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Rod35hall

Engine idle trouble

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Hi all, 

I searched the forums and didn’t find anything related to my issue. I recently installed my G4+ in my R32 GTR and I’m having issues with idle when the MAP sensor is connected to a vacuum source. Without the vacuum source it idles somewhat fine, but when i connect the vacuum source to the MAP sensor, it idles rough then dies. I’m getting my vacuum from the same line that was feeding the stock boost pressure solenoid. Any help would be appreciated.

NOTES:

I’ve disconnected the MAFs, I’m running correct base map that was supplied with ECU. 

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8 hours ago, Adamw said:

Has it been tuned or is this just the start up map?

 

It has not been tuned. It’s the start up map with slight modifications to fuel and ignition tables to stabilize the idle.

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3 hours ago, Brad Burnett said:

The start up map is just that, a start up map.  It will still greatly benefit from a proper calibration on a chassis dyno.

Understood, but still trying to figure out why the car runs fine when the MAP sensor vacuum hose is disconnected and stalls when the vacuum hose is connected.

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56 minutes ago, Rod35hall said:

Understood, but still trying to figure out why the car runs fine when the MAP sensor vacuum hose is disconnected and stalls when the vacuum hose is connected.

It is because it hasn't been tuned, your fuel master and/or fuel map is obviously miles away from correct. 

Manifold pressure is part of the fuel equation, if you disconnect the MAP sensor hose then the ECU sees higher manifold pressure (no vacuum) so increases fuel.  If you run better with the hose off then it suggests you don't have enough fuel.

Have you been through all the pre-start checks and first start up steps in the manual - base timing, fuel master etc?

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