LaserK04

The car:

Non DBW 97 A4 1.8TQMS, borla, K&N panel, GIAC/AWE K04. Just had the newest K04 file installed as well. (less than a month ago) Has run flawlessly until lately.

Over the last 3 weeks or so the performance of my AWE K04 kit has been steadily deteriorating. The car still runs fairly well, but I was holding a solid 17-19 psi (depending on ambient conditions) thru most of the rev band, and spiking a bit higher at times. Now, I get boost surging (3-4 PSI) if I go WOT below about 3800-4000 revs. Boost is down too, I spike to 15 psi and hold 13 or so, even in 4th (where I typically saw the highest boost readings).

MAF sensor is top on the list, but at $280, it's pricey. I've datalogged MAF values and they are solid, (peaking at 175 g/s or so, but never tested before this issue arose, so I have no baseline) no weird spikes or dips in teh signal that I figured I'd see. Not a single code, ever. Before dropping that sort of cash on a new MAF that MIGHT fix it I'd like to see if anyone has other ideas or expereinces with things I should test or check.

cuatrokoop

isn't boost creap, spikes, or anything of that sort related to vacuum issues?

I know that before i yanked the engine out of the 5ktq, it'd run either 1.1 or 1.4bar gauge peak, it was never consistant, never 1.4 all the time, or 1.1 all the time. big cause was many of the vac lines had deteriorated, way past their prime. One of the fabric covered lines was actually missing some of the rubber half-way down the line, others were cracked, broken, or had broken plastic fittings/unions.

I know that on the '97 A4tq sitting outside, it could use some new vac. lines, as one of the fabric covered lines is hard/brittle already, and I'm sure others are as well...

Mike O.

Four years looking at the boost gauge and I can tell you that your boost will be down in the winter because the air charge is more dense. The easiest explanation is that the turbo does not have to work as hard to move 175g/s through the MAF and the charge is cooler (more dense) downstream of the turbo.

Mike O.

RS4@LAST

if not, try that for starters. Cheap, and you'll need it anyway.

RS4@LAST

But you shouldn't get a decrease in HP/perforamnce.

Mike O.

...colder intake temps prevent the car from detonating (pinging) which keeps the timing as advanced as the chip tells it to.

It's not about the boost, it's about the volume of air you can pump into the cylinder.

Mike O.