Topic

Hi,
I am trying to use my pscan diagnose high CO emissions on my 98 R400 1.4

Fast Idle 0.669
2nd Fast idle 0.658
Nat Idle 0.801

Lambda and HC are ok.

The ECU goes into closed loop, the oxygen sensor voltage varies mainly between 0.1 and 0.8 and the temp sensor goes up, from memory ECU reads 90 dash is just under half way.

A couple of questions,
What is the 'normal' operating temp of the engine?
and if I were to average all the O2 sensor voltages should it be near 0.45v if its working correctly?

currently the engine seems to sit in the high 80s and my average voltages come to 0.35 ish

Cheers

Neil

So just warmed the engine up with the pscan logging CTS. it warms steadily to 89-90 deg and then stays put for a while I assume wile the thermostat lets the coolant through the rad. then steady warm to 104-105 deg when the fan cuts in, the fan cuts out again at around 97 deg. The dash gauge didn't get to half way.
Does this look about right or is the CTS reading a little hot?
any comments welcome,
Cheers,

From my old r45 Haynes manual (doesn't actually cover this model though) the figures are consistent with the CTS figures I have been getting from Pscan. Checking the average O2 sensor voltage on the same warm up I get 0.47v so close to the 0.45v that I think is the ideal value.

I think there may be a better way to approach this but I can't think of one at the moment. Any ideas welcome
Cheers,

plan9 wrote: wrote:

The ECU goes into closed loop, the oxygen sensor voltage varies mainly between 0.1 and 0.8

To the best of my knowledge this is normal.

Narrow band lambda sensors are either "on" or "off", and so what the ECU does in closed loop mode is richens the engines slightly until it goes "on" and then weakens it slightly until it goes "off", on a continuous basis. The idea is to keep it near the "switch" point which is where the mixture is correct.

If it is either stuck high or low and not cycling then that would be a problem.

Thanks for that, maybe the emissions are ok after all and there is some kind of error with the original diagnostics,
I cant find any signs of a fault with the pscan (not that I am an expert on these things!)

Ill see what happens tomorrow at the MOT,

Thanks for the help,

Leaking exhaust system? Catalyst core loose?

The normal operating temp for the K series is between 88 and 110'C.
If all other things are equal the car will be in between these two temps.
The "up to temp" mark on the dash gauge covers these two temps.