T5 2.5tdi 130 Starting problems again..! |
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mikecarr4
Not Quite Newbie Joined: 23 May 11 Location: Hull Status: Offline Points: 13 |
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Posted: 23 May 11 at 13:49 |
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Hi all, Sorry if this has been covered but i've been on the T4 forum and searched also and can't seem to find a solution...here goes...
I have a problem with my van not starting for the first time if its been left to sit for long periods whether it be uphill, down hill or flat. It will start after 4 or 5 turns of the engine and sounds like its priming the fuel lines or building up pressure before it kicks into life...I read a post where a guy had the same problem and he changed out the LP pump on the fuel tank and this cured the problem..with the theory behind that that the pump was allowing fuel to drain back into the tank. I have installed a Non Return Valve on the supply line to the fuel filter and initially this has improved starting but still has the problem if left for a couple of days...
I have had it into VW to carry out diagnostic checks on it, but came back with no codes found....Glow plugs changed out for new...Performance tests on both LP and HP pumps all ok...Fuel filter changed for new...
What would be your next thing to look at? I thought possibly Fuel Injector seals leaking? but there doesnt seem to be any signs of fuel lying about in the engine bay..although it is hard to tell....If this is possibly a cause does anyone have a guide as to how to change the injector seals out? or is it a garage job??? Also would it be worth getting the injectors ultrasonically cleaned...costs about £14 a injector on ebay..
Kind regards
Mike.
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gregozedobe
Vanorak Joined: 22 Dec 06 Location: Canberra, Oz Status: Offline Points: -998266 |
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Welcome Mike.
Lots of threads here with info about hard starting - try an advanced search with "any date", that should find them.
If the injector seals or cracks in the fuel galleries in the heads are leaking the diesel usually ends up in the engine oil.
Other causes are low voltage due to battery/wiring/earth/solenoid problems, starter motor on the way out (any cause of slow cranking speed causes trouble with injectors not getting any fuel). VW ECUs don't like low voltage either (or too high for that matter).
Presumably it's not currently cold enough where you are for glow plugs to really be needed, but faulty temp sensors (engine) have also been culprits for some.
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mikecarr4
Not Quite Newbie Joined: 23 May 11 Location: Hull Status: Offline Points: 13 |
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Hi Greg,
Thanks for your swift reply....The Starter motor or battery hasn't been checked yet which is a good call....thanks. Would this still be the case even though my van will struggle to start as described above, but then if I were to turn the engine off and then re-attempt straight away she will fire up no problem, and be fine for the rest of the day until left it again...would this not point towards a fuel issue? or do you think that the initial start would provide enough amps to get the starter motor speed up for the rest of the day? Kind regards, Mike. |
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PETE.T28
Yardie Joined: 13 Sep 08 Location: DORSET Status: Offline Points: 321 |
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Hi and welcome to the poor starting section
of the forum. There's another thread goin about the same prob, have you tried clamping the return pipe just before the filter. I clamped mine overnight and removing It in the morning and it started first time. ( this might rule out injecter seals an cracked heads) Problem is it has started first time every morning since. Bit of a head scratcher I feel mine could be a temp related problem ie the coolant temp sensor on the block ( still not found it) as it's been quite mild in the mornings? pete |
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mikecarr4
Not Quite Newbie Joined: 23 May 11 Location: Hull Status: Offline Points: 13 |
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Hi Pete thanks for the reply, I think I read your solution on the other forum...I did try that and it didnt have any effect...by the sounds of it there could be air getting drawn into the fuel line causing the fuel to drain back into the tank...but then surely the NRV I installed in the supply line would stop this? unless the return line draining would effect the starting do you think? Maybe by clamping your line, you caused the 'clip' connectors to seal and stop pulling in air?
Temp sensors were read by a vw 'specialist' using their computer and they confirmed all were reading correctly....unless, the sensor is faulty and then when started it corrects itself, which is when they plugged the van in to their computer.....hmmmm?? theres a new thought.... |
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mikecarr4
Not Quite Newbie Joined: 23 May 11 Location: Hull Status: Offline Points: 13 |
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Pete, I stand to be corrected, I didn't clamp the return line I did the supply line last time, So I have clamped the return line tonight, hopefully this will rule out the injectors....fingers crossed
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gregozedobe
Vanorak Joined: 22 Dec 06 Location: Canberra, Oz Status: Offline Points: -998266 |
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Hmm, it is still possible if the starter motor cranking speed is just a fraction below the limit initially, but I think it is much more likely to be a fuel problem based on your description.
A few minutes with a multimeter at the battery and the starter motor will quickly tell you what is happening voltage wise (switched off, switched on but not cranking starter, when starter motor is cranking, and for the first minute or so after engine starts).
