3.0tdi CAPA limp mode

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bhodgkiss

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Hi All

My 3.0tdi CAPA engine is randomly going into limp mode
No faults logged in VCDS
It’s fine half the time, and limp mode the other half
Sometimes it also seems to misfire on startup and stall - only the last couple of days. But then full power again shortly after, and hitting full boost and full fuelling
I’ve checked the throttle body (taken apart, it wasn’t too clogged and the gear mechanism was fine when I looked inside)
I’ve chatted with desertstorm and I do get 0% throttle activation at idle whereas he has 55% - so could it the the throttle body?
I was thinking could be EGR related?
I still have the full egr system
Such a pain not having a fault logged!
Maybe I should change the throttle body assy anyway?
Any help appreciated
Many thanks
 
Ben is this tuned? could be the tuner has killed DTC's but the hardware is still plugged in, therefore if there is a electric fault with the device it will put the engine into limp mode but no dtc will be shown.

I had a CAPA today in with a strange issue whereby the car would randomly lose power or feel jerky, turned out the EGT sensor was tripping the protection map
 
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Btw you could just remove the butterfly in the ASV ("throttle body").
Also could be swirl flaps semi shut and someone has done a swirl flap delete?
 
Many thanks Bobby (and Karl for all your help)
Yes I believe it has a mild remap and boosts to 1.56bar (requested) - which is higher than standard?
Is it possible to plug in a spare standard ecu for fault finding? I’d have to get one…
I’ll do some more logs and see if anything stands out
It does have the RH swirl flap motor arm missing as it keeps falling off, but it’s been like that for ages with no apparent issue - I haven’t replaced as the bottom plastic piece that rotates keeps falling out as the clip doesn’t hold it in …. So as suggested this needs threading and tapping
But maybe if it still has swirl flaps these have slowly rotated into a sub-optimal position, although im
Not sure why that would give full
Power sometimes and not others…
Where’s the best place to get a swirl flap delete kit please?
 
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ECU swap is not pnp as the immo will need to be turned off or ported.
Its easier to take a back up and revert the ECU back to stock and then check for faults.
As mentioned in pm's there is no need for a swirl flap delete kit:
1) Remove the lower manifolds
2) Remove the flaps
3) The lever hole now will need blocking off you can either use the stock lever (if its in good condition) or use m10 bolts (20mm long approx) and tap threads into the manifold. Some sealant on the threads for good measure doesn't hurt as a leak here would mean a boost leak.

If you need help to do these tasks drop me a mail on BobbySinghRacing@outlook.com

Cheers
 
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My 3.0TDI CAPA would go into limp mode due to one of the swirl flaps actuators not working, but a DTC wouldn't be present. No light on the dash shouting at me. However, if you cleared the non-existent fault codes, you could hear the engine come out of limp mode, and then drop straight back in. Replaced the swirl flap motor, problem solved.

I'm pretty sure someone sat on the laptop connected to my ECU in its previous life and called it a job well done.
 
Ok so today it’s limp mode and buckaroo’ing when I drive down the road
Maybe I just start changing sensors…
Would lambda be the first to try? Would that cause these issues?
Or then map and maf?
 
Have you checked the EGT sensor readings to see if they look sensible. This is one of the things that is quite often mapped out . Fuel pressure checks between specified and actual. You could spend a lot of money and time randomly changing sensors out and still not sort the issue.
 
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audi upgrades
Ok so an update, the car is quickly deteriorating and now stalls shortly after I start it up
So I presume I now check all fuel pumps and fuel filter?
 
A petrol nozzel wont fit in the fill hole. It doesn't mean it's impossible that it was filled with petrol though. At this point, If you don't know what it could be, you need a mobile mechanic to come look at it. They can then access it appropriately, especially with the right software and tools.
 
A petrol nozzle will fit as its smaller than a diesel nozzle. If you believe this is the case its time to remove the fuel pump and check if you've damaged it.
 
The garages have confirmed that from the recent transactions, the diesel pump was used
I’m surprised how quickly it’s degraded, so what’s the best thing to check/do first please guys? Check lift pumps are running and then a fuel filter swap?
 
