D4d Jerky Acceleration, Mil, Power Loss, Code 34

[Laimis]

Hello all

My Avensis Verso 01' d4d ( 1cd-ftv engine, CLM20 model) experiences jerky acceleration between 2000 and 3000rpm.

it is like power is reduced about 3-4 times for a fraction of second until it reaches 3000rpm.

Otherwise everything else is normal: millage is good, acceleration fine, no strange sounds, etc.

it happens almost 100% when the engine is under some load: accelerator pedal to the bottom, 3d or 4th gear and/or uphill. My impression is that when the engine is completely warmed the power loss is less noticeable or goes off completely.

if accelerator pedal is to the bottom and the power loss is prolonged then MIL warning switches on and the engine goes into emergency mode. After power off/on the MIL is cleared.

When checked MIL flashes the dreaded code 34. Toyota reader got trouble code 34(2) which should mean "turbo pressure problems"

I have cleaned MAF, checked electromagnetic vacuum actuators (both VSV and turbo pressure control), vacuum actuator for turbine vanes moves some millimeters when vacuum is applied, air filter changed recently and clean.

On sensors side: turbo pressure sensor shows some resistance, MAF sensor shows some resistance too. However I am not 100% how to check electrically those sensors on this model.

I am wandering what else to check before submitting into the hands of toyota dealer:

-fuel filter ?

-SCV valves. I am afraid those can be checked only by replacing them :)....

-EGR ??? I see no unsual white or black smoke.

- something else :o ?

[igormus]

Hello all

My Avensis Verso 01' d4d ( 1cd-ftv engine, CLM20 model) experiences jerky acceleration between 2000 and 3000rpm.

it is like power is reduced about 3-4 times for a fraction of second until it reaches 3000rpm.

Otherwise everything else is normal: millage is good, acceleration fine, no strange sounds, etc.

it happens almost 100% when the engine is under some load: accelerator pedal to the bottom, 3d or 4th gear and/or uphill. My impression is that when the engine is completely warmed the power loss is less noticeable or goes off completely.

if accelerator pedal is to the bottom and the power loss is prolonged then MIL warning switches on and the engine goes into emergency mode. After power off/on the MIL is cleared.

When checked MIL flashes the dreaded code 34. Toyota reader got trouble code 34(2) which should mean "turbo pressure problems"

I have cleaned MAF, checked electromagnetic vacuum actuators (both VSV and turbo pressure control), vacuum actuator for turbine vanes moves some millimeters when vacuum is applied, air filter changed recently and clean.

On sensors side: turbo pressure sensor shows some resistance, MAF sensor shows some resistance too. However I am not 100% how to check electrically those sensors on this model.

I am wandering what else to check before submitting into the hands of toyota dealer:

-fuel filter ?

-SCV valves. I am afraid those can be checked only by replacing them :)....

-EGR ??? I see no unsual white or black smoke.

- something else :o ?

hello mate

firstly have the fuel filter changed + all four injectors tested.

there must be your head ache.

cheers/Igor

[cmia]

have you checked the ovbious...

Ie no pipe split in the turbo, or charger?

[Laimis]

have you checked the ovbious...

Ie no pipe split in the turbo, or charger?

visually and judging from sounds this side is ok.

turbine whistles joyfully starting from around 1500rpm.

igorm:

there is no doubt that clean fuel filter and/or injectors test is a reasonable start. As well as presence of fuel :)

But does it correlate with a really sharp loss of power for 0.3-0.5 seconds under load?

My experience with traditional diesels is that a general lack of fuel displays as a gradual loss of power, inability to speed up, etc...

Common Rail is a different beast of course but still "less fuel" = "less power" not "less fuel" = "no power" must hold, mustn't it ?

[cmia]

No,

The common rail has a sensor on it.

If pressure drops on the rail it will cut the engine and drop it into MIL or safe mode.

If you are having a sharp loss of power I would recommend you start by following Igormus recommendations,

and before you do, do this.

1- Full Service

(oil, oil filter, air filter and fuel filter)

2- Check and clean MAF Sensor

3 - check and clean egr valve

[Laimis]

No,

The common rail has a sensor on it.

If pressure drops on the rail it will cut the engine and drop it into MIL or safe mode.

Thank you.

I want to clarify a bit though. Under certain conditions I have JERKY acceleration:

...2000 rpm, ok, ok, then loss of power for 0.5 second, ok, ok, ok,...ok, loss of power, ok ok, loss of power, ok, ok..ok 3000 rpm and then fine.

if I produce a longer loss of power only then MIL, safe mode, etc.

the computer gets trouble "code 34(2) - turbocharger pressure...."

My impression is that prolonged loss of power is the cause for MIL and safe mode. This is what repair manual says at least: if parameter readings are out of norm for about 1 second only then MIL and safe mode.

