kafercup

This is the scenario: The car was running stock boost nicely (1.3-1.4) since purchasing the car in February. I recently needed to have the car smogged, so to avoid any delays/problems in the process, I replaced the O2 sensor and catalytic convertor (the cat was original and the O2 had one wire almost completely broken). After the swap the car ran even smoother and stronger while still hitting the stock boost levels.

I took the car to be smogged and it passed beautifully. The issue came later that day when I noticed the boost coming on sooner and then climbing to 1.5-1.6 before hitting the fuel cut. It's almost as if the boost regulation is completely gone. I checked the hoses to and from the wastegate and wastegate solenoid and while one vacuum line was a bit aged (replaced now), the boos problem is still there.

Any ideas? Possibly a tear in the wastegate diaphragm?

Sergei

hoses

HTH

Eric NY

Check the upper IC to manifold hose. Remove and thoroughly check the bottom for rips and or cracks. Oil mist on bottom exterior is a tell-tale sign. As also stated, could be the wastegate diaphram. Use a vacuum tester, will tell you if wg diaphram is bad.

Also seen the lower ic hose tear, but not as common as the top one!

Eric

Kneale Brownson

Check Scott Mockry's wastegate operation information for possibilities. There's a whole bunch of suggestions at the link. Scroll down for overboost.<ul><li><a href="http://www.sjmautotechnik.com/trouble_shooting/10vwaste.html">Overboost Leaks</a></li></ul>

kafercup

Thanks guys, i'll check all of the above. I pulled the upper hose and it seemed to be intact, i'll check the bottom one tomorrow.

smcg3

I had almost the same thing happe on my 1990 200tq, and I chased it for a little while, thinking it was computer/fuel mixture problems... it ended up being a rubber gasket inside the wastegate. Don't know exactly what it was, had the mechanic replace it, not me, but it's worth thinking about possibly....

itsav8

***off topic**** smcg3 whats AVS tuned mean? Too your V8.

smcg3

Tuned by Max MacDonald. No longer run his show under the AVS name... but when the car was tuned...

He used to be in Chehalis, WA. I think he's now in Tacoma somewhere, not really sure. Made the thing fast and fun though.

jurq

Run your ecu output tests to ensure the wg freq valve is functioning correctly?

itsav8

I'd be interested to know what difference it made..seat of pants difference...unless you have dyno'd the car?

My Black 5spd is chipped &amp; it's a blast.