2005 T25 2.0 VVT i D4 Automatic

[Niko_I]

Hi ! I had this car for couple of months and noticed that when engine is "half Warm" it hesitates when trying to accelerate.

When engine is fully warm it goes ok. Could it be bad temperature sensor? I have changed Denso spark plugs, air filter and cleaned throttlebody.

Idling is also rough ocasionally when warmed up, especially when ac is on. When i cold start the engine revs go up to 1800 and takes couple minutes to drop about 1000 rpms, finally settling about 700 rpms. I use 98 E5 gasoline.

I live in Finland so pardon my English.

[mrfixer]

The cold start behaviour is correct, 1800rpm slowly falling to 700rpm.  The idle will jump up and down a little as the A/C switches on and off.

Hesitation could be due to many things. Coolant sensor, O2 sensor or throttle position sensor is possible, plus other things (e.g. fuel pressure).

I would suggest getting a copy of Toyota Techstream software and a connecting cable (try Ebay).  Then take a look at your sensor readings and lambda sensor signal as the car warms up.

[Niko_I]

Thanks for reply! 

I found a website Toyota Tech Eu where you can download Techstream for free, havent tried it yet. 

Has anybody tried CRC Gdi intake and valve cleaner? I have read that D4 engines are prone to carbon deposits. 

This is my first Toyota car. 

[doc_14]

Hello.

 

I also have a T25 2.0 D4 engine (1AZ-FSE) and mine hesitates too. It only kicks above 3000rpm, like if it has a turbo kicking in at that rotation and above.

 have used Liqui-Moli Valve cleaner and saw a bit of improvement in engine response but the hesitation keeps. If there is a lot of carbon build-up, maybe the valve clean wouldn't do much.

 

[Niko_I]

My car only hesitates when half warmed, when engine hot it pulls fine. 

I also have that "turbo kick" after 3000 rpm, though could use more torque on lower rpm. 

When it hesitates and i push gas pedal harder, it kinda makes sort of growling sound before it changes lower gear. 

If that makes any sense. 

Should "cold start" rpms rise near 2000 when there is above 30c warm outside? 

Thanks for replys

[mrfixer]

Yes, the cold start rpm is always quite high on nearly all Toyotas.  However the idle rpm should drop to less than 1000 quickly (couple of minutes) if the air temperature is 30C.

The kick you can feel above 3000rpm is probably the VVT switching in.

The engines are direct injection and so prone to carbon build up, however I doubt it is the problem causing your hesitation.  The carbon is difficult to remove with chemical cleaners - you really need to use Shell blasting or scraping..

[Niko_I]

9 hours ago, mrfixer said:

Yes, the cold start rpm is always quite high on nearly all Toyotas.  However the idle rpm should drop to less than 1000 quickly (couple of minutes) if the air temperature is 30C.

The kick you can feel above 3000rpm is probably the VVT switching in.

The engines are direct injection and so prone to carbon build up, however I doubt it is the problem causing your hesitation.  The carbon is difficult to remove with chemical cleaners - you really need to use shell blasting or scraping..

Ok. Thanks! 

[doc_14]

About the 'kicking in', few days ago I changed all my Oxygen sensors due to a P0420 and P0430 error and the hesitation almost vanished. (New catalyst already installed and errors still present) Now after 3000rpm I don't feel so much kick but the car accelerates better. Maybe one or more sensors of your car are getting lazy until engine is full warmed and working 'normally'

[mrfixer]

1 hour ago, doc_14 said:

About the 'kicking in', few days ago I changed all my Oxygen sensors due to a P0420 and P0430 error and the hesitation almost vanished. (New catalyst already installed and errors still present) Now after 3000rpm I don't feel so much kick but the car accelerates better. Maybe one or more sensors of your car are getting lazy until engine is full warmed and working 'normally'

This is why I suggested to connect a diagnostic tool to the vehicle and monitor sensor outputs.  Its the basic first step.

[Niko_I]

Got to get me a diagnostic tool then 🙂 Thanks for all replys!

[xzirri]

On 7/23/2020 at 3:16 PM, Niko_I said:

My car only hesitates when half warmed, when engine hot it pulls fine. 

I also have that "turbo kick" after 3000 rpm, though could use more torque on lower rpm. 

When it hesitates and i push gas pedal harder, it kinda makes sort of growling sound before it changes lower gear. 

If that makes any sense. 

Should "cold start" rpms rise near 2000 when there is above 30c warm outside? 

Thanks for replys

That "growling" noise is probably from the plastic duct that goes from the air filter box and to the front of the car. To see if this is the case, try to move the duct by hand and listen for any plastic on plastic sound. You can open the air filter box, remove the filter and poke the duct where it connects to the air filter box.

I had a similar issue with my car (low power under load when cold) and it got better after I cleaned some of the carbon from the intake air control swirl flaps. I thought the sound was gone until it came back a few weeks ago. Fixed it by mounting some foam where the duct connects with the air filter box.

[Niko_I]

On 8/3/2020 at 11:46 PM, xzirri said:

That "growling" noise is probably from the plastic duct that goes from the air filter box and to the front of the car. To see if this is the case, try to move the duct by hand and listen for any plastic on plastic sound. You can open the air filter box, remove the filter and poke the duct where it connects to the air filter box.

I had a similar issue with my car (low power under load when cold) and it got better after I cleaned some of the carbon from the intake air control swirl flaps. I thought the sound was gone until it came back a few weeks ago. Fixed it by mounting some foam where the duct connects with the air filter box.

Thanks for advice! I bought a bluetooth scanner and installed Car Scanner for phone. Have been lookin fuel trims but it is confusing.

After cold start stft B1 and B2 are about -17% and ltft +17%. Yesterday with warm engine ltft was +13% when idling an about +7% when 1500 rpm.

Today ltft was +3% idle and fluctuated between +2% and -1% with acceleration. Been searching for vacuum leaks with spraying water around intake without results.

[xzirri]

If the long term fuel trim is +17% and short term fuel trim is -17% then your total fuel trim level is 0%. When looking at fuel trims, you should look at the total. If you disconnect the Battery for a little while your fuel trims will be reset.

Usually, a total fuel trim level of +/- 10% is within acceptable levels. Excessive positive fuel trim means that the ECU is correcting for a lean condition, while excessive negative fuel trim means it is correcting for a rich condition.

Also, I've heard that cars often run really rich when cold to get up to operating temperatures quicker but I don't know if that would show up on fuel trim readings. I am still quite new to reading scan data.

[Niko_I]

xzirri was it difficult to get intake manifold out, and do you have to remove high pressure pump? Thank you! 

[xzirri]

Yes, the high pressure pump has to come off to take off the manifold. I wasn't able to get enough clearance to get the manifold out of the engine bay and I even had to remove the studs to get the swirl flaps out. I don't recommend doing this before you have done more diagnostics. Could you post a video of the problem?

[Niko_I]

I will try to post video anyday soon...