Dumb question #1

[GT Kruzr]

Opening statement is that I'm new to this forum, but I have over 18 years dealing with turbo engines. The wife's 12 second Grand National is parked in the same garage with my PT/GT.

With that said: If we use a spring to hold the waste gate closed, does the PCM realise that we are doing this and add more fuel??? OR are we running LEAN and going to burn pistons?

The added air requires additional fuel to keep the balance correct. Does the PCM sense the differential in the sensor in the Cat and add more fuel? There is only SOOOO much fuel the stock injectors can add.[:I] Do we have a problem here ?

[03baggedturbo]

No dumb questions.. especialy for running lean..

People are doing this mod.. They are talking about it a couple threads down.. under wastgate mod 2003..

ADAM

[divots]

No the PCM will not add any more fuel to compensate. However, DCX did put a little margin of safety into it's programming so the car tends to run quite rich (about 10:1 afr). Thus you do have a litte headroom to work with. Many (mostly the SRT-4 folks) have safely upped the stock boost up to around 14-15psi & 16-17psi w/Stage 1.

One important thing to note if you're going to do the spring mod is that you need to take the PCM out of the equation as far as boost control is concerned. This means you will need to bypass solenoid #2 and get your pressure source for the wastegate actuator from the turbo housing or the manifold. If not the PCM will eventually "learn" your mod and you will find your boost levels returning to normal. This thinking also applies if you are upgrading to an aftermarket wastegate actuator with a stiffer spring.

I would also recommend that you attach a small turnbuckle to the spring so that you can adjust the tension. Also if you up the boost on the stock PCM you may trigger a P1188 fault code (Part throttle overboost). There are ways around this you can search for here.

Welcome to the Forums!!!


Aloha,
Mark

[Cal Cruzer]

Actuall, once your engine is up to temp and it goes closed loop, the input from the O2 sensors will add extra fuel if it senses lean. HOWEVER ( the big however) at WOT the computer does not look at the sensor input, it uses "look up" tables and this is where you could run into problems. But as Mark said, these cars are programmed rich @ WOT which means there is some hidden HP there. Just don't overdo it. Watch your boost guage.

[sakigt]

I think we've pretty much come to the conclusion that spiking 16lbs and holding 15 is a safe zone for our stock injectors...

Just gotta get used to the engine light

[GT Kruzr]

Thank you all for that input..... It's nice to see that we do have some professionals' here that can provide technical input.

While I phrased it as a "dumb" question,,,, I "kinda knew" the answer. I think the turbo PCM ( and the other PCM's) deserves a whole thread for it's own discussion. What can they actually DO, Learn, Forget,,, etc..... How do we trick them ???

More "dumb" questions to follow............[8]

Oppzz, almost forgot,,,,,, Stage One is ordered and on the way. When I get back from Ireland on the 7th of May, I'll be tired but red e to install it.

George C. Thomas