Omega Owners Forum
Omega Help Area => Omega General Help => Topic started by: Liam on 13 October 2010, 12:59:09
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Hello folks,
Some may recall I've been having some engine trouble recently! To cut a long story short, one camshaft pulley came loose, met its neighbour, they ate each other a little bit, locked into mesh, stripped several teeth off the cambelt and bent some valves.
Compression test said I got away with it on one bank so I did just one head swap. Taken me ages on and off to get it done, having other things to do and finding other little things needing replacing like a faulty hydraulic lifter etc etc. New cambelt timing checked and checked and rechecked.
Finally got it reassembled a few weeks ago now and started her up. Never started a car after such major work before but sort of had an idea what to expect. Took a lot of cranking before fuel came through and it finally fired up. I guess not helped by the fact I serviced the lifters on the head i swapped so they must have taken a while to pump up and actually be able to move the valves a decent amount.
Started up on 5 by the sounds of it, soon started running on all 6, sounded like a bag of spanners at the top end, but quietened down when the lifters pumped up. All was good I thought. However as it warmed up it started briefly dropping out every 5-10 seconds or so, this got worse then it cut out.
That's where I am today. It can idle initially, but as soon as it's warmed up a little and the 'choke' (warmup enrichment) backs off and idle speed wants to drop to normal, it just cuts out. I can keep it going if I hold some throttle on and it is smooth and can rev. Just can't idle.
There's a slightly worrying sound though I can hear seemingly from the top end/plenum area. Every now and then, normally when I come off throttle a little, a metallic sort of sucking/scraping sound. Ch ch ch ch - a bit like a turbo wastegate chuffing. Definate metallic ring to it though, and I'm really not sure if it's a scrape (hope not) or a suck.
If it's a suck perhaps I have an air leak somewhere? That could also explain why it can't idle, maybe? Be buggered if I know where it's from though. I didn't replace inlet manifold/plenum seals but haven't in the past either and have been fine. I have the plenum off now - didn't miss an o-ring which i was hoping could be an obvious cause.
Idle control valve? Was fine before but maybe not now? I can blow through it easily off the car - should it be closed by 'default' when disconnected, or maybe it's stuck open? How to tell?
I'm also convinced it sounds a bit more rumbly than before. Exhaust blockage? Family of mice moved in while it's been off the road? Any idea how to tell?
Any advice greatly appreciated! I'll be damned if I'm putting all this time and money into my baby and failing to fix it!! But a little lost as to what to investigate next :(
Cheers,
Liam
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Hi
First of all, which car is it, your profile doesn't say.
Do a paperclip/pedal test for fault codes and report back.
Alan
Hello folks,
Some may recall I've been having some engine trouble recently! To cut a long story short, one camshaft pulley came loose, met its neighbour, they ate each other a little bit, locked into mesh, stripped several teeth off the cambelt and bent some valves.
Compression test said I got away with it on one bank so I did just one head swap. Taken me ages on and off to get it done, having other things to do and finding other little things needing replacing like a faulty hydraulic lifter etc etc. New cambelt timing checked and checked and rechecked.
Finally got it reassembled a few weeks ago now and started her up. Never started a car after such major work before but sort of had an idea what to expect. Took a lot of cranking before fuel came through and it finally fired up. I guess not helped by the fact I serviced the lifters on the head i swapped so they must have taken a while to pump up and actually be able to move the valves a decent amount.
Started up on 5 by the sounds of it, soon started running on all 6, sounded like a bag of spanners at the top end, but quietened down when the lifters pumped up. All was good I thought. However as it warmed up it started briefly dropping out every 5-10 seconds or so, this got worse then it cut out.
That's where I am today. It can idle initially, but as soon as it's warmed up a little and the 'choke' (warmup enrichment) backs off and idle speed wants to drop to normal, it just cuts out. I can keep it going if I hold some throttle on and it is smooth and can rev. Just can't idle.
There's a slightly worrying sound though I can hear seemingly from the top end/plenum area. Every now and then, normally when I come off throttle a little, a metallic sort of sucking/scraping sound. Ch ch ch ch - a bit like a turbo wastegate chuffing. Definate metallic ring to it though, and I'm really not sure if it's a scrape (hope not) or a suck.
