Tacuma: slight depressing on gas leads to RPM jump

[vit]

Hi All,

Another observation about my Tacuma 2.0.

I can't direct engine to make slight increase in RPM - it's jumps right to 2500 mark.
- Pedal and cable are OK - the same happens if I rotate throttle by the hand. Very slight movement - vuala - 2500 or so
- Throttle body cleaned. No probs with idle - stable as rock.
- TPS is OK too. At idle it reports 0.33V and _smoothly_ increases voltage while I rotate throttle (metered by voltmeter, not scanner though).
- no CEL error

Car runs great at high speed only, and fuel consumption is OK for highway (8 L/100km).
But if I want to hold on 60 km/h I should remove my foot from gas periodically, say every couple of seconds: slight touch and car speed-ups more then I want. I think thats a reason of poor fuel economy in the city.

Is anyone have similar observations with Daewoos? Is it repairable or this is what ECU wants?
Is excess or luck of the fuel pressue can lead to this? What else I can check?

Thanks

[Trey05Woo]

Could be leaky injectors, fuel overpressure, evaporative emissions fault, or a vaccum leak. Though correct idle will normally disclude the last option. Is idle always good, or does it sometimes hover high for a while and then return to normal?

You need a scan tool that will display current/history/pending codes, and engine data. Your o2 mv, fuel trims, and purge valve readings, and fuel trims are what you should be focused on.

Have you checked for engine codes? Even though your TPS was working correctly when you checked it with a DMM, it could still be giving a voltage too high reading, this sets a fault code BUT WILL NOT light the CEL...

[vit]

Could be leaky injectors, fuel overpressure, evaporative emissions fault, or a vaccum leak. Though correct idle will normally disclude the last option. Is idle always good, or does it sometimes hover high for a while and then return to normal?

Idle is always good. Is it possible to attach usual tyre pressure meter to the fuel rail (I have "connector" on it)?

Have you checked for engine codes? Even though your TPS was working correctly when you checked it with a DMM, it could still be giving a voltage too high reading, this sets a fault code BUT WILL NOT light the CEL...

No, it's not easy to check codes for my Daewoo... it has ODBII connector but looks like car is not ODBII. (it has ITMS-6F ECM). I've bought scanner (ELM-based) but it can't read data. Will try to find mechanic with scanner.