O2 Readings Say Rich But Spark Plugs Say Otherwise

[waqar_lionheart]

Hi Guys,

Sorry to disturb. Some of you might already know that I have had a very long thread about pinging/pinking in my 1.8vvti 1zzfe 2001. I tried many things and it has not sorted the problem out. Putting super unleaded helps a bit but the quick succession of knock on uphill or under load between 2-2200 rpm is still there. Anyways. After much struggle i managed to get hold of a software to show me live data and last night was a shock.

I plugged in and it showed me that my O2 was switching 0-6,7,8v suggesting I am running rich. This was also evident from my short term fuel trim as it showed in single figures most averaging -3.5%. Having said that My Maf readings ( I think this is where the problem might be) showed 3-4g/s on idle and upto 17/18 g/s on wot.

I am slightly puzzled as when I look at my spark plugs I see that they are fairly clean actually more on the lean side than dark sooty rich.

So my question is that is this a false reading due to maf going a bit nuts. This richness is also confirmed by the exhaust as there is HC soot in there as well as smells like eggs/beans when I give it the beans.

This is bothering me as Its leaning the mixture thinking that its rich but in actual fact the mixture is already lean (according to spark plugs). I think I might be running false rich condition but I dont know what is causing it or why am i running rich if I am actually running rich.

Any help is much appreciated.

Regards,

Waqar

[Konrad C]

Waqar my friend, I cannot answer regarding your diagnostics, but wonder if the device you are using is working properly for your car. The plugs condition is conflicting with the live data diagnostic and the soot in the exhaust!

What about the emissions? That can tell you what is coming out of the exhaust.

Your science is way better than mine, so it hard for me to comment on your data.

You will be changing your fuel filter so that may change readings/car behavior.

There may a diagnostic guru who can understand your readings and say what could be your problem.

The pinging was not bad, unless it has got worse since my last visit.

Konrad

[waqar_lionheart]

That is whats puzzling me as something is causing a false reading of my o2 sensors. I wonder If an exhaust manifold gasket it leaking, would it cause a rich reading. i.e. not enough o2 in the chamber where this is being read. Anyone?

The actual condition is still as I am going for spark plugs as oppose to o2 data as thats a more reliable source.

Regards,

Waqar

[Konrad C]

Hi Waqar

If the exhaust manifold is leaking, then it would make a sound like it is pinging when under load. I had this with an older car few years back. In my case it was blowing but could only be changed out. If the gasket between the head and the manifold has failed, then that could be the problem. That could also interfere with the sensor operation.

When I heard your car it was pinging, but only for a second or two then it went away. I would look at the vacuum side of things.

Konrad

[waqar_lionheart]

HMMM Is there a test for exhaust manifold leak as i also think that the gasket might be the culprit. I have held a paper against it and it blew about but i am not sure. Is there a definite test????

Much appreciated,

Regards,

Waqar

[waqar_lionheart]

Hi Konrad,

The news is not good. The Intake air Temperature generally seems to be few degrees higher than whats ambient. This is very puzzling and there isn't a lot on google about it and whatever there is suggests that its normally a few degrees higher. So that's a kick in the butt.

Now this thing with manifold gasket leaking, I have read that generally that causes o2 sensors to report lean as opposed to rich? or am I wrong? please advise.

And if the manifold gasket was leaking then would it not sound houbiky?????? hmmm hmmm? :)

Regards,

Waqar

[Konrad C]

Hi Waqar,

You may not have a leaking exhaust manifold, but the sound is very similar. The difference is that a leaking exhaust manifold continues under load, yours stops pinging after a couple of seconds as the ECU adjusts.

I would go the cleaning engine route and checking vacuum pipes route. Carbon build up and leaks need to be sorted.

From what you are saying the sensors are compensating for an issue. I have never touch that side of diagnostics of live data, only basic fault finding.

It will take a specialist to make sense of your readings and what is happening. That cost time and money.

Get the cleaning stuff to clean the induction, fuel system, engine, cat's and exhaust system of muck and carbon.

Any dodgy connection checked and secured and retest until the pinging starts to reduce.

This will take up to a month before the engine pinging reduces and disappears. Especially the carbon removal.

Since you have the live data, you now know what sensors are being checked and that they are working within specs or not.

That at least is saving you money.

Konrad

[waqar_lionheart]

Hi,

Just done some reading on the internet and it seems that if I am not driving my car enough then it might not foul the spark plugs. So assuming that I am now leaning towards high pressure from the fuel pump.

I have been searching about fuel pressure regulator for my car and it seems that it might be integrated in my fuel pump. Its either this or my injectors are leaking. In order to know both these things I wanted to do a fuel pressure test and fuel pressure leak down test. Or know of any garage that wont charge the earth for such a simple test?????????????????? anyone please :)

I live near box hill and would appreciate any help from whoever has a fuel pressure guage.

The only other thing I can think of is a bad maf but then I have a live data logger and I can see my maf idling at 1.9-1.8 grams/second of air volume and going up accordingly.

I am initially doing all my tests at idle and at closed loop as I have heated o2 sensors.

I am only focusing now on fuel. Since timing on these engines is controlled via ecu. Has any one got any specs as to what the timing should be at idle and other certain RPM?

All the help is really appreciated.

Regards,

Waqar

[Konrad C]

Do the exhaust leak test again. Switch off the engine to make sure the wind is not affecting the test and then turn on the engine if you are satisfied that the wind is not a factor. Retest.

If the exhaust manifold is ticking, it gets louder on an open throttle. The ticking will stay audible so long as the throttle is open, but becomes quiet once the throttle is closed. I hope this makes sense.

If you do find the leak then lets hope that is the fix.

I still go by the carbon build up. Wynn's, Redex or BG44k and a good drive will clear the system from fuel injection, engine and cats, to clear the system.

Konrad

[Konrad C]

Hi Waqar,

In your other thread, I linked you to a thread about using two stroke oil as an additive. The relevant part you need is Roker's comments about upper cylinder cleaners.

This may assist with clearing your problem.

[waqar_lionheart]

Hi Konrad,

Thanks for that I have just read it and I am gonna give it a try. My main worry is that at some point its going to turn around and report a rich condition. I am dreading that. I can deal with it but I don't want anything to happen during my trip. I pray to God that Please let there be no breakdowns.Amen.

Regards,
Waqar