I'm out of ideas

9dreizig · 04-16-2009, 09:06 PM

Ok guys I've been slowly getting both my cars running.. Trac dog is running like a champ. Now back to the black 86..
It was running like crap,, everyone said it had a boost or vacuum leak.. so I replaced everything in the system.. gaskets on the injector blocks, all O rings, rebuild the diverter valve, confirmed the waste gate is functioning correctly..

So now the engine runs great,, idles perfect, just doesn't develop much past .4-.5 bar boost.. I'm at a total loss as to where my leak can be.. I don't have power either ,so I know it's not a bad reading on the boost gauge..

Any ideas ?? Can a turbo have a leak ? I have an extra one I can throw on if that seems logical ...

Help!!

beepbeep · 04-17-2009, 12:38 AM

Pressurize everything past CIS @ 0.8 bar and listen for leaks. That's only sure-fire way of finding leaks.

Spraying starter-gas around doesn't really work.

When I was working for SAAB couple years ago, this is factory procedure for finding leaks. We even had factory tools + pressure regulator to do this. You remove the hose from air filter, pop a disc with a nipple and pressurize everything. Any leak will be imediatly noticeable.

Look for Alan's posts here, he fabricated his own adapter to find leaks on his engine using this method.

Regards,

Speedy Squirrel · Speedy Squirrel's Garage

Don't forget to check the backpressure (pressure between turbo outlet and cat), if you still have a catalyst on your car. My car has a fitting for this purpose (don't know if all years and models do). With enough misfire and/or rich operation the catalyst material (substrate) can break up and cause alot of backpressure. No enthalpy across the turbine = no boost!

Jim2 · Jim2's Garage

"doesn't develop much past .4-.5 bar boost"

"I don't have power either"

Lack of boost compounded with the engine not making much power (given the low boost) makes me think timing way out of whack, or perhaps something like fuel starvation. I don't recall your history, but did your cam timing get upset?

What was changed when this issue occured?

9dreizig · 04-17-2009, 07:26 PM

Nope timing checked out fine,, The engine is running fine except there's no boost.. starts and idles like a champ, accels to 3000 rpm fine until the boost should kick in. Just hooked up a plug from the flexible elbow from the intake and am pressurizing from the waste gate hose.. I need one more hose clamp and should be able to pressurize the whole system now.

beepbeep · 04-18-2009, 02:30 AM

Quote:

Originally Posted by Jim2

Lack of boost compounded with the engine not making much power (given the low boost) makes me think timing way out of whack

On the contrary. If timing is delayed, boost will come quicker than stock, it's just that car won't make any power. Headers will glow too.

Delayed timing = more heat into headers = quicker spoolup

Regards,

staffanbe · 04-18-2009, 05:35 AM

Quote:

Originally Posted by Speedy Squirrel

Don't forget to check the backpressure (pressure between turbo outlet and cat), if you still have a catalyst on your car. My car has a fitting for this purpose (don't know if all years and models do). With enough misfire and/or rich operation the catalyst material (substrate) can break up and cause alot of backpressure. No enthalpy across the turbine = no boost!

Had the exact same thought.
Worth looking into if you have a cat.

Miguel Antonett · 04-19-2009, 06:44 PM

What gauge do you have showing the boost pressure? sometimes you're there and the gauge shows .4 ~.5

9dreizig · 04-19-2009, 06:52 PM

Quote:

Originally Posted by Miguel Antonett

What gauge do you have showing the boost pressure? sometimes you're there and the gauge shows .4 ~.5

Just my stock one. As I said ( just took it for a test drive after checking another potential suspect for a leak), it really runs fine with the exception of the lack of boost. Now my other problem is compared to the relattively modded track dog there's just not that head snap). It always did have full boost and was a kick in the butt when it clicked in.
Game plan is tomorrow I'll have a set up to fully charge the system and listen for a leak. Just need to run to Home Depot for a ring clamp.
T

Miguel Antonett · 04-20-2009, 03:43 AM

The stock gauge is not that accurate. It is sensitive to too many factors. You might be getting all the boost but indicating less...

fredmeister · fredmeister's Garage

It could be the throttle plate not opening fully? Did you check throttle movement?
Also, the diverter valve could be not sealing properly....you mentioned rebuilding it, but did you make sure it was sealing/done 100%?
Other than that, if you have no vacuum leaks to make it run poorly via bad oring seals in the intercooler plumbing, then it has to be specific to the boost system.
How did you verify wastegate function?