Well this is 280 bar at idle and 1450bar full wack so yes to knife.... hehe.
Actually it's not at all like tdi, tdi motors us VP37 rotary injection pump - this is common rail. On the VW I can log into the pump and interrogate it and see everything on screen, plus it will tell me if any sensors have issues and I can see live data and perform output tests etc. Sensor data etc is easy to come by. The later ones are PD unit injectors, different again but simple to deal with and very durable.
The common rail system raises questions like 'does the rail have pressure' and 'how do I know if the pressure regulator is operating' and such, not really anything tdi compatible. My main issue with this motor is lack of data, it's in a movano which is a rebranded master. As an auto electrician or mechanic I can transfer skills, but you still need some info about the motor you are working on!
However I have some sensor data and info I'll post below after further tests, I may be on to something.
AndersDK wrote:Its surely a HP issue. Sounds like a fuel stop solonoid or something wont let the high pressure build up in the pressure line.
The injectors wont open until a minimum feed pressure is present. The electric injector solonoids are just UN-blocking the injection.
Warning : do not use your finger to gauge injection from an injector. If it works, 200bar is a real good knife.
The crank/cam position sensors are dead simple wirewounded pickups, with a finite ohmic resistance from the wounded wires. In the region af a couple of 100 ohms. Dead simple to check out.
They should simply not be shortcircuited (less than 10 ohms or so), or not be high ohmic (disrupted by any normal means).
Úsually they are 3 wire, one wire being a stranded shield for electric noise protection, the other 2 wires simple each end of the coil sensor. They are not normally earth or ground referenced.
Could be simple 2 wire sensors though.
There might be slight differences in methods to achieve a running HDI from the TDI, but basically I cant see why you should not be able to directly apply your TDI knowledge to this engine type. Its downright the same principles used.
Of course you can get a live picture of whats going on in a HDI. You just dont have the option forking out the £££'s needed for the correct test equipment
Anyway - my experiences with HDI's are nil, I just put on some logic deduced from the working principle and components fitted.
Something just came up : could it by any means be down to any sort of a priming issue on the HP pump ?
This sounds logic as its a known problem from other high pressure systems that have been opened up for service.
Good point Anders - I hear that can be a problem on some too, but not this one as it's in tank pump primed & self bleeding, bled through in about 3 cranking attempts (you can hear the bubbles in the return line in the tank below the front seat - it's remarkably efficient. Anyhow that could be an issue with other types of CR so I'll look out for it, but I found the resolution to this just a half hour ago it was a wierd one, I'll post below.
Greg.
AndersDK wrote:Of course you can get a live picture of whats going on in a HDI. You just dont have the option forking out the £££'s needed for the correct test equipment
Anyway - my experiences with HDI's are nil, I just put on some logic deduced from the working principle and components fitted.
Something just came up : could it by any means be down to any sort of a priming issue on the HP pump ?
This sounds logic as its a known problem from other high pressure systems that have been opened up for service.
If anyone has a similar 'no start' after a cambelt or engine rebuild, this may prove of interest. This issue only applies to engines with the cam (cylinder) position sensor on the fuel pump rather than on the camshaft.
For those who are interested, on the 2.2dci/dti Renault/Vauxhall/Nissan engine with the Bosch CP3 common rail (CR system similar to many others) I tested the following and got these values, which turned out to be correct:
Crank sensor - 231 ohms (2 pin sensor)
Cam position sensor on fuel pump cover 10.16k ohms (2 out of the 3 pins)
With ignition on, centre pin on Pressure Sensor on the common rail gave 0.5v = 0 pressure, under cranking went up to 1.7v = approx 350bar
Injecor two pin connections gave 12v or more pulsed during cranking, 0v with ignition on.
All the above were correct and proved good rail pressure, sensors and pulses to the injectors. I did a leak off test to test if any of the injectors were leaking HP to leak off pipe, none were, just a very slow trickle/bubble after about 5 seconds of cranking out of the top of the injectors, as one would expect from new injectos (they leak out worse as they get older, one peeing out can empty the pressure of the CR and be enough to stop it starting).
So what on earth could it be I thought. I then went back to the cambelt timing, all spot on. BUT, the HP pump is gear driven 'on a 1:1 ratio with the crankshaft' according to the manual. The HP pump isn't sensitive to timing, it just has to spin, so shouldn't be an issue. But I dug out pictures of the timing end of the engine and it had a big cog on the HP pump and a small one on the crank, so evidently the HP pump turned at 1/2 crank speed. Now this wouldn't cause an issue, BUT on the renault dci the cam sensor is on the front of the HP pump sprocket cover, stupidly, rather than on the camshaft. So, I figured the manual was wrong about the 1:1 ratio and if you timed up the crank and camshafts perfectly, it's possible for the HP pump sprocket and thus cam timing signal to be 180 degrees out. There is no way in the manual or that I can see, without lifting the timing case cover, to check this. Normally it wouldn't be an issue as you would mark stuff up before removing belts, but this was a dismantled engine that I had to rebuild so I had no idea of a reference position and just timed the crank up.
Anyhow, I took off the timing belt, spun the crank 360 degrees and as I thought the HP pump moved round 180 degrees even though the crank was back to the same position. Refitted and tensioned the belt, spun it over on the spanner and re-check everything - the crank/cam timing just like before but now the HP pump is 180 degrees out from before and thus the cam timing signal (signals when no1 cylinder is coming up) is 180 degrees from what it was.
Turn the engine over on the starter for 5 seconds and it fires into a steady idle like it's been running a year, smooth as a baby.
Moral of this story is, if your common rail engine has the cylinder/cam sensor anywhere other than the camshaft (whcih can't get 180 degrees out) it's possible that if you have to rebuild a ripped down engine or lost your timing marks, you can put the cambelt on properly and lined up, but have the signal off of the 'cam' sensor 180 degrees out and get a no start with absolutely no codes/faults to see. The engine was merrily injecting the wrong cylinders! The second moral is never trust the manual. If I had believed it's 1:1 ratio (which didn't even make sense, you can't get a cam signal from a crank ratio as a crank spins twice for one revolution of a cam) or didn't think outside the box of the instructions for timing up the engine, I'd never have got this solved.
Hopefully this will be useful to someone else one day, who rebuilt an engine and timed it all up as per the book and £200 worth of sensors later still can't get it started, all because the crank needs spinning round 360 degrees and the belt putting back on again.
I wonder if only renault managed to put the cam sensor on the HP pump and invent this problem that didn't need to exist?
Drinks all round guys.
Greg.
Last edited by greg123 on 26 May 2008, 10:27, edited 1 time in total.
Thanks you guys!!! And thanks for the help, could easily have been one of the other things and good to rule them out and have ideas bouncing round the ole grey matter.
Or in my case black matter, as I won't accept being old enough to have grey anything
