Down on power…

[G-olf]

It may be worth a phone call to them, explain whats happening. They will point you in the right direction.
Have you tried it with the other map settings? maybe one with less aggressive settings and is it still the same?
Retarded timing can sometimes make it feel flat?
What about an air leak before the MAF? something which it can't fuel for? Just ideas

[pudding]

That's the good thing about VCDS, you can log up to 12 measuring blocks at once, but that isn't enough for the full picture, so I do two runs.

Run 1: For general fuelling and boost health.

Engine speed, MAF, intake air temp, Lambda requested, lambda actual, current fuel pressure (LPFP), fuel rail requested (HPFP), fuel rail actual, Boost pressure requested, boost pressure actual, throttle position.

Run 2: For checking detonation as the engine will be fully up to temp.

Ignition advance, knock regulation (ignition retard) cylinder 1, " cylinder 2, ", cylinder 3, " cylinder 4, engine coolant, VVT angle requested, VVT angle actual.

If you enable 'Turbo', you get instantaneous readings, rather than the slower non-turbo refresh rate, which can help if you feel the requested and actuals are slow to match.

With that you will get an overall picture of what the engine is up to.

I normally just load up the logging, close the laptop lid and go for a 30 min drive.  Get home, save the log file to my desktop PC and assess the results over a glass or 5 of wine.

I might also get a cheap windows tablet and use VCDS's gauges for some live monitoring action.

[JoshB]

I’ve just been out doing some data logging, got the screen below? Can anyone help???

[pudding]

Lol, is that a Fast & Furious reference? 

[JoshB]

So I replaced my MAF sensor last night, and it actually made a difference. Not massive but deffo pulls stronger and smoother, but the reading has also gone down quite a bit. Was previously around 220g/sec, but with the new sensor it peaks at 160g/sec, but as said it’s now a bit faster…

Had a good look round the engine bay and spotted a couple of things.
1) This bracket between the coolant and brake fluid reservoirs has snapped which beans the pipes are free to bounce around. Not sure if it matters but it’s not good. Unfortunately the bracket is attached to some sort of plastic tube that the pipes go down inside. Not sure how the hell you're supposed to replace it.


And 2) I noticed that my HPFP was covered in oily petrol. The connector in particular was full of fluid (smelt more oily than petrol). I’ve never had the pump off so not sure if it’s normal to spill a bit when you replace the cam follower? I didn’t do it. The underside of the airbox was also covered, you can see some on the vac pipe to the PCV above. But according to my logs, the fuel rail is getting 125bar, and it doesn’t weep on idle.


Again, I’m not sure if any of this matters but it’s things I’ve noticed if it jogs anyones thoughts?
I’ve sent an email to R-Tech last night, see if they reply and see if they can fit me in for a diagnostic.
Booked in for all 4 wheels refurbing and trying to sort my rear calipers before I tried to sort this… turning into a right money pit…

[pudding]

220 and 160 g/s would roughly equate to 270 and 200hp respectively.  Strange that the new MAF is reading considerably lower.  Did both tests hit the same rpm, in the same gear, and both full throttle etc?

Can't see the pics currently but oil around the HPFP and under the airbox could be a PCV issue or a torn O-ring on the HPFP?  They can get pinched quite easily when sliding the pump back into it's hole.

Money pits indeed, but once sorted they're damn good cars.  I've been putting off the wheel refurb for years as it's the final cherry on top, which my car doesn't deserve until it starts behaving itself 

[JoshB]

Well I think I’ve got to the bottom of it, but not fixed yet.
Was digging around in the engine bay and wiggling all the vacuum pipes until I finally heard a hiss. Found this little bugger right under the HPFP off the brake booster. Another symptom was the engine bogs down if you pump the brake pedal at idle.


It pulled off with ease. It looks ok and there was no obvious signs of damage to the pipe but I instigated a “repair” anyway, PTFE tape solves leaks on my radiators!


Took some getting back on and stopped the hissing. And whilst I was fiddling, Phil from R-Tech rung me up to reply to my email. Had a good 20min chat (much appreciated!) and he thought it was definitely a vacuum leak somewhere. His first question was actually if someone had changed the map, and luckily I’d actually checked that in the morning! As soon as described the leaky oil he was adamant it was the top PCV pipe.

Looked fine to me but I’d heard they go brittle, a single wiggle resulted in catastrophic failure…


So I instigated yet another professional engineering repair.


I’ve instantly gained about 50ftlb’s of torque. Can trigger the traction control light again!
It still not back to where it was but loads better. New brake booster hoses and PCV hoses are in the post.
I’ll report back when fitted, although I’ve no idea how the hell you’re supposed to get that bottom PCV hose off, I can’t get my hand in.

[pudding]

I replaced the bottom PCV hose on mine last year and it's actually not too bad a job.  Mine was almost plugged with baked in carbon deposits and it snapped in half like a dry reed, so well worth replacing that.

Yep, the oily mist on your HPFP sensor is from the PCV.  Either a cracked top hose as R-Tech said, or gasket/O ring related.

Glad to hear it's finally on the mend    Strange that a vac leak that big wasn't flagged by the ECU.  Normally get 'system too lean' codes and really big long term fuel trims.

[rich83]

Glad to see you are making progress

[JoshB]

Go on then, any tips on how to get the bottom PCV hose off? I literally can’t even get my hand on there. I don’t have to take the inlet manifold off do I?

[ROH ECHT]

As Pudding said; Mass Air report will vary depending on which gear each pull was done with.
Also, it may have been leaking (in the locations you've discovered) more so during one pull than the other.
Disconnecting the breather tube from the filter housing has its difficulties for it being a tight spot, but I managed with giant hands. And since you are replacing it...do not worry about damaging its clips on the end.

[LC5F]

I replaced mine when my manifold was off  - it split in the same location while taking it off
Can you get to it from underneath - past the oil filter and intake hose?

[JoshB]

All done! Managed to get a finger on the top and a wood chisel underneath. I couldn’t believe just how brittle both pipes were. Full of gunk and full of cracks, managed to get some Febi Bilstein parts for under £30 and they fit perfectly, just have to keep an eye on them in future. Obviously these were the original parts so some black plastic being subject to heat cycles over 17 years, they’ve done OK I guess. I just can’t believe the whole PCV system can cost you like 50bhp.

Just glad it was something so simple in the end. And it doesn’t shake anymore on idle. Thanks for everyone’s help!

[pudding]

Yeah it's not a bad job that pipe.  I just did a classic reach around behind the runner flap motor and managed to get it off.  If the pipes are that bunged up with crud, I hate to think what the oil separator in the filter housing looks like.  Next time my intake comes off for injectors/walnut cleaning, I think I'll be sticking a new one on.  R-tech have mentioned in the past about those getting clogged up and causing running problems.

[G-olf]

Its nice if you can find the problem and its not too expensive to fix 

So this looks like another thing on the maintenance/check list.
What happens with that bottom pipe? Blocks up with crud??