If it's a suck perhaps I have an air leak somewhere? That could also explain why it can't idle, maybe? Be buggered if I know where it's from though. I didn't replace inlet manifold/plenum seals but haven't in the past either and have been fine. I have the plenum off now - didn't miss an o-ring which i was hoping could be an obvious cause.
Idle control valve? Was fine before but maybe not now? I can blow through it easily off the car - should it be closed by 'default' when disconnected, or maybe it's stuck open? How to tell?
I'm also convinced it sounds a bit more rumbly than before. Exhaust blockage? Family of mice moved in while it's been off the road? Any idea how to tell?
Any advice greatly appreciated! I'll be damned if I'm putting all this time and money into my baby and failing to fix it!! But a little lost as to what to investigate next :(
Cheers,
Liam
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Ah sorry - could have sworn I filled out my profile ages ago?? It's a 98 mini-facelift 3.0 elite auto. I should have mentioned - no engine light, but I'll paperclip it anyway and see what it says.
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I was hoping this wouldn't be necessary...
(http://locostbuilders.co.uk/upload/3kitten.JPG)
Anyone :(. I mean this must happen all the time, right? :(
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Air leak sounds reasonable, and ISTR that the idle control valve should be 'normally closed' when electrically unconnected so that is an avenue to investigate..
What happens if (when it's warm) you restrict the air feed to the idle valve? Maybe it's leaning up to the point of dying.
I suspect you really need to get it on to a Tech2 or something that can pull live data though and see what is up at the point that it stalls.. do you have anyone nearby with a Tech2/similar?
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Hello folks,
Some may recall I've been having some engine trouble recently! To cut a long story short, one camshaft pulley came loose, met its neighbour, they ate each other a little bit, locked into mesh, stripped several teeth off the cambelt and bent some valves.
Compression test said I got away with it on one bank so I did just one head swap. Taken me ages on and off to get it done, having other things to do and finding other little things needing replacing like a faulty hydraulic lifter etc etc. New cambelt timing checked and checked and rechecked.
Finally got it reassembled a few weeks ago now and started her up. Never started a car after such major work before but sort of had an idea what to expect. Took a lot of cranking before fuel came through and it finally fired up. I guess not helped by the fact I serviced the lifters on the head i swapped so they must have taken a while to pump up and actually be able to move the valves a decent amount.
Started up on 5 by the sounds of it, soon started running on all 6, sounded like a bag of spanners at the top end, but quietened down when the lifters pumped up. All was good I thought. However as it warmed up it started briefly dropping out every 5-10 seconds or so, this got worse then it cut out.
That's where I am today. It can idle initially, but as soon as it's warmed up a little and the 'choke' (warmup enrichment) backs off and idle speed wants to drop to normal, it just cuts out. I can keep it going if I hold some throttle on and it is smooth and can rev. Just can't idle.
There's a slightly worrying sound though I can hear seemingly from the top end/plenum area. Every now and then, normally when I come off throttle a little, a metallic sort of sucking/scraping sound. Ch ch ch ch - a bit like a turbo wastegate chuffing. Definate metallic ring to it though, and I'm really not sure if it's a scrape (hope not) or a suck.
If it's a suck perhaps I have an air leak somewhere? That could also explain why it can't idle, maybe? Be buggered if I know where it's from though. I didn't replace inlet manifold/plenum seals but haven't in the past either and have been fine. I have the plenum off now - didn't miss an o-ring which i was hoping could be an obvious cause.
Idle control valve? Was fine before but maybe not now? I can blow through it easily off the car - should it be closed by 'default' when disconnected, or maybe it's stuck open? How to tell?
I'm also convinced it sounds a bit more rumbly than before. Exhaust blockage? Family of mice moved in while it's been off the road? Any idea how to tell?
Any advice greatly appreciated! I'll be damned if I'm putting all this time and money into my baby and failing to fix it!! But a little lost as to what to investigate next :(
Cheers,
Liam
two questions come to mind,
are you sure the other bank have no damage ?
is the timing belt correctly set up?
and dont you have any eml light?
if its an air leak the engine must work better when it warms up imo.. but you can check this by spraying carb cleaner around engine.. :-/
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I wonder if the metalling sound you describe is the result of a lean mixture. I have seen this before where the engine "coughs" back into the intake when lean and the sound you hear is the pressure wave hitting the throttles.
How does it run with the MAF disconnected?
Kevin
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Thanks guys. Leaning out till it dies would be my thoughts. If you've heard a similar noise in that sort of situation, kevin, that's possibly encouraging!
