1999 Yaris Flat Spot 1.0 Vvti

[tommygreg]

Hi new to this wonder if any one can help,

from idle the car has a flat spot when you press the gas, its ok when over 1500 revs, but again when changing gear

you get the same probs.

doesn't really bother me but have got the car for my son who is still learning and it makes the car difficult for him to drive.

I have serviced the car plugs oil and air filter, dont know where the maf is but that is my next thing to try.

has anyone any other ideas. by the way have had it on a fault moniter and shows no fault codes.

thanks.

[toyotawolves]

ye i would say almost certainly mass air flow sensor, try cleanin it first, be careful with it tho they are very senstive. take the air filter out, then 3 bolts out the air box. dis connect the connecor to the sensor. pull the air box away from the throttle body than u should be able to get the sensor out, just two srews hold it in.

[Wez T3]

mine has the same flat spot but i just thought it was me not giving it enough revs on pull off with it only being a 998 and being used to more torquey larger engines.

[tommygreg]

ye i would say almost certainly mass air flow sensor, try cleanin it first, be careful with it tho they are very senstive. take the air filter out, then 3 bolts out the air box. dis connect the connecor to the sensor. pull the air box away from the throttle body than u should be able to get the sensor out, just two srews hold it in.

Thanks tried this no difference, some one has said check the canister purge valve, any one know how to do this thanks, and any other suggestions greatly received.

[alfiejts]

Are you sure it really has a flat spot? As a small capacity, 16 valve engine, there isn't any power under 1500 rpm or torque. You have to drop to first to pull away from junctions, because if you trickle around in second, there's no power to pick up sped until the revs rise. That's the nature of the car.

I suppose the key question is does it pull away OK in 1st gear?

If it does, then its normal, but if it doesn't then you probably do have a problem...

[tommygreg]

Are you sure it really has a flat spot? As a small capacity, 16 valve engine, there isn't any power under 1500 rpm or torque. You have to drop to first to pull away from junctions, because if you trickle around in second, there's no power to pick up sped until the revs rise. That's the nature of the car.

I suppose the key question is does it pull away OK in 1st gear?

If it does, then its normal, but if it doesn't then you probably do have a problem...

no there is a definate hesitation, hard to describe, in the old days when we had carbs it feels like a jet is blocked but these days i just cant find it.

will probily end up taking to the main dealer and see if they can come up with anything, will end up paying more than the cars worth ,

[Mikehkay]

I have exactly the same issue with our 1.0 vvti Yaris (04 plate), except ours is an intermittent fault, some days its drive perfectly the next it very nearly catches you out. The car has done 47k miles and has been serviced regularly, inc a new set of plug at the last service. The flat spot started prior to this service and had expected the new plugs to resolve the issue. I have also replaced the plugs again since the service just in case, but still no luck.

What would you recommend cleaning the MAF sensor with, i.e. cotton bud or some kind of electrical cleaner etc. If this fails I think I shall start checking the coils as I’ve read that these have gone on occasions causing similar related effects. Some times the car just feels like its really struggling and runs a bit rough, i.e. like its running on 3 cylinders.

Tommygregg, I would be very interested to know what is causing the issues with your car if you manage to resolve it.

[alfiejts]

Ah - you've cracked it Mike...

It wants to be a new Yaris - they have 3 cylinder 1.0 engines..... It's just trying to make you think you have a new car......

(Sorry - couldn't resist that one... - no help really...)