overboosting options

[BMFB]

ok, so i am overboosting. the truck is all stock except for the exhaust, which has an aftermarket catback, and a gutted cat. Now, i know that its my gutted cat that doing it (dont worry, its parked for the winter so its no tbeing hurt, also, i didn't do it, its how it was when i bought it) I was wondering if there was anyway to cure my overboosting issue other than putting a working cat back on it. over this winter ive been converting over to code 59, and am wondering if there's anyway to change the positions on the boost control solenoid through that control system that would be effective, or possibly adjusting the waist gate actuating rod, or if i should just suck it up and get a new cat. I do live in Michigan, which has no smog laws. any help would be super great

 

[midnightbluS10]

Re: overboosting options

You can try an external wastegate. The stock wastegate has to be inoperative and "permanantly" closed IIRC.



edit: here's some good info.

 

[BMFB]

Re: overboosting options

so, i see an external is a good solution, i also see a few people saying a chip programed to work with the situation will help, but im not sure if they're saying with everything remaining stock, or reprogramming it to work with a changed waistgate. It looks like a new cat would be a simple solution, i just wonder how much power id give up

 

[BoostedSUV]

Re: overboosting options

The gutted cat is why you're overboosting... The factory wastegate and boost control can not effectively control boost on a stock setup with a gutted cat. 2 options, put a cat back on it or look into another wastegate/boost controller. Do a search, I've read about this 100 times on here...

 

[It's just a six]

Re: overboosting options

You can take off the turbo & port the wastegate hole larger so it can flow more exhaust.

Or send it to a turbo shop to do the work or install a larger wastegate flapper valve.

It works on mine.:tup:

 

[Foot Performance]

Re: overboosting options

You could also try and find a JSM downpipe cut the puck out completely and get all kinds of flow my stock set up(it is stock turbo but has waller upgrade done to it internally) seems to control boost fairly good and I am open downpipe right now

:edit: here is a link http://www.syty.net/forums/showthread.php?t=59183&highlight=downpipe

 

[UR50SLO]

Re: overboosting options

I use the RJC boost controller on almost all my stuff. (www.rjcracing.com)

our 98 turbo jimmy runs no cat with stock turbo at 9psi.

Sometimes when the turbo get's hot the actuator will stick and limit how far it can open and make

it over boost. Our housing is ported.. and flows very good too. So I'd do that as well.

~Scott

 

[turbodig]

Re: overboosting options

Your instincts are correct... you can change the WG duty cycle init table in code59 to handle the gutted cat.
Reduce the duty cycle by 15-20% and it should be ok.

code59 won't generate an overboost code, though, unless you specifically turn it on. Boost will just go wherever it wants (which is a bad thing on street gas)

As Scott mentioned, the wastegates are notorious for sticking when hot. No external controller or ECM programming will compensate for that.

I've had stock turbo systems with completely open exhausts running within a psi of the setpoint, all the way through the run.

 

[BMFB]

Re: overboosting options

Alright thanks everyone, i may take off the turbo and do some port work, but i think ill try changing the duty cycle on my boost solenoid first, i was hoping that was a solution, and i will definitely be turning that overboost detection code on, no reason not to, good to have eyes on it, especially when im distracted by cops and things...

 

[ZavzTy547]

Re: overboosting options

Alright thanks everyone, i may take off the turbo and do some port work, but i think ill try changing the duty cycle on my boost solenoid first, i was hoping that was a solution, and i will definitely be turning that overboost detection code on, no reason not to, good to have eyes on it, especially when im distracted by cops and things...

Cheap fix for stock turbo and no cat: 1. Get a functional new cat. 2. Stronger waste-gate spring and adjust the rod. 3. Boost valve and set it to 12psi.