Hi hope someone can help me, I got a p reg cinq sporting which has developed a major flat spot in engine revs and performance which keeps occuring when i pull onto roundabouts or pull away, it tends to happen when engine is hot. It idles fine and i cant see any physical issues under the bonnet, its as if it is starved of fuel then clears and takes off! any ideas???

try changing the fuel filter - i had the same prob with my cinq and this cured it.

Check the pipe run to the MAP sensor. Actually remove the pipe, check the pipe, the connections, and whether its full of liquid (it shoudn't be).

Cheers

D

Wow a reply! :slayer: I just took the liberty of getting a fuel filter today as i noticed a couple similar threads with my cars symptoms, seems the fuel filter can cause a fairly common problem? Checked the map sensor pipe, it did have a tiny hole, i fixed this but the flat spot remains. Will be putting the filter on saturday morning, hope it does the trick!

Sorry it took so long, I had to work!!

Cheers

D

spark plugs?

i had this problem once. was fine when it was cold, but once it warmed up, it sempt as thought it would hesitate every now and then. then bolt off like someone kicked it up the arse.

the car had just been for a service at the time, so never thought it would be that, but the garage put a dodgy spark plug in.

Might be worth taking the fuel pump assembly out the fuel tank as the internal filter could be getting blocked with some crap floating round in the tank.
I have had experience of this and it gave the symptoms you discribe.

Wow thanks guys! didnt think I'd get so much response! I will be doing the fuel filter first thing tomorrow. Hopefully this will sort it, if not I'll wip the plugs out and go from there, thanks again, will let you know what sorts it!

chazzer said:

Wow thanks guys! didnt think I'd get so much response! I will be doing the fuel filter first thing tomorrow. Hopefully this will sort it, if not I'll wip the plugs out and go from there, thanks again, will let you know what sorts it!

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Hey back to the drawing board. This morning I have fitted a new fuel filter, road tested the car only for it to be exactly the same. Decided it could be the plugs so I fitted a nice shiney set, still no improvement. Is there any possibility of a faulty sensor on the engine? and the location so i can inspect and if need be, try and find another from a scrappy? or any way of testing? Is it worth me having a look at the tank sender for clogging? Any ideas??

Oh and I noticed the idle has a very slight jump in revs every 10 or so seconds? but nothing serious. I have seen threads about ECU resetting? how do I go about it? Also I'm beginning to suspect my Lambda sensor...?

99% sure its not the lambda. If it produces the fault when the car is under G-Force , Then it's either loose wiring/connector, or blockage in fuel.

Ok well reckon my next step is to have the sender unit out and check that for blockages, I disconnected the battery overnight as I'm guessing this will reset my ECU. I'm really in two minds about the Lambda sensor so wont fork out for one just yet. I'm clinging to the hope of finding a simple fix! The saga continues......

My P reg sporting had exactly the same symptons. It really struggled through the mot emmissons test, and the idling speed was hunting around like you describe. I had a new fiat fuel filter fitted, put in a petrol additive, and tried running it on shell v-max. All helped a bit, somedays its absolutely fine and goes like a bomb, then sometimes the flat spot comes back, a bit annoying when pulling out of junction, it just feels like my old AXGT when the it was cold and needed a bit more choke. But in the cinq the temperature makes no difference. I have a theory, i know my cinq is on its original fuel tank, maybe its full of crap. I have learned to live with mine as it is for the last six months.
But good luck with yours.

Cheers wozwoz, I have come to the same conclusion at present so am gonna go take my sender unit out my tank right now and have a look inside the tank! There are so many similar posts on here suggesting fuel blockage or maybe lambda. I gotta check out the cheaper option first! I'm still determined to get to the bottom of this so will report my findings.

Ok just taken out the in tank pump and what I assume is the float tube for the level gauge? which has a kind of gauze under it and all appears to be fine. There is no major contamination or particles floating around in the tank, had a thorough look at the pump assembly and it all appears to be spotless so I guess this rules out a blockage here.... Lambda sensor????

looks like a trip to the scrappy for a lambda sensor.

does it run fine when cold? i.e. before the neddle gets to 50 degrees?

mine has started with simular symptons, only my idle is perfect concistantly. i'm thinking its related with the lambda sensor, as its started since i've changed apart of my exhaust, which is serverly blowing.

Yea it does seem to run perfect when cold, i must admit I am being slightly picky about my idle, I'm sure its not really that bad. Yep got the day off work tomorrow so will pay a visit to my local scrappy, Hope they got some new or should I say old stock??!! as last time I went the cinqy popularity was few and far between. Will be nabbing every sensor possible if i find one tho me thinks!!

Had the same problem with my punto. had to put my foot to the floor to get above 30mph. jus put a lambda sensor on today and cured the problem. try to buy a new one because second hand ones may be clogged up. around £40

i'm hoping my problem is purely because of the exhaust blowing. cos if its blowing i would of thought all the pressures are incorrect, therefore making the sensor read wrong.... i hope. lol.

No luck at the scrappy, gonna try some super unleaded!