Boxman Posted September 24, 2013 Report Share Posted September 24, 2013 I've spent about a month on this now, and it's time to call for your help. It started with my car experiencing a loss of power, occasional stuttering, and progressively harder to start when the engine is cold. Fuel mileage is in the gutter, I'm struggling to make >400km on a full tank. It's horrible. At first I thought it was running rich, due to the bad mileag. I checked a lot of things (list will follow) an I can't figure it out at all. I then installed a wideband O2 sensor with AFR gauge (Innovate MTX-L) to see what was actually going on (also I suspected the old O2 sensor), and to my surprise, it's telling me it's running VERY LEAN. I'm talking about AFR over 19 when accelerating mildly, and ~17 @ 120km/h. It also takes me at least 10 cranks to start the engine cold, and it seems to be getting worse. The Lambda light will come on a few hours after a fresh reset. So here are the symptoms: - Extreme lack of power - Sputtering on WOT, runs very bad, AFR >19 during WOT - Idle AFR 15.5 - Cruising AFR 120km/h 17 - Cold start very hard (17 C ambient temperature), >10 cranks and sputtering during startup And this is what I have replaced: - New HT leads - New distributor cap - New rotor - New spark plugs - New O2 sensor (wideband, sending narrowband signal to ECU) - New air filter - New turbo hoses (silicone) I also replaced the following parts with second hand parst: - T5 MAF sensor - Throttle position sensor - Fuel pressure thingy under the injector array - All 5 injectors Also, this summer, I installed a Walbro 255 fuel pump and a new fuel filter. I replaced most of the vacuum lines I could reach I checked the intake hose for leaks, and taped the oil vapor heater thing on there air tight with ducttape I measured the signal the AFR gauge is sending to the ECU, and it's perfect narrowband signal (1.1v if 14.7) If I disconnect both the TPS and Idle regulator, it'll run idle at exactly 14.7 AFR, at an elevated RPM. Seems to me like the engine regulates itself then. Doesn't solve any problems under load though. And now I'm about out of ideas. What are the main causes for running lean on a T5? What have I missed? Link to comment Share on other sites More sharing options...
Keaton85 Posted September 24, 2013 Report Share Posted September 24, 2013 Have you replaced the temp sensor yet? That would cause issues with starting. It's also an item that should be replaced anyway due to age. Link to comment Share on other sites More sharing options...
Boxman Posted September 24, 2013 Author Report Share Posted September 24, 2013 My coolant temp sensor? Would that make it run lean? My dash gives normal readouts, dead horizontal or a little bit below. Sure a lot of stuff can be replaced anyway due to age but I want to nail this problem in particular. Also my fan turns on when I'm at idle standing still, so it seems to be working correctly. Link to comment Share on other sites More sharing options...
Boxman Posted September 25, 2013 Author Report Share Posted September 25, 2013 Nope? Nobody? Too little information or have I discovered an entirely new problem? Link to comment Share on other sites More sharing options...
Fudge_Brownie Posted September 25, 2013 Report Share Posted September 25, 2013 And now I'm about out of ideas. What are the main causes for running lean on a T5? What have I missed?I'd say the popular cause is vacuum leak.I think someone once had a very difficult to find vacuum leak that turned out to be a very fine crack in their air intake pipe. The part that joins the MAF housing to the turbo inlet.Has the intake manifold or throttle body been off in the past maybe 3 months? Maybe a gasket is pinched, allowing some air in? Link to comment Share on other sites More sharing options...
Volvometer Posted September 25, 2013 Report Share Posted September 25, 2013 man, check for vacuum leaks, evap solenoid partially open, skewed maf...get a voltmeter, power probe, a few safety pins, vacuum pump, brake cleaner and you can solve the problem... Link to comment Share on other sites More sharing options...
Boxman Posted September 25, 2013 Author Report Share Posted September 25, 2013 I have had the manifold off a few months ago to do the PCV system including the thingy on my intake tube that was clogged. Where can i find the evap solenoid? Will check for vacuum leaks tomorrow. Link to comment Share on other sites More sharing options...
Fudge_Brownie Posted September 25, 2013 Report Share Posted September 25, 2013 You can spray starter fluid around the intake manifold gasket and listen for a change in engine pitch.But I'm going to bet this is going to be something less complex like an overlooked lose fitting or disconnected hose. The EVAP solenoid is almost behind the driver's side headlight. It sits in a rubber holder attached to the radiator fan shroud.I just described another common spot here the other day : Link to comment Share on other sites More sharing options...
Boxman Posted September 25, 2013 Author Report Share Posted September 25, 2013 Great stuff, thanks. Makes me a bit more hopeful for tomorrow. Link to comment Share on other sites More sharing options...
BoostedMoose517 Posted September 26, 2013 Report Share Posted September 26, 2013 Also my 850 T5 had a very lean issue and very hard starting and with him stating he did the fuel pump... Check the rubber hose that comes from the pump to the Pump assembly unit, Mine was swelled and coming off the pump and not getting enough fuel pressure. IF you dont find any vacuum leaks Link to comment Share on other sites More sharing options...
Boxman Posted September 26, 2013 Author Report Share Posted September 26, 2013 Well, I checked compression, vacuum leaks and fuel pressure - compression was fine, 162-170psi on all cylinders. No vacuum leaks. And then: yep. Half the fuel pressure, and instantly no pressure when car goes off. Checked the pump, and oh boy the damn hose did come off, it was only barely making contact and therefore unable to build up pressure. I re-tightened the hose and clamped it as tight as I could this time. Thanks for all the suggestions, my engine is now in tip-top state again, AFR 12 under WOT (i finally have my powah back) and 14 while cruising and idle (should it be 14 or 14.7?) Link to comment Share on other sites More sharing options...
Martijn_B Posted September 26, 2013 Report Share Posted September 26, 2013 14.7, but it Will be in open loop so between 14.3-15.2 oid Link to comment Share on other sites More sharing options...
BoostedMoose517 Posted September 26, 2013 Report Share Posted September 26, 2013 Pretty sure Idle and cruise conditions are Closed Loop while mild accel and WOT are Open loop. IIRC Link to comment Share on other sites More sharing options...
Boxman Posted September 26, 2013 Author Report Share Posted September 26, 2013 Hm, so under idle and cruise it should trim to 14.7? Maybe I should lookup the exact characteristics of the original O2 sensor, and program the wideband to that exact profile. Link to comment Share on other sites More sharing options...
Martijn_B Posted September 26, 2013 Report Share Posted September 26, 2013 I might have messed up with open/closed loop. Dont you have the innovate wideband? Might want to re-calibrate it, to be 200% sure. Mine is weird..sometimes.. Link to comment Share on other sites More sharing options...
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