Engine Hestitates

[charles]

during my holiday to austria last week my 97 2.3 petrol

engine hesitates :angry: (cut out) after 600 km driving. When I pressed the clutch the

the engine picked up again. After a while, driving with full trottle the problem dissappeared. No problems with driving back home at average of 150km/h (german autobahn :lol: )

 

Any suggestions?

[Ivor_E_Tower]

Just one of those annoying things that happen. Mobile phone interference?

[charles]

The hesistation reoccurs when engine is warm. I made a appointment with my ford dealer. They will read out the motermanagementchip. I will let you know the outcome.

[charles]

I just have a phone from my dealer. The read out the diagnotics, but could not found error codes.

 

They confirmed that the engine cuts out which is stronger when the engine is warm.

 

 

They suspect the EGR valve, or maybe the MAF sensor (allthough not out of range with diagnostics).

 

Could the EGR valve have been gone?

[charles]

As the garage could not find any fault readings I have my car back, but still running poorly and sometimes hesitating.

 

In order to safe labour, I decided to replace the sensors by myselves. The most suspected are:

1. MAF

2. EGR valve

3. EGR solenoid

4. Lambda sonde

 

I first will try to clean the MAF with a pad with aceton.

[Ivor_E_Tower]

NO!!! First simply unplug the MAF and drive the car. If it drives OK but not quite normally, then the MAF is U/S and needs changing. Don't change it "on spec" - it is expensive and the above substitution will effectively tell you whether or not it is OK.

[rwtomkins]

in fairness he says he's going to clean it, not change it. but unplugging it would be easier still

[charles]

found this excellent description of the MAF on a german site www.odb-2.de/tech_sens.html

 

Air measure knife (LMM) or engl. Measure-Air-Flow (MAF)

The air measures knives, in the following LMM named, consists of two resistance wires (sensors), that in a Venturi-nozzle in the by passports of the air currents of the air taken in by the motor. Therefrom the one sensor-element is heated on a temperature of 200 degrees centigrade above the environment temperature measured by the cold sensor-element. That is sensor-element air is cooled off of the past strokes. The current that is required in order to hold the temperature of the hot sensor-element on 200 degrees centigrade, is proportional the mass of the air quantity. The LMM sends an analogous volt signal at the motor computer, proportionally the entrance air-mass. The motor computer calculates from that the required opening time of the petrol injectionnozzles corresponding to the desired Petrol-/air-mixture

 

 

Interferences that are led back to the LMM can result to the one out of interferences of the connection cable (cable breach, short circuit, connector contact etc.), to the other also by the LMM itself.

 

 

Before one replaces the LMM, can be tried to repair the LMM. But CAUTION: both sensor-elements exist also breath fine wire that no hard contacts endure. A repair is restricted therefore to the careful cleaning evtl. become polluted sensor-elements.

 

 

Remove the connector and unscrew you carefully the sensor from the housing off. They see then how in the lower picture shown, both sensor-elements.

 

 

Avoid the use of cleaner (solvent), the residues leave behind. Proved cleaning sprays have itself for electronics part or Azeton. If you have no success with spray, you can use extremely carefully a Q-hint soaked for cleaning. But ATTENTION: if a wire tears at the same time, it was that then. The LMM is over. Below you see the sensor-element enlarged.

 

 

Do not bend the connections of the elements in the procedure because the elements lie otherwise no longer in the defined air current. After drying of the LMM, you incorporate it again carefully without activating with the elements somewhere.

[Ivor_E_Tower]

unscrew you carefully the sensor from the housing off

 

Ah, the famed translation using the dictionary rather than someone who speaks both languages.

One for Nik here - the Volvo owners book that my parents have and which refers to "manuel gearbox" - the infamous Spaniard who lives under the bonnet, swapping cogs for you.

[charles]

Final report: problem solved.

 

As suggested i first disconnected the MAF. The car did not jump anymore, but was still not driving smoothly. Then I tried to clean the sensor with no effect.

 

Finally I bought a new MAF sensor (EUR139,-) . The sensor comes complete with the aluminium housing.

 

The car is now driving greatly, just the way it did ever.