Omega Owners Forum
Chat Area => General Car Chat => Topic started by: TheBoy on 16 April 2013, 19:16:50
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Hope this helps those learning diagnosis and fault finding, esp as its quite an easy one. I have Webby in mind, but hopefully useful to others.
Saw a 3.0l auto this evening, report was "EML on when accelerating a bit harder than normal".
Upon starting, the car had a distinct misfire, felt like it was only running on 4 or 5. Tech2 showed no fault codes. So, we are immediately suspicious of HT, aren't we, with it being a non OBDII car ;)
Before going further, always worth a quick look at the trims, as these can give a lot of info about the car. Motronic 2.8.x have 2 trim values per bank:
Idle
Partial Load
(No need for full load, as it will be open loop)
Bank 1 idle was trimmed to the endstop on Bank 1, trying to lean it off.
So, that makes us particularly interested in the HT on Bank1 (Cyl 1/3/5), as that side is too rich, as one pot is throwing unburnt fuel towards the lamda.
We now use the function to individually disable each injector one at a time, to pinpoint the pot. Cyl 2/3/5/6 all showed a noticible decrease in revs when their injectors were disabled. Cyl 1 showed no difference, cyl 4 slight difference (remember 4 is 1's firing partner, and its wasted spark, hence the affect on 4)
So, its Cyl 1.
HT lead off, plug out, looks past its best, but OK. Look back to lead
(http://i14.photobucket.com/albums/a319/IamTheBoy/8F30C325-9E5C-4689-B930-C922E5E928BF-8111-0000020EF67CB70C_zpsebffd55f.jpg)
And that is my idea of fault finding - methodical and logical. Not what you'd get from most garages, sadly.
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Nice one ... :)
So that's using fuel trims on the 3.0 (non - OBDII) ... but you never finished answering about the fuel trims on the 3.2 ...
http://www.omegaowners.com/forum/index.php?topic=113851.60
pretty please ?? :)
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Hope this helps those learning diagnosis and fault finding, esp as its quite an easy one. I have Webby in mind, but hopefully useful to others.
Saw a 3.0l auto this evening, report was "EML on when accelerating a bit harder than normal".
Upon starting, the car had a distinct misfire, felt like it was only running on 4 or 5. Tech2 showed no fault codes. So, we are immediately suspicious of HT, aren't we, with it being a non OBDII car ;)
Before going further, always worth a quick look at the trims, as these can give a lot of info about the car. Motronic 2.8.x have 2 trim values per bank:
Idle
Partial Load
(No need for full load, as it will be open loop)
Bank 1 idle was trimmed to the endstop on Bank 1, trying to lean it off.
So, that makes us particularly interested in the HT on Bank1 (Cyl 1/3/5), as that side is too rich, as one pot is throwing unburnt fuel towards the lamda.
We now use the function to individually disable each injector one at a time, to pinpoint the pot. Cyl 3/4/5/6 all showed a noticible decrease in revs when their injectors were disabled. Cyl 1 showed no difference, cyl 2 slight difference (remember 2 is 1's firing partner, and its wasted spark, hence the affect on 2)
So, its Cyl 1.
HT lead off, plug out, looks past its best, but OK. Look back to lead
And that is my idea of fault finding - methodical and logical. Not what you'd get from most garages, sadly.
:y :y
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I love it when a plan comes together. :y
.. only, isn't cylinder 1 paired with 4 rather than 2? :-X
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I love it when a plan comes together. :y
.. only, isn't cylinder 1 paired with 4 rather than 2? :-X
Somebody was paying attention... ...that trap was set for Mr DTM, I didn't think anyone else would spot it. Smart arse
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Original post modified
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Thanks again for looking at it. I did ask her if it drove normally, she said yes ::)
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I find spraying a flammable liquid around the engine bay is good way to find a stray short on the ht side of things. Only downsides is eyebrow shortened life span and irate owners who don't share your sudden bout of hysterical giggles.
::)
OK OK I'm shutting up no need to swear under your breath while sat at your keyboard
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nice one TB. looks like a very logical way to go about it. I have a few questions re the fuel trim lol but ill ask tonight as i aint got the laptop :-)
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Right now i'm on laptop ::)
just re-read the fault finding. excellent work and I wish i'd have been so astute when diagnosing my exhaust leak ::)
anyway, when you say about switching off injectors one by one I am presuming you do this via the techII?
