aygo engine choking while accelerating when engine is wasm

[dvizi]

I have a strange problem with my aygo 2007 1.0. When the engine warms up, rapid acceleration (with strong pressure on the gas pedal) causes the engine to choke (almost to shutdown) for 1-2 seconds, and after that engine continues to work normaly. the twitch is felt in all gears of transmission (from 1st to 5th), the higher the gear, the less intense the twitch.  No check engine light, no problem when the engine is cold, no problem while accelerating smoothly (with gentle pressure on the gas pedal) and no problem when decelerating. 

After the problem started, the car underwent a major service (changed oil, spark plugs, filters), replaced the fuel pump with filter, replaced the crankshaft sensor. Due to the high cost of new fuel injectors, my mechanic got me 3 sets of used fuel injectors. Tried all three sets, problem still exists. The rubbers on the fuel injectors have not been replaced, my original fuel injectors have been cleaned and put back into the engine. The catalytic converter has also been checked, it is clean and in good condition.
the car has been regularly maintained, apart from the above, there are no other problems. It has traveled about 190,000 km.
I have changed 3 different mechanics (a local mechanic who used to maintain my car, an authorized toyota service and a large mechanic specializing in Japanese cars), all connected it to a diagnostic after driving it for 10-15 mins untill engine is warm, all felt the problem, all changed some part/s, but no one found the cause of the problem.

Please help me if you know of a similar situation or some kind of advice.

[Billyboy81]

Looks like you've tried everything except changing the coil packs.

[dvizi]

thank you for an idea, i forgot to mention it, mechanic specializing in Japanese cars tried to put new coil pack (he had it as a spare part in his garage), but problem persisted.

[Bper]

Did live data show up any faults.

[dvizi]

Thank you for reply. yes, live data showed weird readings of crankshaft sensor, then crankshaft sensor was replaced, and after replacement no faults on live data.

[Bper]

Have you looked at throttle pedal sensor.

[dvizi]

thank you, i didnt check it, but i will asap

[flash22]

Is it doing it under throttle (load) or coming off the throttle ??

Sounds like the parts cannon has been fire at it, without diagnosis

edit. What plugs were used (make and model) also what grade oil ??

[Cyker]

It sounds like some sort of over-fuelling issue - Dumping too much fuel and not enough air can cause petrol engines to 'choke' like this...

Thinks worth checking off the top of my head:

Any piggy-back 'power' chips installed? (Common mod with diesels but less so petrols; Still worth checking)

'Black boxes' (Insurance black boxes wired into the ODB2 are garbage and can cause weird problems as they age and break down)

MAF sensor (Clean? Functioning correctly? Check signal and compare with known good. Has it been replaced at some point? Non-Toyota ones are notorious for causing weird problems.)

Air filter (Clean/Not blocked? Also check air intake path for leaves, plastic bags, bras, dead animals or other debris creating a restriction)

Cabling (No frayed, chewed, corroded or otherwise damaged cables from ECU to injectors, MAF, etc. )

 

[Devon Aygo]

A Blocked or faulty VVTi controller can cause these issues, so can too thick an engine oil, a 2007 needs a good quality 5w30 oil meeting API SL specification or higher.

As you look at the engine on the rear left of the cylinder head is the VVTi controller (11101J in picture) below this behind a small plug (11117B on picture) is a small oil filter (15678A on picture) in normal operation this should never need attention but too thick an oil or extended oil changes can clog this up, make sure it is clean and if the oil could be at question an engine oil flush and oil and filter change should be completed.

The VVTi controller can also be active tested to ensure correct operation using a quality diagnostic machine

[Stecha]

Could be inlet manifold (to head) gasket leaking.

Edited February 2, 2023 by Stecha
not head gasket

[flash22]

My thinking was the same as Devon, that's why I asked about the symptoms

OCV oil control valve issue don't always throw a fault code, I would also pull the OCV filter - inspect and clean/replace

 

plugs - anything apart from Denso plugs makes these engines run like carp

oil - too thick an oil can play havoc with the vvti

 

[dvizi]

19 hours ago, flash22 said:

Is it doing it under throttle (load) or coming off the throttle ??

Sounds like the parts cannon has been fire at it, without diagnosis

edit. What plugs were used (make and model) also what grade oil ??

Thank you for your message.

The problem shows only on powerful (strongly pressed acceleration pedal) throttle load, and only when the engine is warm. there is no choking when im coming off the throttle, and i use that a lot - i often break with engine. there is no choking on slow accelerations (gentle press on acceleration pedal).

Im not sure what oil and sparks were before replacement (when problem first started), after replacement oil valvoline 10x40, sparkplugs NGK.

[dvizi]

16 hours ago, Cyker said:

It sounds like some sort of over-fuelling issue - Dumping too much fuel and not enough air can cause petrol engines to 'choke' like this...

Thinks worth checking off the top of my head:

Any piggy-back 'power' chips installed? (Common mod with diesels but less so petrols; Still worth checking)

'Black boxes' (Insurance black boxes wired into the ODB2 are garbage and can cause weird problems as they age and break down)

MAF sensor (Clean? Functioning correctly? Check signal and compare with known good. Has it been replaced at some point? Non-Toyota ones are notorious for causing weird problems.)

Air filter (Clean/Not blocked? Also check air intake path for leaves, plastic bags, bras, dead animals or other debris creating a restriction)

Cabling (No frayed, chewed, corroded or otherwise damaged cables from ECU to injectors, MAF, etc. )

 

Thank you for your message.

There is no power chip installed or black box in odb2.

MAF sensor was cleaned and checked.

air filter was replaced and visualy checked after

Im not sure about cabling, cables look ok on visual, i guess they work ok since car was on live dijagnostic and no strange values were noticed (except for crankshaft sensor, and after crankshaft sensor was replaced readings were normal).

[dvizi]

12 hours ago, Devon Aygo said:

A Blocked or faulty VVTi controller can cause these issues, so can too thick an engine oil, a 2007 needs a good quality 5w30 oil meeting API SL specification or higher.

As you look at the engine on the rear left of the cylinder head is the VVTi controller (11101J in picture) below this behind a small plug (11117B on picture) is a small oil filter (15678A on picture) in normal operation this should never need attention but too thick an oil or extended oil changes can clog this up, make sure it is clean and if the oil could be at question an engine oil flush and oil and filter change should be completed.

The VVTi controller can also be active tested to ensure correct operation using a quality diagnostic machine

Thank you for your answer.

I will drive the car for another oil and sparks change, ill ask for quality 5w30 oil meeting API SL specification and Denso sparkplugs, and ask mechanic to also inspect

throttle pedal sensor

OCV oil control valve and OCV filter

VVTi controller

Cabling 

I will let you know about results

[flash22]

The oil is too thick, and the plugs are wrong, the fact this has only happened after service means It's something you/they did - and parts have been thrown at it costing you money you didn't need to spend

using a too thick of an oil will cause premature engine wear, poor starting and oil burning in the long run

 

Flush, oil and filter change, and get the correct Denso plugs in it, NGK and Champion plugs are not direct replacement for the OEM Denso

 

leave everything else alone till you get at least the oil changed

[Cyker]

10w40 is the sort of oil the Mk1 Yaris diesel used!  

 

[dvizi]

Thank you, all forum member that replied and tried to help.

I have an update. I have replaced oil (with 5x30 Valvoline), sparkplugs (with Denso),  airfilter,  oil filter and cooling liquid. Beside that, I took out and cleaned  OCV, MAF, PCV and O2 (upper)sensors. Problem is still here.

I also have aditional notice, problem DOES NOT show if outside air temperature is low (under 4-5 C).

I was driving on Highway (100-130km/h) for one hour without any problem, car was behaving normaly. But when i stoped to pay toll, i needed to wait the line, and after 2 minutes of standing still, the car just turned off and i could not start the car for next several minutes (crancking sounded normal, gived normal lights on dashboard, but engine didnt start). eventually engine started and i could drive it but with significant engine choking while driving. There was no check engine sign on.

 

Please, if you have any idea or this sounds familiar, point me in some direction, I am kinda desperate.

 

[flash22]

Coolant temp sensor or a bad thermostat - if its running hot (or thinks it is) it will lean out the fuel

i take it the cooling fan kicks in as it should ?

[dvizi]

4 minutes ago, flash22 said:

Coolant temp sensor or a bad thermostat

i take it the cooling fan kicks in as it should ?

Thank you for your reply. I can hear cooling fan kicks in ocasionaly when i turn off the engine, I was checking coolant temperature using ODB dongle, temperature seems normal (80-100C)

[flash22]

If you watch the temp as soon as the stat opens you will see the temp drop is the thermostat is working

[dvizi]

28 minutes ago, flash22 said:

If you watch the temp as soon as the stat opens you will see the temp drop is the thermostat is working

It seems that it doesnt open, engine colant temp rise to 86 without dropping, and i have read that thermostat should open on 82 C(so i guess on 82 C temp should drop). I will replace it ASAP. Thank you again

[dvizi]

I have replaced thermostat, without any change with my problem. I also did professional Wynn's fuel system service (by mechanic using wynns machine). After treatmant i notice some improvement, but i still feel power losses (right after treatmant very slight, but gaining in intensiti how the time passes). I took the car for the half hour drive, measuring the data with torque app and taking screenshots. Since today is cold here (aroun 4 C) i felt only few gentle loss of power in last few mins of the drive. Only strange thing that i notice is LTFT which is constantly on +15. If anyone can see something else in the posted data, please let me know.

[flash22]

B1S2 o2 sensor post cat, it's within the voltage specs but is acting strange

what is your map reading ?

reset your fuel trims

if you replace the sensor, replace it with a Denso item - DOX-2066

 

Contaminated fuel maybe another problem drain the tank and put some premium fuel in it

[dvizi]

14 minutes ago, flash22 said:

B1S2 o2 sensor post cat, it's within the voltage specs but is acting strange

what is your map reading ?

reset your fuel trims

if you replace the sensor, replace it with a Denso item - DOX-2066

 

Contaminated fuel maybe another problem drain the tank and put some premium fuel in it

Thank you again for looking at bunch of screenshots. I presume tha MAP reading in torque app i Intake manifolld pressure, values are 4.2 - 4.4 psi on idle engine, jumps up to 14 psi when pressing accelerator pedal.

I doubt it is fuel contamination, i have the problem for 9 months now, usually i pour 28-30 litres in my gass tank and always fill it full, in this period i did it more than 10 times.

I will reset fuel trims now and see what will happen in the future.

I will also clean O2 aftercat, it reading remain similar  I will replace it.

Thank you again so much