seafoam in the oil technique to fix it, whatever piston rings you had left before the Seafoam is most defiantly gone after the Seafoam. Someone else tried it in the vacuum lines and had all kinds of problems getting it to run right afterwards. Try taking a temp sensor (If you can find one) and see if the tempurature is considerably lower on the output of the cat compared to the input. This might work, but then again it might not unless you have an exhaust leak somewhere before the cats. Link to comment Share on other sites More sharing options...
gathermewool Posted May 20, 2009 Author Share Posted May 20, 2009 I was only 1/6 serious. While I'm not sure about about sucking some in through a vacuum line, i would most definitely not put a freaking solvent in the oil for any period of time : / I think I'll grab my buddies laser temp indicator to compare the cat upstream/downstream temps. '15 FB25 Magnatec 0W-20 + FU filter (70,517 miles) RSB, Fr. Strut Bar, Tint, STI BBS, LED er'where Link to comment Share on other sites More sharing options...
gathermewool Posted July 25, 2009 Author Share Posted July 25, 2009 A couple of weeks after posting I started to get random cold misfires P0302 Cyl #2 misfire with A LOT of hesitation. Car still runs great when up to temp. For reference, #2 is the cylinder closest to the driver-side head light. I changed out the spark plugs and wires two weeks ago. The misfires have gone away, but the cold hesitation is still there, albeit not as bad. The coil resistance was just above spec at .8 ohm or so. Also, the P0400 code has been solid since then, no change. I checked all of the vacuum lines I replaced last year, and some were starting to degrade so I replaced with fuel line, which seems a lot more resilient. One of the smaller portions - the small bit that goes from the back pressure Xducer to the exhaust side of the EGR valve - wasn't replaced before, and was rock-hard. The EGR system still seems to work perfectly, but the code came back with in a few starting cycles after clearing the code with the scangauge. So far, it seems that the code comes back on my way to work when the engine has not fully warmed up. With emissions coming up I'm going to try a little experiment. Since the hesitation goes away when the engine is fully warmed up I'm going to allow the car to idle until it reaches op. temp. before driving to see if this changes anything. I did this this morning after clearing the code, but only started and stopped the car at temp twice - not enough to go through all of the emissions checks. I'm not sure what will be proven if the P0400 code stays away if I only drive the car at temp., but I think it'll be interesting to see. Any further input or suggestions would be great! '15 FB25 Magnatec 0W-20 + FU filter (70,517 miles) RSB, Fr. Strut Bar, Tint, STI BBS, LED er'where Link to comment Share on other sites More sharing options...
oncesir Posted August 3, 2009 Share Posted August 3, 2009 What have you done to remedy the p0400? Usually that code indicates carbon buildup in the EGR passages. Have you cleaned these passages? http://endwrench.com/images/pdfs/Emissions.pdf http://forums.nasioc.com/forums/showthread.php?t=1453414 Link to comment Share on other sites More sharing options...
gathermewool Posted August 3, 2009 Author Share Posted August 3, 2009 When I first started trouble shooting the sporadic P0400 code I noticed that the system seemed to work just fine, but the engine would only slightly bog down when I opened the EGR valve at idle. Starting here, I started my journey toward remedying this problem as cheaply as possible All vacuum hoses have been replaced. The MAP filter has been replaced. The EGR valve was cleaned and a vacuum pump used to verify proper operation. The EGR line was replaced since it was leaky (afer my high temp RTV quick-fix failed ). The engine almost stalls when the EGR valve is operated at idle. The EGR valve operates when the throttle is opened, and only when the engine is up to temp. The system works as far as I can tell. The only other thing I can think of is that the cats might be on their way out. While not being bad enough to throw a cat inefficiency code, they may be causing just enough excess back pressure to cause the malfunction code. The code was actually sporadic UNTIL I cleaned everything and made sure the system worked properly. Afterward, the code remained on steady, and will return almost immediately when I clear it. IRRC, there are two codes associated with the EGR system are 'EGR Low Flow' and 'EGR Flow Malfunction.' It seems as if the P0400 Flow Malfunction code is much more prevalent, and maybe the other (can't recall the CEL P0XXX, sorry) isn't even applicable to our cars. : / '15 FB25 Magnatec 0W-20 + FU filter (70,517 miles) RSB, Fr. Strut Bar, Tint, STI BBS, LED er'where Link to comment Share on other sites More sharing options...
blackfang Posted August 4, 2009 Share Posted August 4, 2009 If cat is clogged, you would get a different code altogether, like say a p0420. The p0400 codes are a pita to diagnose. Sometimes the system just needs to be de-carboned and cleaned very well. Sometimes it needs a EGR, EGR solenoid and a cleaning. Why would you recommend changing spark plugs and wires to address a p0400 code except to throw parts at it? [SIZE=1][URL="http://public.fotki.com/blackfang/"]Pics[/URL] [B]08 KawasakiZZR 600- exhaust and other mods 98 Camaro Z/28 HT- some mods......street/strip car 07 Legacy 2.5i- SPT exhaust...daily driver[/B][/SIZE] Link to comment Share on other sites More sharing options...
gathermewool Posted August 4, 2009 Author Share Posted August 4, 2009 I never recommended changing plugs and wires. I changed out my plugs and wires because they were 30kmi old and the stumbling issue was getting worse and resulted in a P0302 #2 misfire code. Also, the rear O2 sensor might be a little lazy, and the cats just good enough to prevent throwing the P0420 code. EGR low flow obviously causes a CEL, but I haven't had any one tell me one way or the other what too much flow or a change in back pressure, which feeds the BPT, might do. I need to get this cleared by Nov. for emissions, and with out throwing parts at it. Again, everything is clean, and the vacuum hoses are good to go. All of the tests in my Haynes Manual passed, and the system works perfectly according to my untrained eye ; ) '15 FB25 Magnatec 0W-20 + FU filter (70,517 miles) RSB, Fr. Strut Bar, Tint, STI BBS, LED er'where Link to comment Share on other sites More sharing options...
blackfang Posted August 4, 2009 Share Posted August 4, 2009 I wasn't referring to you. Also look into the A/F sensor in causing p0420 codes as well. They can be lazy in correlation with the rear o2. Yes, EGR flow or lack of it can cause the P0400 DTC. [SIZE=1][URL="http://public.fotki.com/blackfang/"]Pics[/URL] [B]08 KawasakiZZR 600- exhaust and other mods 98 Camaro Z/28 HT- some mods......street/strip car 07 Legacy 2.5i- SPT exhaust...daily driver[/B][/SIZE] Link to comment Share on other sites More sharing options...
Platinum_Racing Posted August 5, 2009 Share Posted August 5, 2009 As far as the plugs and wires are concerned... I was just trying to see if the plugs were fouled causing the fuel smell at the exhaust. I'm not too familiar with OBDII trouble codes in the least... I've only owned 1 OBDII compliant vehicle. My bad. Link to comment Share on other sites More sharing options...
gathermewool Posted August 5, 2009 Author Share Posted August 5, 2009 plugs were fine. I didn't check the gap, but it was much larger than what I replaced them with. '15 FB25 Magnatec 0W-20 + FU filter (70,517 miles) RSB, Fr. Strut Bar, Tint, STI BBS, LED er'where Link to comment Share on other sites More sharing options...
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