VW T5.1 2.0 CAAC Long Crank / Starting Issues?

J

JohnDeere

Member
Hi

My 2015 T5.1 2.0 CAAC has never been a great starter in the 16 months I have owned it but its got worse in the past few weeks. If often starts the first time, I go out and it fires but I drive down the road 2 miles, engine off and it then struggles to restart, cranks for a good 10 seconds sometimes.

Long story short, went into a garage today and they said no codes coming up but the fuel pressure is all over the place, even with the engine off.

He said the first thing to change is the fuel pressure sensor? I don't mind changing this (haven't had a price yet) but concerned I am going to just throw money at it.

Should the sensor throw a code?

Once it starts, it seems to drive ok as far as I can tell. Idles fine, doesn't cut out or stutter etc. The only symptom is an intermittent long crank.

The long crank happens every journey, its just whether its the first crank or the second etc, ambient temp makes no difference and there is no pattern to it.

Can you test the sensor?
Thanks
 
Update

Have a friend who works for Audi stick his laptop on while it was doing it.

You could see some white smoke coming out while it was cranking, he said this was a symptom of the long crank, dumping fuel into the exhaust.

Reckons the fuel pressure it about 4bar at crank which is plenty to start it and whilst running, the pressure it around what it should be.

Said one of the injector readings was high, showing 2.67mg and the rest were -1 or similar and were compensating for the injector with the high reading to get the overall value from all four to zero.

Said it’s worth changing the fuel pressure regulator first as if this has an issue, it can cause the readings for the injectors to the off. Failing that, it’s a leak down test for the injectors and replace any that are failing.

Reckons it’s worth letting the garage change the fuel pressure sensor Monday for the sake of £95 but he doesn’t think that will fix it.
 
Changed that sensor and made no difference.


Garage who I took it so reckon it could be the HPFP disintegrating and instead of throwing parts at it, they want to remove the pump and check for metal filings!

It runs fine, its just an issue with it turning over.
 
Have the EXACT same issue, i am suspecting a possible missing signal to injector when the issue is present, cause if I use starting fluid, it starts right up.
 
Might be worth looking at fuel rail pressure regular too. On the other end of the rail to the sensor.

Mine had a wildly fluctuating fuel pressure and rough idle, and replacing the reg fixed it.

Garage did the fuel metering valve on the HPFP first and it had no effect.
 
Is it turning over fast enough ? Ours starting cranking for longer than normal and started dragging the battery down .
Didnt initially sound slow turning over . Took a punt and swapped to starter out ....problem solved .
 
Haven’t got round to doing anymore on this but it’s still happening.

First start of the day is fine, fires in a second or two.

Then it’s hit and miss. I drive somewhere, turn it off and restart quickly (petrol station for example) and starts instantly.

If I park her up and leave for a few hours, I then get the long crank. Like 30 seconds sometimes.

If I am honest, I think it’s not driving right either. Like is feels sluggish. It’s the 140bhp and it doesn’t feel like it has full power, if I drop below 70 I need to
Shift down to 5th and below 60 down to 4th.

Going to do an injector leak off test next. If injectors are ok, I may swap the fuel regulator next
 
I have checked all of the injectors and they were fine(one was a tad bit off, but replacing it didn’t change anything).
Removed the ECU and saw some green corrosion in some of the pins! I am sending the ECU to be checked and overhauled, will update…
Hope this fixes it
 
Leak off test done, nothing particularly to note. All fairly consistent with each other.

Guy reckons the next step is the fuel pressure regulator.

Weirdly I’m now having issues with it not even cranking sometimes, I get in and turn the key and it just clicks. Sometimes I have to turn the key 15 times before it starts to crank.

Not sure if I have two issues here, one fuel pressure related and a starter motor issue too!

Only reason we are looking at fuel pressure being the cause of the long crank is because the pressure is erratic with the engine off. Pressure seems fine when idling, no issues with idling either or stuttering while driving etc.

IMG_0788.jpeg
 
If you might have starter issues you could also try a BM2 Bluetooth battery monitor on the battery to check the cranking voltage, and it's a handy thing to have for the future anyway.
 
Maybe not the issue, but try a jump lead from the negative post on the battery to a solid good connection on the engine. Might be a long shot but you've got little to lose.
 
DaveD said:
Maybe not the issue, but try a jump lead from the negative post on the battery to a solid good connection on the engine. Might be a long shot but you've got little to lose.
Click to expand...
Just tried this. No difference

Also cleaned up both battery terminals and removed the earth from the starter motor and cleaned it up, although it didn’t look overly dirty.

Starter motor looks a bit of a mess though, lots of black bits although unsure if this is normal

IMG_0790.jpeg
 
meza said:
If you might have starter issues you could also try a BM2 Bluetooth battery monitor on the battery to check the cranking voltage, and it's a handy thing to have for the future anyway.
Click to expand...
IMG_6597.png

This is the info you can get. The BM2 is about £15-£20.
 
You could just put a voltmeter on the starter battery when cranking.
 
Battery seems fine as far as I can see from the BM2 app. It was 12.8v when I got in the van and cranking voltage looks ok. Typically it started fairly quickly during these tests, will
Try again once I get the long crank, likely tomorrow.

IMG_0804.png

IMG_0805.png
 
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