Technical what is wrong with my car ?????

[punto16v]

hi again as some may know i have mk1 85 16v elx .

I decided to change the exhaust a couple of days ago but when i fitted the brand new rear section i put the cat back in as it was decatted .

But since i put it on the car it seams to be a way down on power and very heavy on fuel aswell and is very uneven idle speed .

any ideas wat the reason for this is would be much appreciated thanks alan

 

[fingers99]

Dodgy lambda connection(s)?

 

[Ziggy122]

Cats dead? so the lamba's mis-reading?

I'd be tempted to see what the lamba's are saying

No power + Serious over fueling = low mpg + un even idle speed

Could be temperature sensor? but thought only mk2/b did the limp home thing?


Ziggy

 

[hitherematey]

It may be worth resetting the ecu after any change that could effect the engine

 

[Ziggy122]

It may be worth resetting the ecu after any change that could effect the engine

True...
How many lamba did you remove from the Decat version? if any had to be removed?

ziggy

 

[muse2112]

Wouldn't the engine management light come on permenantly on the dash if the lambda sensor was faulty due to incorrect readings to the ecu? Resetting the ecu would clear the errors, however, after a few starts the ecu would pop on the mil light on the dash again. So without a "mil" light on the dash i'd rule out the lambda (unless it doesn't trigger the mil light??)

I'd get a scan reading 1st and take it from there.

 

[m20b25]

Sounds like a clogged cat to me...

Check through the exhaust for blockages, you'd be surprised how little it takes to clog these things up

 

[Ziggy122]

lamba sensor can often read way out then they should be for ages
And when it goes a little further past gone - then it activates the EML

To check lamba's you need the voltage readings as it works
IIRC .9v is rich
.1v is too lean

should hover around .5v
Ziggy

 

[s and b]

if you have honestly only changed the back box and its gone wrong since then i would consider the back box to be blocked
you say decatted?
if it decatted itself by self destruction then the honeycomb might be stuck in the pipe somewhere and causing the blockage
as always i suggest a vacuum test to confirm a quick cheap easy diagnosis

 

[muse2112]

Last shot for me here. What about the maf ?? Had an Alfa with exactly the same problems ... erractic idle, excessive fuel and loss of power.

 

[muse2112]

if you have honestly only changed the back box and its gone wrong since then i would consider the back box to be blocked
you say decatted?
if it decatted itself by self destruction then the honeycomb might be stuck in the pipe somewhere and causing the blockage
as always i suggest a vacuum test to confirm a quick cheap easy diagnosis

Sounds the best way to go to me 1st

 

[punto16v]

hi again .

When i said that I replaced the exhaust I meant to say with brand new parts and the lambda didnt have to be touched as that is up near the manifold on the mk1 .

The lambda was replaced about 6 months ago with a brand new part .
Is there any way to check map sensor to see if it is working correctly ??

 

[muse2112]

As already mentioned you may have a collasped cat causing a blockage somewhere in your new exhaust. May be you could de cat again and check the cats condition ?

As for the maf, you could swap it over if you have a friend with a punto (you need the same model/serial number) and see if power and idling issues stop. A Alfa trick was to disconnect the maf, start the car (will run rough) go for a quick drive if power is back .... maf gone. However not too sure whether this is ok with these little Punto's.