Hey guys, a buddy of mine developed a problem recently, but he's having trouble registering here. Anyways, the boost gauge shows 11 psi, but the car doesnt accelerate like it used to, and the lag (14B) has increased (full boost acheived at 4000rpm), and when he shifts gears, theres lots of lag again, and he has to wait for the turbo to spool, when before, it was almost instant.... He says it happened almost overnight. He says he tested the compression and it was perfect, the timing, the grounds, the ecu caps and it was all perfect, vacuum leaks as well, cat is not clogged. I suggested a boost leak because my GF's car experienced the same thing, and it ended up being a loose intercooler hose. In his case, its different because you can see the boost rise, and you can hear the turbo, but you can't really feel the boost. Its worse in the lower gears. If you step on it in the higher gears, it KINDA pulls better. For the record, it's a 1G.

I'm thinking the timing is being pulled by the ECU. I guess there's no way to tell without a datalogger, and he doesnt have one. Plugs are new, wires are new. The clutch isnt slipping. And the boost DOES build, so I don't see how it could be a wastegate issue.

So, any ideas?

Well....I experienced a huge lag when I spun a bearing last summer, and the thrust washer for the turbo was in 6 pieces in my oil pan. I could hear the turbo spooling, but no power until higher in the revs. I'm not sure if this is what his problem is, but the description matches exaxtly to what happend to me, and that was my outcome.

Billy, you're describing no power in the higher revs, but what he experiences is like barely any power when boost hits. And it does hit full boost. I took a ride in his car before, and drove it today, and its a WORLD of difference.

Someone suggested that it could be a faulty knock sensor that's sensitive, and the ECU is pulling timing accordingly. But of course, to confirm this, i'd need a data logger That would explain everything -- lack of power, slow spoolup because the engine isn't operating at full load... etc etc...

Thanks for the suggestion however, Billy.

For the small amount of time it takes, you might want to actually inspect the wastegate actuator arm. When mine slipped off, I was still able to make some boost, but with huge lag, and a lower peak. But I couldn't really hear the typical spool-up whoosh, which differs from your description.

Good luck!

- b.

Check for leaks between the exhaust manifold and block. Also, the turbo to manifold bolts like to work there way out if lock tight was not used during install. Sounds like an exhaust leak before the turbo to me.

Ali, you hit the nail on the head, that was it, thanks.

But i can't really figure out why it was still showing full boost. *shrug*

Ah well!

No problem Ross, I've learned alot from experience.

You'll still see full boost but likely at a higher RPM becuase the exhaust is leaking instead of spinning the turbine.