Just out of curiosity, have you tried switching off after cranking for a few seconds (without starting), and then trying to start again (after waiting for the glowplug light to go out) ? If it starts immediately on the second attempt I would be looking more closely at something electrical (which might still be fuel related).
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mikecarr4
Not Quite Newbie Joined: 23 May 11 Location: Hull Status: Offline Points: 13 |
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Greg,
I did as you said this morning, in cranking the van but not starting then going for a 2nd attempt and she fired up straight away....?
Once I got to work I measured 13.31v at the battery with the engine switched off...so i will check again in 10 hours or so and see if there is a voltage drop...
Thanks
Mike.
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gregozedobe
Vanorak Joined: 22 Dec 06 Location: Canberra, Oz Status: Offline Points: -998266 |
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That's very interesting indeed.
Tomorrow morning could you please try this variation to see what happens if you:
1 Turn the "ignition" on but don't turn it further to start cranking, after 15 seconds switch off (ie no cranking of starter motor at all).
2 Turn the "ignition" on but don't turn it further to start cranking, after 15 seconds start cranking.
If it starts immediately it might be behaving as if it really needs the glowplugs to start easily. Given that your weather isn't that cold at the moment I would then suspect low compression as a possible cause.
If it consistently starts easily the 2nd time (after initial cranking and without the glowplug delays) that could be caused by some kind of control issue that is stopping diesel from being injected, and not an issue with no/insufficient fuel being available (ie maybe not a fuel pump or lines issue at all, although a delay in developing normal fuel pressure could also cause your symptoms).
When it does start does it run and rev normally. or does it hesitate for a short time as if it is being starved of fuel ? When it is warmed up does it easily accelerate to 4,000rpm even with a load (or uphill in 3rd and 4th gear) ?
All the above will be very helpful info to a "professional" trying to figure out the cause of the problem ( some live VCDS logs of fuel pressures and injection events during starting attempts may assist to diagnose properly). It won't be the immobilizer (that allows the engine to start normally, then cuts it after about 2 seconds).
I'd expect it to drop back to around approx 12.5V after it has been sitting for a few hours (that's normal). If it goes under 12V (resting) that would indicate a problem with either the battery retaining charge or some kind of parasitic drain.
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mikecarr4
Not Quite Newbie Joined: 23 May 11 Location: Hull Status: Offline Points: 13 |
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Hi Greg,
I clamped the return line once again today and left it for 12 hours just out of curiosity...Usually when I try to start it I tend to put my foot on the accelerator when the engine is cranking say 5-6 times then rev it up to say 1500rpm then the engine will idle fine after that. Tonight I tried starting it with no foot on the gas what so ever and it initially stalled twice with a bit of juddering and on the third time cranked engine once and she fired up...so in total there was only 3 attempts of cranking the engine..?
The van drives really smoothly all the way to 4000rpm in all gears and even uphill etc...
Another thing, you was right about the voltage returning to around 12.65v but on initial startup tonight the battery voltage dropped to around 9v..is this normal?
I will try your other recommendation of starting in the morning and report back, thanks again for your input...
Regards, Mike.
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mikecarr4
Not Quite Newbie Joined: 23 May 11 Location: Hull Status: Offline Points: 13 |
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Started the van as you mentioned this morning but still no different. It failed to start 2nd time but did start 3rd time...?
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mikecarr4
Not Quite Newbie Joined: 23 May 11 Location: Hull Status: Offline Points: 13 |
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See this clip Greg....
http://www.youtube.com/watch?v=qtuV1d-lre4 My money is on a fuel problem...hopefully not cracks in head...? |
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gregozedobe
Vanorak Joined: 22 Dec 06 Location: Canberra, Oz Status: Offline Points: -998266 |
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Edit: Just watched the video, and it definitely sounds like an engine that isn't getting enough fuel at first (I never put my foot on the accelerator when starting).....
.... but then is getting plenty of fuel once it has been running for a while (so not a blockage in the filter or lines, and the pumps are supplying enough for high revs).
So possible explanations include:
1 the fuel is bleeding off somewhere (is the engine oil level increasing and is there even a slight diesel smell to it ?), or
2 air is getting into the fuel system somewhere.
Possibly a fraction low, I'd have to check on mine to see what it drops to while cranking to be sure. Does it sound like the starter is cranking over at a normal speed, or does it sound like it is struggling a bit ? Edit - after watching the video it sounded like it was cranking OK.
But I don't think slow cranking speed is the only explanation for your starting issues - fuel issues of some kind seem much more likely to be the culprit.
