High Idle 4500 RPM

On Sun, 28 Nov 2004 09:47:12 -0600, Michale >
wrote:

>What I meant was is that when I am am drive and and not giving it any
>gas, I estimate my speed at approx 40mph hehehehehe
>

Why on earth would you put the car in Drive with it idling that fast?
The lurch in to drive could easily break motor/trans mounts or worse.
Stopping the car with the engine running that fast will burn up your
transmission in short order.
>
>> That distributor will go
>> in 2 ways, 180 degrees out, or the correct way, if it was out 180 the
>> engine wouldnt run, start with looking for a vacuum leak, possible the
>> brake booster/supply line
>
>Would a single leak cause the excessive idle? Or would it be more likely
>several leaks?

The brake booster is one large vacuum hose. With your idle speed I
dont have a beter suggestion for you on where to start looking for the
leak, but wherever it is it is one heck of a leak and should be pretty
easy to find. Also make sure that you haven't somehow blocked the
throttle partially open. If you can look down in the throttle body
the blades should be almost closed.

Steve B.

it is the same thing regardless if it is the throttle blade opening or a
huge vacuum leak, the MAP sensor determines how much fuel to give it, not
the throttle blade. if you disconnected the TPS sensor and opened the
throttle blade, the map sensor would compensate for it, thus causing a high
RPM The throttle blade does not have anything to do with giving more gas, a
carburator would but not this vehicle
"Matt Whiting" > wrote in message
...
> maxpower wrote:
>
> > depending on the size of leak, keep in mind that when you open the
throttle
> > blade, it is the same as making a vacumm leak, alittle open a higher
rpm,
> > alot open alot more RPMs
>
> Except that opening the throttle also calls for more gas to be injected.
> Adding air alone will only lean the mixture. You might get a little
> bump in RPM, but you shouldn't get 4500 unless way too much fuel is also
> being injected along with the air leak.
>
> It sounds like something more fundamental than an air leak is involved
> with his problem. Beats me what, though.
>
> Have you checked for a malfunction code in the ECM?
>
>
> Matt
>

it is the same thing regardless if it is the throttle blade opening or a
huge vacuum leak, the MAP sensor determines how much fuel to give it, not
the throttle blade. if you disconnected the TPS sensor and opened the
throttle blade, the map sensor would compensate for it, thus causing a high
RPM The throttle blade does not have anything to do with giving more gas, a
carburator would but not this vehicle
"Matt Whiting" > wrote in message
...
> maxpower wrote:
>
> > depending on the size of leak, keep in mind that when you open the
throttle
> > blade, it is the same as making a vacumm leak, alittle open a higher
rpm,
> > alot open alot more RPMs
>
> Except that opening the throttle also calls for more gas to be injected.
> Adding air alone will only lean the mixture. You might get a little
> bump in RPM, but you shouldn't get 4500 unless way too much fuel is also
> being injected along with the air leak.
>
> It sounds like something more fundamental than an air leak is involved
> with his problem. Beats me what, though.
>
> Have you checked for a malfunction code in the ECM?
>
>
> Matt
>

maxpower wrote:

> it is the same thing regardless if it is the throttle blade opening or a
> huge vacuum leak, the MAP sensor determines how much fuel to give it, not
> the throttle blade. if you disconnected the TPS sensor and opened the
> throttle blade, the map sensor would compensate for it, thus causing a high
> RPM The throttle blade does not have anything to do with giving more gas, a
> carburator would but not this vehicle

Last I knew, the TPS sensor was also factored into the fuel map for ECM
controlled vehicles. Maybe Chrysler was really stupid with their ECM,
but I doubt it. If the throttle is closed as indicated by the TPS, then
I'd be really surprised if the MAP input alone would be enough to
command fuel be added. If that is the case, then the TPS is completely
unnecessary.


Matt

maxpower wrote:

> it is the same thing regardless if it is the throttle blade opening or a
> huge vacuum leak, the MAP sensor determines how much fuel to give it, not
> the throttle blade. if you disconnected the TPS sensor and opened the
> throttle blade, the map sensor would compensate for it, thus causing a high
> RPM The throttle blade does not have anything to do with giving more gas, a
> carburator would but not this vehicle

Last I knew, the TPS sensor was also factored into the fuel map for ECM
controlled vehicles. Maybe Chrysler was really stupid with their ECM,
but I doubt it. If the throttle is closed as indicated by the TPS, then
I'd be really surprised if the MAP input alone would be enough to
command fuel be added. If that is the case, then the TPS is completely
unnecessary.


