Terios 2003 poor accelleration


i own a 2003 terios sl which has previously never had any problems.
over the last month i have noticed an intermittent lag between pressing the accelerator and the increase of power output (sometimes there is a slight lurch)and a loss of power on hills.

it starts perfectly every time

i have checked for loose connections, sprayed the electrics with wd40(in case of damp)checked and changed the plugs for bosch super 4's, added injector cleaner to the fuel tank but so far there is not any improvement.

Any suggestions, (i used to be able to fix own my cars but with all these sensors and computer controls i don't have a clue and am just throwing money at it) (my local mechanic is too busy to fit me in for 2 weeks)

i have toyed with the idea of buying a cheap fault code reader but don't know if i would be wasting more money

Les Wilkins

Bad Puller

Check Oldminimans post on the subject of engine management systems, this is a mine of information for novices on management systems.

Have you the following symptoms:

When starting from cold, the engine is slightly erratic, or not running as it was prior to this fault, yet when it is warm it seems to run nearly normally. If so it is the coolant temperature sensor or switch, this puts a default value in when it becomes defective to allow you to get home.

Does the situation worsen when it is damp or wet, if so it is a cracked sensor casing, wiring fault, or water ingress into the management system.

bad puller

starts perfectly every time and runs smoothly until the accellerator is floored then there is a lag and slow pickup, roughly the same effect when climbing hills (need to change down earlier than usual) since adding the injector cleaner and spraying with wd40 the problem is not as severe and i'm wondering if i picked up some dirty fuel. (the problem seemed to start just after the last tanker strike)I'll read the post you suggested but if you have any suggestions i'd be obliged


Potential Problems

Could be anything Les, personally, i would begin by having the fault codes read to try to identify which aspect of the circuits are causing the problems.

If this shows nothing it is most likely the ECU, or a wiring defect somewhere on that circuit, but it gives you a starting point, and isolates the circuit which is problematic.

If it identifies a specific problem, you then have it.

Nearly Forgotten

Possibly a fuel problem if it began during this time, fuel tanks running low always guarantee water or debris in the fuel, it sounds the most likely source of the problem.

Break the fuel lines from the tank to the fuel filter, replace this as a matter of course; get someone to turn the ignition on and check the flow of fuel, catch this in a jar and check for debris in the fuel, stand it for about an hour and see if it seperates out, if it does then it is water in the fuel.

Blow the lines out from the engine to the filter, then from the filter to the fuel tank, remove the fuel pump from the tank and see if the strainer is blocked, if so, clean it, drain the tank, and clean it. Also check the tank breather is not blocked.

terios 2003 still poorly

I've tried the obd2 on the car , no fault codes, readings as follows:

Absolute throttle 0.4%
Engine rpm 712 (tickover)
Calculated load value 2.0%
Timing advance cyl 1 3.0 deg
Intake manifold pressure 29 kpa
Fuel system status "closed loop"
Short term fuel trim 0.0%
Long term fuel trim +26.6%
Intake ait temp 43 deg C
Coolant temp 87 deg C
02 Sensor bank 1 0.065v @ -0.8% st fuel trim
02 Sensor 2 bank 1 0.0790v @ +12.5% st fuel trim
ODB conforms to EOBD

unless there is anything obvious above I'll get a new fuel line and try cleaning the system out.



The wife said the car was playing up in the wet yesterday so you may have been correct on your previous message.

I have ordered an obd2 diagnostic scanner and software for the laptop so hopefully I'll be able to get to the bottom of this.

Thanks for the advice, I'll let you know what happens.

Regards Les

poor acceleration

Hi Did you resolve the problem. I have 2003 terios also with the exact same problem