captan mike

iTrader: (1)

Hello I was wondering if anybody knew how I managed to fix bad over boost/fuel cutting with an oil change.

I switched from 10W-30 to 10W-40 and put on a good oil filter. This is the 6th oil change since I bought it, I always used 10W-30 in the past.

I have been researching how to fix this problem for a year now. And the only solution was port the waste gate or restrict the exhaust. I was a bit surprised when everything was magically fixed.

I Drive a 1988 TurboII with 190,000 km's on it. Never been rebuilt. Still has great compression very well taken care of. I live in Nova Scotia so It was not to hot for 10W-30

Could this mean there is something else wrong with my car that thicker oil helps?

Thanks

1SWEET7

iTrader: (1)

Oil has exactly zero to do with boost control! Do you have a catalytic converter on? Maybe it's crapped out and clogged your exhaust.

No_love_for_pistons

iTrader: (4)

Agreed, you didn't fix anything. And this is when diagnosing becomes a problem.. since the issue has resolved itself, even temporarily, it makes it harder to determine exactly what went wrong in the first place.

RotaryRocket88

iTrader: (7)

It's summer. The warmer weather "fixed" your boost creep problem. Port the wastegate before it gets cold as hell, and the dense air brings the problem back again.

arghx

iTrader: (3)

yes I've found that boost creep is worst when ambient temps are below 45-50 F

captan mike

iTrader: (1)

Yea i Didn't think thicker oil would fix it. But the problem turned off like a light bulb the day i changed it. But the temperature solution makes sense because i noticed the problem was way worse in colder weather.

I don't think i have a cat. I was told by the previous owner that it was hollow. it came with a spare new cat for emissions testing in Ontario where my car spent most of it's life. It has header wrap to hide the missing pre-silencer as well.

Thanks for the help I will just half to bump wast gate porting up a few notches on my to do list.

captan mike

iTrader: (1)

Case solved.
It was cool and dry this evening and over-boost returned.
Thanks for the help.

maac0953

case not really solved but i have the same problem.87TII with no cats and iam boosting 7lbs when it should be 5.5lbs. so iam hitting fuelcut

1SWEET7

iTrader: (1)

Port your wastegate. That is it.

RotaryRocket88

iTrader: (7)

Fuel cut is at 8.6psi, so you're creeping even more than you think. Get that taken care of.

captan mike

iTrader: (1)

The stock boost gauge goes to 400 mmHg.
400 mmHg = 7.73 psi
Fuel cuts at 8.6 psi

If you are getting fuel cut before you go off the top of the boost gauge something else is wrong.

No_love_for_pistons

iTrader: (4)

The stock gauge is inaccurate... get an aftermarket to verify. And port your wastegate!