Assistance required with my DTM 2.0T - issues with cutting out under load

jaybv6

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I've had my 2006 A4 DTM for over two years now. When I first got the car it was treated to a new Cam chain and oil pick up for the revised item as a preventative measure. Since then there has no expense spared on the car, it has been regularly serviced with Mobile 1 oil and Genuine filters. I also use the car for my daily commute to and from work (around 12 miles round trip) giving it good runs on journeys back to see my dad in Birmingham. Performance has been great (especially as it's a stage 1 Revo) and has been faultless until recently.

A Month ago I was returning from work and put the hammer down, the car surged forward till it got to 3500rpm and then it cut out. I tried it again and the same thing happened. I drove the car slowly and gingerly let the revs rise and they managed to get over 3500rpm and towards 5500rpm without any issues.

I plugged in VCDS and monitored a number of things especially as the errors being thrown were around P310B - Low Fuel Pressure Regulation - Fuel Pressure outside of specification initially and then after repeatedly forcing the issue to log data I got
P0087 - Fuel rail/system Pressure Too Low.

I did some reading up on this and monitored the rail pressure and the efficiency of the Lift pump in the tank. This was showing outside of the tolerance levels (at idea was showing around 65%) and when the issue occurred the rail pressure dropped dramatically.

New lift pump was bought and fitted, after which the issue was still there but was getting worse (car would not go above 1500rpm).

New High Pressure Fuel Pump bought along with Cam Follower cap, Fitted the new HPFP and things seemed better but the issue returned after a prolonged drive.

New G410 low-pressure Fuel pump sensor, fuel filter and spark plugs all fitted and although it's improved things I cannot deploy any sort of load and have to nurse the throttle to get it up to speed. The car sounds great, no weird noises on idle or when the car is being driven.

I'm now at a loss as to what the issue could be but wondered if anyone had any suggestions. Just to recap the list of new, genuine Audi parts fitted are as follows

Complete Lift pump in the tank
HPFP which included a new Fuel Pressure regulator
G410 low pressure sensor
Cam Follower cap (old one was hardly marked)
Fuel Filter
Oil Filter and Oil Change
Spark Plugs (NGK Iridium BKR7EIX one stage cooler)

I'm not opposed to spend more on the car to fix this but don't want to take it to Audi unless I really have to, seeing as I've shelled out over £650 already.

I'll gladly stump up a few beers and a chat for the person that gives me the winning solution to my issue.
 
When was the fuel filter last changed?
 
Coil packs tested?? Injectors tested?? Air flow meter tested??

Cheers for the pointer. Any tips for testing the above?

I have a fully licensed VCDS so it's at my disposal for checking.

Thing is the engine is not running rough. It purrs like a kitten and this only happens under heavy load and at the same point in the rev range. But careful slow driving I can get it past that point up to and near the red line.

It's as though something is cutting the fuel.


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How's it drive with the MAF unplugged?
 
Not tried driving it with maf unplugged. Will need to try

I live in Reading.
 
I had both of those fault codes when my engine control relay packed up. They were amongst other codes but could be related
 
Not tried driving it with maf unplugged. Will need to try

I live in Reading.
A fellow reading member!!!
I can recommend a company called TVED to test the injectors. A injector could be breaking down under load causing the ecu to cut power to safe guard the engine. What coil packs are you running?? Red top from audi r8??
 
A fellow reading member!!!
I can recommend a company called TVED to test the injectors. A injector could be breaking down under load causing the ecu to cut power to safe guard the engine. What coil packs are you running?? Red top from audi r8??

Cheers for the tip about TVED, looks like they are not far my mates workshop or my mates MOT Centre. Not sure on the coil pack but they aren't the red top ones for certain. I'm gonna try pulling the MAF first and see what happens.

I've also seen some article about changing or restring some setting after replacing the LPFP and HPFP in VCDS but details have been sketchy.


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Ok so pulled the plug for the MAF and the problem still persists. It's like a stutter at 3500rpm and then it's ok but only under light throttle.

Also checked the pipercross panel filter and that looks ok also.

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Next job for this week is to log data for boost, fuel pressure and rpm to see if there is any correlation.


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Did you manage to get to the bottom of the problem??

Not yet. Been a slow couple of week. Off to my mates workshop Saturday to have a look over the car and see if we can get it up
On the ramp and see if we can see what the issues is. Also going to do some vacuum tests aswell. Did take the following snap of what boost is doing when the issue happens.

