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Slow climb to 16#

G

gatorlance

Well-Known Member
So I got #689 back together this weekend. Changed oil with some Mobil 1, Napa 1086 filter, changed coolant and it runs great. Can't wait to put the TT chip in next weekend to see how much smoother it will run with a bit less timing.

After it warmed up, I made a short run at WOT and did notice that the boost pretty much hovers around 10psi and then will make a slow but sure climb to the 16# limit. Stock turbo, IC and DP on the car.

I'm thinking this may be a leaky wastegate, but can't tell. I did verify that the Y-fitting is connected correctly per the old diagram - with the straight-through going to the turbo.

Any thoughts? or should I just go get a new wastegate actuator? Any suggestions on where to get one for a TTA?

Thanks all.

Regards,
Lance
 
Yeah, I'd get a complete wastegate and hoses, it should shoot to 16.5 and stay there. Test with good fuel.
 
For sure get an adjustable wastegate, tuning at 5000 ft elevation will require it. What PSI did you tell Eric you'd be boosting at?

Did you get all new IC hoses with new clamps?


...
 
Thanks RatFink and Rich. I have a stock chip from Eric, so we did not discuss custom boost levels. He did say that was the best fit for my modest/just past stock needs. At least for now ;-)

Yep, I installed the new/upgraded IC hoses and clamps too. Sounds like I need the adjustable wastegate act. and hoses. In the meantime, I'll continue to look for a stock wastegate actuator for my box of stock parts...
 
So when I did the oil, I noticed it was a weird color brown/green. The oil has maybe 700 miles on it from when I bought the car last year. I'm now starting to think that one of the head gaskets may be toast. And I'm wondering if that may be a cause/contributor of the slow/low boost.

Brought the car down to my mechanic to take a look as I have way too much work this week...
 
I suppose that's possible, that one of the gaskets is hurt. But I would suspect much more evidence of it to be sure. Like a dead cylinder.

I would also expect that antifreeze in the oil would seperate out from each other by the time it's in the pan. So you'd have antifreeze pour out first then oil. It could also be someone put way too much UV dye in the oil trying to pinpoint a leak.That stuff is green/brown in regular lighting.

How's the antifreeze in the radiator look?


...
 
Yep, turns out it was too much UV dye. Nice call.

Got called out of town to MSP so haven't had time to look more. I'll PM you back later today Rich.
 
Sounds like a it may be a problem with the boost solinoid. This solinoid bleeds off thru the "y" fitting. if it is none functioning and closed the stock car will boost will be held to about 12 psi boost. if the waste gate actuator is leeking or the waste gate hoses are leeking a stock car will overboost. If you have the service manual suppliment the section on the boost solinoid is a good read. It sould help finding your problem.
HTH
Glenn
 
Here's another option. The RJC boost controller.
http://www.rjcracing.com/RJC_Buick_Products/BoostC/boostc.html
And if the wastegate solenoid is the problem, this eliminates it since it bypasses the solenoid. Really helps the turbo spool up a little quicker, and eliminates the slight creeping-open of the wastegate before it fully opens.

Another thing to check is the catalytic convertor, my car had a similar issue a few years back, turns out the cat was clogged. After that was fixed, it boosted up just fine.
 
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So we tested the wastegate and it turns out it is holding just fine. Also the garage guys put smoke on it and the whole system is tight - but we did replace the boost solenoid/turbo vacuum hoses. All said and done, the boost still creeps. The active theory now is that I have some old gas from winter in the car and that may be causing the computer to see some knock and keeping the boost low (thus the creep). Going to drive that beast today :cool1: and see what a fresh tank of gas will do. Sounds like I need to also invest in some octane boost - and some StaBil.
 
Look into a gas/xylene mix. There's a write-up on that on gnttype.org.
Homebrew Octane Boosters
You'll get much more of a boost in octane from that than from the little octane booster bottles at the store for what you'll pay. Or just mix with race gas.

Also, like my previous post, don't count out the catalytic convertor. My car was struggling to surpass 12-13lbs boost before I resolved that problem.
 
turbota633 said:
Also, like my previous post, don't count out the catalytic convertor. My car was struggling to surpass 12-13lbs boost before I resolved that problem.
Click to expand...

+1, A plugged cat will kill it. Try good fresh fuel. Disconnect the cat from the downpipe, you can secure the hanging pipe with wire and go for a test run with just the open downpipe. I used do that, it won't hurt for a test run for the exhaust to just hang there. (I actually drove to the drag strip back in 1991 or so this way for a 8.23 in the 1/8 on stock rubber) You'll find out real quick what's up with boost creep. With an open DP, it should feel in the seat faster and your boost should rocket!
 
