okay color me ignorant, [X(]but what is/does the MAP sensor and TIP sensor do?

 

The MAP provides intake vacuum information to the PCM. Not 100% sure what the TIP does...[&:]

 

TIP = Throttle Inlet Pressure, located next to the inlet of the airbox, bolted directly to the inner fender, square looking sensor, just like the MAP. Provides ambient pressure reading.

MAP = Manifold Absolute Pressure, located on the intake manifold itself, below and to the right of the oil dipstick handle. Provides pressure reading right at the maifold.

The PCM (powertrain control module) uses these for its evil boost control schemes.

 

My stock PCM's days are numbered....[sm=smiley36.gif]

 

The Stage PCMs are just cooler evil geniuses. Like a Bond bad guy. More toys, ya know

 

Ok hope i can explain this well enough. The Manifold Air Pressure(MAP) sensor, located on the intake manifold, relays data to the pcm via a vacumm/pressure signal, present in the intake manifold. The PCM uses this information for fuel delivery, spark timeing, fuel injector opening modulation, and it also provides info that the PCM uses to prevent lean/rich fuel mixtures based on out side air temperature.
The Throttle inlet pressure(TIP) sensor, located on the TB, serves dual roles. First it Relays the inlet pressure at the Throttle Body(TB) to the PCM, which uses this info combined with engine rpm to open or close the Wastgate Actuator(WGA), or add/reduce turbo boost pressure. When boosting the PCM relies on the signal from this and the Air Charge Temperature(ACT) sensor that is mounted after the intercooler, on the pressure pipe of srt-4's. The signals from the TIP and ACT sensors are what the PCM uses to determine max boost, and when to send a signal to the Blow-off Valve. Second, the TIP sensor also acts as a BARO sensor, or a Barometer, which tells the PCM what the air pressure is at that point.
As you can tell this does not cover half of the sensors used on the srt-4's 2.4L engine. And would reguire more typing then my fingers would take, and someone would read. But to continue this the newer chrysler/dodge/jeep cars/trucks are useing Electronic throttle control(ETC), put simple your gas pedal is not connected to the TB, by means that no matter were your foot is, the PCM gives the final word on power.
Here is a good link, thought it is about a PT turbo engine, in this hot rod issue they tore one apart to see what made it tick. This was one of the articles that made me less affraid to go into my srt-4 engine. It is a three page article you have to scroll down to go to the next pages, its under the advertisements.
http://www.hotrod.com/techarticles/e...srt/index.html

 

So why does the throttleplate move when I push on the gas pedal? With the car off, of course. There is a throttle cable.

 

Yes there is a throttle cable. But the ETC with the PCM runs the show. So no matter how far you have it down if the PCM gets mixed results from the senosors it limits power and boost. If you want to see it first hand unplug the TIP sensor and tell me what kind of boost you get...I actually had the ACT or air charge temp sensor pop out of the pressure pipe on mine under boost, and it layed down. There was like 1psi of boost and i lost some hair till i seen it hanging down. But since it did not become disconnected from the electric loop the engine light never came on. But it was the PCM that noticed the conflicting data with the TIP sensor,that services as a baro gauge also, so it cut boost. Like the article oin hot rod said and i have been told this makes aftermarket speed parts hard to do. Now as far as the trucks go, like my '03 hemi quad, there is not a throttle cable connected to the TB, instead the pedal is connected to a reostat which is connected to the PCM which tels the fuel injectors how long to stay open and how far the seloniod is to open the throttle body plate, or butterfly, i'm old school.

 

andy, controlling boost is NOT the same as controlling throttle.

"put simple your gas pedal is not connected to the TB, by means that no matter were your foot is, the PCM gives the final word on power."

Boost, yes. Power, no.

 

Ok then tell me exactly what happens when you hit the redline, or some major fault is picked up by the PCM. I will. First Fuel and timeing are cut back lowering engine rpm, as well as boost. Second if severe, all boost is lost as the vacumm signal to the WGA tells it to stay open, no boost. Second it cuts the duty rate of the fuel injectors by 50% and retards the spark timing by up to 15 degree's. One other feature not talk about that will save an engine is the fact that if you loose cooling, such as a radiator hose, or the tempt sensors raises above a preset default, the PCM will cut the a/c if running, injector duty cycle, kill any boost as it opens the WGA, and it fires the cylinders on every other stroke to keep from doing any major damage, of course the problem will have to be fixed as soon as possible but if your out in the BFE, at least you can drive it to a station, me i would call for a tow.
BOOST AND POWER ARE IN THE HANDS OF THE NEVER SLEEPING EVIL SRT-4 PCM!
The thing i love the most about the pt cruiser and srt-4 PCM's is that they can adjust to mods, not wild mods, but basic mods, borla cat back, bov, upgrade fuel pump, etc. Not like older computer cars that would flash the power loss/check engine light if you put bigger pipes under it. IT has its own mind.