|
|
Post by remmington on Apr 16, 2016 18:08:43 GMT 1
Been working on a Mk7 2.2 Transit today.
Done 136.000 miles.
Came in yesterday, no power and black smoke (engine rocking about - misfire).
No fault codes or warning lights! Starts OK hot or cold. Recent EGR has been fitted, EGR seems to be doing what it should on live data.
Traced it down to high injector leak off values and odd correction rates with two injectors.
Replaced two injectors today (coded and did idle learn with Delphi diagnostic tool).
Van starts and idles ok now.
But I have still got very low power and white smoke.
Stripped it again...
Did compression test, got 19bar on two cylinders and 17bar on the other two cylinders.
I think, it is just slightly too low to get rid of higher fuel injection rates above idle.
Very flat throttle, sort of misfire and loads of smoke on a test drive.
I would have expected well over 20bar compression cranking thru glowplug port, with a charged battery and the other three glowplugs out.
Any ideas?
|
|
french crap fanatic
Apprentice
french car specialist based in dagenham east london
Posts: 3,355
|
Post by french crap fanatic on Apr 16, 2016 18:20:23 GMT 1
What's the history of the van.
A customer of same van needs needs engine,can't get used unit anywhere,therefore I think these engines go bang a lot!!!
|
|
|
|
Post by remmington on Apr 16, 2016 18:38:26 GMT 1
What's the history of the van. A customer of same van needs needs engine,can't get used unit anywhere,therefore I think these engines go bang a lot!!! History of the van is: Serviced regular intervals Van overloaded and driven hard by the bosses son. What do you think the compression reading should be? |
|
|
|
Post by Karl on Apr 16, 2016 19:52:15 GMT 1
I'd expect to see between 22-25 bar
But you generally don't get given manufacturers figures
|
|
|
|
Post by Karl on Apr 16, 2016 20:07:11 GMT 1
At my old dealers workshop the transit lads always had at least 1 engine apart
I think they just get a hard life
I wonder if the old injectors contributed as well ie fuel in the oil ?
I remember hearing that transit warranty costs where nearly twice that of the car line
Commercial are now at a separate site so I don't get involved now a days
|
|
|
|
Post by remmington on Apr 16, 2016 20:11:52 GMT 1
I'd expect to see between 22-25 bar But you generally don't get given manufacturers figures 17.5 : 1 ratio quoted To me should be 350psi or 24 bar on a new engine! (multiply ratio by 20 for new) Or 306psi or 21 bar on a old tired engine (multiply ratio by 15 for an old tired end of life engine that runs). Cam timing effects compression readings! So with even (ish) reading across the cylinders, I would guess the chain has jumped? Gonna quote out the whole ball game... Engine, clutch-flywheel, chain kit, set of injectors, oils fluids gaskets plus buckets of labour. |
|
|
|
Post by Karl on Apr 17, 2016 21:21:21 GMT 1
Well I never knew that compression ratio could be used to figure out what individual cylinders should be. !
|
|
|
|
Post by Karl on Apr 17, 2016 21:23:20 GMT 1
Learn something new everyday , then forget something else
|
|
|
|
Post by valhalla on Apr 17, 2016 22:05:05 GMT 1
I think that the fact it is down on two cylinders is enough to condemn the engine anyway, irrespective of any risk of jumped chains. If I saw 19BAR across all four cylinders on one of these engines, I wouldn't be too worried, not least if the compresion readings were done with the other three injectors left in the respective bores and the cranking speed was below 200rpm during the test.
These aren't great engines anyway, very much fit, wear-out, throw-away sort of rubbish that Dagenham knocks out these days. They are pretty well despised in Defender circles, a major step backwards from Landrover's own diesel units of the past. It would probably do the customer more good to get a new + known complete replacement under the bonnet, then pray that the rust can be held at bay long enough to get some service out of the van again.....
|
|
|
|
Post by Joepublic on Apr 17, 2016 23:00:58 GMT 1
I'm a bit lost, if you compress atmospheric pressure (1 bar or 15 psi) 17.5 times do you not get 17.5 bar? (262.5 psi)?
