'99 1.8 16V High/rough idle, and hesitation.

[pphilpot]

Hi all

I'm having another hesitation problem with my 1999 1.8 16v 406. Here are the symptoms:

1) Rough high idling: it idles between 1100 and 1300 whereas before it was a steady 950
2) Sudden quick hesitation (enough to jerk the car forward), cured by giving more fuel.

This began after I changed the thermostat and caused a leak in the coolant system from the housing. I ran this for a couple of weeks trying to seal it with silicone, but eventually replaced the housing and hose to finally cure the leak. Since then I've had this running problem.

Yes, water leaked onto the TDC connector, and I moved it aside, so that it wouldn't leak on it any longer, but I didn't think that the TDC would cause these symptoms - could it?

Could the coolant temperature sensor have gone bad while low on coolant (the engine never overheated) and would a faulty CTS cause these symptoms?

I have previously changed the following during the previous (cured) hesitation issue: TPS, Lambda probe, coil pack, stepper motor.

Last time I had a hesitation problem when I disconnected the lambda probe all ran well - it turns out (I believe) that the ECU then just ignores the throttle body sensors, and so my last problem went away. This time though, when I disconnect the lambda probe the probe is still there, so it must be a different electrical problem.

Has anybody else had these symptoms after having a heavily leaky thermostat housing???

Would be very grateful of any ideas?

Cheers

Paul

[FarmerPug]

get it into a fault code reader and see whats wrong first