Checking a/f ratio

Discussions related to Nissan DataScan I (NDSI) Windows PC software.
Redwine300
Posts: 7
Joined: 08 Apr 2013, 08:16

Checking a/f ratio

Post by Redwine300 » 08 Apr 2013, 08:54

Hi all,
New to data scan, so please excuse my lack of knowledge. I have a 300zx tt manual and would like to know if I can check the fuel mixture under varying conditions. Thanks in advance everyone.

onephatser
Posts: 31
Joined: 02 Jan 2013, 02:46

Re: Checking a/f ratio

Post by onephatser » 09 Apr 2013, 01:48

I don't believe so. What problem are you having?

Redwine300
Posts: 7
Joined: 08 Apr 2013, 08:16

Re: Checking a/f ratio

Post by Redwine300 » 09 Apr 2013, 05:17

Not so much a problem as more curiosity really.
I have just replaced both 02 sensors and wanted to check their functionality using Data Scan.
I also fear that I may have a small air leak somewhere, which in turn may lead to running too lean.

onephatser
Posts: 31
Joined: 02 Jan 2013, 02:46

Re: Checking a/f ratio

Post by onephatser » 09 Apr 2013, 05:54

You can check that by looking at the o2 sensor function on bank 1 and 2. As long as they fluctuate between .1 and .9 volts very quickly, the o2 sensors are good. In turn that would correct you air fuel ratio to within specs as long as fuel pump and pressure regulator are good.

Redwine300
Posts: 7
Joined: 08 Apr 2013, 08:16

Re: Checking a/f ratio

Post by Redwine300 » 09 Apr 2013, 06:43

Cheers Onephatser,

Really appreciate you help. I will hook up Data Scan as you say and check out the sensors.
On a separate note, I am a little unsure as to whether or not my AAC valve is working correctly.
Could someone explain it's exact function and what I should be looking for please?
Is there a specific multi meter check I could perform as to determine if the required voltage is there for example?

onephatser
Posts: 31
Joined: 02 Jan 2013, 02:46

Re: Checking a/f ratio

Post by onephatser » 09 Apr 2013, 06:53

The AAC actually stands for auxillary air control valve. It's basicly an Idle control valve. I've never seen one completely fail. They do get dirty though. Take the valve off and clean with carburetor cleaner where the plunger is. The only test I'm aware of is to hook the valve to a 12v source and see if the plunger open and closes all the way.

Cheers,
Ken

seb.racing
Posts: 101
Joined: 10 Jan 2012, 06:45
Location: France

Re: Checking a/f ratio

Post by seb.racing » 09 Apr 2013, 09:26

the AAC valve can be ordered in active test
if the motor reacts is that the valve operates
a cleaning of the valve is a good ;)

for the sensor O2, he should the engine speed to 2500rpm
for motor control of wealth
you need a wideband O2 ;)

skylinegtrhr
Posts: 39
Joined: 20 Mar 2012, 00:26

Re: Checking a/f ratio

Post by skylinegtrhr » 09 Apr 2013, 18:17

seb.racing wrote:
> for motor control of wealth
> you need a wideband O2 ;)

Innovate WB kits are working with Datascan software without of problem, You can log everything together .

onephatser
Posts: 31
Joined: 02 Jan 2013, 02:46

Re: Checking a/f ratio

Post by onephatser » 10 Apr 2013, 03:14

The AAC valve is located on the upper intake plenum. Are you having a problem with an unstable idle?

Redwine300
Posts: 7
Joined: 08 Apr 2013, 08:16

Re: Checking a/f ratio

Post by Redwine300 » 10 Apr 2013, 04:26

Thanks guys, some very usefull information for me to look into.
As for my idle oneohatser, these are the results. from cold she always starts first time, it's just that the tick over starts at 1200rpm and does not return to 750rpm untill she is fully up to temperature. As you can imagine, this may take a long time during these cold mornings, and as I have a difficult gearbox, it is made more troublesome to change gear due to the high tick over. Surely it should not take that long to settle down?

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