Low boost issue, need to know what to do next - Page 3

kdjones2000 · kdjones2000's Garage

If you pinch off the hose going directly to the WG, you should be able to get boost up to whatever will grenade your engine, even with a stock WG setup.

Sounds like either your WG has failed, or your crossover pipe has collapsed.

How does the engine run when on boost? If it's choking, then it's likely the crossover. If not, then I would look at the WG.

Mike Goebel · 10-30-2019, 10:21 AM

Quote:

Originally Posted by kdjones2000

If you pinch off the hose going directly to the WG, you should be able to get boost up to whatever will grenade your engine, even with a stock WG setup.

Good to know as I get about 1.8 BAR fully pinched off.

Quote:

Originally Posted by kdjones2000

Sounds like either your WG has failed, or your crossover pipe has collapsed.

How does the engine run when on boost? If it's choking, then it's likely the crossover. If not, then I would look at the WG.

Checked WG and its good 5psi to open 11psi fully open. The only thing I haven't checked is the Crossover and the CAT pipe!!!

I had the Downpipe off 400 miles ago and it looks perfect! Engine does not choke on hard acceleration.

Thanks
Mike G.

Mike Goebel · 08:35 AM

Used an endoscope for iPhone and here is what the Crossover pipe looks like going in from the Waste Gate "T". Looks good but its kinda difficult to get a good view farther down the pipe.

P.S. I've got an aftermarket CAT. Are these typically straight thru? If so I'm going to try the scope going from the rear of the car.

Why doesn't it show my pic. I attached it with IMG from smugmug???

Thanks
Mike G.

Mike Goebel · 11-01-2019, 12:07 PM

Quote:

Originally Posted by Mike Goebel

P.S. I've got an aftermarket CAT. Are these typically straight thru? If so I'm going to try the scope going from the rear of the car.

FYI CATs don't go thru!!

Thanks
Mike G.

chip18 · 11-02-2019, 01:18 PM

LOL ... but seriously a scope is not gonna work?? If you constantly run rich at part throttle and idle, you'll cook it!

But a lot of crap would have had to been blown out for you to see daylight thru one??? I doubt that ever happens but if the honeycomb structure has broken down it will tend to rattle over bumps and stuff??

Anyway ... here's a good clip and most likely more that you wanted to know.??

https://www.youtube.com/watch?v=v9ju2rZ8YmM

Mike Goebel · 11-02-2019, 02:08 PM

I'm going to try something else now. I'm going to put a vacuum on the WG hose to insure the WG is not opening at all or much less. I still believe that the WG is the culprit even tho it tested ok with 5 psi to open and 10 psi full open condition.

Thanks
Mike G.

Mike Goebel · 11-03-2019, 10:19 AM

Lazy mans update!

I unplugged the power to the CV and 1 BAR absolute was achieved. So I still thinks its the wastegate! Just not ready to dump $450 into a trail test!

Thanks
Mike G.

chip18 · 11-03-2019, 01:46 PM

Quote:

Originally Posted by Mike Goebel

Used an endoscope for iPhone and here is what the Crossover pipe looks like going in from the Waste Gate "T". Looks good but its kinda difficult to get a good view farther down the pipe.

P.S. I've got an aftermarket CAT. Are these typically straight thru? If so I'm going to try the scope going from the rear of the car.

Why doesn't it show my pic. I attached it with IMG from smugmug???

Thanks
Mike G.

I think on here you have to use the "Click Here to Upload Photos" button where it says attach a photo?? I've done it and it seems to work fine.

Mike Goebel · 11-03-2019, 02:06 PM

Quote:

Originally Posted by chip18

I think on here you have to use the "Click Here to Upload Photos" button where it says attach a photo?? I've done it and it seems to work fine.

DOH!!!!!!!!!!!!!

Crossover pipe looking from WG "T" off towards Turbo!!

Thanks

Mike G.

