1.8 Zetec problem - Wales Forester
My 1997 Escort 1.8 Zetec engine is misbehaving, there is a distinct hesitation or miss of some kind when driving normally, doesn't seem to happen if I give it some welly, but under normal conditions there is something not right.
Even cruising at 70mph it is still noticeable, there is a very mild jerk, almost as if the engine loses power for a split second.
The air con seems to cause the engine problems too, it idles at around 400rpm with air con switched on and the throttle is very slow to respond when I take my foot off it, then it jerks as the revs drop right off.

It's a common engine, so hopefully someone has experienced something similar?

1.8 Zetec problem - Andrew Moorey (Tune-Up)
The fact that the engine idle speed drops with the ac on indiates that the idle speed controller is not functioning correctly. whether it is a fault with the unit or the control system is impossible to guess at. I would hedge a bet that possibly the throttle position sensor may be at fault giving spurious signals at odd times when cruising and more so at idle. Some faults may be logged on the ECU so it would be worth having the codes checked either by Ford or a competent independent. Problems with the Hego sensor can cause odd symptoms so should be checked on an oscilloscope.Similar checks should be made on the Mass Airflow meter as faults with both these sensors may not trigger a fault code to be logged on the ECU.Other causes could be air leaks either side of the head (inlet/exhaust)EGR valve etc etc etc.

Happiness is a T70 at full chat!
1.8 Zetec problem - Wales Forester
Thanks Andrew, you've given me plenty to chew on there, I'll let you know how I get on.


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