Also, re the fuel trims. I understand that this is where the o2 sensor, on receiving the fuel/air ratio through the exhaust, will make the mixture richer if it detects its lean, and vice versa... and that's why on the techII youll constantly see the o2 readings changing from rich / lean and back constantly.
and also, in effect, what you were doing by switching off the injectors was cutting off the supply to that cylinder... if the sound changes then you've affected the cylinder.... no change meaning it wasn't doing anything to begin with ? :y
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anyway, when you say about switching off injectors one by one I am presuming you do this via the techII?
yup
Also, re the fuel trims. I understand that this is where the o2 sensor, on receiving the fuel/air ratio through the exhaust, will make the mixture richer if it detects its lean, and vice versa... and that's why on the techII youll constantly see the o2 readings changing from rich / lean and back constantly.
yup
and also, in effect, what you were doing by switching off the injectors was cutting off the supply to that cylinder... if the sound changes then you've affected the cylinder.... no change meaning it wasn't doing anything to begin with ? :y
yup
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I'm getting there ;D :y :y :y
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I'm getting there ;D :y :y :y
You just now need your own £thousands TechII to diagnose faults from a single manufacturer ..... ::) ::)
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I'm getting there ;D :y :y :y
You just now need your own £thousands TechII to diagnose faults from a single manufacturer ..... ::) ::)
;D :)
ill just take a trip to visit semi-naked TB in his pants ::) ;D ;D
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ill just take a trip to visit semi-naked TB in his pants ::) ;D ;D
Waaaaaaaaaaaaaaaaay waaaaaaaaaaaaaaaaaaaaaay too much information!!!!! :o :o :o :o :o
To quote Jimbob ...... where's the mind bleach? !!!!!!!!! ??? ??? ??? ???
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ill just take a trip to visit semi-naked TB in his pants ::) ;D ;D
Waaaaaaaaaaaaaaaaay waaaaaaaaaaaaaaaaaaaaaay too much information!!!!! :o :o :o :o :o
To quote Jimbob ...... where's the mind bleach? !!!!!!!!! ??? ??? ??? ???
Get me a gallon too please :-X :-X
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I'm getting there ;D :y :y :y
You just now need your own £thousands TechII to diagnose faults from a single manufacturer ..... ::) ::)
The tool is irrelevent, the method/logic is what I'm trying to get over ;)
Something that is frequently lacking in the skills of many mechanics.
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I'm getting there ;D :y :y :y
You just now need your own £thousands TechII to diagnose faults from a single manufacturer ..... ::) ::)
The tool is irrelevent, the method/logic is what I'm trying to get over ;)
Something that is frequently lacking in the skills of many mechanics.
That's because they are taught to instantly diagnose the most expensive part as faulty. Well that's how TG does it when you ask him about a problem.
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Evans Halsaw in MK will have a job for him ;D
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My colleague made me laugh this morning. Turned up to work with plumes of smoke coming from under the bonnet of his Volvo. Had been to a "specialist" on the way to work complaining about terminal sounding noises. They muttered about the engine being "knackered". (they did a head gasket on the same engine about 4 months ago, but still...) ::)
5 seconds looking under the bonnet and it was obvious by what was left of the air con compressor clutch smouldering away what the problem was. ;D Engine sounded perfectly sweet. ::)
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Always start with the basics. How many times have we chased an electrical fault without checking the fuse first?
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The tool is irrelevent, the method/logic is what I'm trying to get over ;)
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The logic bit OK, but without the proper diagnostic gear most mortals aren't able to turn injectors off individually ;)
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The tool is irrelevent, the method/logic is what I'm trying to get over ;)
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The logic bit OK, but without the proper diagnostic gear most mortals aren't able to turn injectors off individually ;)
There are other ways of doing it, aren't there ;)
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Bringing this back up again, as its still fubared! :'(
Its had brand new HT leads, tripple checked they are on the in the right order at the dis pack end. Brand new plugs in 2-4-6, known good ones in 1-3-5 (ran out of new plugs! Some fat admin nicked them ::))
Its got a clear miss-fire, slight metallic noise at idle, but not always present. Hold revs at say 900, sounds ok, no bad sounds but has a miss-fire. Sounds like its missing on a single pot :-\
Dispac has been inspected and its in perfect condition, think it had a new one very early on in our ownership but forgotten >:(
Tech2 plugged in, drop 2,3,4,5,6 injections you can notice the change. Turning off/on injector one no change. So pot1 is not firing, yet its had new plug & new lead.
Its possible I could have nicked/knocked the connector for injector one, although unlikely. Even more unlikely is injector 1 has failed.