The question now is what could be causing the jerky acceleration in the first place: fuel supply(filters, SCV valves, etc) or "code 34(2) Turbopressure" is correct after all?

Can the D4D Variable Vanes Turbine be tested in the garage or is this a task for a serious toyota master ?

[igormus]

No,

The common rail has a sensor on it.

If pressure drops on the rail it will cut the engine and drop it into MIL or safe mode.

Thank you.

I want to clarify a bit though. Under certain conditions I have JERKY acceleration:

...2000 rpm, ok, ok, then loss of power for 0.5 second, ok, ok, ok,...ok, loss of power, ok ok, loss of power, ok, ok..ok 3000 rpm and then fine.

if I produce a longer loss of power only then MIL, safe mode, etc.

the computer gets trouble "code 34(2) - turbocharger pressure...."

My impression is that prolonged loss of power is the cause for MIL and safe mode. This is what repair manual says at least: if parameter readings are out of norm for about 1 second only then MIL and safe mode.

The question now is what could be causing the jerky acceleration in the first place: fuel supply(filters, SCV valves, etc) or "code 34(2) Turbopressure" is correct after all?

Can the D4D Variable Vanes Turbine be tested in the garage or is this a task for a serious toyota master ?

hello LAIMIS

the nature of this JERKY acceleration is as follows:

both an air mass and fuel amount are variable depending on the load, so in case a mass of diesel is more than air per cycle -- let's say the injectors just pour diesel instead of injected with good diesel fog. The result is you push the pedal but the diesel can not be burnt fastly by reaching of TBC and it demands time to have diesel vapoured converted into fog. That is the problem. Even all parts condition in in order -- you will fell such Jerky drive unless this matter ewould be rectified. Cheers/Igor

[Laimis]

hello LAIMIS

the nature of this JERKY acceleration is as follows:

both an air mass and fuel amount are variable depending on the load, so in case a mass of diesel is more than air per cycle -- let's say the injectors just pour diesel instead of injected with good diesel fog. The result is you push the pedal but the diesel can not be burnt fastly by reaching of TBC and it demands time to have diesel vapoured converted into fog. That is the problem. Even all parts condition in in order -- you will fell such Jerky drive unless this matter ewould be rectified. Cheers/Igor

Very nice explanation indeed, thank you very much.

That brings two possible causes: too much fuel (SCV valves?) or problems with turbocharger ( stuck variable vanes and/or general turbine failure ? )

Or anything in between like turbine control units ( I checked vacuum valves and piping but what about pressure sensors and/or ECU ? )

Is there a way to check turbine's variable vanes w/o tearing it apart ? I am starting to suspect those as the acceleration is better when engine is fully warmed.

p.s. Looks like a good parameter analysis is needed anyway, code alone is not sufficient...

p.s.s. Looks like space technologies call for space engineers :) Let's see what cost of repair will be for Common Rail 01' model in 09' :)

[igormus]

hello LAIMIS

the nature of this JERKY acceleration is as follows:

both an air mass and fuel amount are variable depending on the load, so in case a mass of diesel is more than air per cycle -- let's say the injectors just pour diesel instead of injected with good diesel fog. The result is you push the pedal but the diesel can not be burnt fastly by reaching of TBC and it demands time to have diesel vapoured converted into fog. That is the problem. Even all parts condition in in order -- you will fell such Jerky drive unless this matter ewould be rectified. Cheers/Igor

Very nice explanation indeed, thank you very much.

That brings two possible causes: too much fuel (SCV valves?) or problems with turbocharger ( stuck variable vanes and/or general turbine failure ? )

Or anything in between like turbine control units ( I checked vacuum valves and piping but what about pressure sensors and/or ECU ? )

Is there a way to check turbine's variable vanes w/o tearing it apart ? I am starting to suspect those as the acceleration is better when engine is fully warmed.

p.s. Looks like a good parameter analysis is needed anyway, code alone is not sufficient...

p.s.s. Looks like space technologies call for space engineers :) Let's see what cost of repair will be for Common Rail 01' model in 09' :)

hello again

you ve initially stated that yr T/C is in order with typical whistle heard. do not be focused on this unit.

in case yr acceleration is better once the engine is warmed up -- this is direct confirmration of poor iinjection at cold starting.

as to SCV -- they are both mounted on the HP pump body and both are responsible for enging starting (suction of diesel) and running.

as to common rail -- this is ordinary pipe that has some connections for injection pipes; retainer valve and recirculation.

cheers/Igor

[Laimis]

you ve initially stated that yr T/C is in order with typical whistle heard. do not be focused on this unit.

well, I try to rule out possible causes. turbo is one of them.

I here the whistle from around 1500rpm-2000rpm, that's true.

