I have a '94 900cc Cinq (well, it's my girlfriend's actually) and today it failed it's MOT (the Portuguese equivalent) because of high CO levels. The tester also noticed that if you try hold the revs at around 2-3000 they oscillate slightly - ie, you don't move the throttle pedal but the revs rise a little, then fall a little, then rise a little etc.

The tester reckoned it was a dirty or dodgy lambda sensor - sound reasonable?

The fuel injection light also comes on every so often with no noticable effect on power or anything else. Car starts and idles fine.

Cheers,
Michael.

Cinqs are prone to eating lambdas - so it is a fair assumption, yeah.

welcome to the forum

try bottle of add to fuel injector cleaner, then thrash the balls of it

michaelab?
in Lisbon?
are you the michaelab from Zerogain?

If so, I never expected to meet you here

are you the michaelab from Zerogain?

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Indeed I am . It's a small world. Someone on one of the BMW forums I'm on also "recognized" me from Zerogain.

try bottle of add to fuel injector cleaner

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Do you mean try adding a bottle of fuel injector cleaner to the fuel tank (and then really thrash it)?

Michael.

michaelab said:

Do you mean try adding a bottle of fuel injector cleaner to the fuel tank (and then really thrash it)?

Michael.

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yep sometimes dose the job

The cat might be buggered!

If the cat is buggered that would be the worst case scenario . Allthough I'm sure that a replacement cat for a Cinq is a little cheaper than the twin cats on my BMW M3

Michael.

Right - getting this checked out tomorrow. I chatted with my local independent mechanic yesterday about it and he was saying it was likely to be either the lambda sensor or the cat and he quoted me some prices for replacements:

125 Euros (about £85) for a Lambda sensor
300 Euros (about £200) for a cat

Do those sound about right? I thought they'd be a bit cheaper!

Cheers,
Michael.

for a geniuine sensor, thats about right. the cat is pricey though

michaelab said:

125 Euros (about £85) for a Lambda sensor
300 Euros (about £200) for a cat

Do those sound about right? I thought they'd be a bit cheaper!

Cheers,
Michael.

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And all of a sudden the BMW became cheaper! lol

Alex22 said:

And all of a sudden the BMW became cheaper! lol

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Not quite...recently replaced the twin cats on my M3 which set me back £1000, and those weren't original BMW ones (allthough they're made by the same people). The BMW ones cost nearly double that

Michael.

Right - took it 'round to my local chappy and here's the results:

Emissions at idle: all fine
Emissions at 3000rpm: CO at 0.60% when it has to be below 0.30% to pass
ECU diagnostic: no faults
Test lambda sensor: all OK

As I mentioned before, if you try to hold the revs at 3000rpm they oscillate up and down slowly instead of remaining steady.

The guy said that lambda sensor seems fine, cat is probably fine and it's likely to be something up with the injection system. On Monday he's going to check the plugs, air filter and fuel filter and then check out/clean up the fuel injection system and see if that improves things. Otherwise he's saying it could be a new FI module Reckons the injectors could be "pissing" rather than spraying (his words!)...

Given the extra info anyone else have any more ideas?

Michael.

Update:

Checked all the cheap problems (plugs, fuel filter, air filter) and allthough the plugs were well knackered replacing them didn't make a significant enough improvement to pass the 3000rpm emissions test. Reckons it's the injector and has told be it costs €371.14 for a new one :yuck: . Sounds mighty high. My fear is spending that cash and it still not solving the problem...

Michael.

Hi,
Couldn't you get a throttle body from a car breakers yard, seems a lot to spend on a 11 year old Cinq, I didn't pay too much more than that for my whole cinq....

Thanks
Paul T

I'll see if I can find out about breakers yards here in Lisbon. The trouble is the temporary "MOT" (Portuguese equivalent) it has runs out on the 27th so there's a bit of urgency in getting this sorted. OTOH I can always take the risk of driving it around for a while with no MOT but the fine for getting busted is fairly steep too!

I checked up on the price and it's about right since, for reasons best known to FIAT, they don't supply the injector on its own, just the whole throttle body

Michael.

Hi,
Does the car hesitate when you accelertate hard....?, if so it could be a small leak in the map sensor hose..... , that would cause the 3k engine speed to vary under part throttle load.

Thanks
Paul T

oh dear about the cat i had to have a new one and don't get me started cause that was expensive

for a part time worker such as myself

paul_treg said:

Hi,
Does the car hesitate when you accelertate hard....?, if so it could be a small leak in the map sensor hose..... , that would cause the 3k engine speed to vary under part throttle load.

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Hesitate in what way? When I accelerate hard there seems to be a bit of dip dead spot in the middle of the rev range which does manifest itself as hesitation, yes.

Would such a leak in the MAP sensor hose also cause elevated CO emissions at fast idle (3k)?

Michael.