have done loads to my mrs 2001 mpi sporting in last 6 months and thought i had finally finished working on her car ...but no.
car has had complete exhaust system,head gasket,full service,cam belt,leads,both coil packs,map sensor,water temp sensor and both lambdas.
the car every now and then idles crap and when put foot down the management light comes on and brings up code for 1st lambda.the lambda has been tested and only a month old so i know its something else that is making the car randomly run lean or rich and the lambda is picking this up but what???
i have done everything that i have been taught to do and puzzled now.
a lot of the advice on here is for the spi not the mpi so anyone got any ideas as otherwise the car is going as doing my head in.:bang:

The only things that spring to mind for lean running is the fuel pump, but if it only does it when warmed up? maybe it's the lambda wiring you should be looking at it might have an intermittent short caused by engine movement.

all the wiring is spot on and checked when the lambdas were replaced.had issue with fuel pump pick up being covered in sealent from a tank change before i bought it and pump running ok now.going to double check timing later as if its jumped a tooth could give same poor running.

you changed the in-line fuel filter?

its an mpi and only has the in tank filter which was cleaned last week.

marcevs72 said:

its an mpi and only has the in tank filter which was cleaned last week.

Click to expand...

Think you'll find the small mesh bag on the bottom of the pump is only a pre-filter, there is a non replaceable paper type cartridge built inside the plastic housing- if the snot has clogged this....

Amazing what you can learn with a second hand Punto fuel pump & a hacksaw :devil:

haven't you just decatted or was that someone else? Did you get that fault code before you did it?

yes just decatted it but been having problems for ages.the actual cat was blocked so needed to be done.car is running randomly lean every now and then and bringing code up as lambda but its not the actual fault.checking all the inlet and injector seals at weekend as head was off for head gasket not long ago and might have air leak from there.trying another pre-cat lambda as well just in case i have a dodgy new one.

want this sorted as well as might be selling the car as the mrs wants a bright green lupo...:bang:

What happens if you run it with the lambda unplugged?

the pre cat lambda has to be connected as thats the one that the ecu uses for mixture.just done another voltage test on that lambda with the car hot and getting a reading of 0.01-0.02 volts when should be between 0.1 and 0.8 volts so getting another lambda tomorrow.
shame this happened as lovely little car and even the mot tester couldnt believe that there is no rust anywhere.

well new lambda and code reset.done ecu reset as well so will take a bit to settle down but loads smoother now.old lambda was completely black so car running silly rich.

well after a bit car running lumpy and hesitating again so decided to check everything again.when i did head gasket and cambelt a few months ago i set it to marks that were already painted on when i double checked today using bore scope at tdc a valve was still slightly open so pulled the cam back 1 tooth and so much better.timing up didnt help as bit where factory mark is has been broken off.
before:

after: