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ayukawa

My 450 CDI cranks ... but no go

108 posts in this topic

My 450 CDI cranks but doesn't start. Suddenly after a round of two maintenance tasks (see below). It started briefly but conked out.

It cranks very well but it sounds way too smooth. Not sure if this is the sound of no injectors injecting.

With the good weather finally here in Ontario, I decided to clear two maintenance items that were backlogged over the winter.

1) ABS reluctor ring replacement (Mine had a big crack in it. Discovered it in the late fall when replacing my rear wheel bearings).

Took 3 weeks for the replacement rings it to arrive from UK. It got way too cold and I am without garage. Somehow the ring

held up over the winter.

2) Rubber intake turbo hose (Mine had a patch over the wear hole that was duct taped and hosed clamped to get by). The patch

was working well enough that replacement got pushed out to today. But it was leaking (by the look of oil blow mess in the area).

I did the intake hose first. It is a bit awkward to get it in and out. But I did it before to inspect and patch the old one.

I don't think I buggered anything up in the process. But I could have. I just wormed the old one out and wormed the new one in.

Didn't remove any connectors etc. The only hard part is getting the hose onto the intake manifold.

I "should have" tested it at that point. But I didn't. Lesson learned.

I then replaced the passenger side (RHS) ABS reluctor ring. I did this by disconnecting the X to the De Dion tube

and gently jacking up on the motor. You can get just enough space for the shaft to clear the hub. I didn't pull the shaft from the

transmission but replaced the reluctor ring "in situ" (Dremel grinding tool is very handy to clean up the body). The rings are an

interference fit so there was some work with a brass drift to get the ring in place.

I'm suspicious of the turbo intake hose replacement. It is right by the fuel injection hoses. Maybe I flexed something too

much. But would the gentle "lift" of the engine stress something in a bad way?

What I'm thinking:

1) Check to see if fuel is getting to the rail and check the electrical connections to the injectors.

2) Check to see what may have been pulled out of place when jacking then engine up (could not have been more than 1 inch or so).

3) Check the crank sensor? It is close to the drive shaft. Maybe it got mangled with my messing around with the crank shaft.

Any other ideas on what I might have disrupted today? Any hints on diagnosing the problem?

I don't have a proper manual for this car so I'm a bit lost as to where all the components are located.

Thanks,

Mike

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Turn by hand to confirm alterator is not seized.

Confirm electric feed pump runs whenever you switch on ignition.

Spray a few bursts of WD40 or similar penetration oil into inlet manifold. The purpose of this is to restore cylinder compression. Engine may fail to synchronise if compression is low.

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i have s similar problem

Starter new, alternator not seized, ful pump OK

When i wont to start the car, i hear a click from the starter, but nothing happens

checked all, ground wires, starter repaired,.

maybe ignition lock

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Posted (edited) · Report post

OK. Finally got back to this. It didn't fix itself. Still cranks but no go. Always hopeful.

I loosened what I believe to be the fuel input to the common rail. First high pressure fuel fitting on the left. Lots of fuel squirted out when I cranked. Also I could hear what I believe to be the fuel pump buzz when I go to start the car. Regardless, seems that there is fuel getting to the rail.

I checked the wires and connector on the end of the fuel rail, close to where I was working on the hose to the air inlet. It looked 'OK'. Did not test electrically.

QUESTION: What is the purpose of the sensors on either end of the fuel rail? I see an electrical connector going to something on both ends.

I'll assume one is a pressure sensor? /QUESTION

Thinking to check for pulses getting to the injectors. First I checked all the fuses in the SAM. All were fine (tested with a meter).

I pulled one of the connectors to the left most fuel injector. Connected a cheap digital multimeter. Tested on DC and AC when cranking the engine.

Nothing at all. I may try again, this time with an old school analog meter and look for a "pulse".

QUESTION: Should I see any life by connecting a multimeter to the injector when cranking? /QUESTION

I took a good look underneath where I was messing around with the drive shafts. The only wire I could see was something going to the

oil filter area. I'll guess this is the primary oil pressure sensor. It was tucked away and didn't look touched at all.

I'll probably try a squirt of WD40 as Torsten suggested.

Edited by ayukawa

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Shogun ... a bit different problem from mine. My engine cranks like a bandit. If you get a distinct "click", I'd check your battery connections. First because it is easy to do. Second because you should have disconnected them before dicking around with the starter.

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Thinking to check for pulses getting to the injectors. First I checked all the fuses in the SAM. All were fine (tested with a meter).

I pulled one of the connectors to the left most fuel injector. Connected a cheap digital multimeter. Tested on DC and AC when cranking the engine.

Nothing at all. I may try again, this time with an old school analog meter and look for a "pulse".

QUESTION: Should I see any life by connecting a multimeter to the injector when cranking? /QUESTION

Injectors are rapidly pulsed with only 5 VDC. You need a sophisticated meter or better an oscilloscope to see the signal.

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Injector pulse voltage is around 70 volts. Both leads are switched by ECM.

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3) Check the crank sensor? It is close to the drive shaft. Maybe it got mangled with my messing around with the crank.

That must surely be oil pressure switch.

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I'm struggling to determine all the required prerequisites for getting a signal to the injectors.

The lack of access to a service manual is frustrating.

1) Minimum pressure on fuel rail? What sensor and how to measure?

I did find this that is part of the Bosch system on our Smart cars.

PressureSensor.png

2) Crank sensor? If not there, the fuel pump is turned off. And then item 1 is not met.

** HOW to measure this without pulling the engine half apart? Should there be code I can read out?

3) Minimum pressure on oil? My Toyota 2H diesel has this (disabled during startup though).

Since its cranking ... I'm assuming that all the demobilizer stuff passes muster.

I'm also assuming that things like the EGR if not working only throws a code.

Also assuming that any ABS fault would not prevent the engine starting.

Then there is this angular velocity timing sensor to determine compression vs. exhaust stroke.

(the bit that avoids having a camshaft sensor in this diesel; Saab did it another way by detecting

evidence of a plasma at the plug by measuring resistance after ignition).

I can't see how I would suddenly lose compression ... but where is this sensor?

I have the start of a debugging flowchart that I would like to put somewhere.

CURRENT WORKING THEORY

- Not getting enough pressure on main fuel rail due to crack in one of those clear fuel lines and air getting into the system.

- Injectors are disabled as a result.

To Do: get my analog meter connected and look for a pulse on injector when cranking.

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What is a good location to spray the oil into the manifold? As in easy access point.

I'm assuming that it should be downstream from the turbo and therefore I can't just squirt it

into the airbox (removing the filter of course).

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BTW, I put up a start of a "car won't start" debugging in the wiki.

As I learn more ... I'll add to it.

Pretty basic so far.

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There are two easy locations for spraying oil into inlet manifold.

  1. Through hose to boost sensor.
  2. Directly into inlet manifold by removing rubber elbow between EGR valve and inlet manifold.

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Posted (edited) · Report post

Well, tried two separate squirts of frozen/rusted bolt lubricant. Did it by removing the rubber hose to the inlet manifold.

No change after squirt 1. No change after squirt 2.

Maybe I should use engine oil (something higher in viscosity. The penetrant is very light. I was actually hoping/expecting to get self ignition.

Put an old analog meter on the injector electrical connector. 10V DC scale. Differential measurement.

Got a "small" pulse about 1x per second. Repeated again. Definitely there.

1) Seemed 'small' given the comment that I should be getting 70V. Expected a bigger swing.

2) Seemed lower in frequency than I originally expected. However, maybe OK (it is a 4 stroke).

So maybe back to a fuel feed issue? Maybe I have an air bubble?

I tried to measure the fuel pressure sensor but I need to verify the pinout.

