Boost no higher than 19psi

[NM Tom]

I put an adjustable WG on and the boost will only rise to 19psi. Im running a Thrasher 100 with K\N and Hooker with no cat. Have walbro 340 with afpr. with the stock WG it would run up to 17psi and settle back down to 16. With the adjustable I was able to turn it up to go 19psi with it dropping back down to 18 at WOT. I have tuned the rod 5 more turns with no effect. The car runs fine and pulls well but the boost just won't go up any further. This is a stock turbo with 90k. The only odd # on scanmaster is that the MAF will still not peg even at 19psi, it tops out at 227. Is the turbo just tired or am I overlooking something? Thanks for any help you guys can give. Tom

 

[77tech9]

Does the thrasher chip use the computer to control boost? or do you have the race chip?

 

[NM Tom]

Not sure, the wastegate solenoid is still hooked up and operating. I just put the chip in and went, no other changes. I was able to up the boost from 17 to 19, but no higher. The rod is so tight now I have to pull it out about 3/4 of an inch just to get it hooked back on. Not sure the range of movement, but it is now quite a bit less.

 

[hcox10]

hi
did you check to see that maybe your
gauge is not reading right or there
could be a leak in the hose.

 

[Taffy]

Are you still on the stock turbo?

You probably have a cracked header. I tried to take my stock turbo up past 19 psig years ago by adjusting the wastegate actuator with no increase in boost. The wastegate puck had almost no travel. Ended up having a cracked driver side header.

 

[TurboDave]

Originally posted by NM Tom
I put an adjustable WG on and the boost will only rise to 19psi. Im running a Thrasher 100 with K\N and Hooker with no cat. Have walbro 340 with afpr. with the stock WG it would run up to 17psi and settle back down to 16. With the adjustable I was able to turn it up to go 19psi with it dropping back down to 18 at WOT. I have tuned the rod 5 more turns with no effect. The car runs fine and pulls well but the boost just won't go up any further. This is a stock turbo with 90k. The only odd # on scanmaster is that the MAF will still not peg even at 19psi, it tops out at 227. Is the turbo just tired or am I overlooking something? Thanks for any help you guys can give. Tom

19# of boost and only 227 on the MAF??

 

[NM Tom]

Header is good, i took it off and had it welded months ago. There does not appear to be any pre turbo leaks. Thanks for the replies!

 

[denn454]

i used to have the exact same problem

i tightend up the rod as short as it would go, i got 18#. i cut the rod and threaded it on even tighter, still got 18# I said a few bad words to it, and still got 18 #

i think it was in the chip, but i didn't have anyther chip to compare it to.

you can get a new chip and hope thats the problem, take the rubber hose going to the boost solenoid on the passenger side valve cover completely off, then you should see 22+# if you have good gas then its an ok thing to do at the track.

OR i would strongly sugest a boost controll vlave of some type. there are lots of them out there, from $20 on ebay, up to $600 fully electronic ones. A guy here by the name of sinful6 makes (used to make?) bleeder vlaves, he called them quick spool something another. I put a similar one on my car and never looked back. It spools faster, and is very easly adjustable. you dont' have to play with hot linkage or tools, just turn a knob.

 

[NM Tom]

I took the hose off of the WG solenoid and there was no change. With the hose wide open and bleeding the line pressure boost still did not go any higher. It seems 19# is all the stock turbo wants to give.