I tried to listen whats is happening after 2000rpm but it's difficult to judge as wind, engine and turbo noises interfere. At least I can not distinguish the whistle after 2000rpm... Some measurement is really needed.

Given all that, couldn't it be that stuck turbocharger vanes cause the problem? How do they function: is it either closed ( when low RPM) or opened ( when high rpm ) or gradual closing-opening ? My model has vacuum actuator, newer models have electric step motor I believe.

In principle even with vacuum it's possible to play with open degree...

If this is what is happening then can stuck in closed position vanes choke engine/reduce turbo effectiveness when engine tries to accelerate ?

[igormus]

you ve initially stated that yr T/C is in order with typical whistle heard. do not be focused on this unit.

well, I try to rule out possible causes. turbo is one of them.

I here the whistle from around 1500rpm-2000rpm, that's true.

I tried to listen whats is happening after 2000rpm but it's difficult to judge as wind, engine and turbo noises interfere. At least I can not distinguish the whistle after 2000rpm... Some measurement is really needed.

Given all that, couldn't it be that stuck turbocharger vanes cause the problem? How do they function: is it either closed ( when low RPM) or opened ( when high rpm ) or gradual closing-opening ? My model has vacuum actuator, newer models have electric step motor I believe.

In principle even with vacuum it's possible to play with open degree...

If this is what is happening then can stuck in closed position vanes choke engine/reduce turbo effectiveness when engine tries to accelerate ?

- Given all that, couldn't it be that stuck turbocharger vanes cause the problem? ---> THIS POSSIBLE ISSUE IS THE RESULT OF POOR INJECTION -- IN OTHER WORDS CARBON ACCUMULATING IN ALL T/C GAS FLOW AREA.

- In principle even with vacuum it's possible to play with open degree.. --->

THIS VACUUM ACTUATOR IS LINKED (BY IMPULSE TUBE) TO SUCTION MANIFOLD -- -THE MORE RPM THE CHANGABLE VANES ATACK ANGLE.

[Laimis]

- Given all that, couldn't it be that stuck turbocharger vanes cause the problem? ---> THIS POSSIBLE ISSUE IS THE RESULT OF POOR INJECTION -- IN OTHER WORDS CARBON ACCUMULATING IN ALL T/C GAS FLOW AREA.

probably a final question just for my curiosity: how can pure injection be diagnosed ? Will it show up in emissions control ? black smoke ?

[igormus]

- Given all that, couldn't it be that stuck turbocharger vanes cause the problem? ---> THIS POSSIBLE ISSUE IS THE RESULT OF POOR INJECTION -- IN OTHER WORDS CARBON ACCUMULATING IN ALL T/C GAS FLOW AREA.

probably a final question just for my curiosity: how can pure injection be diagnosed ? Will it show up in emissions control ? black smoke ?

ok follow me:

- you must to have normal fuel valves (injectors) without solenoids -- correct??? in case of positive all of them must be tested on the special injection stand.

normally each injector is tested for twos: leak proof in each joining surfaces and jet quality that must be very sharp with typical jet crash having given no anyy diesl drops on th einjector tip (!!!) -- otherwise these drops are an exxtensive diesel portion per cycle etc etc;

- take a white A4 sheet of paper and hold it opposite of the exhaust tail pipe edge (with assistant , of course)-- the man in the cain must to repeatedly push the gas pedal -- but you will disclose whether or not carbon is appeared on the paper . This methos is very simple but selfexplained.

Good Luck/Igor

[Laimis]

- take a white A4 sheet of paper and hold it opposite of the exhaust tail pipe edge (with assistant , of course)-- the man in the cain must to repeatedly push the gas pedal -- but you will disclose whether or not carbon is appeared on the paper . This methos is very simple but selfexplained.

this is a good one.

[Laimis]

hello mate

firstly have the fuel filter changed + all four injectors tested.

there must be your head ache.

ok now. I had air and fuel filters changed.

Problems did not disappear just as I was expecting but at least I am ready for a serious diagnostics session.

Toyota guys are pointing to turbine ( this is what code 34 tells actually ) Not a big surprise. I even assume they might be right.

Let's see what diagnostics is going to tell.

[igormus]

hello mate

firstly have the fuel filter changed + all four injectors tested.

there must be your head ache.

ok now. I had air and fuel filters changed.

Problems did not disappear just as I was expecting but at least I am ready for a serious diagnostics session.

Toyota guys are pointing to turbine ( this is what code 34 tells actually ) Not a big surprise. I even assume they might be right.

Let's see what diagnostics is going to tell.

the turbo is only result but

not a reason.

Cheers

[Laimis]

the turbo is only result but

not a reason.

Cheers

it depends on the millage I believe. mine is 150th miles.