513b4d88a9e8f96f4aefdabaf12b535c.jpg



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So another update on this. Started to look into loss of boost as the boost cuts when the issue happens. Found that the N75 was knackered, one of the pipes connected hard plastic connectors coming off the N75 was snapped and would not have been helping matters. So replaced that. Was going to replace the Dv at the same time but for two reasons I didn't. Reason 1 was that TPS gave me the older part instead of the latest part, which I did not realise till I got home and the second reason is that I have found out that I have a Forge Recirculaton valve on there instead. Plan is to remove the forge and fit the later DV. However after fitting the new N75 things see a little better, it's bosting better and goes quicker but still get the hesitation, sometimes manifested as a cut in power and other times as a stutter. Always apparent when nailing it.

Have cleared the DTCs and still get the following

012555 - Low Pressure Fuel regulation
P310B - 002 - Fuel Pressure Outside Specification
Freeze Frame:
Fault Status: 01100010
Fault Priority: 0
Fault Frequency: 2
Reset counter: 255
Mileage: 179738 km
Time Indication: 0
Freeze Frame:
RPM: 3039 /min
Load: 6.3 %
Speed: 50.0 km/h
Temperature: 75.0°C
Temperature: 16.0°C
Absolute Pres.: 990.0 mbar
Voltage: 13.843 V

which has been joined with the following

000135 - Fuel Rail/System Pressure
P0087 - 002 - Too Low
Freeze Frame:
Fault Status: 01100010
Fault Priority: 0
Fault Frequency: 1
Reset counter: 255
Mileage: 179739 km
Time Indication: 0
Freeze Frame:
RPM: 2385 /min
Load: 60.0 %
Speed: 66.0 km/h
Temperature: 86.0°C
Temperature: 16.0°C
Absolute Pres.: 990.0 mbar
Voltage: 13.716 V
 
Job for this weekend. Remove the forge DV and fit the OEM piston type DV and see if it's any better.


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Removing the forge was a pain in the ***. All the bolts were rounded inside so I had to chisel them off. Fitted the OEM piston DV and although it's not as severe the issue is still there. Absolutely baffled as to where to go next. MOT ran out the weekend so the old girl is in for that tomorrow (thank god they don't have to drive it) and then I'm going to book it into a local garage and see if they can figure out what I've spent an age trying to sort.


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MOT done and new coil packs. Slightly better but still no joy. Now booked in for an independent to take a look.


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Sorry to hear about all your issues. I think it's highly likely the crank sensor located under the oil cooler is faulty. It fails on these TFSI engines alot, but dealers and specialists are not good at finding the fault, as it won't show up in VCDS.... It's a tiny part, with basic electrical connector. Trouble is it sits under a very hot, oil and water cooler on the engine block...

I'm in Solihull, so a local beer is possible!

Alistair
 
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Thanks for the advice. Although the car hasn't been exhibiting the symptoms of an issue with the crank sensor as it's repeatable on demand and directly related to more fuel being required to fulfil the 280 horses waiting to be unleashed.

So I gave in and took it to a local Garage. They test drove the car and it's definitely fuel related. Tracing the wiring back it seems to be an issue with the low pressure fuel module which sits on top of the fuel tank, when the car is on WOT and demanding fuel the low pressure module cycle does not change. Car goes in again on Friday to have this replaced along with the off side front window mechanism replacement and hopefully the might DTM will be driven once again. Will keep you updated.


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Update on the issue.

Fuel module replaced and did not resolve. Left hand side of saddle tank was empty when right side was half full. Tracing of fuel pipes and they found that one of the pipes that come up at the back of the wheel arch liner and into the engine bay was linked and folding under load. This was rectified and the car is back to normal again.

There were a catalogue of issues. The LPFP failed and took out the fuel module. That along with the fuel pipe issue caused the issue. On top of that the N75 had a snapped connector.

On the plus side after replacing all the bits detailed the car is pulling better than ever and is strong. Pleased to have the DTM back .

Thanks for all your suggestions.


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Glad to hear it's sorted pal.

Not heard of the tfsi engines having those issues though.
 
Glad to hear it's sorted pal.

Not heard of the tfsi engines having those issues though.

It's typical I'd get something different.

The car now pulls well and the hesitation high in the revs in 3rd gear has been eliminated now (was there when I bought the car). It feels better than ever.


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