Brake servo assistance - or lack of it

[norwichphoto]

Recoded key and now they're being recognised.

Another test drive. Throttle response at low revs after a stop poor - eg entering a roundabout. Better when gearbox in sport mode. Fine at higher RPM. Wondering which channels to log on VCDS whilst driving to try and work out whats going on. engine speed, road speed, throttle position - but what else?

[Shoppinit]

Mass air flow, turbo boost requested and achieved. And trim: additive and multiplicative.

Then later, if that doesn't show anything, ignition advance and cam dephasing.

I bet the MAFs will tell the story.

[norwichphoto]

Drove car home and into work this morning. CEL came off during the journey to work.

I also logged various things, but not examined the log file yet.

Interrogated error codes:

17535 - Fuel Trim; Bank 1 (Mult)
P1127 - 002 - System too Rich - Intermittent

17537 - Fuel Trim; Bank 2 (Mult)
P1129 - 002 - System too Rich - Intermittent - MIL ON

17544 - Fuel Trim: Bank 1 (Add)
P1136 - 001 - System too Lean

17546 - Fuel Trim: Bank 2 (Add)
P1138 - 001 - System too Lean

17416 - Mass Air Flow Sensor 1/2
P1008 - 008 - Implausible Signal - Intermittent

[Shoppinit]

My feeling is that you haven't seated the airbox properly. It's a pain to get right. Stupid design.

[norwichphoto]

I'll pull it off and try again.

The seals looked to be in good shape, but I may get some replacements.

[Shoppinit]

I hate the bloody thing. If there is any springiness in it when you push down on the back then it's not in properly.

Anyway,those codes are pretty indicative of an air leak.

Use a bit of water to lubricate the seals before inserting, maybe.

[norwichphoto]

I've removed and reseated the airbox. Agree its a somewhat flawed design as all the physical fixings are at the front, and the important end relies on two rubber seals.

Anyway, its improved idle and on the short test drive, seems to have improved drivability - but will wait for a longer test drive later.

Logging MAFs shows a slight imbalance between one bank and the other, but its quite low. Is there a tolerance?

Prior to the brake servo issue, the CEL would occassionally come on due the secondary air injection system, the pump was failing and making a screeching sound, and one of the thin bore vacuum pipes had a split in it. I've replaced the pump with a good s/h one and new thin bore vacuum pipes. Never got any other error codes relating to that side of things.

[Shoppinit]

Yeah, 10% difference between banks is normal as long as it’s all the up the power curve. You should have about 5g/s on idle and more than 200 at WOT. Each bank.

[Shoppinit]

Clear your ecu fault codes (even if there are none) to reset the trim and then observe how it ends up after 10 miles or so.

[norwichphoto]

So far, so good. No error codes. Smooth idle.

Still got the brake light to sort out. At some point I've got to look at the door microswitches - but I'm having a weekend off this weekend. My other projects have lapsed - finish fuel injection conversion on Lancia Montecarlo, replace some rotten wood in the floor of my motorhome, and at some point dismantle a garden shed which is approaching the point of falling apart.

Thanks to all who have contributed advice and assistance.