I got turbo pressure measured and yes, it deviates from the norm. Sometimes it underboosts, sometimes it overboosts.

The most probable reason is variable vanes.

Tomorrow turbo will be taken off for inspection.

[igormus]

the turbo is only result but

not a reason.

Cheers

it depends on the millage I believe. mine is 150th miles.

I got turbo pressure measured and yes, it deviates from the norm. Sometimes it underboosts, sometimes it overboosts.

The most probable reason is variable vanes.

Tomorrow turbo will be taken off for inspection.

hello

in case you're going to dismantle the turbo, then it is reasonably to substitute all consumables that might be worn down.

Cheers/Igor

[cmia]

the turbo is only result but

not a reason.

Cheers

it depends on the millage I believe. mine is 150th miles.

I got turbo pressure measured and yes, it deviates from the norm. Sometimes it underboosts, sometimes it overboosts.

The most probable reason is variable vanes.

Tomorrow turbo will be taken off for inspection.

hello

in case you're going to dismantle the turbo, then it is reasonably to substitute all consumables that might be worn down.

Cheers/Igor

inother words,

whilst u have it off

rebuilt it ;)

[Laimis]

the turbo is only result but

not a reason.

Cheers

I let turbo garage do the checks. the turbine check revealed varying turbo pressure. Connecting pressure sensor directly w/o VSV valve helped to stabilize it. I checked VSV before but who knows... I'd like to know what is the exact function of VSV valve on Toyotas.

At least turbo pressure is fine now. And I haven't managed to produce MIL light after those "modifications"

However jerky acceleration is still present :) BUT: it virtually disappears after a few good boosts until 3000-4000rpm.

Is this fuel injection issue, temperature sensor issue or ECU issue remains to be seen.

According to guys who did the diagnostics injection is fine.

[t-spiritpete]

the turbo is only result but

not a reason.

Cheers

I let turbo garage do the checks. the turbine check revealed varying turbo pressure. Connecting pressure sensor directly w/o VSV valve helped to stabilize it. I checked VSV before but who knows... I'd like to know what is the exact function of VSV valve on Toyotas.

At least turbo pressure is fine now. And I haven't managed to produce MIL light after those "modifications"

However jerky acceleration is still present :) BUT: it virtually disappears after a few good boosts until 3000-4000rpm.

Is this fuel injection issue, temperature sensor issue or ECU issue remains to be seen.

According to guys who did the diagnostics injection is fine.

Hello mate, I totally agree with Cmia & Igormus and so if you don't fully understand how it all works then here is a Toyota reference ... it is not exactly for your car which is diesel but it may help you get your head around what exactly is going on ( i'm sorry if you already know about all of this, but it may well help others who don't). I think your fault lies in the region of the egr/vsv/egr vacuum modulator so study this attachment and let us know your views. h61_Toyota_eg_r_vsv_explained.pdf

Best regards Pete.

[Laimis]

Hello mate, I totally agree with Cmia & Igormus and so if you don't fully understand how it all works then here is a Toyota reference ...

Best regards Pete.

thank you very much.

What Igor advised and I followed I am not sure how well injection test was done. but we did a test drive which did reveal pulsating turbo pressure issue. It did not reveal any injection issue though.

Engine starts and runs well.

For that reason I am inclined to believe the problem lies somewhere in between turbo regulation system and EGR. I'd like to get hold on another turbo pressure sensor just to check the existing one.

As for fuel supply (e.g. SCv valves ) I have doubts that ECU can not differentiate between fuel pressure and turbo pressure deviation. At least all professionals I have talked with agree that ECU either fails to catch an error or catches one which points to the right direction.

[Laimis]

hello mate

firstly have the fuel filter changed + all four injectors tested.

there must be your head ache.

cheers/Igor

now I am 100% sure that this jerky acceleration and/or pulsating turbo pressure is an issue only when engine is not completely hot.

I mean I have to have a few 3000-4000rpm bursts. After that everything is fine.

too bad Avensis has no temperature indicator just this blue warning light...

I am wandering if thermostat and/or temperature sensors are failing.

[Laimis]

My thanks to everyone for help. I am impressed.

The fault was intermittent circuit fault of air temperature sensor in the mass air flow meter.

Apparently more air flow would "fix" the circuit temporarily hence the issue with problem disappearing after some harsh accelerations...

Conclusion: turbo was not the issue. But sensors do need to be checked carefully one by one. I was pointed that water(engine) temp sensor is often a problem too. Engine computer however was not able to catch the exact reason but pointed to some direction at least.

[cbrf7]

Hi. I'm new on the forum and I expirience the same problem on my corolla verso 2.0 D4D, 03 plate. Would you please tell me, how did you solved the issue with circuit fault of air temperature sensor? And, please excuse my English.

Cheers, Andrej