Weird hesitation at full throttle/hesitation 1st to 2nd

[_alexms]

Hi all, stuck now. 

1999 1.0 Vitz 1SZ-FE, 120k miles. 

Had air filter, oil and filter and plugs twice in the last year/8k miles and a new O2 sensor in exhaust in November to fix a CEL. Just done a gearbox oil change. Car runs spot on all the time under normal conditions. 

Firstly, When in a traffic light GP race with the bin lorry for example, foot to the floor, change gear at 5 or 6000rpm, change 1st to 2nd 'fairly quickly' - once into 2nd, clutch fully out and back on throttle, car feels like it rocks slightly and doesn't accelerate for about a second. Then it goes. 

Secondly, say coming up an onramp onto the motorway, 3rd gear, full throttle, 6000rpm into 4th. Smooth gear change, back on the throttle. You can physically feel the car coming into life a full second or two after putting the throttle back down. It's like you put your foot down, and the car gives you 40% throttle for a second or two, and then it jumps to 100% throttle. 

 

Sorry it's hard to explain. Has anyone got any ideas? All I've read on Google is things about a new fuel filter or cleaning the oil control valve. 

 

Thanks

[Cyker]

Could it be the clutch slipping? My dad's Verso's clutch needs changing and we currently can't use more than 50% accelerator or it slips, but when it first started I noticed that at high accelerator inputs it would take a second or so for the clutch to 'grab', and the engine revs would climb but the car wouldn't accelerate as quickly as the revs indicated (Almost exactly like driving a CVT!).

Or is your problem that it *isn't* revving up for a second or two when you accelerate, like the engine is lugging, like if you're in too high a gear, only you're not?

[_alexms]

1 hour ago, Cyker said:

Could it be the clutch slipping? My dad's Verso's clutch needs changing and we currently can't use more than 50% accelerator or it slips, but when it first started I noticed that at high accelerator inputs it would take a second or so for the clutch to 'grab', and the engine revs would climb but the car wouldn't accelerate as quickly as the revs indicated (Almost exactly like driving a CVT!).

Or is your problem that it *isn't* revving up for a second or two when you accelerate, like the engine is lugging, like if you're in too high a gear, only you're not?

It's literally like the feeling you get of a small but laggy turbo. I don't go easy on the car mind you as it's a toy/commuter. 

Anyway a gearbox oil change seems to have cured the 1st to 2nd hesitation and i got a feeling that the hesitation at higher speeds might just be a lack of air getting to the throttle body quick enough (when the throttle is jammed to wide open quickly). That's my theory anyway lol

[Madasafish]

Dirty MAF sensor?  Clean carefully with carb cleaner...Take care.. wire is fragile.

[fordulike]

Take a look at www.mafcleaning.co.uk

 

[_alexms]

Thanks I will give it a go.

It was cleaned last summer to try to rectify the CEL I had (turned out to be O2 exhaust sensor).

I know they stuff up as a common problem but is cleaning it something that should happen regularly? I'm new to sensors altogether...

[fordulike]

Using good fuel, regular changes of air filter, spark plug check and the occassional Italian tune-up works for me.

[_alexms]

Worked for all my other cars... lol

[Devon Aygo]

There is a Technical service bulletin from Toyota that may apply:

Ref: EG-7017

Model Name : YARIS

Model Code : SCP10

Subject : HESITATION/LACK OF POWER

The fix is to fit a modified engine ECU

Part numbers 89661-0D012 & 89661-0D370 replaced by 89661-0D371

Part number 89661-0D022 replaced by 89661-0D026

Part numbers 89661-0D022 & 89661-0D392 replaced by 89661-0D393

Part number 89661-0D222 replaced by 89661-0D223

The issue was noted after Mk1 yaris production had ended so it will be almost impossible to source a modified second hand part

 

[_alexms]

26 minutes ago, Devon Aygo said:

There is a Technical service bulletin from Toyota that may apply:

Ref: EG-7017

Model Name : YARIS

Model Code : SCP10

Subject : HESITATION/LACK OF POWER

The fix is to fit a modified engine ECU

Part numbers 89661-0D012 & 89661-0D370 replaced by 89661-0D371

Part number 89661-0D022 replaced by 89661-0D026

Part numbers 89661-0D022 & 89661-0D392 replaced by 89661-0D393

Part number 89661-0D222 replaced by 89661-0D223

The issue was noted after Mk1 yaris production had ended so it will be almost impossible to source a modified second hand part

 

Service bulletin... I assume that taking it to Toyota wouldn't get me a free ECU upgrade would it?

[Devon Aygo]

Not a chance, a service bulletin is repair assistance it is not entitlement to a free repair, also just noticed you have a Vitz listed in your profile not Yaris so it is possible the bulletin won't apply, to confirm i would need your Chassis number

[Theresa Angeletti]

My 2018 has under 1500 miles and has this also. I took it to the dealership yesterday and they said the diagnostics showed nothing. Nothing they can do. It is scarey when you must accelerate quickly.... I have no idea what to do next. 

[Parts-King]

3 hours ago, Theresa Angeletti said:

My 2018 has under 1500 miles and has this also. I took it to the dealership yesterday and they said the diagnostics showed nothing. Nothing they can do. It is scarey when you must accelerate quickly.... I have no idea what to do next. 

Take it back to your dealer and ask if there is a bulletin applicable to your country, it is a new car, they should fix it, especially if there is a fix they are too lazy to look for 😉

 

[Sala296]

I had the same problem with my 2000 1.0 Yaris. Check the hoses around the air box, I had one come loose on the right side underneath the air box. I also replaced the MAF with one for £30 off eBay. Problem solved, and it drives like new. The hose seemed to be the bigger problem, but the MAF finished off the repair. Good luck 🙂 

[_alexms]

On 7/9/2018 at 7:03 PM, Sala296 said:

I had the same problem with my 2000 1.0 Yaris. Check the hoses around the air box, I had one come loose on the right side underneath the air box. I also replaced the MAF with one for £30 off ebay. Problem solved, and it drives like new. The hose seemed to be the bigger problem, but the MAF finished off the repair. Good luck 🙂 

Thanks, I'll take a look at that.