etnaskynet

Hello guys,

yesterday during the emissions check of my XJ 4.0 1989, the values of
CO (percentage) were too high.
Maximum allowed was 3.5
Mine as about 9

O2 is new, but still remain to 0.22V (too rich).
Checking with the software Renixcom.exe, the MAP value ad idle is
about 38 KPA (11.2 in.Hg).

Is this right or is too high?

Should be 28 KPA (8.2 in.Hg) at idle?

Attached you can find the screenshot taken from RenixCom.exe

Regards,
Lucio.

cruiser54

O2 sensor isn't switching?

Check the hose from your throttle body to MAP sensor.

and, I would do Tips 1,3,4, and 5 in my link below.

etnaskynet

Hello Cruiser,

right, O2 doesn't switch (0V - 5V), but remain fixed to about 0.22V.
At first startup, the voltage, from 5V, drops to 0.22V gradually.
(see attached screenshot).

Attached you can find my "etnaskynet.bin" to be renamed in .$$$
and loaded in ViewLog.exe

Engine HOT and idle, if I try to disconnect the vacuum line from
the MAP, the engine stops.

If I try to restart (with vacuum line disconnected from MAP), the engine
starts but stalls at idle.
If I reconnect the vacuum line to the MAP, the idle goes correct.

Cracked exhaust collectors (28 years old), can be the cause of O2 fixed to 0.22V (rich)?

If oxygen enters from the cracks, O2 read lean at the beginning and the ECU try to compensate with very rich...


Regards,
Lucio.

cruiser54

I am suspecting a problem with the O2 sensor or it's relay which provides voltage to heat it up.

What brand sensor did you use?

This may help. Also performing Tips 1, 3, 4 and 5 at www.cruiser54.com should be done.

etnaskynet

Hello Cruiser,
the heater is working, because at idle, O2 connected, 14V are present between red and black (gray is the signal).

I replaced with this O2 Sensor (Meat Doria 81040).

http://www.meat-doria.com/en/product_meat/81040/4597

All the tips were already done three years ago.

However, here an update.
ECU goes now in closed loop, but not during idle.
Only during driving goes in closed loop.
When I release the gas pedal, ECU back to open, then closed when run.

See attached.

cruiser54

At idle, your TPS reads high at 16.8%.

Have you ever adjusted it like this?:

http://cruiser54.com/?p=54

etnaskynet

TPS already adjusted.

In addition, I measured the output voltage (HOT and idle) of
the MAP sensor, and the value was 1.5v

Concerning the TPS,
the output voltage (throttle plate closed) is the 17% of reference measured.

OUTPUT = REFERENCE * 0.17

On rectangular connector (the one that goes to the ECU):
My REFERENCE voltage is 4.89v
so:
0.83v = 4.89v * 0.17


A question:
at idle, which value of TPS should be read from the software?

Thanks.
Lucio.

cruiser54

Rectangular connector goes to trans computer. Flat connector goes to ECU.

etnaskynet

Flat = rectangular >> ECU
Square >> TCU (trans computer)

So, my measurement was correctly done on Flat = rectangular >> ECU

cruiser54

Good.

My factory tester will indicate 2 things when looking at the TPS. One is the actual percentage, for example 13 to 14%, and it will indicate whether the ECU is seeing that reading as open or closed throttle.

etnaskynet

So,
in my case both two values should be aligned (the same).

The 1st >> measured by me with voltmeter >> 17%
The 2nd>> measured by the ECU-Renixcom software >> 16.8%

According to this, the TPS is setup correctly.

I think that the root cause is the (probably) cracked exhaust collector
(28 years old), so, oxygen can leak inside (before the O2 sensor).

CTS, IAC and Intake temperature manifold are OK (tested with the ohmmeter at different temperatures).

To confirm this, Viewlog shows right temperature from sensors.

At the same time, I'll try to check also possible vacuum leaks, that could
impact the reading from the MAP.

At Idle (and HOT), MAP output is 1.5v and the corresponding reading
from Viewlog is about 40KPA (12 in.Hg).

Could be too high as value (40KPA <> 12 in.Hg)???

Regards
Lucio.

cruiser54

12 inches of vacuum is low. Normal is 17 to 21 at sealevel.
The exhaust manifold being cracked has no bearing on this issue.
Perhaps the MAP sensor is faulty or the exhaust is restricted.
Do you have a regular old vacuum gauge you could hook up?

etnaskynet

Clear Cruiser54.
I've to check if MAP is bad or the vacuum is wrong.

So,
the first thing to do is to check the vacuum on the MAP, right?
I've to detach the vacuum line from the MAP, and connect it to the gauge, right?
Value that should be 17 to 21.
I live 6 hundred meter from the sealevel (hills).

I'm looking for vacuum gauges on the web.

etnaskynet

Found!

This would be ok? (scale and values)

cruiser54

Try and find an automotive one. Usually called a vacuum/fuel pressure gauge.
And by the way, tee into the map sensor line or find another vacuum source for the gauge.