Mike Goebel · 11-03-2019, 03:15 PM

Just ran a test pulling 15in of vacuum on the WG hose to help keep the WG valve closed. Makes a huge difference. Can reach 2 BAR absolute easy!!! Tried to keep it to 1.8 in 1 ,2, 3 gears. Makes me think the WG is the culprit!! BOO!!!

Thanks
Mike G.

dme · dme's Garage

You can always add shims to help tighten the springs. A manual boost controller shouldn't even let the WG see boost till you near your desired level.

Mike Goebel · 11-15-2019, 12:14 PM

Quote:

Originally Posted by dme

A manual boost controller shouldn't even let the WG see boost till you near your desired level.

I was thinking about this and I came to the conclusion that I wouldn't be able to reach my desired boost level even with a MBC. Reason is that I've already pinched off the WG hose and still could barely reach the 1.8-2 BAR. So its either a WG spring that sagged or the CAT pipe. I'm going to try to get my **** together this weekend and check the CAT pipe.

Thanks
Mike G.

Mike Goebel · 11-21-2019, 06:44 PM

Added 1/8 inch shim to WG and now getting about 1.6 BAR. Need to test on fwy tomorrow morning in higher gears. BTW there is a noticeable difference in acceleration. Wouldn't have thought so.

Thanks
Mike G.

soxnail · 11-30-2019, 08:07 AM

Had similar issue, was a clogged catalyst.
Sox

Mike Goebel · 12-02-2019, 08:09 AM

Quote:

Originally Posted by soxnail

Had similar issue, was a clogged catalyst.
Sox

The Cat has less than a 1000 miles on it

Thanks
Mike G.

Mike Goebel · 12-08-2019, 08:42 AM

Added another shim for a total of 1/4 inch!!! Still didn't reach 1.8 BAR!!!

BOO!!

Thanks
Mike G.

dme · dme's Garage

I picked up an OEM waste gate off of eBay that had 5 shims on it!

DannoXYZ · 10:06 AM

Mike's wastegate is fine, one of the best stock ones I've ever seen. Tests fine. It's not issue. With this strong of wastegate, pinching off line should generate 20-25psi boost no problem!

Problem is there's excessive exhaust backpressure forcing wastegate open or turbo to not spin.

- Either crossover is collapsed. Most likely issue as I've replaced over 5 of these over the years.
- exhaust clogged, not likely. Modern cats are ceramic and do not melt with heat to cause restriction.
- or turbo is worn-out with dragging bearings or wobbling has caused extra clearance at edge of blades. This could be possibility.

Grab turbo's axle and wiggle it up & down. How much radial-play do you feel?

Mike Goebel · 12-09-2019, 03:55 PM

Quote:

Originally Posted by DannoXYZ

- Either crossover is collapsed. Most likely issue as I've replaced over 5 of these over the years.

Looked as far as I could with a bore scope on my cell phone and it looked ok, but I guess I need to take it off and really check it out. Unless there's another way to do a lazy A$$ check!

Quote:

Originally Posted by DannoXYZ

Grab turbo's axle and wiggle it up & down. How much radial-play do you feel?

Turbo rebuilt by evergreen less than a 1000 miles ago!

This is starting to wear me down a bit!!

Thanks
Mike G.

91cab · 12-11-2019, 12:18 PM

Just because the turbo was rebuilt recently does not mean it is in good condition. I have had new parts that are bad right out of the box. The best rebuilders do make mistakes. Or maybe something went through the exhaust and damaged the turbo. Remove the j boot and look at the blades, also try and wiggle the shaft - both right - left and in - out. While the j boot is off check it for any cracks.
I would do a pressurized leak test to check for vacuum leaks. If you have a big leak you will never get full boost. With wastegate out of the picture you should run unlimited boost. Since you are not it comes down to turbo working properly or air leak or restriction.[img]http://forums.pelicanparts.com/uploads2
6/20191211_1612351576098852.jpg[/img]
Here you can see a split in the bottom of the hose coming from the aos into the j boot. Not visable, but will cause slow spool and low boost. Visual inspection is not good enough.