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Thanks guys. I'm going to try both. Still have 1/2 tank to go to empty the old gas. I also went to see the best exhaust guy in town and he took temps on the cat and said it's toast. He didn't say it was clogged, but whatever is messed up with it is certainly not helping.

I should have the new cat installed and some new fuel by Tuesday.

Oh, and he also said that the flex was hanging WAY too low on my car. Going to fix that too...
 
Update:
- New gas definitely did not help.
- Turns out that the cats do have temp drop across them, but they flow fine... cause the PO must have gutted them :thumbup:
- The Y-fitting in the car must have been a replacement because the restrictor is actually 0.050". We're getting a 0.040" Y-fitting from John's Performance and will see what happens with that in place.

If it's not the Y-fitting restrictor then it's either the boost solenoid or something between the wiring at the solenoid and the ECM. The boost solenoid did check out and it holds pressure in both directions.

More to follow this week after parts get in.
 
less air can escape the engine, therefore more is trapped in the intake manifold, thats why doing things such is porting cylinder heads or increasing exhaust size generally reduces boost all other things remaining the same

perhaps its different in turbo cars but most of the time if someone is getting less boost its due to a reason other than a clogged cat
 
Rodimus_Prime said:
less air can escape the engine, therefore more is trapped in the intake manifold, thats why doing things such is porting cylinder heads or increasing exhaust size generally reduces boost all other things remaining the same

perhaps its different in turbo cars but most of the time if someone is getting less boost its due to a reason other than a clogged cat
Click to expand...

Disagreed.
I've experienced first hand what clogged cats do....in my case, they took a 17 psi car down to about 10-12 psi. Plus our turbo's rely on circulation, in the case of a clogged cat, a back-up is created, the turbo is trying to throw the air through the exhuast system via the downpipe, and there's a big "pile-up" at the cat, and it gets backed up all the way prior to the exhuast air entering the turbo therefore allowing less air at a lower rate of speed traveling into the turbo causing lower boost psi that is built up at a slower rate of speed.

Similar to the reason why people see little quicker spool and sometimes a 1-2 psi higher max boost from their turbos with the big downpipes as opposed to stock, the air escapes quicker allowing the incoming air to enter quicker/sooner.

Put your mouth over a coffee stirer, now blow.....put your mouth over a straw, now blow.....see the difference?
Now put your mouth over that same straw, stuff part of the straw wrapper inside of it and blow...I bet your cheeks expand from the backed up air. That's what a clogged cat will do for ya.
 
Yeah, I thought that didn't jive...and I bet any forced induction engine will react the same way to a clogged cat.
 
on a supercharged car its certainly not the case, I went from 17psi down to 16.0 psi changing from a crush bent factory cat 2.25 inch system to a stainless all 3 inch system with high flow cat with no other changes

efficiency is everything more boost isnt always more power
 
Rodimus_Prime said:
on a supercharged car its certainly not the case, I went from 17psi down to 16.0 psi changing from a crush bent factory cat 2.25 inch system to a stainless all 3 inch system with high flow cat with no other changes

efficiency is everything more boost isnt always more power
Click to expand...

Supercharger boost is relied upon the size of pulley. It's mechanical, running of the crank. The boost will be or should be the same no matter what exhaust it's running through. 17 psi through a little bitty hole will run hotter, but 17 psi through a dump cap or fat hole will run cooler and make more power. Turbo boost is depends on the exhaust energy from between the heads and turbine and from the turbine out. Just my $.02. Check the pic, short wide dump that exits at the front bumper
100_0382.jpg
 
gatorlance said:
Update:
Turned out to be the Y-fitting. Got a new Y-fitting from John's Performance and it boosts great now....
Click to expand...


Did you get the Y-fitting and the .040 orifice?

As shown below......

Were the stock ones black or gray?

I received the .040 orifice from him but have been afraid to pull mine off and put it on as not to break what I have on it now. So I e-mailed him to see if he had the Y-fitting and new hoses.

I am glad you posted because I was going to post were can you get the Y-fitting and hoses.

large-orifice.jpg
 
Nice collection in your sig. I'm not sure what the stock Y-fitting is, but I assume it is black. The one in my car was black and it was 0.050" according to a local mechanic. I will have to look again, but I remember the restriction hole being internal to the piece itself. Wish the car came with the original Y-fitting. It must have been replaced with a newer part with the wrong restriction.
 
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