On Board Diagnostics Codes

would need to scan car with diagnostics tool to be able to start with it, as what ever fault code you find you still need to do live data scans and maybe picoscope it see wave forms for parts etc or even multi meter and check resistances for components as well, best and cheapest scan tool and proper dealer level is autocom cdp plus works very well on mine pre 2014 bit more limited after this date as bmw have like other car makers put diagnostics behind a cloud and inter based etc to keep people from repairing them,,

benito_s6 said:

So just scanned and only fault code is a misfire on cylinder 4 (P0304). Have also reset ECU and self diagnosis codes are still there. Thanks for the recommendations on scanners. Will see if the engine light comes on again later in week on way to work as that’s when I can drive the car hard.

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there were stories of valve springs going soft on gen 1 tritec engines and causes a misfire codes only and a 02 sensor plausibility or lean or rich run running when really pushed as unburnt fuel air would would leak in to exhaust manifold on compression strokes.. think at this point i would do a leak down test maybe pull the inlet and exhaust manifolds off and spray wd40 on rears of valves while charging the plug hole with compressed air. as for buying £800 diagnostics tool when i promise you that under £50 is bang on the level that is on most cars,, i work on cars 6 to 7 days a week and just wont pay the min £3k needed for a scan tool that covers everything on every level on all cars,, autel do a pro range starts off around £2k goes as high as £25k fine for a garage that charges people £200 per scan will pay for its self not so good for someone who owns a car that has a fault,, bare in mind that autocom will do same as a £800 scanner in most cases,

SurreyPete said:

I almost went with the Autel MK808 before I got my iCarsoft but the update fees of about £120 a year to keep it current ruled it out for me, like you say if your using it everyday or don’t mind outdated software then great, but for me was too much

I find it’s good to have one that covers a broad range of makes and models, even though you may have a Mini, you may want to get something else or know someone who wants to buy a car and asks you to tag along, once you have one you will use it, I have another OBD2 reader made by Sealey that also has a voltmeter and oscilloscope built in, very useful

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that autocom wil code inceptors and keys on some stuff abs pump on most things to 2011 can all so program bcm on some stuff i got access to snap diagnostic latest tools at work and most of time my £50 autocom sorts what i need sorting, i also have a lot 1 brand only full function stuff for when need something thats dealership only,, car makers are doing their damned to stop anyone repairing their products by code and need of dealer level gear ford and volvo were one of the first to put it in the cloud so cant be used unless are a registered paying dealer and not cheap per month and registered approved garages only
Sealy gear is pretty good for the money , my picoscope just under £800 without it its near impossible to pin point faults with a 100% it that at fault,, even scope on cps sensors can tell if chain stretched out of time ie read one thats just had a chain done then save the scope on it for ref point,

mike1967 said:

there were stories of valve springs going soft on gen 1 tritec engines and causes a misfire codes only and a 02 sensor plausibility or lean or rich run running when really pushed as unburnt fuel air would would leak in to exhaust manifold on compression strokes.. think at this point i would do a leak down test maybe pull the inlet and exhaust manifolds off and spray wd40 on rears of valves while charging the plug hole with compressed air. as for buying £800 diagnostics tool when i promise you that under £50 is bang on the level that is on most cars,, i work on cars 6 to 7 days a week and just wont pay the min £3k needed for a scan tool that covers everything on every level on all cars,, autel do a pro range starts off around £2k goes as high as £25k fine for a garage that charges people £200 per scan will pay for its self not so good for someone who owns a car that has a fault,, bare in mind that autocom will do same as a £800 scanner in most cases,

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I have heard about the valve spring issue. However my problem seems very electrical based. I have noticed tonight that there’s a noticeable change in engine power and feeling right before the ASC light comes on so I can actually call when the car will go into limp mode. Right as that happens the misfire starts. Then turn off and back on. Misfire gone, runs perfect again, all be it with the engine light still on, until the same thing happens again. It might happen once, not happen or happen 4/5 times in as many minutes like tonight. Valve springs wouldn’t be fixed with a cycle of the key. I could do with a live data reading to look at when driving so I could see any changes when the misfire starts. Edit: I have now found out that the ASC light comes on with the misfire due to power loss so perhaps it isn’t limp mode at all and just a huge power loss with the misfire. Most of the time it’s just the engine light on and running fine.

So basically all I’m trying to diagnose now is why the misfire is occurring. I am pretty sure it is more down to a sensor issue. So will be cleaning MAP sensor tomorrow and checking coil packs and stuff. Also forgot to mention it has had fresh oil, filter, spark plugs and air filter right before I bought it. May check injectors and even run some cleaner. Have also read someone say they’re serpentine belt snapped not long after this issue. Well mine is squealing so needs changing anyway. So looking at: Sensors, Injectors, Plugs, Leads, Belt, Fuel Pump/Filter, Coil/Distributor. Thanks for the replies so far will keep you updated.

Just an update. Intermittent misfire had gotten really bad last few days. Having to restart about 10 times in a mile to keep clearing it. Having been told by the seller when I bought it last week that the car had had new spark plugs, oil, oil filter and air filter, when I saw the oil and air filter were brand new I believed him. I work long hours so haven’t had the chance to check when getting home late but removed the plugs last night and what a mess. Earth straps missing and corrosion on two. Ironically the best looking one was the one that was misfiring. It’s a wonder it was running at all. 4 Bosch super 4s later and it’s running perfect again. Just goes to show, check the basics before doing extensive diagnostics that are most of the time unnecessary. Thanks for your help, so glad it’s such a simple fix and can’t believe I didn’t check these. Never believe everything when buying a used car!