I have a 2001 eclipse GT that has a very rough idle and the check engine light on. The code is P1400 for the manifold differential sensor malfunction I believe. When I idle the car vibrates quite and bit and will stall if I don't press the gas soon enough. Does anyone know if these are related or what could be causing the rough idle? I haven't been able to get an answer from a mechanic yet.

The only thing I've been told is about the sensor is that it is working but the system thinks its failing. Two mechanics have told me I have to 'guess' on a $320 part and see if it works.

 

well if the sensor is working then i wouldnt replace it. To me it sounds like you have an air leak somewhere, maybe around the intake manifold or a manifold gasket. But that would be my guess

 

Is there anything that can be done about the Service Engine Soon light if the part is working? I need to get my car inspected soon and it will fail with the light on.

Also, is there anyway to find out about an air leak without taking it into a mechanic?

 

if you dont find an air leak then try ad clean out the throttle body, or check the ISC motor. (Idle Speed Control).

 

unplug the battery for a little bit, that will clear the code. Just do it right before you go. Hopefully it stays off long enough.

 

i got a write up for yah =D let me type it in the new post k

 

GENERAL INFORMATION
Computer Relearn Procedures
All Models

* PLEASE READ THIS FIRST *
The following general procedures are to be used if
driveability problems are encountered after power loss or battery has
been disconnected. These procedures may provide an aid in eliminating
these problems.
To reduce the possibility of complaints, after any service
which requires battery power to be disconnected, vehicle should be
road tested.

COMPUTER RELEARN PROCEDURES
Vehicles equipped with engine or transmission computers may
require a relearn procedure after vehicle battery is disconnected.
Many vehicle computers memorize and store vehicle operation patterns
for optimum driveability and performance. When vehicle battery is
disconnected, this memory is lost. The computer will use default data
until new data from each key start is stored. As computer memorizes
vehicle operation for each new key start, driveability is restored.
Vehicle computers may memorize vehicles operation patterns for 40 of
more key starts.

Customers often complain of driveability problems during
relearn stage because vehicle acts differently then before being
serviced. Depending on type and make of vehicle and how it is
equipped, the following complaints (driveability problems) may exist:
* Harsh Or Poor Shift Quality
* Rough Or Unstable Idle
* Hesitation Or Stumble
* Rich Or Lean Running
* Poor Fuel Mileage
These symptoms and complaints should disappear after a number
of drive cycles have been memorized. To reduce the possibility of
complaints, after any service which requires battery power to be
disconnected, vehicle should be road tested. If a specific relearn
procedure is not available, the following procedure may be used:

Automatic Transmission
* Set parking brake, start engine in "P" or "N" position.
Warm-up vehicle to normal operating temperature or until
cooling fan cycles.
* Allow vehicle to idle for one minute in "N" position. Select
"D" and allow engine to idle for one minute.
* Accelerate at normal throttle position (20-50%) until vehicle
shifts into top gear.
* Cruise at light to medium throttle.
* Decelerate to a stop, allowing vehicle to downshift, and use
brakes normally.
* Process may be repeated as necessary.

Manual Transmission
COMPUTER RELEARN PROCEDURES Article Text (p. 2)1997 Mitsubishi Diamante
* Place transmission in Neutral position.
* Ensure emergency brake has been set and all accessories
are turned off.
* Start engine and bring to normal operating temperature.
* Allow vehicle to idle in Neutral for one minute.
* Initial relearn is complete: process will be completed during
normal driving.

Some manufacturers identify a specific relearn procedure
which will help establish suitable driveability during relearn stage.
These procedures are especially important if vehicle is equipped with
and electronically controlled automatic transmission or transaxle.
Always complete procedure before returning vehicle to customer.

(Diamanteowners.com, 2007)[/align]

 

ooo this just gave me an idea also. If you want to do alittle troubleshooting on it then check out the 3g repair manual.
https://mitsubishiforum.com/m_128780/tm.htm

 

Now THAT I needed. Thanx TE