Hi there, I own a 99 fiesta MK4 1.3 petrol, a great car until it decided to go wrong. Itīs been at the " mechanics" for TWO MONTHS, getting worse instead of better while they tinker with it and scratch their heads. Symptoms; poor idling,starting and rough running,huge fuel consumption accompanied by stinking fumes( no air in the mixture). Work done so far to no avail; new throttle sensor,new idle air control valve, replaced ECU, tried entire new injection ramp, no difference.Any ideas?
cheers,matt

 

Have you checked/cleaned out your air filter? You say that the car is consuming more fuel and it their is a strong smell coming out of the exhaust.. It also may be a bad o2 sensor making the car act this way

 

Obviously throwing parts at it doesn't do the trick. are your mechanics any good? Considering your story that question is justified.

First things first:
Do you have compression?
Is the cam timing correct?
Is it firing on all cylinders?
Is the catalytic converter unclogged?
Is the fuel pressure correct?

Is the check engine light on? what are the codes?

 

Thanks bluewind and go-part for your replies . As to wether the mechanics are good or not,theyīre nice blokes but 2 months without a diagnosis? At the end of the day itīs only a Ford Fiesta ,not a Ferrari.
Iīve removed the air filter whilst looking for the MAF sensor( there isnīt one), I will have to find and check the O2 sensor. The car is firing on all cylinders, plugs are new,cam timing donīt know, cat. converter, fuel pressure ditto,will check it out, as for compression, one worrying thing is the coolant hose from the rad to the thermostat is clearly not under pressure.
It wont run at all ( suffocates) with the vaccuum hose behind the inlet manifold connected.
cheers, thanks for helping, matt

 

Matt:

There is a MAF sensor (see #18). So do you have any digital Trouble codes? We need to know.


1.3l
Reduced: 51% of original size [ 992 x 659 ] - Click to view full image

#1 - CamShaft Position Sensor
#2 - CrankShaft Position Sensor
#5 - Engine Coolant Temperature Sensor
#6 - Evaporative Canister Purge Valve
#7 - Engine Control Relay
#9 - Fuel Pressure Regulator
#11 - Fuel Pump Relay
#12 - Heated Oxygen Sensor (Lambda)
#13 - Idle Air Control Valve
#14 - Ignition Coil
#16 - Injectors
#17 - Intake Air Temperature Sensor
#18 - Mass Air Flow Sensor
#19 - Throttle Position Sensor

 

There isnīt a MAF sensor, maybe there is supposed to be but my car never had one,anywhere on the air intake or manifold, also there is a MAP sensor on the back of the manifold,and the fuel pressure regulator must be somewhere else. The IAC valve is brand new,the diagnostic computer blamed the throttle position sensor,but that was also replaced ( new). Sorry I donīt know what digital trouble codes are.

 

I will check the O2 sensor,the catalytic converter,the fuel pressure sensor,the timing belt,the MAP sensor,and find out about fault codes. Thank you for your help, Iīll post any results ( even if the end result is me setting fire to the car,which has been suggested).

 

Matt, these cars have what's called OBDII systems. That stands for On Bord Diagnostic vrsion 2. If there is something wrong you get a CEL (check engine light, aka MIL malfunction indicator light, or Service Engine Soon light). If that's on you use a scanner and read the digital trouble codes. They help you narrow down where the problem is.

There must be a MAF sensor. MAF stands for Mass Air Flow. It works like this: an electrical current heats up a couple of thin wires and as the intake air streams by the wire gets cooled off, so it pulls more current. By measuring the amps the computer can calculate how much air is coming in and thus how much fuel to inject. This has become a standard set up and your car is modern enough to have it. Did somebody modify your car?

MAP stands for Manifold Absolute Pressure. It is used to determine when to actuate the EGR and possibly a few more things.

Don't cinge your hair, we will figure it out.

 

I think the tube with the white dot is the maf sensor.
Some individual pix. Now you know what to look for.

Find another MK 4 and have a look under the hood.

Cheers

 

Usually from the symptoms described in the original post, all lead to a defective fuel pressure regulator. The diaphram is ruptured and the extra fuel is getting sucked into the intake through the vacuum line. It is located on the fuel rail that feeds the injectors.