boycie

I'm afraid I can't advise on where you can go to get a new engine fitted. However, I had very similar codes and symptoms when my timing chain jumped. I have a trusted VW specialist who removed the engine after confirming there was no piston to valve contact (I was very lucky). I then had the top-end rebuilt anyway (with the better KB pistons etc) by an engine specialist and put back in. So you have two options, both of which will ideally need a VW/VAG specialist: 1. Replace the whole thing with a reconditioned engine. 2. Get yours checked to see if there's been any internal damage, cylinder compression etc. If you've gotten away with it, you might be able to just get a new chain kit put on.

For anyone who has the same query, the 03C906036N variant is not a direct swap for CAVE engine. They were issued in CTHE engines and have different connector plugs. They can still be fitted, but the connector plugs for the wiring loom have to be changed first.

@sepulchrave Thanks for the advice, I’m hoping you’re right. I’ve got a set of N variants on order, I’ll update this post with the outcome in case anyone else has the same query. 👍

Hello everyone. I'm looking to replace the fuel injectors on my 2011 CAVE. It is currently fitted with the 03C906036F variant, which is known to have a narrow spray pattern that doesn't atomise well. I've looked at various parts catalogues and can see there are 2 subsequent revisions - M and N suffix. It is usually stated that M is for vehicles manufactured before 08/12, and N for those after. My question is, why doesn't the N suffix just supersede M for all twinchargers regardless of manufacturing date? The switchover date makes me wonder if it's due to the different ECUs in CAVE vs CTHE engines - can anyone confirm if I'm along the right lines, please? There's info out there saying the M variant's wider spray pattern fouls the spark plugs, so if the N variant rectified this and can be applied to a CAVE engine, I'd naturally rather go for those! Thank you.

PS. It has had a pending ‘Rich off idle code’, and recently triggered the P0420 cat below threshold code, which has since gone away itself.

Thanks for your reply. I've been led to understand that a failed PCV system can cause either a lean or rich condition depending on whether it is stuck open or closed? I'm perhaps optimistically thinking if one of these valves is stuck closed it may be preventing the cranckcase from being vented properly, thereby causing a rich condition? I'm using a Carista dongle and the Car Scanner Pro app, which can map basic OBD2 data onto a live graph. The 'tracking' of the fuel trims with engine load is particularly evident when the supercharger kicks in... at this point both long and short trims are at or around zero. I also notice the long term fuel trim occasionally rockets back up to 0 from around -20 when coming off the throttle. I'll see if I can map the data for both sensors at idle and higher RPMs. I assume I'm looking for the usual yoyo-ing of the pre-cat and a steady halfway reading from the post-cat accross all ranges? Thank you/ Thanks for your reply also. It's a late 2011 CAVE that had the breather modification done early in its life, presumably due to oil consumption. It has the latest revision of the breather hose into the cylinder head (03C103558AA) and the check valve system from the timing case (03C103474AD). I also updated to the latest ECU software last year (9971) as it was previously running 9970 (not sure if this was the version being flashed with the breather mods at the time).

Hi everyone, I'm looking for some advice regarding the circled breather hose and valve (03C103558AA), please. Does anyone know if this would contribute to a rich condition at idle if it fails, and is there an easy way to test if it’s still functioning? Could the check valve system from the timing cover to the intake (03C103474AD) have similar effects? The HPFP has recently been replaced (since the photo) and has helped to an extent, but I’m still getting 15-20% negative long term fuel trim at idle. This appears to normalize under boost (the fuel trims seem to track with calculated engine load on the live data graphs). I'm not getting any logged misfires, but the idle is rough and doesn't sound healthy. It's a recently rebuilt engine and measured almost 190 psi on each cylinder. I'm basically trying to rule out a breather issue before moving onto the (more expensive) injectors… thanks all.

It appears they still do, I’ll reach out to both and see what they have to say. Thanks for your advice.

