Shifty Posted May 20, 2016 Share Posted May 20, 2016 Howdy peeps. Got a bit of a problem in that my motor failed its MOT on very high CO levels but everything else was within limits. Managed to bribe the mot man to shove his probe up another tailpipe in order to get a ticket but I need to sort this out as he says it will kill eventually kill my cats. Have tested the fuel pressure regulator and pump are working as expected and there are no leaks via a dribbling injector (pressure steady after 20 mins standing) so the fuel system is sound. When using SSM to have a look at fuel trims I see a very high long term fuel trim 18+ and sometimes an even higher short term fuel trim. Strange thing is no error codes other than the odd (every two months or so) P0420 which is because of the high CO levels. I have no vac leaks and both O2 sensors have been tested and are working fine. Any ideas as to what I need to look at? I am struggling to understand why only the CO readings are high. All suggestions gratefully accepted. Cheers Shifty Quote Link to comment Share on other sites More sharing options...
Buggyeye Posted May 20, 2016 Share Posted May 20, 2016 Burning oil maybe? Could be wrong can't remember but it rings a bell Quote Link to comment Share on other sites More sharing options...
stants Posted May 20, 2016 Share Posted May 20, 2016 Cats could already be dead and working below efficency ? Sent from my SM-G930F using Tapatalk Quote Link to comment Share on other sites More sharing options...
Scoobyghost Posted May 20, 2016 Share Posted May 20, 2016 Been decatted? Quote Link to comment Share on other sites More sharing options...
Greenmamba Posted May 20, 2016 Share Posted May 20, 2016 When were the plugs changed/gapped correctly? Quote Link to comment Share on other sites More sharing options...
Shifty Posted May 21, 2016 Author Share Posted May 21, 2016 Engine does not burn oil and I never have to top it up between changes at 4k miles. Plugs were new just under a year ago as were the leads. Sparks are good and healthy. No apparent vac leaks. The cats were also new just last year when I had the stainless exhaust made by longlife. I'm worried that the rich fuelling may have killed the new cats but I've not had any error codes logged. As best I can tell the O2 sensors are both working as expected as are the MAF MAP IAT and ECT sensors. If I unplug each sensor while the engine is ticking over I get instant response on each one so I am sure the wiring is ok and the ecu is reacting to each one when disconnected. Each sensor throws an error code when disconnected so I am pretty sure they are all within spec and working. Fuel pressure is 1psi at idle above what Haynes says but that may be my cheapo fuel pressure gauge. Pressure tops out at about 45psi at WOT but its hard to read the gauge whilst swerving round buses and pedestrians. System also holds 35psi pressure overnight so no dribbling injectors or other leaks. I blew compressed air through the fuel return and can hear it bubbling in the tank so it is not blocked. If I pinch the return line the pressure climbs to over 60 psi then drops to 35psi at idle when un-clamped. Is there a check valve in the return line as it needs about 10psi to blow bubbles in the tank? I was thinking it should be completely open? There must be something causing the black soot in my tailpipes and very high CO readings but all other emissions are within MOT levels so I'm sure the cats are doing their best. Cheers for the suggestions keep them coming. The only other alternative is to book it in for an hour diagnostic session to point me in the right direction but I hate spending money for somebody else to find something I could have. Of course if it needs specialist equipment to find the problem I dont get so upset. Quote Link to comment Share on other sites More sharing options...
savage bulldogs Posted May 22, 2016 Share Posted May 22, 2016 Is the Air filter in good nick and not restricting air flow ? Fuel purge system ,charcoal filter and vac lines in good order ? Would a ecu reset bring the trim back to factory? If it's not broke .....upgrade it 😊 Quote Link to comment Share on other sites More sharing options...
