Erratic Vacuum readings!!!.... help!!

[Master_Sentra]

I’m using a Haltech E6X EMS, the car is running but we are having some problems due to erratic vacuum readings. Since the GTiR motor was swapped into my B13 Sentra all the vacuum lines were disconnected and at the time of re installation the vacuum lines were all mixed up and connected different to their original position.

The ECU’s MAP sensor is reading vacuum from a single line that is connected to each runner (after the throttle bodies) grouped with T-fittings, but we still get erratic vacuum reading. :doh:

What is the best place to have a stable vacuum reading so we can connect the map sensor and the boost gauge to that line??

I will appreciate your help.

Cheers,

PS: Here is a little video of my car we took this Saturday

http://www.youtube.com/watch?v=TRLhuImXH-U

 

[rx jamie]

yeah thats a bad position as the vacuum and pressure will pulse between throttle bodies. i d say its best to take it from the plenum head space above the bodies. should be a nipple on the plenum below where the charge pipe from intercooler enter the plenum. the line to my bov uses this line...T- into it.

 

[steve963]

I thought a BOV line would need to be between the bodies and the engine, so when they shut you get vacume...

 

[Fusion Ed]

you need to put all the vacuum pipes into a chamber to smooth out what the boost pressure sensor sees.

 

[Master_Sentra]

yeah thats a bad position as the vacuum and pressure will pulse between throttle bodies. i d say its best to take it from the plenum head space above the bodies. should be a nipple on the plenum below where the charge pipe from intercooler enter the plenum. the line to my bov uses this line...T- into it.

Yeah, both the readings from the ECU's MAP Sensor and the Vacuum/Boost Gauge receive something like a pulse, really erratic.

But at idle, when the Throttle Bodies are closed is there vacuum in the plenum?? :?

The vacuum of my BOV is connected between the TBs and the engine.

Cheers,

 

[rx jamie]

yes at idle it pulls vaccuum as you throttles arent totally closed, they stay open slightly to allow air into the engine to keep it running. if they were completely closed the engine would stall.
try hooking it up to the plenum as above and see if it works. i'll look at my car again this afternoon and i'll try get a picture up for you.

 

[Master_Sentra]

Great!!!!..... I'll be waiting 4 the pics....


I got another question.... How many milisecs should the coils charge before sending the signal to the distributor??... mine is set at 1.8 milisecs and the spark seems a little weak...

Cheers

 

[Fusion Ed]

IF you hook it up to the plenum, you will NOT read vacuum, which means the haltech will have absolutely NO hope in running this car correctly.

You have to run the vacuum pipes to a chamber that smooths out the pulses. That is the only way to do this right, and is why there is a chamber below the intake manifold on a stock gtir.

 

[Fusion Ed]

Just seen the next question. The spark duration changes dependant on RPM. This is called the dwell duty, I have not used haltech but this is something that may need setting up. Too long the coil will burn up, to short you'll get missfires.

Ed

 

[Master_Sentra]

Thank you Ed, we will re-install the chamber below the plenum to read vaccum for the Haltech and to connect the Vacuum/Boost Gauge there cause that needle is driving me crazy.... :frusty:

Cheers,
Enrique