Hi Guys and Gals,

Just the other day my Cinq has started some really bad hesitation problems and feels like it's not revving cleanly.

I searched the forums and have narrowed it down to the following order

1. Most likely Lambda Sensor

2. Possible Map Sensor

3. Maybe fuel filter

My main question is will a Diagnostic show up faults without any warning lights being seen on the dash?

Any help or advice appreciated.

Cheers

Liam

Re: Diagnostic Testing?

Hi,
Check for signs of head gasket leaking if there's no warning lights on, water in the oil, oil in the water etc......

Thanks
Paul T

Re: Diagnostic Testing?

Sometimes yes but most times no. As the computer is a lot slower than the ecu anyway so you only see 1/20th of what is happening anyway. As long as the plugs are good and leads are good and you have a good spark from the coils then it will more than likley to be a slow lambda sensor. no responding quick enough when throttle is required. Lamdba sensor only work at light throttle or when cruising. They do not work at full throttle or when deaccelerating, at this point the lambda goes to open loop allowing the full fuel mixture to be entered into the engine, a slow lambda does not go open loop as quick thus trying to keep the correct fuel air ratio of 14.7 /1 and that then gives the hesitation.

Re: Diagnostic Testing?

Decided to start with the cheapest items to eliminate the possibles, these are plugs and leads.

I'll get some decent insulated pliers and see if I can get a good spark from each one then I'll move onto the bigger stuff.

Does anyone know how to test coils with a multimeter?

Thanks

Liam

Re: Diagnostic Testing?

Update, check plugs and leads, seemed fine, erm coolant and oil seem fine too, I'm puzzled.

Liam

Re: Diagnostic Testing?

Liam
Sounds like a problem that i`ve been dicussing with a guy on here called tom,he tried everything even replaced the lambda with a new one,still had the hesitation so he took it to fiat for a diagnostic check and it turned out to be the lambda,(the new one he had fitted was faulty too)
Car now runs fine
Cheers
Adrian

Re: Diagnostic Testing?

God Adrian, I was following that thread and I do hope it's the Lambda or MAP or indeed something other than the head gasket!

Oil is fine looking, plugs are fine as are lead but on start up it's more sluggish than usual, sounds lumpy or rough on idle and has numerous flatspots through the rev range in any gear though with time will still do 110 with coaxing!

I wonder?

Liam

Re: Diagnostic Testing?

Liam didnt it stall the other day or summat for ages then started bak up!

Perhaps whatever is causing these problems also caused that!

Re: Diagnostic Testing?

AppleSei said:

Liam didnt it stall the other day or summat for ages then started bak up!

Perhaps whatever is causing these problems also caused that!

Click to expand...

Sneaky bas*ard told me it wasn't excepting the key and refused to start with the code light on! Cheeky c*nt!

Got it going like 5 mins later and it's never done it again.

Liam

Re: Diagnostic Testing?

I searched the forums and have narrowed it down to the following order

1. Most likely Lambda Sensor

2. Possible Map Sensor - fitted one today and it seemed a bit better but will find out for definate tomorrow on cold start up.

3. Maybe fuel filter

Would a Lambda from a MPI 1.1 work?

Liam

Re: Diagnostic Testing?

MPI's have 2 lambdas, so may confuse things if they're slightly different etc not 100% sure though

Re: Diagnostic Testing?

It could be head gasket, but not between a cylinder and a water way, between two cylinders. At low gas speeds there is no compression because it is leaking into the other cylinder. At higher engine speeds the engine will appear to run normally.

Cheers chum

D

Re: Diagnostic Testing?

I have been thinking this D, do you think it will show up on a simple DIY compression test? My mate has one from his K-series days.

Liam

Re: Diagnostic Testing?

Update: Tried the car today with the new MAP sensor and it wasn't any better, well maybe it was but I felt it still isn't revving cleanly through the gears.

Will get a hold of the compression tester and hope for the best.

I've ruled out Lambda since th ewarnign light hasn't come on after nearly two weeks of strange running.

Liam

Re: Diagnostic Testing?

Hi Liam
I wouldn`t rule out lambda i don`t think Toms warning light came on and he had 2 different faulty lambdas.
His diagnostics check only cost him £30 at his local fiat dealership,could have gone on forever changing bits but would never have sussed the brand new lambda was faulty!!!!
Cheers
Adrian

Re: Diagnostic Testing?

Suppose I should try it out but getting a diagnostic done is a pain work wise, would love to try another one myself just incase it's not it.

Liam

Re: Diagnostic Testing?

OK UPDATE:

Changed MAP, no difference.

Getting hold of Lambda to try, if no joy with that could it be a coil pack at fault?

Sometimes the car is rough to start and other times it's fine.

Cheers

Liam

Re: Diagnostic Testing?

Right, fitted s/h Lambda and at times the flat spot is worse, thought maybe this would point to it being the lambda. Do the universal ones do the same job or must I get the Fiat one?

Could a duff coil pack give flat spots?

Liam

Re: Diagnostic Testing?

bloomfieldliam said:

Could a duff coil pack give flat spots?

Click to expand...

Quite possibly. My 1242 was having difficulty starting (could only start at WOT) and wouldnt idle (unless cranked at WOT and revs raised to 2krpm prior to releasing the pedal). Then it got a misfire. I tested the coil pack and it fooked. Replaced and everythings been fine (on that side of things) since!

As for the universal vs Fiat MAP sensor, nope the manufacturer shouldnt matter as long as the output is within 0 and 5vDC. I would advise the Fiat one tbh as it fits in that space nicely and is a known working solution!

Re: Diagnostic Testing?

Liam, I thought damaged coil packs make the engine misfire? Which, would rule that out.