Matt

Your right it isnt that nessassary. more of a reference point of open and
closed throtlle, u can unhook the tps sensor and the engine will run, it
will give a hesitation on take off but will run because the MAP sensor
determines load and how much fuel to deliver
"Matt Whiting" > wrote in message
...
> maxpower wrote:
>
> > it is the same thing regardless if it is the throttle blade opening or a
> > huge vacuum leak, the MAP sensor determines how much fuel to give it,
not
> > the throttle blade. if you disconnected the TPS sensor and opened the
> > throttle blade, the map sensor would compensate for it, thus causing a
high
> > RPM The throttle blade does not have anything to do with giving more
gas, a
> > carburator would but not this vehicle
>
> Last I knew, the TPS sensor was also factored into the fuel map for ECM
> controlled vehicles. Maybe Chrysler was really stupid with their ECM,
> but I doubt it. If the throttle is closed as indicated by the TPS, then
> I'd be really surprised if the MAP input alone would be enough to
> command fuel be added. If that is the case, then the TPS is completely
> unnecessary.
>
>
> Matt
>

Your right it isnt that nessassary. more of a reference point of open and
closed throtlle, u can unhook the tps sensor and the engine will run, it
will give a hesitation on take off but will run because the MAP sensor
determines load and how much fuel to deliver
"Matt Whiting" > wrote in message
...
> maxpower wrote:
>
> > it is the same thing regardless if it is the throttle blade opening or a
> > huge vacuum leak, the MAP sensor determines how much fuel to give it,
not
> > the throttle blade. if you disconnected the TPS sensor and opened the
> > throttle blade, the map sensor would compensate for it, thus causing a
high
> > RPM The throttle blade does not have anything to do with giving more
gas, a
> > carburator would but not this vehicle
>
> Last I knew, the TPS sensor was also factored into the fuel map for ECM
> controlled vehicles. Maybe Chrysler was really stupid with their ECM,
> but I doubt it. If the throttle is closed as indicated by the TPS, then
> I'd be really surprised if the MAP input alone would be enough to
> command fuel be added. If that is the case, then the TPS is completely
> unnecessary.
>
>
> Matt
>

maxpower wrote:

> Your right it isnt that nessassary. more of a reference point of open and
> closed throtlle, u can unhook the tps sensor and the engine will run, it
> will give a hesitation on take off but will run because the MAP sensor
> determines load and how much fuel to deliver

I don't think Chrysler publishes its ECM algorithms, but I've be very
surprised if the TPS is used only to sense closed and WOT. If that were
the case, they would use two cheap switches rather than a relatively
expensive rheostat sensor. I'd also be very surprised if they don't
make a check for closed throttle when the MAP is indicating low pressure
and thus calling for more fuel and not rev the engine wildly with a
closed throttle. Maybe the Chrysler engineers aren't that smart, but
I'm betting they are.

Have you ever seen a Chrysler engine have a vacuum leak that made it run
4,500 RPM with the throttle closed?


Matt

maxpower wrote:

> Your right it isnt that nessassary. more of a reference point of open and
> closed throtlle, u can unhook the tps sensor and the engine will run, it
> will give a hesitation on take off but will run because the MAP sensor
> determines load and how much fuel to deliver

I don't think Chrysler publishes its ECM algorithms, but I've be very
surprised if the TPS is used only to sense closed and WOT. If that were
the case, they would use two cheap switches rather than a relatively
expensive rheostat sensor. I'd also be very surprised if they don't
make a check for closed throttle when the MAP is indicating low pressure
and thus calling for more fuel and not rev the engine wildly with a
closed throttle. Maybe the Chrysler engineers aren't that smart, but
I'm betting they are.

Have you ever seen a Chrysler engine have a vacuum leak that made it run
4,500 RPM with the throttle closed?


Matt

In article >,
Matt Whiting > wrote:

> maxpower wrote:
>
> > Your right it isnt that nessassary. more of a reference point of open and
> > closed throtlle, u can unhook the tps sensor and the engine will run, it
> > will give a hesitation on take off but will run because the MAP sensor
> > determines load and how much fuel to deliver
>
> I don't think Chrysler publishes its ECM algorithms, but I've be very
> surprised if the TPS is used only to sense closed and WOT.

~Excluding transmission/transaxle functions~
Rate of change in order to increase the injector pulse width when
the throttle is opened.
Idle air control valve diagnostics (fault sensing)
The TPS is the least important of all the input sensors, its
biggest effect on fuel delivery is when the PCM is receiving a
changing voltage from it indicating throttle movement.

> If that were the case, they would use two cheap switches rather than a relatively
> expensive rheostat sensor.

Some manufactures have been known to do this.

> I'd also be very surprised if they don't
> make a check for closed throttle when the MAP is indicating low pressure

Closed throttle low MAP pressure is a heavy decel, which is a
whole different situation from the potential mass vacuum leak
being discussed.
A vacuum leak that can/does add hundreds of RPM to idle speed
-raises- manifold absolute pressure, raising manifold pressure is
usually responded to by the PCM by as an increased injector pulse
width.

> and thus calling for more fuel and not rev the engine wildly with a
> closed throttle. Maybe the Chrysler engineers aren't that smart, but
> I'm betting they are.

Some things are beyond the limits of control of the system.

> Have you ever seen a Chrysler engine have a vacuum leak that made it run
> 4,500 RPM with the throttle closed?

You've got a minivan or two at your disposal...
Hook up your scanner, pull the PCV or brake booster hose off,
start the engine and report back with the results, i.e., RPM
changes, MAP changes, pulse width changes.
You may not see 4500 RPM exactly, but you will experience the
causes and effect.