@Ootohere Thank you for your reply. I’ve been looking at the APR remap and also RTMG (who are actually fairly local to me). If either of these would be beneficial in the long run then I’d happily pay the money. As I said, not interested in more power… obviously it’s an outcome of these remaps, but the car is already plenty fast enough for my needs since the overhaul. My car had the cylinder head breather mod done in 2012, and was running version 9970 of the stock ECU software when I got it. I updated this to the latest 9971 version about a year ago, this is the revision that tackled the knock sensitivity and fuelling issues in the original code (mentioned in Lucifers Ultimate Guide). I had CAVD oil spray jets installed when the engine overhaul was done, since they appeared to be the ultimate solution for the twincharger’s oil consumption woes (six months and 5000 miles later it hasn’t needed topping up once). Very pleased with it now, feels like the engine it should have been from factory (there I go jinxing myself again). Just wonder if a remap is the final piece of the puzzle to help ensure some long term reliability… On a side note, do APR insist on remapping the gearbox alongside the ECU? I know some tuners do due to the 250nm torque limit.

Hi everyone, I've recently had my CAVE engine overhauled. Having spent all this money, I'm keen to try and make sure it stays healthy for as long as possible. I've read here and elsewhere that some folks believe a decent stage 1 remap can be beneficial for the long-term health of a CAVE, mainly due to improved fuel delivery (ie. not running as lean under boost, less cylinder starvation). I have aboslutely no interest in chasing BHP, especially not at the expense of engine reliability. Just want to get an idea of your thoughts on this? I'm currently running stock ECU software 9971, NGK SIZR spark plugs, latest revision coil packs and HPFP, no hardware mods. Aside from an occasional blip at idle, it runs beautifully. The DQ200 has also been remapped with TVS Driveability Upgrade software for longevity (unsure if an ECU remap would then warrant another remap of the DSG)? Thanks in advance for any advice/opinion.

@Rooted I've seen a few sources stating VW 504 is a newer and more demanding spec to meet than VW 502, such as VW 507.00, VW 504.00, etc: Volkswagen Motor Oil Specifications Explained - oilspecifications.org which includes the following: These sources give me the impression 504 is preferred in all instances, but that you can 'get away with' using 502 spec as long as you don't exceed fixed service intervals. Your comment about bore wash is interesting though, as well as the description (in the links you posted) of 502 spec oil being preferred in 'arduous/strenuous conditions'... such as in a highly-strung twincharged engine. It does make me wonder if 502 spec oil is seen as more 'robust' and able to resist heat degradation? As I said, just genuinely curious as to the science behind the debate. Luckily, consumption does not seem to be an issue for me with a 504 spec 5w30, but if a 502 spec 5w40 will serve my CAVE engine better in the long run then it's worth considering a switch. Is it the cylinder 4 spark plug that tends to get coked/fouled, by the way? Thanks for the replies everyone, much appreciated.

Hi everyone, Firstly, a thank you to you all for sharing your knowledge and experiences with these engines over the years. I've been a long-time 'lurker' on this forum after buying my CAVE twincharger 18 months ago and have found it an invaluable source of info. As a bit of backstory, my CAVE was originally an oil drinker. I did find moving to 5w40 and using manual shifting on the DSG helped slow down consumption. I've since had the engine overhauled with (amongst other things) the improved Kolbenschmidt pistons, CAVD oil jets, and latest ECU software. It is currently running on 5w30 and shows no signs of buning oil after nearly 2000 miles post-overhaul. My question is - why is 5w40 is so often recommended as the preferred oil grade for this engine? Is it purely due to the reduced consumption in oil-thirsty examples, or are there other benefits over 5w30 even for a non-oil-burner? I ask mainly because VW 504.00 spec appears to be superior to 502.00 in every way on paper, and I'm yet to see a 5w40 grade oil that meets 504.00. The 'longlife' aspect isn't a concern, as I've been changing the oil and filter change every six months under my ownership and will continue to do so. I appreciate any insight you might be able to give. I've spent quite a lot on this engine trying to get it the way it should have been from the factory and want to do all I can to keep it running healthily! Thank you.