Edited by ayukawa

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Posted (edited) · Report post

A bit more web research on common rail diesel suggests the identification of the two electrical bits and connectors on the common fuel rail:

1) Pressure sensor. 3 wires. Gnd, Signal, 5V. In that order on the connector.

2) Pressure regulator. 2 wires. A PWM (pulse width modulated) solenoid.

The regulator apparently can either be modulated to boost pressure or relieve pressure.

If I understand the installation of these "TuneIt" boxes that remap the rail pressure, the sensor is on the RHS (by the dipstick).

I don't know the frequency of the PWM but we are dealing with a mechanical solenoid so it can't be that high.

I'll see if I get anything on my multi-meter in DC or AC mode.

Edited by ayukawa

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Posted (edited) · Report post

Update:

1) Pressure sensor is getting 5V. Measured to ground pin. Active when ignition in position 1(?). Still active for 10 to 15 seconds after ignition is turned off. Distinct relay click and then the power disconnects. I wonder why.

To test the sensor would require a bit more messing around with clips. I deferred this exercise for now.

2) Pressure regulator is definitely energized. Not exactly sure what this means about if we are above or below set point. But the wiring is OK and that is what I was most worried about. There was a bit of tugging when installing the rubber hose to the intake.

3) Cracked the fuel lines again. The fuel just pours out when ignition in position 1. So the electric pump is just fine. The mechanical pump will run regardless.

So I still don't yet know if the common rail is getting to full pressure. Have to think about how to test that. I'll probably start by disconnecting the pressure regulator and the fuel bypass to see what polarity in service we have.

I'm also wondering if the EGR could have any effects on starting? There was a bunch of black crusty crap in there, some of which fell south when I replaced the rubber hose. Maybe it jammed something? But I can't imagine how this could affect starting of the car.

The car did start and run for about 5 seconds before coming to a halt and never starting again.

I wonder what this says about the failure. Maybe some of that black crap got somewhere it shouldn't.

Edited by ayukawa

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BTW, there is a sensor on the bottom of the intercooler. You can see clearly from beneath the car. Has some funky looking clips that will probably break if you don't do it quite right.

Apparently this is a temperature sensor. I wonder if some funky crap landed on it. It is reported to be quite fragile.

Also, how might this play into the starting problem? Or does it just throw a code?

Did a bit more research. It modulates the intercooler fan. Makes sense. So, probably NOT my problem.

Edited by ayukawa

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Inlet air sensor does not affect starting. Remove by first disconnecting connector. Connector intelocks with tab that locks sensor in place.

Perhaps you have interfered with wiring to crank position sensor when you did the other work.

When you checked pulse to injector, did you leave injector plug connected? It won't pulse if you disconnect. Also, you must measure between the two leads.

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Torsten ... thank you for posting your advice.

I haven't even located the crank position sensor ... I'm lead to believe it is buried under the mess of egr and intercooler piping.

I should check to see if somehow the cable got mangled somehow.

What you say about the pulse to the injector makes sense. With a coil to energize, you want to dump a spike of current. So you need a good load. Not sure if the circuit counts on the inductance of the coil. Would not surprise me to see that it does.

A bit more testing and learning (for me):

1) fuel feed to rail from pump is this odd "clip" fastener. It is on the regulator end of the fuel rail. You press the "U" in to disengage the plastic C clip that holds the feed plug in place. I now recall messing with this a bit, first thinking it might help to get things out of the way so I could more easily install the rubber hose to the inlet. I never removed it but ... a little air goes a long way in a diesel.

2) it is very awkward to get signals out of the connectors, while electrically connected. I really need to build something out of some dead connectors to properly connect to the pins. So I bagged trying to check the fuel pressure sensor.

3) I decided to go old school and bleed the fuel lines. I cracked the high pressure line fittings with a 14mm wrench. Cycled the ignition and watched fuel pour out. Closed the fittings. Repeat.

The sound of the engine has definitely improved. Still no start. But it at least sounds like it is trying now.

