Omega Owners Forum
Omega Help Area => Omega General Help => Topic started by: hotel21 on 27 September 2007, 20:47:11
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OK peeps, a wee puzzle and a Q or two ...
My beastie now regularly runs away with itself and holds revs circa 2 - 2.5 k when warm and the only way it can be dropped is to brake whilst in gear and force the revs to drop. Even then does not work every time. Air leaks checked and none apparent. ICV rubber to intake replaced with 2 spares.
There is a slight misfire/hesitation when accelerating from low revs/gears until circa 4k revs then it picks up clean.
Belt, tensioners and timing replaced/set/confirmed by M_DTM and TB at the nearly Wales meet.
VERY slight oil in plugwells but now dry and leads are in first class condition.
HBV replaced at first hint of suspected leakage/non performance with VX gen original so DisPak thought A1.
ICV cleaned, oiled and swapped between the three I hold in stock..... :(
Second replacement front multiram electric actuator fitted but still apears non working (cheers Timbuck for the first and FFCGary for the second... :y )
I fitted cruise myself several months ago and it still does the same when cruise is disconnected - both electrically and mechanically from the throttle bodies - and I am now at a loss.
Anyone any edumacated clues or guestimates?? :-/
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Don't know if its FBW or throttle cable .. if the latter.. I had a similar problem on the MGB years back .. it was a knackered throttle cable .. replaced it all OK .. took old one apart .. as you do :) .. and it had 2 broken wires about 2/3rds along .. seems these were catching on the outer sheath and acting like a little spring putting tension on the cable. as the damage slowly got worse the problem got worse..
just a thought ?? :)
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Thanks for that. Its a cable, prefacelift 3.0 MV6.
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an overnight issue Brocie, or gradually getting worse?
Idle spot on the button?
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Then I'd try disconnecting the throttle cable and checking for free and untensioned movement .. it it snags or pulls I'd replace it ... (but I have no idea if that is easy or hard !! :) )
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Pretty much ongoing.... Much more noticable after the belt/tensioners/front multiram actuator done at the last meet. :(
Idle is spot on, with and without aircon. Inst Consumption 0.2 gall/hr or whatever when on eco or aircon off, 0.3 when on...
As to free cable, will check in the morning but, TBH, dont think that is the case... :y
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Pretty much ongoing.... Much more noticable after the belt/tensioners/front multiram actuator done at the last meet. :(
Idle is spot on, with and without aircon. Inst Consumption 0.2 gall/hr or whatever...
So were looking at something that was interrupted last time and hasnt settled again....
that iacv is really tight in isnt it and not at an angle....?
in mine the grooves on the rubber are out of sight when its in correct BUT when doing the breathers on Bobs i had a similar experience and it transpired ICV was not in far enough
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Yup, rubber is well into the plenum, no grooves are visable. tried swapping out with the others I have as well, in case its a split or overly soft.... No change..
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dispack can have issues regardless of HBV how known good is it, may well be on way out any idea of dis history?
similar issues on one of mine, asmentioned
, was fixed by a combo of leads, dispack, crank sensor and breather clean here - trouble is i now dont know which one finally cured it ;D
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Brucie, I know you don't suspect the cable, but I just wonder if there is something from stopping the throttle bodys from entirely closing..
Other than that, what are your plenum O rings like (I cant remember)..
Air filter ok?
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I flashed the codes as well. 15 and 31 when off - Coolant Temperature Sensor (CTS) High voltage and Engine RPM signal (crankshaft sensor) No signal - but the latter obviously clears when engine running.
Would the temp sensor have any input into this, bearing in mind we reset the assorted settings on the dash binacle to get the temp display back into range???
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Could the butterflies be sticky?
CTS, causing warm up program?
Failing MAF reading high airflow, ecu pumping in fuel to accomodate?
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I flashed the codes as well. 15 and 31 when off - Coolant Temperature Sensor (CTS) High voltage and Engine RPM signal (crankshaft sensor) No signal - but the latter obviously clears when engine running.
Would the temp sensor have any input into this, bearing in mind we reset the assorted settings on the dash binacle to get the temp display back into range???
I replied at same time. If Engine ECU CTS is reading low temp, it will be on warm-up program. Different sensor to dash gauge (though mounted next to each other)
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Dispack is untouched from getting the car (2 years ago now) so parentage unknown. Maint History is quite good with lots of (expensive) receipts for work done, no mention of dispack so probably original.
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Cheers TB but revs are a lot higher than the warmup 1500 or so. Talking 2 - 3k rev range. At idle, revving much more than I want it to be...
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Coolant temperature is a possibility. If it's telling the engine ECU it's sub-zero it might result in a rich mixture and elevated idle speed.
Can you reproduce it with your head under the bonnet or is it only when driving?
Don't suppose the EGR valve is leaking air into the system?
Idle air valve sticking open?
Might be worth listening round the induction system, breather pipes, etc. with a length of hose held to you ear. An air leak that big will be audible, IF it's happening at idle with the bonnet up :-/
Kevin
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Cheers TB but revs are a lot higher than the warmup 1500 or so. Talking 2 - 3k rev range. At idle, revving much more than I want it to be...
Silly Q I know, but presumably it actually is revving, and not just an instrument failure?
What about the sticky butterfly suggestion?
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I have another MAF that I can substitute but prefer to not do the standard Fitter option of diagnosis by substitution, if you follow....
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Cheers TB but revs are a lot higher than the warmup 1500 or so. Talking 2 - 3k rev range. At idle, revving much more than I want it to be...
Silly Q I know, but presumably it actually is revving, and not just an instrument failure?
What about the sticky butterfly suggestion?
;D Its revving mate!! ;D
Gives the same effect as the cruise failing to disengage!! ;D
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Unplug the engine ecu cts (alas plenum off job) - look in TIS, sure there is a substituted value. Also worth measuring and comparing to TIS
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Thanks for the input peeps. Been head under the bonnet for the past day or two trying to suss out whats wrong and you are pretty much suggesting what I deduced. :y
Will confirm free cable in the morning.
Throttle bodies were cleaned at the Lakes meet but will remove and redo, just in case.
Floor mats are secure and not impeding accelerator movement.
Will exchange MAF for substitute.
Had the listening tube out already and nothing heard as regards air leaks....
Will run without air filter for a wee bit to remove potential fault from diagnostic loop!
Been meaning to put a blanking plate in the EGR for a while so good oppertunity to get it done!
Anything else? ;)
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Thanks for the input peeps. Been head under the bonnet for the past day or two trying to suss out whats wrong and you are pretty much suggesting what I deduced. :y
Will confirm free cable in the morning.
Throttle bodies were cleaned at the Lakes meet but will remove and redo, just in case.
Floor mats are secure and not impeding accelerator movement.
Will exchange MAF for substitute.
Had the listening tube out already and nothing heard as regards air leaks....
Will run without air filter for a wee bit to remove potential fault from diagnostic loop!
Been meaning to put a blanking plate in the EGR for a while so good oppertunity to get it done!
Anything else? ;)
Don't buy new sensors without further tests. Most have a substitute value by ecu if failed. So if you unplug sensor, it will put in sub value ;) - OK, it'll run far from optimum, but should help you pinpoint if it is a sensor.
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Sounds like an air leak or a frayed throttle cable
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I think it could be the butterfly sticking open, I had the same thing on a Senator I owned once.
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Not a problem (crack/seal..) with the bagpipes that might have been made worse when you were working on the cambelt?
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Cheers TB but revs are a lot higher than the warmup 1500 or so. Talking 2 - 3k rev range. At idle, revving much more than I want it to be...
They will be once the engines warm and 'loose'. The enrichment/IACV control map for the cold start may give silly revs if still present when everything's warmed up, been there, seen that. I've just cut open a (failed) CTS as it happens... a little bead thermistor surrounded by silicone heat-transfer compound, inside the brass housing. Thermistor had a chunk blown out of it (I had a short-circuit to injector wiring fault!). I think the usual failure mode is that they go gradually higher-resistance with age, effectively telling the ECU the engine's colder than it really is. If you google "NTC thermistor failure mode" you may come across the reference where I discovered this. HTH.
Edit: Oops, just replied to the last post on page 1, hope this is still relevant. :-[
Edit2: Oh, and if it's harder to start than you'd expect when hot, that would be more evidence, I think for this hypothesis. Mine was almost impossible, 'cos the CTS was telling the ECU it was -40°C!
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Got to be CTS fault....the revs will be higher if the engine is hot and its on warmup cycle than if it was cold and on warm up cycle.
Do you have a spare CTS, if not I do, Pm me your address and I will chuck it in the post for you.
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Will confirm free cable in the morning.
Throttle bodies were cleaned at the Lakes meet but will remove and redo, just in case.
Floor mats are secure and not impeding accelerator movement.
Will exchange MAF for substitute.
Had the listening tube out already and nothing heard as regards air leaks....
Will run without air filter for a wee bit to remove potential fault from diagnostic loop!
Been meaning to put a blanking plate in the EGR for a while so good oppertunity to get it done!
Cable is free, no obstructions or resistance
TB's cleaned - but were not dirty in the least......
Mats removed - still happens....
Second hand MAF substituted - no difference....
Removal of filter makes no (actual) difference....
Ran out of time for the blanking plate due to other commitments....
Still the CTS fault showing, nothing else.
M_DTM - PM sent
Thanks for the input all. Appreciated. ;)