Shifty Posted May 22, 2016 Author Share Posted May 22, 2016 Air filter is new genuine Subaru item. Fuel purge line disconnected and vac line plugged to make sure it was not that or the charcoal canister feeding vapour into the mix. Would have expected negative trims if that was the case though. ECU reset to clear learned trims and readiness states just sends short term trims high until the learned trims stick and kick in. My understanding is that positive fuel trims (which I have) is the ECU trying to correct a perceived LEAN condition as signaled by the upstream O2 sensor? Upstream sensor shows classic toggling between rich/lean as expected but no indication of steady rich or lean condition. I get the same readings on both the new and old O2 sensors so pretty sure they are reading accurately. Lean as far as I know is either not enough fuel or too much air. MAF was replaced but reads virtually the same as the old one. However my downstream O2 indicates a mainly RICH condition, and my sooty exhaust tends to confirm this, as do the the high CO readings which I would have expected to see negative fuel trims to try and lean the mixture. I may just have to bite the bullet and get it plugged in at Subaru to find out whats wrong. Bummer. Thanks for the suggestions. Quote Link to comment Share on other sites More sharing options...
stants Posted May 22, 2016 Share Posted May 22, 2016 If the pre cat sensor shows lean, and the downstream one shows rich would that point to the cat being knackered, have you tried swapping the sensors between locations and seeing what readings you get ? Sent from my SM-G930F using Tapatalk Quote Link to comment Share on other sites More sharing options...
savage bulldogs Posted May 22, 2016 Share Posted May 22, 2016 If it's a standard car on a standard map I'd have thought it would be a mechanical issue causing the trim . Ie failing cat ,blowing upipe or manifold ,air leak (maybe just under boost ) ect . As they Might cause parameters between sensors to conflict ,add fuel and !Removed! timing. I've never had the equipment to read the esl or current apexi, so don't know much about codes but i think my esl'd ecu used to pick up noise from my forged pistons and add fuel to the map as it thought it was exessive knock .So could it be a minor intermittent issue that's not logged a code ? Has the tps posibily been disturbed ? as this would give incorrect readings for throttle positions to the ecu . Maybe a dyno would help to pin point it ? If it's not broke .....upgrade it 😊 1 Quote Link to comment Share on other sites More sharing options...
Shifty Posted May 26, 2016 Author Share Posted May 26, 2016 As far as I know its a standard map. Not had any work done on it so not likely the TPS has moved. It reads about 7% at idle and shows full 100% deflection (with no dead spots) when operating the the pedal with ignition on but engine not running. I have got it booked in for a full diagnostics tomorrow morning so hopefully they can get to the bottom of things. Watch this space and thanks for all the input. 1 Quote Link to comment Share on other sites More sharing options...
Shifty Posted May 28, 2016 Author Share Posted May 28, 2016 So £120 lighter and still none the wiser. The Subaru techs had it for two hours and their findings are as follows: ECU map is standard and original to the vehicle as from new. Compression good on all cylinders and all within 4psi of each other. Leakdown test shows no problems. Fuel pressure and flow all within specs and ignition strong and healthy. No fuel pressure drop shown after 20mins with ignition off so no fuel system leaks or weeping injectors. All sensors responding as expected with no codes logged. All readiness codes correct at time of test. No vacuum or exhaust leaks. Vehicle fails on fast idle with HC 24ppm, lambda 0.979, and CO 0.78% (limit 0.2%). No trace of fuel in the oil and vehicle serviced with new plugs, filters, oil. Evap canister not contaminated and purge system working as expected but disconnected for the above tests. Tech suspects that the stainless exhaust system is not creating enough back pressure so the exhaust gasses are flowing through the cats to quickly and not allowing them to fully convert the CO into CO2? Confirms there is some cat activity as the HC readings are low. Not sure if this is possible? However I still suspect that the ECU is running the engine rich for some reason. Apparently the Subaru tech says the ECU does use the downstream O2 sensor to adjust fuel trims as well as the upstream one which may tie in with an exhaust flow problem? Geting a tad frustrated with this now. I have gone back to the exhaust manufacturer with the report findings to see what they come back with. Not expecting them to accept it is the exhaust at fault but lets wait and see. Quote Link to comment Share on other sites More sharing options...
savage bulldogs Posted May 29, 2016 Share Posted May 29, 2016 What about a dyno run? As this might show where in the Rev range the afr is getting richer and detect any exessive knock or detonation. At least it might give you peace of mind to know whether the engine is slowly eating itself due to bore wash or leaning off . If it's not broke .....upgrade it 😊 Quote Link to comment Share on other sites More sharing options...
Shifty Posted May 30, 2016 Author Share Posted May 30, 2016 I guess thats the last option I have but dont know anyone local that could do a proper dyno run and diagnostics. Starting to spend too much money now so its days may be numbered unless I get to the bottom of it quickly. Quote Link to comment Share on other sites More sharing options...
savage bulldogs Posted May 30, 2016 Share Posted May 30, 2016 Where about are you ? As someone might know a reputable 4wd dyno nearby. or just get a sports/ de cat and a remap If it's not broke .....upgrade it 😊 Quote Link to comment Share on other sites More sharing options...
