Hesitating at low revs.

[Woodsta888]

Hi,

After fixing my misfire, post fuelling by replacing the switch that regulated the evaporation canister I have a horrible hesitation at 1500-1800rpm. (Z3 1999 2.0). The hesitation is exactly at the same rpm everytime or in 2 places within that range.

Car always starts fine, idles well as perfect upto and beyond the above rev range. But the car almost kangaroos in this rev range and has become VERY annoying. Does it hot or cold. It's ALWAYS there.

What I don't want to do is chase the issue by changing parts. Any ideas how you would tackle this methodically? INPA shows 123 avtivate grid-controlled cooling which is thermostat but from what I've read - broken thermodstats dont cause any symptoms?

Thanks in advance

 

[TaffZee]

Loads of possibilities.

• Worn or defective spark plugs

• PCV hose air leak

• Air flow meter

• Intake valve deposit

• Exhaust gas sensor

• carbon canister

• fuel pressure

• fuel pressure regulator

• Injector

• injector circuits

• ignition coil and circuits

• Transistor ignition unit

• ECU harness connector

• ECU power supply & ground

• ECU

• AAC valve

• Air regulator

• clogged idle screw

• Temp sensor

• Temp sensor connector

• Throttle position sensor

• Idle switch

• Cone Air filter

• Crank angle sensor

• Fuel temp sensor

• Speed sensor

• Incorrect timing belt installation

• Crank Angle sensor and circuits

• Ignition Timing

 

[t-tony]

Hi,

After fixing my misfire, post fuelling by replacing the switch that regulated the evaporation canister I have a horrible hesitation at 1500-1800rpm. (Z3 1999 2.0). The hesitation is exactly at the same rpm everytime or in 2 places within that range.

Car always starts fine, idles well as perfect upto and beyond the above rev range. But the car almost kangaroos in this rev range and has become VERY annoying. Does it hot or cold. It's ALWAYS there.

What I don't want to do is chase the issue by changing parts. Any ideas how you would tackle this methodically? INPA shows 123 avtivate grid-controlled cooling which is thermostat but from what I've read - broken thermodstats dont cause any symptoms?

Thanks in advance

Might be a daft question, but have you read the codes since fixing the miss fire?

Tony.