DocWyte

Well, before lunch I ran out and redid the throttle adaptation. Yanked the ECU, waited 30 minutes, hooked it back up, key in on position 3 minutes, started and let it idle for 3 minutes.

The hesitation is gone now, to be replaced with boost surging and a boost leak of EPIC proportions!

Basically what's happening now is if I nail the throttle in 4th gear I'll boost to 15psi momentarily, then it'll bounce between 12-16psi rapidly. Meanwhile I can hear the turbo spooling as well as a pretty loud ppsshhhhhh sound.

I'm going to yank out the Forge valve and replace it with my stock one and see what happens...

What's up with this surging?

Any other suggestions welcome!!

EdP

That way you might remove the chip from the equation of it still does it, but to a lesser degree. If it goes away completely, then maybe your program is old?

BPV probably, but doubt it's a leak from the boost readings you're getting.

DocWyte

That I've tried with the same result.

I'm down at least 5 psi of boost. Not sure if the BPV is leaking that much or I have some sort of wastegate problem...

EdP

You need to put back the STOCK chip to really determine that. Try it.

Also...

OEM Endtanks are nasty. Try Duramix or epoxy around the place where the plastic endtanks meet the core.

BPV.

ALL 4 hoses - actually pull them and inspect them top to bottom.

Check valve and vac lines

Silver Sled

I've upgraded the bypass valve with a Bailey unit and I've replaced my boost frequency valve, but I still the exact same problem as you. It's extremely frustrating. If you manage to figure this one out please let me know, as I'm stumped. I've tried all types of gas, ecu calibration...etc. Nothing has helped.

98 1.8TQ K04, Giac (with K04 programming), Bailey Valve, Borla Exhaust

DocWyte

Drove the car up to Shine Racing after work. Had the ECU scanned and there were no codes. Cursorily checked the boost hoses, all looked well.

Took their business manager out for a ride, he watched my boost gauge as I played. If I hit the gas in 4th or 5th gear below 3200 rpm, I'll boost to 15psi and then rapidly oscillate between 10 and 15psi. Once over 3200 rpm or so, everything settles down and I'll hold 14.5psi in 4th. Bear in mind I'm supposed to have around 20psi with this chip. If I hit it in the lower gears, 1-3, I'll boost to maybe 13 psi and once I crest 5000 rpm it dials boost back to 10psi. I'm supposed to be holding at least 15psi up top.

I'm beginning to wonder if the GIAC programming is just too aggressive timing wise for my car. The ECU may be pulling out boost and timing in response. That would definately explain the surging.

I'm going to be trying a friends Wett K04 chip/ecu this weekend. With any luck my car will act just the same as his. That'll tell me that more than likely I'm having a software issue...

Silver Sled

Dying to hear the outcome of this one... exact same issues here.... I thought I was the only one

Silver Sled

<ul><li><a href="https://www.audiworld.com/forum/m/a4/msgs/249257.phtml">https://www.audiworld.com/forum/m/a4/msgs/249257.phtml</a</li></ul>

TimA4

or something with the CPU that isn't chip related at all. Have you tried a VAG run?

TimA4

DocWyte

Maybe a bad intercooler end tank? We'll see what I come up with when I put in the Wett chip/ecu this weekend...

If I still have the problem with the Wett chip/ecu then I know it's not a software issue, it's a leak somewhere in my intake tubing and IC. At that point I'll have to figure out some way to pressurize the IC and intake tubing and listen for the boost leak...