Boost Issues

[fanatic26]

I just got back from a 1500 mile round trip over the weekend and noticed something odd on the way home. I was unable to boost past 7 psi. It stayed like this for about an hour, then when I accelerated to make it past someone it shot back up to around 10 like normal. It stayed working normally for another half hour or so then went back to the restricted boos setting. My first thought on this was that the wastegate arm or flapper is sticking. From the outside it appears everthing is working as intended and until the weather clears up I have no way of checking internally. Can anyone else think of what this might be from? When I do finally get a clear day to work on it I want to be able to check everything possible that day.

Thanks in advance,


Geo

 

[hereitcomes]

You said that this was an intermittent problem? That strays away from the typical boost leak because those are usually all the time. The lack of boost leans to a boost leak though.

 

[fanatic26]

Yes it is an intermittent problem. It would go back to normal, then back to low boost randomly...all while cruising at freeway speeds. Also wouldnt a boost leak cause a rough idle or other signs as well? I will verify everything is tight and pressure check the intake tract to make sure tho.

 

[fanatic26]

well the turbo feels a little loose as far as shaft play goes, but no more so than a 17 year old turbo should feel. I disconnected the wastegate vac line completely so it shouldnt even open the wastegate. This was done to test if it was the turbo or factory boost controlle causing inconsistant pressure levels. Wth the line compeltely open I peak at 15 psi and hold about 14 to redline. My friends Laser would hit 20 psi on the stock turbo if he attempted the same thing. Im thinking this means my turbo is bad? Could there possibly be anything else limiting the boost being made? Timing is at factory spec and there are no other engine mods besides the open vac line.

 

[fanatic26]

bump for an answer in the next 30 minutes before I leave work!

 

[oldman]

bump for an answer in the next 30 minutes before I leave work!

Please do not bump your thread again unless you want your thread closed.

Unable to boost past 15psi with the wastegate disabled can mean alot of things, boost leaks, exhaust leaks before turbo (including cracked manifold or turbine housing), tired actuator (flapper being blown open by exhaust pressure) and of course a dying turbo. Process of elimination is how I would approach this.