I'll pop the plenum back on and see how it runs with no MAF. What should that tell me?
Cem - the extent of my confidence the passenger side bank survived the original 'incident' is simply a compression test :-/. It also runs fine (albeit sounding a little deep/rumblier than usual) at anything other than idle where it cuts out. So I'm fairly sure the original mechanical damage is gone, but half wishing I'd delved into that head too to check!
Cambelt was timed up with the kit and checked and rechecked.
No EML when running but I am going to try a paperclip to see if there are any codes stored. Although might i just get a whole load thrown up as when cranking for compression tests etc etc I've essentially been running with tonnes of stuff disconnected, and maybe those codes wont have cleared yet??
Cheers
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I wonder if the metalling sound you describe is the result of a lean mixture. I have seen this before where the engine "coughs" back into the intake when lean and the sound you hear is the pressure wave hitting the throttles.
Ditto.. about 18-19:1 on the MR2 it starts to sound very odd and unnatural (right about when it starts struggling to hold an idle).
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Thanks guys. Leaning out till it dies would be my thoughts. If you've heard a similar noise in that sort of situation, kevin, that's possibly encouraging!
I'll pop the plenum back on and see how it runs with no MAF. What should that tell me?
Cem - the extent of my confidence the passenger side bank survived the original 'incident' is simply a compression test :-/. It also runs fine (albeit sounding a little deep/rumblier than usual) at anything other than idle where it cuts out. So I'm fairly sure the original mechanical damage is gone, but half wishing I'd delved into that head too to check!
Cambelt was timed up with the kit and checked and rechecked.
No EML when running but I am going to try a paperclip to see if there are any codes stored. Although might i just get a whole load thrown up as when cranking for compression tests etc etc I've essentially been running with tonnes of stuff disconnected, and maybe those codes wont have cleared yet??
Cheers
nope.. dont remember exactly but you will need 15-30 succesful starts something like that :-/
honestly still I dont think your poblem is airleak or ICV..
and imo dont trust the compression test :-/
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Hmmm - mechanical damage remaining is playing on my mind, of course, but it seems unlikely to me. On the compression test after the 'incident' I got three equal at about 200PSI on the passenger bank, and on the driver bank I had one at 200PSI, one with nothing at all, and one about 50PSI down at about 150PSI. On inspection the cylinder with no pressure had two very bent valves, and the cylinder down to 150PSI had two only very slightly bent valves so that they were just cracked open instead of seating, hence the low pressure.
Is it really possible I have valves even less bent than those in the other bank such that there isn't even a lower pressure in a compression test, and for that damage to cause the symptoms I'm observing - i.e. can run but wont idle? Not sure to be honest.
Cheers
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Hmmm - mechanical damage remaining is playing on my mind, of course, but it seems unlikely to me. On the compression test after the 'incident' I got three equal at about 200PSI on the passenger bank, and on the driver bank I had one at 200PSI, one with nothing at all, and one about 50PSI down at about 150PSI. On inspection the cylinder with no pressure had two very bent valves, and the cylinder down to 150PSI had two only very slightly bent valves so that they were just cracked open instead of seating, hence the low pressure.
Is it really possible I have valves even less bent than those in the other bank such that there isn't even a lower pressure in a compression test, and for that damage to cause the symptoms I'm observing - i.e. can run but wont idle? Not sure to be honest.
Cheers
the answer "yes" means you need to take the head off.. cant take that responsibilty.. :(
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the answer "yes" means you need to take the head off.. cant take that responsibilty.. :(
I don't know. :-/
I would say if you've got 200 psi of compression there's nothing wrong with the valves myself.
Kevin
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the answer "yes" means you need to take the head off.. cant take that responsibilty.. :(
I don't know. :-/
I would say if you've got 200 psi of compression there's nothing wrong with the valves myself.
Kevin
Kevin, imo the valves may be dont leak when cold but whatever happened there it may leak when hot ..
but you cant do a compression test when its hot :(
edit: also if there is some friction increase with warm up, its not possible to measure that..
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Kevin, imo the valves may be dont leak when cold but whatever happened there it may leak when hot ..
but you cant do a compression test when its hot :(
edit: also if there is some friction increase with warm up, its not possible to measure that..
True but I would say the lifters would have to be pumping up to increase valve clearances when hot, and it would have to take out at least 3 cylinders or it would still idle.