Shifty Posted June 1, 2016 Author Share Posted June 1, 2016 I am in the Woking Surrey area. How does a sports decat get through an mot? I'm thinking of going back to standard Subaru cats with a stainless cat back system if I can get the company that made the current exhaust to cough for some of the cost. Especially as Subaru reckon the current exhaust is causing the problem and not fit for purpose. Waiting to hear back from the exhaust company as we speak. The other alternative is to chop it in against another Scoob. The dealer had a lovely WRX on the forecourt for £18k but my old lady dont like the colour. Quote Link to comment Share on other sites More sharing options...
savage bulldogs Posted June 1, 2016 Share Posted June 1, 2016 The remap would probably correct the fuelling to get it to pass the mot and replacing the (possibly failing ) cat for a sports cat would rule out the cat as the cause .It would also flow better to get more gains from the remap. Mine passes the co2 emissions without a cat as it's mapped correctly off boost . Simon from jgm used to map a lot at "Surrey rolling road" I'm not sure how close they are to you but I'd imagine they've got a bit of experience with scoobs and might be able to point you in the right direction. If it's not broke .....upgrade it 😊 Quote Link to comment Share on other sites More sharing options...
Shifty Posted June 3, 2016 Author Share Posted June 3, 2016 Exhaust company who made the full stainless system and cats are going to give me the cost of the cats back and them modify my exhaust to a cat back system. I have to spring for the OEM Subaru cats but its the best deal I could get out of them. Hopefully that will sort the problem. Quote Link to comment Share on other sites More sharing options...
Shifty Posted November 25, 2016 Author Share Posted November 25, 2016 Howdy peeps. Thought you might like to know the resolution to this issue. After the exhaust company changed out the cats for two new ones the emissions problem still persisted. The exhaust bloke said it must be engine related so as I was sure there was not an underlying engine problem I took a chance and sprung for some OEM Subaru cats. The exhaust bloke fitted the OEM cats and modified the exhaust as a cat back system and guess what? The emissions are now bang on the money proving both sets of cats he supplied were as much use as a chocolate teapot. He has refused point blank to refund the purchase price of the original cats stating that all the extra work he has done was not charged for so we are quits. He seems to forget the extra work and expense would not have been necessary if his cats had worked properly in the first place. Therefore I have now lodged a claim in the courts under the Sale of Goods act as the cats were not fit for purpose. I have all the evidence needed to support the claim and due to his hard nosed attitude I will be claiming for all out of pocket expenses, loss of earnings, and associated costs such as independent Subaru diagnostics etc. The case goes to court in Feb next year and I shall enjoy taking his pants down to the princely sum of some £3000 and counting which he could have resolved for £600. Sorry for the lack of updates until now but I have been a tad busy with work and domestic trivia. 4 Quote Link to comment Share on other sites More sharing options...
Piggysniffer Posted November 26, 2016 Share Posted November 26, 2016 Good luck mate 1 Quote Link to comment Share on other sites More sharing options...
Shifty Posted December 3, 2016 Author Share Posted December 3, 2016 OK at last the saga is over. The exhaust man has contacted my solicitor with an "out of court" offer which I have now accepted. In effect he has refunded me the complete cost of the original stainless exhaust. It seems the notification of court action focused his mind. Thanks for all your input and support over the last year and I now have a motor that easily passes the MOT. I learnt a lot about how modern fuel injection systems work and also have a Subaru diagnostics report that confirms my engine is in tip top order. Now I can just enjoy driving it. Cheers 1 Quote Link to comment Share on other sites More sharing options...
savage bulldogs Posted December 3, 2016 Share Posted December 3, 2016 Always nice to hear that a issue with goods not fit for purpose has been resolved [emoji106] Just a shame that it took a solicitors letter for him to admit that the goods were at fault [emoji53] Quote Link to comment Share on other sites More sharing options...
Shifty Posted December 3, 2016 Author Share Posted December 3, 2016 I think his pride got in the way. Nothing wrong with the workmanship it was just that the supplied cats were not fit for purpose. As you said it was a shame I had to resort to lodging a court claim. Quote Link to comment Share on other sites More sharing options...
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