Techstream data analysis???

[mikey-t]

Hey all, been having an issue with my t25 1.8 petrol.I'm hoping someone can shed some light on before I concede defeat and book it in at Mr T's. If you're sat in the car with it just on idle it feels quite lumpy and irregular, also sometimes if i dip the clutch at junctions it will drop to 600 then quickly bounce back up to 1000, like its just about to stall but the ecu pulls data from another sensor and tries to counter the stall. The worst problem though is the jerky acceleration, worse when cold and less noticeable but still present when warm. If I take it to say 2500rpm in second then come off the throttle it will kangeroo like mad, even worse in 1st and less so the higher the gear. Generally any action of pressing or releasing the accelerator is pretty jerky no matter how delicate I am. The car is fully serviced with fully synth oil and new denso plugs, I have also cleaned the throttle body and MAF with no improvement. Also tried pulling each coil pack with the engine running and it starts to misfire when one is pulled so think they're ok. Can anyone see anything out of place on my techstream data or suggest anything? Thanks in advance.

[ents]

I only noticed one strange thing, the VVT is on then idling. It should be off.

Try to toggle it off and on within active test. If stays on then the problem should be at OCV oil control valve witch operates the VVT system.

[mikey-t]

28 minutes ago, ents said:

I only noticed one strange thing, the VVT is on then idling. It should be off.

Try to toggle it off and on within active test. If stays on then the problem should be at OCV oil control valve witch operates the VVT system.

Thanks buddy, tried the test yesterday and it does exactly what it says it should do in the notes, which is stall when the test is performed.

[mikey-t]

Noticed a couple more things today while tinkering, 1: Did the old trick of disconnecting the MAF sensor to see if made a difference but the car refuses to start without it plugged in. Is this a safety feature or a clue??? 2, If the car is just idling and I pump the brake pedal the revs drop drastically, does this pint to a vacuum leak???  

[waqar_lionheart]

1. Check batter.

2. Check camshaft/crankshaft sensor

3. MAF Sensor disconnect would cause it to die but in my opinion and experience, it should start after a few attempts but would run on default air volume and fuel trim. 

4. Disconnect camshaft position sensor and see if it makes the running a bit better (only for a little while)

 

Regards,

 

Waqar

[mikey-t]

5 hours ago, waqar_lionheart said:

1. Check batter.

2. Check camshaft/crankshaft sensor

3. MAF Sensor disconnect would cause it to die but in my opinion and experience, it should start after a few attempts but would run on default air volume and fuel trim. 

4. Disconnect camshaft position sensor and see if it makes the running a bit better (only for a little while)

 

Regards,

 

Waqar

Thanks for the reply buddy, just disconnected the MAF again and it did eventually start. Don't know if it's just a placebo but did seem a bit smoother. Gonna leave it unplugged and try it again in the morning.

[ents]

Waqar is right, try to test the crank- and camshaft sensors with a multimeter. Locate their connectors inside engine compartment and disconnect them. Mesure the resistance between connetor therminals then engine is cold. Crankshaft sensor resistance should be between 985-1,600 ohm

And camshaft 1,630-2,740 ohm.

[mikey-t]

1 minute ago, ents said:

Waqar is right, try to test the crank- and camshaft sensors with a multimeter. Locate their connectors inside engine compartment and disconnect them. Mesure the resistance between connetor therminals then engine is cold. Crankshaft sensor resistance should be between 985-1,600 ohm

And camshaft 1,630-2,740 ohm.

Thanks guys!! Will check tomorrow and update. Just out of curiosity, what make you think cam/crank sensors?

[ents]

Then not working correctly they usually cause poor starting and lumpy idling.

[mikey-t]

21 hours ago, ents said:

Waqar is right, try to test the crank- and camshaft sensors with a multimeter. