Omega Owners Forum
Omega Help Area => Omega General Help => Topic started by: philhoward on 29 May 2016, 18:52:41
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Now this is a previously running engine (although not in an Omega now).
It started misbehaving a while ago - would start then stutter and stall. I've changed the fuel pump (twice) and the crank sensor (twice - one genuine, one pattern) but still nothing. I appear to have fuel (plugs smell a little after repeated cranking) so I assume I've got signal to fire the injectors.
Paper clip test shows an O2 sensor (bank 2 - is that offside or near side?), 31 (to be expected when not running) and 57 Idle Air Control voltage low. Still won't start if I give it a bit of throttle. Is it just the ISCV duff or a clue to something else?
Any clues welcome..
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Bank 2 is the 246 side :y
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:y
Makes perfect sense!
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Won't start if you give it a bit of throttle or if you don't give it?
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No throttle or some throttle - no joy either way :-[
I did wonder if the ISCV was duff it still might fire with a little throttle - not even a cough though.
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Any luck if you give it a full throttle?
Do you have spark when cranking?
I pressume that you don't have access to diagnostics tool?
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I did try full throttle but assumed that was "flood clear" mode so didn't expect that to work.
Will check again for spark (had spark before I think) although didn't check yesterday.
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Not sure if it's a red herring or not but the ECU light goes out after a few seconds of cranking - in the past its stayed lot if there was a major problem.
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This engine is in other make of car now, right?
Was it running after it was installed?
Have you found out if there is a spark?
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Yes, it has been running in its new home for 3 years.
Spark tester is on its way - as soon as it arrives I'll be checking for sparks.
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Yes, it has been running in its new home for 3 years.
Spark tester is on its way - as soon as it arrives I'll be checking for sparks.
Does it still have the original relays? If yes, check both small purple relays for any signs of scorching... if in doubt swap for known working ones to confirm... one powers the pump, second powers the injectors :y
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Done both relays - even bypassed the pump one "just in case"..and happily heard fuel (and got 3 bar pressure according to my gauge) flowing through.
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:y
Where was the 'genuine' crank sensor from?
And Autovaux/ebay isn't the correct answer... ::)
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Crank sensors - ah yes.
I have (from a friend who isn't running Motronic anymore) one Bosch and one Siemens sensor (both rounded plug versions). I think he got them from Vauxhall but might have been elsewhere. They are genuine though - he wouldn't have spent c.£80 a piece on junk ones. He bought them trying to find an issue that turned out to be his shiny new ECU, not the crank sensors after all.
Anyway - have tried both and a £20 eBay cheapie (worked last time proving another fault). Same result - no start :(
If it's any use, I'll get the numbers off the actual sensors - I have a feeling the one should only be fitted to a specific 2.5 variant?
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There is an issue that has cropped up with the 2.5 in the past, that the sensors are different lengths. Some appear to have a shorter nose than others and don't reach the reluctor ring on the crank to get a reliable signal.
Do you have access to an oscilloscope? Just wondering if you can check the output from the sensor?
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Well we have a spark at least..
I did notice the battery (that I had on charge for 2 days seemed to run out of puff quite quickly - wondering if a below par battery would cause issues? Bit annoyed as its a Bosch silver with a 4 year guarantee that I only bought 2 years ago..
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So, most probably, you don't get fuel in.
Where have you meassured the fuel pressure?
If I was in your position, I would now skip to the brake fluid/starter fluid test (just a small amount, of coursde, to see if it will give a sign of life).
I know most would say it's not a proper way of diagnostic, but it's quite OK and easy for elimination process.
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PS. Just don't spray in the intake (after the aiir-filter) - MAF sensor won't like it, and it has, like, a mile long intake.
Rather take out the IACV, and spray trought the hole in the plenum (partially close the hole with your tumb).
And, yes, you would need somebody do turn the key. Spray in the intake when it starts cranking.
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NOID lights should be here today to check for the injectors firing.
Fuel pressure tested at the Schraeder valve point on the fuel rail.
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I did (as a test) disconnect the MAF (so it might have a go at starting in Limp Home Mode) - got one cough from it but nothing more.
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Can you get a diagnostic tool? Pressuming that you have a OBD socket in your car installed.
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I did buy an "My Naff Code Reader" years ago but doesn't seem to work - fault codes have been extracted by the Paperclip Test :y
Might have to find someone local with a Tech2...
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Have you tried with the Maf unplugged?
Also does it still have the purge valve fitted? t gets really pissed off if the CTS is plugged into the purge valve and vice versa as it puts 12v instead of 5v through it... just a thought if you have unplugged anything recently :-\
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Purge valve? Didn't come across one when transplanting anyway. Only item I had to "fool" was the SAI valve system - relay is there so it thinks it's doing something and not flag a fault code (SAI ports blanked off anyway) and the same with the EGR valve - it's fitted an electrically connected but the exhaust "input" is blanked off. I've fitted C25XE exhaust manifolds so no EGR port fitted to them anyway. Don't think I've ever disconnected the CTS to be fair.
Didn't get anything apart from a quick "cough" with the MAF disconnected but the battery was flagging at this point (to be fair, the "cough" is more than I've had for a while!).
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Purge valve sits on the breather box and connects the breather bridge to the vapour cannister on the right hand a pillar behind the wing :y
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I think I've found a highly probable cause - water in the fuel (enough to turn it to milk). That'll be what happens to a non-sealed fuel system, 12 months off the road and this new-fangled Ethanol-laden water-absorbing fuel we have nowadays... >:(
Only spotted it when I disconnected the fuel pressure tester and saw a white froth coming out of the Schraeder valve..
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It seems there's water everywhere - not much in the tank now, but certainly plenty in the filter! Now to flush the fuel lines and fuel rail.
Next question - how do you remove the fuel rail?
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It seems there's water everywhere - not much in the tank now, but certainly plenty in the filter! Now to flush the fuel lines and fuel rail.
Next question - how do you remove the fuel rail?
Why not just unscrew the return line and let the fuel pump prime the system with fresh fuel? You'll need some rags to soak up the mess that's in there.
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That's where my logic failed me..
I was thinking it would better to flush the lot out by dismantling everything (already removed the top plenum..) being the best way to make sure I get the water out?
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That's where my logic failed me..
I was thinking it would better to flush the lot out by dismantling everything (already removed the top plenum..) being the best way to make sure I get the water out?
The fuel rail doesn't hold that much, and the pump will be forcing it out at over 40psi. Once you get a constant flow of clean fuel you can call it done. That will take seconds. The first few squirts will then clear the injectors.
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It lives!
Drained the tank, flushed the lines out, swapped the filter and after plenty of cranking it finally fired up!
I reckon there was a good couple of litres of "milk" floating about, either in the tank, the swirl pot, the filter or the lines.
Many thanks for all your assistance along the way.
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Glad that you have sorted this out. :y
Really a unusual one.