Low idle, high HC

Encoder1970

Hi, was suggested to try here after my NCT fail earlier.
Old 1996 petrol banger didn't pass emissions.

Engine oil temp 75C
Low idle CO 0.91 vol%
840rpm HC 111 ppm

High idle Lambda 1.01
3280rpm CO 0.34 vol%
HC 49 ppm

So too high on low idle HC and CO and also high idle CO if Ive read the NCT report correctly?

I am retesting it again in a week, is there anything other than new oil/spark plugs/filter I should do? Additives? Catalyctic converter was replaced a year ago because the old one started rattling.
Spoke to a mechanic that suggest lucas oil?
Car is old but good no rust so I dont want send it to an early grave just yet. thanks.

zilog_jones

What car is it?

Encoder1970

It's a volvo s40.

Darsad

On top of what you are doing try and get a couple of bottles of Texaco fuel system cleaner and drop the first into half a tank of fuel and then the second bottle into a full tank before your next test its expensive stuff but really works Ive seen some really impressive results with it .

Encoder1970

A machanic with looked today at it and got a DTC code:
325 ECU Memory failure which seems to be something to do with ignition? Or maybe ECU needs replacing? Car is not idling rough so doesn't seem to missfire or anything...

Since the car is burning oil he pretty much said that it cannot be fixed which seems drastic but then he should know i guess. Will try to dump a tonne of chemicals in it and see if that helps.

itarumaa

at least low idle HC value for me tells that car is not burning petrol properly,

so basically air filter, spark plugs at least should be checked. I don´t think the oil consumption should show up too much in the test, what is milage of the car and how much oil you think it burns, lets say in 1000km?

JHMEG

Is that code (325) gone, or is it still happening?

Encoder1970

Yeah it seems to my untrained eye something is preventing the petrol to burn properly, probably oil. I never noticed the car burning oil before so it must be a new thing. Just a few weeks ago the the car was fine and now the exhaust smells of petrol fumes. Maybe some seal? Car is not overheating and oil looks black.

JHMEG, not sure. mechanic just gave me a piece of paper with the code on and said "it's burning oil, nothing to be done" thats pretty much it. Didn't charge me anything tho.

Encoder1970

Looking at this page http://www.smogtips.com/failed-high-hydrocarbons-HC.cfm maybe there is a problem with the ECU after all...

How do I check my spark plugs and lines to make sure they are good? That I get a good spark and it is timed correctly?

JHMEG

If there is an ongoing problem with the ECU it will run in open-loop mode where it ignores all the sensors. I don't think it'll pass emissions tests when it's in open-loop.

TskTsk

Darsad wrote: »

On top of what you are doing try and get a couple of bottles of Texaco fuel system cleaner and drop the first into half a tank of fuel and then the second bottle into a full tank before your next test its expensive stuff but really works Ive seen some really impressive results with it .

Do they sell that stuff in all Texaco stations? Anywhere else?

Encoder1970

Encoder1970 wrote: »

Low idle CO 0.91 vol%
840rpm HC 111 ppm

High idle Lambda 1.01
3280rpm CO 0.34 vol%
HC 49 ppm

So too high on low idle HC and CO and also high idle CO if Ive read the NCT report correctly?

Hi again
I was down at a garage and tested the car after putting some STP fuel treatment and a bit of Dipetane in the car.

Low idle
CO 0.48 vol%
HC 199 ppm

High idle
Lambda 1.02
CO 0.52 vol%
HC 78 ppm

The garage guy said the low HC wasn't important and NCT is mostly concerned with CO? Maybe I didn't understand him?
Would more Dipetane lower the CO you think? It says on the bottle you can't put too much in