Engine: 2.3 F/Inj B23E/B230F: Lambda/AMM running problems

[czech240]

OK...so having researched and read all I can I thought it was time to stick up a post and see what the collective on here can come up with!

Symptons are:

Car first started hunting/revving up and bogging down but not so much and was still drivable.

Symptons got worse.... Stopped revving up so much but started to bog down so much that drivability became a problem.

The car will always start from cold as normal but when up to normal operating temperature the symptons start and slowly get worse.

I have checked out the following:

Throttle body cleaned
Checked for vacuum leaks
Checked thermo in airbox
cleaned out airbox and filter
cleaned out all intake pipe work
checked/cleaned PCV

The car is definately running rich/over fueling as the plugs are sooty.

Unpluging the AMM the car runs better which I realise points to the AMM being the problem.

I have tested the O2/lambda sensor and I'm not getting the desired fluctuation on the single white into green wire (0.1-0.9v)

I also think I may have a very small leak at the manifold/header pipe joint (due to grounding the car out and few weeks back, the problems started a while after this)
I am also thinking that perhaps this possible leak is effecting the O2 sensor as the leak is before the lambda and may be affecting the readings? Anyone care to comment on this one????

So question is what to change first? If the AMM is faulty would this affect the O2 sensor? With a good AMM would the car burn leaner and perhaps burn the lambda clean? And what about the possible small leak on the exhaust could this be the main culprit?

I have swapped the AMM from my donor car but that one wasn't running the best before it was put on bricks and the same symptons show.

If you've got this far in reading this post then thank you for your time!! My fingers hurt!!

[tannachyallen]

How do you know that the MAF is bad, are you getting any fault codes, is the engine manegment light on on the dash?

If there is an air leak on the manifold before the lambda probe it will affect readings of the oxygen content so the system will add more fuel as it thinks things are too lean.

So, I would fix the leak and replace the lambda sensor if you know it's not working(?) and see what that does first.

[czech240]

Ah...yes, pulled fault code 121 and if I remember correctly 113 but this code cleared after resetting...

When the engine is warm and starts playing up, unpluging the MAF makes it run better...

[tannachyallen]

Originally Posted by czech240

When the engine is warm and starts playing up, unpluging the MAF makes it run better...

The MAF and the lambda are two inputs of the same system that tell the ECU how to mix the fuel. If the MAF is faulty the system copes by running in default mode. However if the probe is dead AND you have extra air getting into the exhaust, I suspect the systems default tolerences won't be able to cope.
For this injection system to work you have to have a working MAF and probe (and no air leaks!) as the system bases it's mixture decisions based on the feedback from those two sensors.

[Mike_Brace]

Before doing anything else sort out the leak and see what happens!

Mike

[czech240]

Thanks for the advise..... I was thinking that the leak should be rectified first....

Will keep you updated

Regards
Jody

[czech240]

OK.....As its chuffin' cold here at the moment pulled the car out of the garage to look for exhaust leaks before the O2 sensor....

Big thumbs up as the exhaust is leak free (well...not exactly as the rear silencer is leaking a bit but this shouldn't affect things!)

So...what next....New O2 sensor? Or try and find an old MAF.

One thing that occurs to me is that there is no change at all between the spare MAF and current MAF. I can't verify the condition of the 2nd MAF.

The car certainly runs fine when cold, so what with the O2 sensor coming into play once hot I guess it makes sense that the sensor could be at fault.....

Hmmmm??