All well and good Dan, but a crook injector won't nessesarliy bring fault codes up...Quote:
Originally Posted by Daniel
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All well and good Dan, but a crook injector won't nessesarliy bring fault codes up...Quote:
Originally Posted by Daniel
Exactly Gav! This is the big problem with electronics and peoples blind reliance that electronics are great – well not this exact example but the notion of everything that is reported must be gospel (bit like the media really).
Now, as some here know, I’m the biggest fan of electronics, I’ve got a habit of converting everything electrical in sight to run a programmable integrated interface – just for the hell of it. Several years ago, my wife asked, “why do you need to be able to turn the kitchen light on/off from anywhere in the world?” I replied “O come on, you don’t think it’s cool that an internet connection in London can click a button that sends a command that is transferred through several different protocols, over several mediums including a standard 240v power line to operate a tiny relay hidden in the wall within a couple milliseconds.” Eyes were rolled as she walk away - she does quietly think it’s cool that she can turn the heating/cooling on or off or just check the inside temp at home, or the pool water temp from her desk at work in the city (or phone on the way home) before she plans her evening! Anyway back on track.
Problem: Assuming that all electronic/electrical issues will log a fault is very naïve – it’s an idealistic notion but that’s it. After reading uteman’s posts I am assuming that he’s NOT a moron. The Electronic Control Modules only log faults for issues/errors/scenarios that they know about, someone has to write the code that executes - firstly in the event of a fault occurring (input from sensors or network data values are identified by the main program), and secondly the entries (fault detail) that are logged. If the ECU receives an analogue value from a sensor or digital value from the network that the original designer did not consider would be received then 2 possibilities commonly happen, either it handles the exception and a vague fault is logged (no or incorrect details recorded) or nothing (the car continues as if nothing is wrong – the computers are oblivious to the issue). I’m trying to ignore the 3rd possibility of unhandled exceptions, which would have the chance of creating a really unpleasant scenario.
What uteman describes here (no one else has seen/heard/felt what’s going on), is typical of the system being oblivious. This could well be a drive train issue, but personally I don’t think so - the lockup should be smooth enough to not cause a drive train shudder and if it is drive train I would think you would feel something during normal gear changes as well. However like vehicle computers, I have ‘returned’ incorrect advice in the past and could be wrong here.
As an example of issues that the ECUs won’t record think about this. The Trans computer (TCU) sends a request to the Engine computer (EMS) when lock up is required. The EMS receives this and reduces engine torque (to allow smoother change) at the same time it sends a message back to the TCU with timing details. TCU receives this message and times the signal (to the millisecond) to the lockup solenoid. The signal to the lockup solenoid is analogue (the TCU outputs voltage from +0.5 to +12v on a dedicated wire which is earthed somewhere – this wire is different to the wire that engages each gear change).
If this wire (or connectors) has extra resistance for some reason (dirt/grease/oil/rust) the voltage received by the solenoid will be vastly lower than expected – Or what if the circuit board/capacitor/mosfet ect (inside TCU) has deteriorated to the point where it is actually outputting lower/higher voltage. Does the solenoid open/respond at the same speed with reduced controlling voltage? Don’t know, but I do know that there will not be a fault logged in any ECU for an example like this, firstly the developer would not have considered it and secondly the TCU is not monitoring what is received by the transmission.
Gav’s point of the injector above is great – the EMS does not check whether the nozzle piezo opens, let alone how much fuel is squirted in. It just checks that a circuit is plugged in and able to receive voltage – it could even be a small resistance short because that check has no redundancy.
These types of scenarios highlights the problem with Computer controlled mechanicals, and it’s not limited to cars. Everything that is controlled by computer where the final output is not monitored with redundancy is prone (down to simple things like my pool heating, computer told the valve to open diverting water to the roof for heating – someone (me) had accidentally cut the wire while gardening so that signal was never received by the valve – computer was happy the pool was heating – mrs wasn’t!).
This is the issue I have with computers in modern cars; there is no where near enough monitoring for the electronics to provide complete diagnostics – we all hear stories about funny errors solved by replacing a sensor. The problem is compounded by the attitude of many people (including dealers & mechanics) that the electronics always report everything and accurately. There is no where near enough focus on signal/data checking.
