(G) Mystery of the 3krpm flat spot solved?

I don't know if this is the same with the Cinq, but here goes anyway.

My brother in laws Astra 1.4 had a flat spot, or 'hesitation' at 4krpm. I said to him about the Cinq having the same problem, and ways to help cure it, via induction kits, breather pipes, etc.

He looked at me and asked if it completly solved the problem. I told him it ALMOST cured it, but its still evident despite my attempts to cure. Being an ex-mechanic, he rings a mate, who then rings a mate, who then rings a mate.....

And 3 days later, he tells me his new part has arrived. Not cheap, but solves his problem straight away. Obviously, i'm dying to know what he ordered that cured his problem! The answer....

Performance Fuel Pump. The standard pump on his Astra just couldn't pump fuel in quick enough when he floored it, so the engine hesitated to respond at 4krpm. Then the penny dropped with the Cinq. So you fit an induction kit to give the engine more air, and a chip to pump more fuel into the engine, but can the standard fuel pump deliver? I now don't think it does.

All this air goes in via your £60 induction kit. Your £150+ superchip tells the ECU to send more fuel. Yet its still not perfect. Could it be that we are asking more of the engine than the standard fuel pump can give?

Just my theory, but makes sense. Proven to work on the Astra at least. I'd be interested to hear of anyone who has upgraded this.

Cinq Sporting 1997 http://www.fiatforum.com/forum/topic.asp?TOPIC_ID=8033 Parts Needed!

Hi mate,

you can start by adjusting the fuel pressure on your cinque (and maybe get the same result as with the expensive fuel pump for free).
Take off your airbox and on the trottle body there is a small screw to adjust the fuel pressure. It is small, normally sealed with some blue stuff, in the front part and you need a six sided screw drived (I know there is a word for this, but I'm german so what do I know).
Turn it clockwise and you raise the fuel pressure.
If you have a voltmeter you can check the voltage at the lambda sensor (optimal should be something like 0.85volt).
http://www.carsfromitaly.goracer.de/wbboard/thread.php?threadid=21426&boardid=22
Is a thread from a german cinque board. A little down you can see the screw to adjust and which cable to choose to measure the voltage (the black one).
Hope this is somehow understandable ;))

Ups .... exchange the 0.85Volt to 0.87Volt

Ups again ... make sure you measure the voltage at full throttle (in 3rd or 4th) otherwise the ECU will kick and change the voltage to give the cat his preferred mixture.

my uno used to have a complete flat spot in second, was only there on early cold mornings... you would go through 1st fine and then into 2nd and after a little reving the engine would just stop accelerating... then it just kinda burst into speed and sped off as usual lol... only ever did it once on every journey.

probably completly different and was just my uno being rubbish heh

Cinq Sporting
1.1L engine
K&N 57i kit
Sparkrite alarm system.
Standard all the rest.

oh.. forgot to say, my Cinq doesnt have a flat spot... or atleast ive never noticed it, it accelerates constantly without any flat spots. Ive just got a K&N asd far as im aware

Cinq Sporting
1.1L engine
K&N 57i kit
Sparkrite alarm system.
Standard all the rest.

floor it in 2nd, pedal hard to floor!

Cinq Sporting 1997 http://www.fiatforum.com/forum/topic.asp?TOPIC_ID=8033 Parts Needed!

yeah i do that... no flat spots.. just keeps going

Cinq Sporting
1.1L engine
K&N 57i kit
Sparkrite alarm system.
Standard all the rest.

driven it on a really cold morning yet?thats when i get it but it stops ya ragging the engine when its cold[}:)]

Custard boy the man who loves the man from Creative

yup.. drieven it on loads of cold mornings... sounds like ur gettin the same i had with my uno.. but once u had pasted the flat spot it never happened again.

i dont get that atall on my cinq

Cinq Sporting
1.1L engine
K&N 57i kit
Sparkrite alarm system.
Standard all the rest.

57i kit sorted mine a treat[8D]

GoGoCinquecento!

Chipping sorts it out. Only does it when cold now, oddly.

Pete.
1242cc cinq,turbo cinq,Cinqs&Seis Yahoo group,Clubcento

yeah mines already got a 57i

Cinq Sporting
1.1L engine
K&N 57i kit
Sparkrite alarm system.
Standard all the rest.

About petrol pumping:

I always thought that the pump pumped a hell of a lot more petrol around the system than was the required to keep as constant a pressure as possible.

I though the lambda added what was required in the way of fuel?

GoGoCinquecento!