Thanks for the suggestion
I was thinking that yesterday, as I read about a chap with fuel issues - and the toothed belt had lost all its teeth! It must have been the older 3.0tdi as the b8 belt is ribbed as opposed to toothed
Is the fuel pump driven off the main aux belt?
sorry if that’s a stupid question….
Does the fuel pump belt have its own tensioner?
 
bhodgkiss said:
Thanks for the suggestion
I was thinking that yesterday, as I read about a chap with fuel issues - and the toothed belt had lost all its teeth! It must have been the older 3.0tdi as the b8 belt is ribbed as opposed to toothed
Is the fuel pump driven off the main aux belt?
sorry if that’s a stupid question….
Does the fuel pump belt have its own tensioner?
Click to expand...
No the fuel pump is driven off a separate belt which is driven by one of the camshafts, it has its own tensioner.
 
Ok so this morning I disconnected the fuel line shown (I believe the feed line to the high pressure pump) and when the ignition is on, no fuel flows out of this pipe
So is that now a confirmed lack of flow from the tank, so lift pump or filter?
Is this the HPFP feed line?
And just to check, I’ve simply pressed the key in with no feet on the pedals and the dash lights up, and I hear various engine bay solenoids activating

924A5918 8AB6 407C 866B 094B680C9E4B
 
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I’ve also checked this yellow 20A fuse which I believe is for the in-tank lift pump?
 

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On the lift pump, is the small separate connector below (that I’ve disconnected) power and ground? I presume I should see 5v (or 12v) on this with ignition on?
 

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Ah maybe those two wires on the smaller lift pump connectors are for the level sensor
So fuel has now started flowing from that pipe (im not sure why it didn’t initially) and the engine fired up, but then just stalls again almost immediately …..
 
… and I now have this constant clicking in the engine bay when ignition is on
Sorry Bobby do you mean run the fuel system priming routine?
 
Ok so the more I’ve looked into this, and chatted with Karl, the more we think it’s a blockage on the exhaust side (dpf or egr related, but not throwing up fault codes for whatever reason)
The fuel side seems fine (I’ve logged fuelling actual vs specified and it’s fine even during the stalling incidents)
On the air side, the turbo actuator moves freely during the output test, so vanes are free to move
It’s now driving down the road in limp mode again, although white smoke out the back, and That’s with me having disconnected the egr pipe from the intake so it can suck in fresh air, as it looks to run better like that
I did disconnect the lambda as well to help if any DPF blockage, but it still stalled
The throttle valve performs its function test ok and is free to move (and fully open when idling)
So I’m thinking it’s the egr always stuck fully open, or DPF blockage

ican easily get an egr blanking kit ordered

If I did delete the DPF, other than an mot failure, where the best place to get one please? I also see there are long and short versions of the delete pipe?
 
Bobby has delete pipes in stock, problem with buying them on ebay is fitment can be an issue lot of the times. You'll also need your ECU recalibrating.
 
Are you 100% sure the car hasn't had any petrol in it. Does the diesel feel diesely. As I said earlier quick test is to see if it is combustible with a match . Diesel doesn't burn at all. Of course only a small amount away from anything else flamable.
 
Hi Karl

Yes I did the diesel test with a match :)
It doesn’t light and smells like diesel
But it could possibly be poor quality or a mix with say 25% petrol - although the garages have confirmed we’ve used the diesel pump at both the last fills

I’ve now put a plate between the egr pipe and inlet manifold incase the egr is constantly stuck open

Aside, is it normal for the egr actuator to suddenly ‘pop’ back about 2-3 mins after the engine stops? It does this at the same time as the Turbo actuator solenoid stops it’s high pitched whine

engine is at 236k miles!
 
ha ha yes agreed Bobby - im just flat out and not sure when i can get down! Is it weekdays only. or is a sat/sun possible please?
I wonder if I could use my breakdown cover and get it recovered to your garage?
 
Ok so just had full power initially down my lane and then limp mode after I briefly came to halt, engine still running and when I then tried to get going again.
I was logging DPF differential pressure, which shows 0hPa throughout
I presume
Not normal to have zero showing here, unless the remap is zeroing this?
Still no fault codes, although as I’d previously disconnected the maf and oxygen sensor on the DPF these has just been cleared before I went out
 
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You sure someone hasn't deleted the DPF from the map but yet its still in the car?
Sounds all messy tbh and hard to help over the forum like this
Without the correct tools you'll be wasting a lot of time
 
Thanks Bobby
I do like to have a go myself first- but I dont want to waste people's time on the forum here!
As you say it could be a lot of different things..... I'll give you a shout if I do plan to head down your way :)
 
This mornings maf readings, this looks pretty ominous on MaF health if it just reports around 500mg constantly?

where is the best place to get a maf please?
 

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