Or am I missing something?
|
|
|
|
Post by valhalla on Apr 17, 2016 23:53:07 GMT 1
It's slightly more complicated than that. For a start, you are compressing from an absolute pressure of 1BAR (or thereabouts) to whatever, but the gas you are compressing does not stay at a constant temperature, it heats as it compresses. So even if the gas was an ideal gas, which is about as close as most equations get to, the equation pV=nrT needs to account for both a changing V and a changing T to account for p (pressure).
If the temperature (T) behaved itself for an ideal gas, then the gauge pressure you saw before the compression stroke (0BAR) would have to be converted to absolute pressure by adding the barometric pressure (typically 1BAR). So you arrive at 1BAR before the compression stroke. The pressure you see at the end on your gauge is also (by no small coincidence) gauge-pressure, so would need a similar adjustment. So you would add barometric pressure on at the end measurement as well. A measured pressure of 17BAR would imply an absolute pressure of 18BAR at sea-level. If the temperature was the same throughout the gas, and no gas was added or lost, then you could imply that the compression ratio was 18:1 for this example. In reality, the gas would not behave ideally, and a raised temperature would give you an increased indicated pressure.
|
|
|
|
Post by Joepublic on Apr 18, 2016 8:54:49 GMT 1
It's slightly more complicated than that. For a start, you are compressing from an absolute pressure of 1BAR (or thereabouts) to whatever, but the gas you are compressing does not stay at a constant temperature, it heats as it compresses. So even if the gas was an ideal gas, which is about as close as most equations get to, the equation pV=nrT needs to account for both a changing V and a changing T to account for p (pressure). If the temperature (T) behaved itself for an ideal gas, then the gauge pressure you saw before the compression stroke (0BAR) would have to be converted to absolute pressure by adding the barometric pressure (typically 1BAR). So you arrive at 1BAR before the compression stroke. The pressure you see at the end on your gauge is also (by no small coincidence) gauge-pressure, so would need a similar adjustment. So you would add barometric pressure on at the end measurement as well. A measured pressure of 17BAR would imply an absolute pressure of 18BAR at sea-level. If the temperature was the same throughout the gas, and no gas was added or lost, then you could imply that the compression ratio was 18:1 for this example. In reality, the gas would not behave ideally, and a raised temperature would give you an increased indicated pressure. I see, thank you  |
|
|
|
Post by thechronic on Apr 20, 2016 20:11:34 GMT 1
We look after a few fleets of Mk 7 2.2 Transits & we have fitted many replacement engines. Usually only good for about 120K. Pistons cracked or holed, big ends gone, timing chain failed, oil pump chain snapped. In my opinion a poor engine. We start with a compression check, any deviation on pressure we would have the head off. Every time we can see a mechanical failure. Whether the injectors are to blame is a good question.
I would prepare your customer for the worst - replacement engine.
|
|
|
|
Post by bowtay on May 21, 2019 13:54:18 GMT 1
Hope some one can shed some light I have a 2012 rwd 2.2 euro 5 transit I can hear popping kind of noise from the intake manifold I have done a compression test I'm getting 480 psi across all 4 cylinders
|
|
|
|
Post by valhalla on May 21, 2019 18:43:47 GMT 1
Hope some one can shed some light I have a 2012 rwd 2.2 euro 5 transit I can hear popping kind of noise from the intake manifold I have done a compression test I'm getting 480 psi across all 4 cylinders What conditions are you testing the compressions under? The figures you quote are way too high for normal cranking cylinder pressures, as if you have got a build-up of compression from a problem in the valve timing or exhaust back-pressure......
This is an EU5 Transit, so I'm guessing you have a DPF? In which case, your first port of call would be to do a back-pressure test during cranking, and at idle, measured at the front DPF pressure sensor. Chances are, the DPF is blocked solid, and someone has "corrected" the soot loading model in the PCM to hide the problem. Anything more than 0.1BAR at idle, or 1psi guage pressure at idle, and you need to get the DPF off and checked by a specialist.
|
|