A few other ideas:
EGR valve leaking? This will screw up the idling. Might be worth blanking off to eliminate it.
ICV sticking?
Crank sensor? OK, there's no code 19 (or is there - worth a paperclip?) but the wiring to this sensor is what fails and it might well have been disturbed during recent work.
Voltage from a crank sensor is speed dependant so could be that as the revs sink to hot idle speed the signal gets too weak for the ECU to decode.
A few things to eliminate before taking it apart, IMHO. ;)
Kevin
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Thanks guys. I'll be checking out egr (just remembered I, er, made a 'gasket' for it out of loctite stud and bearing fit on assembly when feeling slightly frustrated about something else. Could have at least used the VX grey sealant couldn't I :-[), and check out ICV before contemplating anything more drastic.
Cheers
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UPDATE:
Well been playing with it today. Still not wanting to idle when the throttle is fully closed and relying on the IACV. Using the throttle stop adjustment screw hidden under the plastic cover where the throttle and cruise cables connect I put a few turns on the screw and it can idle a little high around 750 - 800 ish without cutting out.
I then decided to take it for a drive. Put 15 or so miles on it and gave it a proper test. Seems to run fine and pull smoothly to the redline under load and appears to make full power. A few more points to note from the drive:
Runs at normal temp - doesn't overheat.
Sounds normal.
No funny coloured smoke.
Not generating mayonnaise.
All this makes me a little more sure I really dont have mechanical damage left from the 'incident' - does that sound fair?
Dunno why I never thought of this before - but the sucking/chuffing/scraping noise does sound a bit bearingy. So I squirted WD40 around the aux belt pulleys and haven't really heard that since. I'll run it a bit without the belt on and if that confirms an issue on the aux belt, check out the water pump and other pulleys (water pump is 5 or so years old and felt fine on assembly - no play).
That still leaves the idle problem which maybe has nothing to do with the noise. As above I can kind of get round it by having the throttle cracked open with the stop screw. Maybe the problem is the IACV?? It seems fine though - the bit that moves in it isn't sticky at all and moves fine.
I paperclipped it whilst running also...
19 - Incorrect RPM signal
21 - TPS voltage high
129 - EGR feedback voltage low
73 - MAF voltage high
74 - MAF voltage low
57 - IACV voltage low
Interestingly repeating the test with the engine not running gave me no 31 which I thought was supposed to be thrown up??
So how do I tell if these codes are current, or just stored from when I've been unplugging sensors? Is there a way to clear codes and see which ones reoccur?
So in my thoughts the potential horrible mechanical damage still remaining has reduced to annoying little problem I can maybe live with. But any ideas on how to solve it appreciated! If an air leak is still a possibility, is it worth renewing all inlet seals/o-rings just to rule them out? Also EGR to plenum gasket. And/or should I get a replacement IACV?
All help so far appreciated! Cheers.
Liam
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Your test drive results sound encouraging; brave to take it to the redline in the circumstances! 8-) Sounds to me like you really have ruled out major mechanical issues within the engine. :)
One thing that I don't think I dreamt - but may have - is that on the V6s there's the possibility of plugging the ICV and something else to the wrong loom connectors, as they use the same plug. Might explain the ICV's misbehaviour, and one or two of the fault codes?
May be worth a visit to, or by a Tech2 to see whether the fault codes are 'present' or stored. A number somewhere between 20 and 30 of clean, no-faults-present starts should clear any that have been fixed, though some seem to clear instantly as soon as the problem is resolved, don't know which sadly.
Good luck with it! :)
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From your paperclip results I'd swap the crank sensor (19) - you may well find some of the other codes will also then go (MAF, ICV & EGR). Then set your idle "adjustment" back to where it should be. Good luck :y
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Hmm thanks. Interesting about the IACV plug. Cant say I noticed that possibility, but will investigate. Obviously I had all those cables out of their plastic conduit over the passenger head, so could feasably have not put them back in correctly...??
Yeah the 19 does seem to be out there on it's own among all the other voltage high/low codes. Thing is it's only a couple of years since I changed the crank sensor. The symptoms of the old one failing weren't like this either - it would just refuse to start every now and again, then finally, permanently. Still worth considering though.