In short a fault is only logged for an error that the ECU receives and expects.
If it was me (because this is my field) I would be checking that the messages between EMS and TCU are indeed on the BUS and that their timing matches. Then check the analogue signal and comparing them to another vehicle. Unfortunately that is above most mechanics – just like rebuilding a transmission and torque converter is above me.
So it’s not the Transmission, Maybe try another TCU and check the wiring loom and every connector.
I’m sorry to hear your pain uteman – I was there with our D2 some 10 yrs ago while still under warranty, after every sensor, loom and injector was replaced, they replaced the EMS and the weird problem was gone, ironically it was torque converter related (only partially lock and then would get surging)… At the time I had a dealer mechanic tell me that it “couldn’t possibly be a computer issue because the other computers would log errors.” I responded as would be expected, I remember being so crapped off with it I wouldn't look at it…. Other than sensors the engine and transmission wasn’t touched, it was a near new car – we still have it, trouble free.
Thank you Harlie
I think that in a long winded and round about way you have substantiated my advice - mechanics that blindly follow previous routine service techniques do not always get their diagnosis correct. And one should always start at the most simple and work up the complication scale.
Harlie: You are either quick at typing or had time in your hands.Quote:
Originally Posted by harlie
A replacement TCU was trialed some time back with no difference.
You have provided some other possibilties that are worth looking at.
I certainly agree with you about the lack of diagnostic skills in many shops these days. If the computers do not show a problem to the diagnostic equipment that has many thinking that nothing can really be wrong.
I still have great faith in the auto transmission shop who are determined to see this through and again this shop has some great transmission diagnostic equipment but sometimes it still comes down to thinking the problem through and looking for the unexpected.
At this time the car is with them so I am not personally involved in trying to sort out the issues however they have been very receptive to my input that may come from my own background or comments such as yours.
Thanks for the detailed post.
Well: I have the car back home at last. The auto shop fitted a transmission from another TD6 and fitted my reco unit to that vehicle. Car still had shudder at around 90 kph.
I expected this as I did have a chance to drive the vehicle and stated that I did not believe the transmission to be at fault.
Car has a "diesel knock" again so I have ordered new injectors as I simply could not risk getting mine serviced again and would never do that again.
Cost wise: I had fitted 3 new injectors by the time I identified the bad fuel including moisture so rack up about $1400 for those. Then had to get all injectors including those 3 new ones serviced as they also had water through them. One of those immediately turned out to be a problem causing a significant diesel knock and had to be replaced with another new one. Ka-ching, Ka-ching and another $1100 including labour. What made that worse was that the failed injector was one that only did about 300 K's before being removed for service by what I had hoped was a good diesel service facility. Did I mention the $1223 they charged for servicing?
Now the car has a further diesel knock meaning that a further "serviced" injector is giving trouble so I have 5 more coming from UK. Yes you guessed it Ka-ching, Ka-ching goes another $1600 bucks and the injector service facility appear to be deaf when I ask for some compensation. My money must all be round! made round to go around and none made flat to stack.
However I do smile that the car is sitting in my driveway under my control at last. With my back operation now a memory I can work on it myself and even kick my own backside if I get it wrong which I doubt.
Thanks to everyone who listed and contributed.
Hi uteman, how did you go with your new injectors? Is it all good now ?
Not sure if he is checking the forum at the moment - he is off the radar for a couple of weeks doing stuff - fun stuff that I would like to be doing...:DQuote:
Originally Posted by neil 90
Cheers - Gav
Cheers gav, thanks for the heads up :-)
As many will recall this car has been a problem for some time.
The shuder turned out to be from the engine. I had previously had the injectors reconditioned and the car had been to 2 different Land Rover workshops since and their determination was that the engine was OK.
I have now fitted brand new injectors and the car is so smooth now that I am over the moon.
The Bosch ECU manual does state that if you have greater than 15 rpm difference in cylinder speeds at idle that you have a problem. Our car did have greater than that but workshops were not concerned. Now that my Faultmate reads a difference of only 10 rpm at idle that car is like a new one so believe what Bosch say.
Uteman thats great news. I just wish that the cure could have been earlier and cheaper. I would have a word with the workshops too, if the cyclinder idles were out of specs why didn't they do/try something ?
Laurie