I think to progress any further in your diagnostics you/your designated mechanic needs to investigate fuel pressure at startup.
There can be a number of reasons for low pressure at startup in the R5 engines, including:
pump/lines/air getting in problems,
faulty seals on injectors,
worn injector lobes on the cams (on PD engines the cams provide the really high pressure the injectors need),
and of course the dreaded cracks in the head (fuel "line" galleries). Edited by gregozedobe - 25 May 11 at 15:20 |
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mikecarr4
Not Quite Newbie Joined: 23 May 11 Location: Hull Status: Offline Points: 13 |
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Thanks Greg, will look into it and report back once fixed...;) Certainly no smell of diesel in the opil which has to be a good sign...
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PETE.T28
Yardie Joined: 13 Sep 08 Location: DORSET Status: Offline Points: 321 |
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Mines started without fail every morning 'touch wood'
I think it's ok, what I discovered was the rocker breather valve had snapped and was hanging around so I have glued it together temp new one on order. what I'm thinking is that maybe it was cracked when I bought the van resulting in the poor starting probs what do you think? Pete |
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gregozedobe
Vanorak Joined: 22 Dec 06 Location: Canberra, Oz Status: Offline Points: -998266 |
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I don't know. I can't think of any obvious reason why a breather issue would make an engine hard to start, but with modern VW pollution control systems getting so complex I suppose anything is possible. Certainly the engine controllers can tell when you muck about about with the EGR system and have a whinge.
Has your weather been getting warmer recently ? That can make a difference to some starting issues.
Any one else got an opinion ? Edited by gregozedobe - 26 May 11 at 11:53 |
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mikecarr4
Not Quite Newbie Joined: 23 May 11 Location: Hull Status: Offline Points: 13 |
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Hmmm I will check that Pete, is that the valve on my video that you can see moving on the turn of the ignition...Top right of the engine??
Mine started last night first time after turning the ignition on, leaving for 15 secs, turn again leave for 15 secs and then fired up with only a little splutter....But then this morning tried it without doing that and it took 3 attempts....One day I think fuel starvation the next day electrical....suppose i'll just have to take it to a garage when I have some spare time!
Mike.
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PETE.T28
Yardie Joined: 13 Sep 08 Location: DORSET Status: Offline Points: 321 |
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Yep has been a bit milder for a week but 12 deg
this morning and still started on the button was down in bude a few weeks ago and it was well warm but she wouldn't start then? I found the damaged breather valve 2 weeks ago stuck back together and it's started every time since just bang the key in wait 2 secs for glow light to go out and crank fires up instantly I have the van for 18 months bought with the fault and it has been a pig to start every morning and that's right through last years summer I'll monitor the starting for the next few weeks starting it daily thanks Pete |
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PETE.T28
Yardie Joined: 13 Sep 08 Location: DORSET Status: Offline Points: 321 |
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Found this bit of info which would be the same as having
a cracked/ broken valve pullin in fresh air possibly? Think this refersmore to petrol cars but if the maf is reading airflow from inlet it won't be allowing for extra cold air being pulled in further downsteam before the turbo or am I talking boll##ks If the pintle inside the PCV valve sticks open, or the spring breaks, the PCV valve may flow too much air and lean out the idle mixture. This may cause a rough idle, hard starting and/or lean misfire (which increases emissions and wastes fuel). The same thing can happen if the hose that connects the valve to the throttle body, carburetor or intake manifold pulls loose, cracks, or leaks. A loose or leaky hose allows "un-metered" air to enter the engine and upset the fuel mixture, especially at idle where the idle mixture is most sensitive to vacuum leaks. On late model vehicles with computer engine controls, the engine management system will detect any changes in the air/fuel mixture and compensate by increasing or decreasing short term and long term fuel trim (STFT and LTFT). Small corrections cause no problems, but large corrections (more than 10 to 15 points negative or positive) will typically set a lean or rich DTC and turn on the MIL. |
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gregozedobe
Vanorak Joined: 22 Dec 06 Location: Canberra, Oz Status: Offline Points: -998266 |
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The above is true enough for throttle-valved petrol engines (a few petrol engines aren't, but they are rare so far). So petrol engines need tight control of both air and fuel.
But diesels run on totally different principles - the only significant control (at startup and idle speed) is fuel supply (it is effectively running on the equivalent of a petrol engine with a wide open throttle), so a bit more air (or a bit less) won't make any appreciable difference to starting. When the turbo boosts it just adds even more air so the ECU can then supply more diesel and the engine makes more power.
This is why a diesel engine that is leaking lots of oil into the inlet is so dangerous - there is no throttle to close so the engine just "runs away" on the oil.
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