Also, I've always had a bit of a rattly exhaust. Always thought it was the loose heatshields round the downpipes, but have ripped those off during this work as they were half rust anyway. Still have a rattle - could this indicate CATs falling to bits and could this cause poor idling without throwing up lambda sensor/mixture related codes??
Cheers,
Liam
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UPDATE:
Well been playing with it today. Still not wanting to idle when the throttle is fully closed and relying on the IACV. Using the throttle stop adjustment screw hidden under the plastic cover where the throttle and cruise cables connect I put a few turns on the screw and it can idle a little high around 750 - 800 ish without cutting out.
I then decided to take it for a drive. Put 15 or so miles on it and gave it a proper test. Seems to run fine and pull smoothly to the redline under load and appears to make full power. A few more points to note from the drive:
Runs at normal temp - doesn't overheat.
Sounds normal.
No funny coloured smoke.
Not generating mayonnaise.
All this makes me a little more sure I really dont have mechanical damage left from the 'incident' - does that sound fair?
yes .. good news.. no need to deal with the other head :y
Dunno why I never thought of this before - but the sucking/chuffing/scraping noise does sound a bit bearingy. So I squirted WD40 around the aux belt pulleys and haven't really heard that since. I'll run it a bit without the belt on and if that confirms an issue on the aux belt, check out the water pump and other pulleys (water pump is 5 or so years old and felt fine on assembly - no play).
That still leaves the idle problem which maybe has nothing to do with the noise. As above I can kind of get round it by having the throttle cracked open with the stop screw. Maybe the problem is the IACV?? It seems fine though - the bit that moves in it isn't sticky at all and moves fine.
I paperclipped it whilst running also...
19 - Incorrect RPM signal
21 - TPS voltage high
129 - EGR feedback voltage low
73 - MAF voltage high
74 - MAF voltage low
57 - IACV voltage low
Interestingly repeating the test with the engine not running gave me no 31 which I thought was supposed to be thrown up??
So how do I tell if these codes are current, or just stored from when I've been unplugging sensors? Is there a way to clear codes and see which ones reoccur?
So in my thoughts the potential horrible mechanical damage still remaining has reduced to annoying little problem I can maybe live with. But any ideas on how to solve it appreciated! If an air leak is still a possibility, is it worth renewing all inlet seals/o-rings just to rule them out? Also EGR to plenum gasket. And/or should I get a replacement IACV?
All help so far appreciated! Cheers.
Liam
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Hmm thanks. Interesting about the IACV plug. Cant say I noticed that possibility, but will investigate. Obviously I had all those cables out of their plastic conduit over the passenger head, so could feasably have not put them back in correctly...??
Yeah the 19 does seem to be out there on it's own among all the other voltage high/low codes. Thing is it's only a couple of years since I changed the crank sensor. The symptoms of the old one failing weren't like this either - it would just refuse to start every now and again, then finally, permanently. Still worth considering though.
Also, I've always had a bit of a rattly exhaust. Always thought it was the loose heatshields round the downpipes, but have ripped those off during this work as they were half rust anyway. Still have a rattle - could this indicate CATs falling to bits
nope.. Cats of miggy is normally robust..unless you hit them somewhere else..
exhaust leaks can effect idle but wont stop it.. also your consumption will be highly effected..
ps : I'm still using original cats
and could this cause poor idling without throwing up lambda sensor/mixture related codes??
Cheers,
Liam
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Cheers,
After looking at another thread with a code 19 and crank sensor diagnosis, does anyone else think my code 19 could indicate a dodgy crank sensor? Bearing in mind my particular symptoms, and the fact my crank sensor is only a couple of years old, and when the old one was playing up it didn't give these symptoms. Or could it be a result of unplugging it during the work? Having said that I'm not even sure I unplugged the crank sensor at all (unless it was required when removing the cable conduit over the passenger head to get the wires out of the way). Hmmmmm.
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After looking at another thread with a code 19 and crank sensor diagnosis, does anyone else think my code 19 could indicate a dodgy crank sensor?
Yep. It's normally quite a reliable indicator of a crank sensor problem. :y
It's the insulation in the wire that fails on the crank sensors, normally due to heat. I'm sure it will have been moved a little during the work, so perhaps it has failed. Crank sensors produce a stronger signal at higher RPMs so could well be that down at idle the signal is not quite good enough for the ECU to synchronise to.
Make sure the crank sensor wiring is routed up the inner wing well away from the exhaust manifold when fitting.
Kevin