There was a distinct smell of eggs as the cats warmed up, in fact it was very, very strong.
Running theory at the moment, is that it was missing on pot 1 for a week or two. MotherT did not notice & its shagged pot1 :(
Because I had had damaged injector one loom/unplugged some how, why the smell of eggs? :'( :'( :'(
Could well be terminal for our dog carrier :'(
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Smell of eggs may be pointing to an over rich mixture reaching the cat due to the misfire. If it was me I'd want to see a spark on one cyl. Now I know it's not ideal but you may have to pull the lead and using a spare plug ark it out on the engine. Don't do it for to long it may well cause the dis pack to cry wolf. If you have a spark your left with compression or fuel. As you've got the smelly eggs I'd say you've got fuel maybe to much. So I'd do the comp test on cylinder 1 and see what it reads. After that I'd be hoinkin (technical term) the inlet off and swapping the injectors around with another cylinder to see if the problem follows the injector around. The only reason I'd carry out the comp test before the fuel saga is it's a damn sight easier to do!!!!
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Yes that's the feeling here too, TB suggested swapping an injector & checking the wiring. Its possible I've nicked it, so need to visually inspect it.
The other thought was swapping 1 & 4 on the DIS pack, see if the fault moves to pot4 :-\
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What does the plug on pot 1 look like? Dry/wet? Black / clean?
Eggy smells suggests it's getting unburnt fuel in the cat, which may have shagged the cat if it's been driven regardless. I doubt it will be anything serious, but worth a compression check on pot 1.
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What does the plug on pot 1 look like? Dry/wet? Black / clean?
Eggy smells suggests it's getting unburnt fuel in the cat, which may have shagged the cat if it's been driven regardless. I doubt it will be anything serious, but worth a compression check on pot 1.
Plug 1 was dry, but red in colour :-\
I'm popping back mid week with a compression tester. If no compression, well thats that. If it does have decent compression then Plenum off again to check injector loom.
Have we seen injectors fail? Usually bullet proof :-\
As there is eggy smell, suggests fuel is not an issue, which suggests injector is working? Leaves either compresson or ignition problem? :-\
Fatty said its same issue he had with goldie, compression, fuel, good spark, good HT lead/DIS. But no firing on that pot, we all know what happened to that :'(
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..but if it was fuelling with no spark the plug would have been soaking wet.
I'd make sure there are pulses at the injector when cranking, and replace the injector to see if that helps. I have a load of spares here if you need a few.
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..but if it was fuelling with no spark the plug would have been soaking wet.
I'd make sure there are pulses at the injector when cranking, and replace the injector to see if that helps. I have a load of spares here if you need a few.
That is a good point :-[
Assume the replacement has to be 3.0 as well? Think 3.2's run at higher pressure?
If you have some spare, that's great. Many thanks :y :y :y
Could drive over, but guess they are small & easy to post? :-\
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Has TuBy not got a test plug you could use and trigger with Tech2 to verify DIS pack and leads?
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Has TuBy not got a test plug you could use and trigger with Tech2 to verify DIS pack and leads?
HT leads are new, dis is in perfect condition too. One test would be to swap 1 & 4 then nick his tech 2 and do the injector tests. See if fault moves :)
Guess could just attach plug to lead and stand back, would want fatty around for the test though :o
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..but if it was fuelling with no spark the plug would have been soaking wet.
I'd make sure there are pulses at the injector when cranking, and replace the injector to see if that helps. I have a load of spares here if you need a few.
Confused.....i am ;D
Smell of eggs from exhuast ...... suggests unburnt fuel in the cat.....which suggest the plug aint firing.
Bone dry plug suggests plug is firing but no fuel getting in....
So which is it peeps :-\
Or could it be an exhaust valve fubared.....so it is fuelling but firing unburnt fuel down the exhaust and it is firing as well.....so explains the dry plug...
I guess a compression test would prove a knackered valve :-\
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The question in my mind is how long after running was the plug checked? Had it dried out, perhaps?
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The question in my mind is how long after running was the plug checked? Had it dried out, perhaps?
Taken out first time, not run in over a week. As MotherT reported it broken, I came back to fix. New HT lead + plug, still same.
I swapped plug later again, as I ran out of brand new ones and stuck all new ones in passenger bank, again with new leads.
Don't recall inspecting the plug when I did that :-[
So I guess when I pop back, start it. See its still same, switch off, then straight away whip the plug out?
Need to anyway for a compression test.