help testing MAF and lamba sensor

[MORRISMINOR GTI-R]

my car is badly overfueling especially on tickover and the power seems to drop off when i put my foot down more than 60-70% would this indicate either a faulty maf or lamba? if so what is the best way to test them? with a volt meter perhaps? or is there a diagnostic machine out there which can tell you the cfm your maf is reading?

thanks

 

[geetee]

odd.

Fuelling on tickover is controlled by the Idle Control Valve (oddly enough!). This is a physical jet adjustment by a screw.

At steady cruising speed the mixture is controlled by the ECU based on feedback from the Lambda sensor. You don't say if you have a problem on running at constant speed. Do you?

During acceleration the fuelling is again controled by the ECU based on input from the Throttle Position Sensor and the MAF. During aceleration the mixture is deliberately rich so the Lambda is useless and the ECU ignores it.

I would suggest perhaps you have a problem with your fuel pressure regulator??

Did you do any work to the car immediately preceeding this or has it come from thin air?

What makes u believe the car is badly overfuelling - u don't say? Black plugs / black smoke from the exhaust / exhaust smells of fuel.... what?

And what mods are you running?

More info required I think.

Cheers
GeeTee

 

[MORRISMINOR GTI-R]

it smells realy rich on tickover and uses loads of fuel even on tickover. on part throttle it seems realy responsive and powefull but when i floor it it doenst seem to do what it should. i can sometimes tell by the exhaust not that it is overfueling but this is at sat 2000-3000rpm when under load at full throttle but easing of the pedal and then pushing it down more gradualy make it go a lot better and doesnt seem to hold back

 

[geetee]

It could be something simple like ur ignition timing. Have u checked it?

It could also be old plugs giving a poor spark - this could also could be the plug gaps, HT leads breaking down or pitting in the dizzy. Poor spark would lead to incomplete detonation and 'rich' smells coming from the exhaust.

You don't say what mods you r running and if this a sudden problem or it has always been there or developing over time?

There's so many things that could cause overfuelling or incomplete combustion it's hard to say. So start with the basics - what have u changed? Check the basics - plug gaps / condition. Then start to worry about the more expensive options.

Cheers
GeeTee 8)

 

[MORRISMINOR GTI-R]

its got usual mods front mount, pump apexi safc 1.3 bar etc. its been there most the time since ive had the car but is most noticeable when the engine is hot but i know its not been going into safe mode. my engine was took out yesterday and is having a new rings put (lost comp on no 4) and was smoking well bad in the end. i just dont want the same thing to happen again.i had a look down the afm and the second piece of sensor wire looks asif it amy havea bit of oil on it. could this be causing it?

 

[geetee]

crap on the maf sensor wire could be causing problems. But you won't know without a decent gauge attached.

I would recommend geting a decent rolling road setup once you have the engine back in. That will pick up any overfuelling at a given rpm range etc.

They should also be able to monitor the outputs from the varius sensors and tell you which one is dodgy.

Cheers
GeeTee 8)