Hi,

having probs with misfire as people know, and proberly sick of me asking questions, just dont know who else to ask, hence asking u experts :worship:

Just took a reading from my lambda sensor when engine was hot, fan kicking on and off, reading in volts was steady 0.007 area. and in ohms 0.7**

(** means various numbers)

Just wanted to know is this normal. readings were taken with a digital multimeter set to 2v.

Also lol when I did my head transfer, I swapped inlet manifolds and use the same gasket, could this be leaking air in. missing at idle, hesitation when driving/poor response, and when engine is warm, if i come to a stop at lights, after I've pressed the clutch down, the engine dips to the needle rest on the rev counter and sounds on the verge of stalling for about 10-15secs then recovers but still missing, also happens when I start the engine when hot.

coil's swapped no difference.
new plugs no difference.
leads less than 2months old.
new engine coolant sensor.
swapped throttle body no difference.
timing, more than 4 times tried, no difference including flywheel marking.

any help appropriated.

thanks and sorry for bugging, cars just getting me down as i cant seem to find the fault. and at the moment im just throwing parts at her and seeing if i get lucky
Dave

Have you tested the head gasket?

Any Help?

http://forums.puntomk2.co.uk/showthread.php?1269-Lambda-Sensors&p=436421

bredsticz said:

Have you tested the head gasket?

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Hi

new head gasket was done when the head was swapped this monday.

no normal signs of head gasket failure to report.

ta

WhiteSei said:

Any Help?

http://forums.puntomk2.co.uk/showthread.php?1269-Lambda-Sensors&p=436421

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yes that did help thankyou, "0.8 Volts (rich)." so mines running rich, also just pulled the spark plugs 2days old and there carbon sutty black all 4.

like the 1st ones in the picture. dry black

:devil:

Sorry to sound ungratfull but this car is really getting me down

could it be because it is a cinq sporting head on a punto engine?

apart from the head, everything else is the original engine and i swear its too small for the rest of the engine block?

looking from the front of the engine. u can see the head gasket and a little bit of the face of the piston block.

dave

Just done this test as suggest on the info WhiteSei gave me, and my multimeter still reads between 0.070 - 0.080 in ohms.

That was with my map sensor pipe removed. the engine did respond, the idle speed went faster.

"To check the sensor's response to changing oxygen levels in the exhaust, first create an artificially lean condition by pulling a large vacuum line. When extra air is introduced into the engine, the sensor's voltage output should drop to 0.2 V"

Could this mean my lambda sensor may be dieing, under normal (misfiring) conditions it still reads between them values.


dave

You need to see the voltage its sending out. I'm guessing now, but it probably needs a break out connector slotted into the connector block so you can get the mutimeter onto it and read the volts to earth. Interesting point about analogue meters causing damage - lambdas must be fairly touchy bits of kit.

http://rover800.gaima.co.uk/Rover800/www.pallant.f2s.com/rover/tech/lambda.htm

WhiteSei said:

You need to see the voltage its sending out. I'm guessing now, but it probably needs a break out connector slotted into the connector block so you can get the mutimeter onto it and read the volts to earth. Interesting point about analogue meters causing damage - lambdas must be fairly touchy bits of kit.

http://rover800.gaima.co.uk/Rover800/www.pallant.f2s.com/rover/tech/lambda.htm

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Hi matey.

Thanks for replying, When its set to voltage the readings are the same, 0.007 - 0.008 in volts multimeter set too 2v, but i will recheck tomorrow, I have a digital multimeter with needle tip points on the probes, so the lambda sensor was still connected to the ecu as i was taking readings, my + probe into the black/green wire and my - probe to the engine block itself. my probe can be pushed straight into the wire as suggest on another site.

Makes you wonder how the survive so well after the pot holes etc we hit along the way and speed bumps!

just wondering what the next best thing to do is?

Dave

Do the checks these folks suggest and if its looking out of range either take the plunge and buy a new sensor or get a garage to test it out.

WhiteSei said:

Do the checks these folks suggest and if its looking out of range either take the plunge and buy a new sensor or get a garage to test it out.

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thankyou, i think i might try a sensor as its alot cheaper than another car

Hi again,

Just done a reading in volts, no engine started .001v

whist warming up .006 - .007v

when warmed up fully .006 - .007v

I take it, it may be faulty?

Also when reving, It does sound as if the choke is on, like on a carb engine.

ps: that .006 - .007v reading comes into action as soon as the engines started.

Dave

The same value when hot shows its not signalling the ECU to reduce the fuel flow. The default is a rich mixture (choke on) turned down when the O2 sensor kicks in.

rite ive replaced the o2 sensor aswell now and no difference.

I think i may have a buggered head as before the transplant the engine worked ok and nothing like this was happening, this misfireing etc started after the first turn on the key on this head, and now im ready scrap it! i replaced everything that could be causeing this problem. :bang:

the old had was making a knocking sound on the camshaft but no missing no hesitation, no idle dipping no loss of acceleration,to the point it nearly stalls.

just knocking.

the other o2 sensor i pulled out was carbon black just like the spark plugs.

this head thats on, is so i was told a cinq sporting no idea wat cc, but it does look less fatter than my head and it looks less fatter than my piston block, could it be a cylinder capacity problem, like as if the valve area/diameter on the head is smaller than the piston bore diameter ? if that makes sense.

O2 sensors are pretty fragile, but I'm sure should not be black. Maybe others can help.

digital multimeter useless for this, get a cheap £5 job with a needle as it reacts faster and more visable.

T14086 said:

digital multimeter useless for this, get a cheap £5 job with a needle as it reacts faster and more visable.

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needle, analog ones damage it so net says, an on them 2 links.

cheers doh

WhiteSei said:

O2 sensors are pretty fragile, but I'm sure should not be black. Maybe others can help.

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oh but it is mate, please see photo's spark plugs are the same. and spark plugs are now 3days old.

the pic of lambda was all black i wiped a bit so u can see the difference.

Just thinking now weather get another head, this time from a punto, the other was through a member on here. cing sporting engine, that's what i was told.

two of the pictures you can actually see the headgasket

Net isn't always right....read yesterday elvis is still alive! Never had a problem in all my years (over 20 years in the trade at highest level), digital are too slow to react and often just take the 'mean' reading.

T14086 said:

Net isn't always right....read yesterday elvis is still alive! Never had a problem in all my years (over 20 years in the trade at highest level), digital are too slow to react and often just take the 'mean' reading.

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i wasnt doubting you mate, I appreciate any help people give me on here, this is stressing me as I have a baby on way soon and need a working car, nobody's problem on here I know, just saying. I still think my problems are much more worse than the lambda sensor, after all two cant be exactly the same.

I thinking along the lines of cc now maybe?

Why do you need a new head? I have a head from a 1.2 8v punto. Blown piston rings but head should be good!