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

 

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.

 

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.

 

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.

 

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

 

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.

 

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

 

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

 

Port your wastegate. That is it.

 

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

 

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.

 

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