Have to research the best ways of doing this. Could be that the battery is getting a bit weak. But it seems to crank at good speed still. Never bled a common rail diesel. You would think it should be more resilient to air than the older mechanical fuel injection pumps.

So current working theories are:

1) Something up with the crank position or virtual cam shaft timing. Sensor or compression (the oil treatment).

2) Still have a air bubble in the system. Preventing full pressure from getting to the injectors.

Edited by ayukawa

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Just read from an older post by Torsten in 2011 that the common rail diesel are "self priming" and any air will work its way out of the system. Assuming you are patient enough and cycle the starter enough. I can't see that I have any significant air in mine, given that I primed it the old school way of cracking the HP fittings to the injectors.

So updated working theories:

1) Pressure regulator is not working right or not getting proper signals. It is stuck in a mode that dumps the fuel rail pressure.

2) Crank position sensor or related.

Who might know what polarity is the pressure regulator? (i.e. energize to open or energize to close).

If there is no signal from the crank position sensor, the low pressure stops pumping (there seems to be a timer of about 5 seconds that cuts out the pump in position 1 ignition). But during my testing and bleeding, as long as I was cranking ... the fuel kept flowing.

If there is no signal from the crank position sensor, does the ECU fault out and never sends an injector signal? I definitely was getting a pulse, albeit small. But with no load.

Therefore, I'd say the crank position sensor is likely OK.

Edited by ayukawa

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OK. Just measured the output from the pressure sensor on the outboard end of the common rail.

3 pins. 5V, signal, ground.

Hacked the connector off a dead fuel pump from a Saab. 4 pin connector with same pitch. Removed the extra socket.

Fit like a charm. Beauty, eh?

Used a DC multimeter.

Initial setting at position 1 ignition measured 0.5V.

During cranking (position 3?) measured 1.32V

So the rail pressure is there. But does it meet specification?

Seems to if that one reference is correct (assuming idle is similar to starting).

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OK. So back to the injectors. Are they getting a pulse signal? I spliced in with my adapter (mangled it to 2 pins now).

Oddly enough, when cranking there was nothing showing up on my multimeter (old school analog).

I had expected to see a voltage spike. Hmm. Maybe the impedance of the solenoid is too low.

Or is it a piezoelectric? In which case, I should see a hefty voltage spike since the piezo is high impedance.

I replicated that I got a weak pulse if the connector was open circuit.

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I would replace the crank position sensor, it's a magnet and collects fuzz which confuses the ECU resulting in incorrect timing.

It's a real bitch to get at, it's located on the rear side of the engine on the bell housing between the engine and transmission.

You can't really get at it to meter it until you remove enough stuff that by this point you may as well replace it, same goes for cleaning it, I would hate to put everything back together and find out it's not working, thus confusing your fault finding even more.

Canman

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I would replace the crank position sensor, it's a magnet and collects fuzz which confuses the ECU resulting in incorrect timing.

It's a real bitch to get at, it's located on the rear side of the engine on the bell housing between the engine and transmission.

You can't really get at it to meter it until you remove enough stuff that by this point you may as well replace it, same goes for cleaning it, I would hate to put everything back together and find out it's not working, thus confusing your fault finding even more.

Canman

I try to get remove mine fews weeks ago, but the bolt was stuck.. Even with all the thing remove, we can't get a good position to force on the screw :(

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Well ... charged up the battery and had dinner. After dinner gave it a test crank. It sputtered. Hmm. Gave it a couple more and it almost caught. Walked the dog (long walk, it was a nice warm evening here). Came back and it started up on the first crank. A bit lumpy but evened out in a couple of minutes. Let it run for a couple more. Turned it off. Waited a bit. Restarted fine.

So ... I would say that I somehow got a nasty air bubble in the fuel system. Not sure exactly how.

Still don't know how to properly test the electrics for an injector.

But I know considerably more about the starting and fuel circuits now.

And there is a start of a "why doesn't my engine start" in the wiki.

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