Wrong diagnosis?!

[paul6]

Hi Guys

As my previous posts say, i was told my car was running on 3 cylinders. Had some 1 listen to it and they said its defo running on all four.

Took it for a spin yesterday and realsied it's very low on power, in 4th & 5th gear sounds like it wants to stall, and my mpg hit 14 when i was doing 25mph.

Is this game over?!

 

[drhowser]

could be a damaged lambda, do you know anyone to borrow one off and try swapping?

also if your engine is running that rich you need to use it as little as possible, you could strip the oil from the bores!

the best thing to do is have it plugged in to a diagnostic machine though.

 

[Da]

Try unplugging the MAP sensor and start the car.
Could be the lambda too as said. Did changing the coil pack make no difference? Have you checked/changed the leads/plugs?

 

[paul6]

hey guys, no havent changed the pack, fella who had a quick look said that all seems fine. Was thinking lambda when i daw my exhaust rattle, but i dont know! whats this map sensor?

 

[Nickharding]

Lambda sensor or the head gasket has gone between 2 pistons, whats the mileage?

It was both on my clio...

 

[Da]

The MAP sensor is on the drivers side of the plenum, under the engine cover. It's a simple check and was the cause of my missfiring issues.

There's a picture of it in this section in a couple of threads.

 

[paul6]

will have a quick look at this now. If i unplug it and start the engine, what should i be expecting?

 

[Da]

Well mine was missfiring from idle and hesitant on acceleration, unplugging the sensor cured the idle issues and made it run better.
I've since changed the sensor and it has resolved my problems

 

[Nickharding]

Ah nice one Da,

Paul if you can, get a compression test sorted out, will soon tell you if your hasget has gone between 2 cylinders, thats what our main problem was, does it stink of fuel? (because its not getting burnt)

 

[paul6]

yeah im going to send it in on monday morn, hope to god its just a sensor.

Although i cant imagine a sensor would made a car run this bad (i dont actually know, just guessing)

 

[paul6]

Nick - Car stinks of fuel always, decat lol, havent noticed it been any stronger though

 

[Da]

The MAP sensor is pretty important, it senses the air pressure difference between what's inside the plenum and what's outside. From that it works out how open the throttle is (as this lets air in) and then dictates to the ECU how much fuel to put in and the ignition timing.

 

[Nickharding]

Yeah if the lambda has gone it will make the car run as you described, Hopefully its just that, How many K has it done out of intrest?

Cool about the decat LOL.

 

[paul6]

its done 100k now, although it had new parts when cambelt snapped! new gasket valves all the stuff. Nice 860quid bill 3k miles ago

 

[paul6]

thanks for the help guys, will have a look at the map sensor this afternoon. Other than that, send it in monday morn for a lambda check

 

[Nickharding]

Hmm, i think its either what Da said, or its the Lambda sensor, cant really be much else..

 

[paul6]

just a quick thought now. I had the decat made 'one off' for the car. Is there anyway, i can check if the lambda sensor hasnt fallen off?! just a thought!

 

[Da]

Have a look?

There should be two, one pre cat and one post cat. They're interchangeable by the way so a quick way to eliminate the pre cat sensor is by swapping it with the post cat one.

 

[Jonny1*2]

have a look under and see if it's hanging?

post cat sensor does nothing, so just swap it to the precat to check it.

 

[paul6]

Hey guys, thanks for all the help, had enough now, booked into the garage tomorrow. Will let you know the solution & costs when complete. Cheers, Paul