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The mystery deepens in relation to parts - ETKA lists a Pierburg fuel delivery unit for a VR, but with a VDO 4 bar pump inside it. The FPR is definitely supposed to be 4 bar, there don't seem to be any other options. The replacement Pierburg unit I was assured is for my year/chassis number is listed as 3 bar! Looks like I will need to pull the pump unit and get some part numbers - or does anyone have any out to confirm? To make matters worse, I found an old fuel rail lying around, and this had a 3 bar FPR in it, but I'm not sure if that was from a 2.8 VR6 off a Golf or the like.

Here is the picture with the mysterious screw. As an aside - is it a big deal to remove the distributor - looks like it's just two hex bolts holding it on, but do you need to line up stuff when replacing?

Thanks Rob - no worries. From what I've been reading: OBD1 2.8 AAA cars have a 3 bar regulator (Golf, SLC etc.) OBD1 2.9 ABV have a 4 bar regulator and run at 3.5 bar, 4 with the vac hose disconnected, this is what I get I've double checked ETKA and cross-referenced the Bosch part numbers and I have the correct FPR. What I don't know is if the vacuum pressure reading is correct.

They've all been replaced, so should be fine. The cars seems to cut out when idling and then won't start for a good while - there's no error codes in VCDS - I can pull all the values from it if anyone thinks it would be helpful or could assist in interpreting them.

Anyone? Am really stuck here.

Checked mine - no screw - I'll post a pic later of the exploded parts diagram though.

Suspected as much! I did however also find a VW diagram that shows a screw holding the rotor arm on - would have to rotate the engine or remove the distributor to get at it though...

While investigating my fuel system (separate thread on here) I decided to take a quick look at my distributor - not good, unfortunately the casing part where the hall sender socket is has broken away due to plastic fatigue - still seems to work, no errors when scanned, but will have to do something about it. My question was - is the rotor arm glued on? It doesn't seem to want to budge at all, and I don't want to destroy it by taking a screwdriver or pliers to it? For anyone that needs them, the part numbers I have found are: Distributor arm - 021905225B Distributor Cap - 021905207 Distributor - 021905205AE

Vacuum test shows 46 hg vac at idle, which converts to 22 PSI or 1.5 bar - at least I think I have that right - what should I be seeing? The engine seems to be flooding and not starting from warm as well - so I'm thinking injectors, fuel lines, fuel filter and is there a valve somewhere else in the fuel system?

There could be a spring on either side of it as well - try sliding something very thin, like a putty knife in on each side, and then pull gently - at least that was how it was done on the one in my old MkII Golf.

Ok - so here are the results of some more testing this morning. With the engine running at idle from cold start - constant 3.5 bar, this agrees with VAG specs and the Canadian source in the link above With throttle variations, the pressure varies slightly up or down. The behaviour is the same when warmed up and running the standard cycle With the vac hose on the fuel pressure regulator disconnected, pressure rises to 4 bar, also seems normal and as expected. When I turn off the engine, pressure drops to just above 3 bar, but then gradually rises to just below 4 bar? Strange. Will leave it sitting for half an hour and then see. Will also do a vacuum test - does anyone know what values I should be getting on the vac test?

Found this: http://www.corrado-club.ca/mods/vr6_fp_test.html and it says 3.5 bar running and 4.0 with the FPR vacuum hose disconnected. Gonna do a few more tests.

Ok - I found two fuel pressure testers - one I can't make head nor tail of the dial on, and I'm not sure it's working properly, and the other for K-Jet systems - this measured 3.5 bar with the engine running, but it leaks very slightly, so I won't get a proper residual reading. From my reading of the Bentley I should be seeing 4 bar? Anyone know what the pressure with the engine off should be, or will it just drop to 0 gradually over time? The Pierburg replacement fuel pump I am looking at is rated at 3 bar.

Lads, really need some help here. I can get a replacement for the whole fuel pump unit for €340, but don't want to spend that kind of money if I don't have to. The fuel pump relay will cost €10, but this was already replaced 2 years ago with a new VAG one, so not sure, but willing to try it because it's cheaper. Or I should I just take the risk and try to do a fuel pressure test tonight to see what's happening and what kind of results I get? My gut feeling says the last option, and I think it's not holding residual pressure somewhere, but I would have thought a new pressure regulator would have helped there... Can I pull an injector to check the flow pattern without removing the intake manifold? It's my daily, so I am kind of stuck. Any ideas appreciated.

Yeah, have that - just have to find my pressure testing kit and take it from there.

That's my plan - I just need to find my pressure tester - I'm planning to use the test nipple/connector on the fuel rail - is this correct?

Well - another update. Replaced FPR with a new one last night. This morning the car took ages to start - it looks like there is no residual fuel pressure even with the replacement. My ideas now: - fuel pump relay (replaced 2 years ago) - ECU relay (replaced 2 years ago) - Vacuum leak (all looks fine - will carry out a vac test) - Fuel filter (replaced 1 year ago) - injectors (have bought a set which I will get refurbished) - Fuel pump? Any more ideas? Thanks.

Oh well - I was going to say you're in luck if it doesn't have a sunroof - ;) - as most of them break. Best of luck with the new purchase - someone should be able to sort you out with a fog light handily enough!

Welcome on board. Does it have a sunroof?

Not looking good there - at least you have another car to swap it over from, assuming it's in better condition of course.

No - thank god. Don't fancy a fuel pump replacement either. The last time I did that on a MkII Golf GTI, the tank sender never worked properly afterwards! VW Classic have what looks like the right Lambda: http://shop.volkswagen-classic-parts.de/vwcp/scirocco-corrado/corrado/fuel-exhaust-system/lambda-sond-021906265e.html Will get on to VW Heritage in the morning.

There's loads on ebay and VW Classic Parts actually have them new - the passenger side rarely fails as it doesn't get the same amount of use.

I've pulled the codes - apart from the standard engine speed sensor error with the engine not running (which goes away), there's only a Lambda probe error: 00537 - Lambda (Oxygen Sensor) Regulation 08-10 - Control Limit Surpassed - Intermittent Time for a new 02 sensor? I'll check again after a few days. As an aside VCDS v15 did not like talking to my ABS controller - lots of comms errors, has anyone seen this before? I've also fitted a new fuel pressure regulator - but there seemed to be very little residual pressure in the system - when I undid the test socket on the left of the fuel rail, nothing came out! I'll check again tomorrow and then dig out a fuel pressure tester to follow up on this.

Anyone have any tips on troubleshooting the cam or hall sensor on a VR6 with distributor?

I have two MAFs, one the original one that came with the car and another that was a new VAG replacement, but the symptoms are the same with both. They're expensive and hard to find as well if they are the earlier type.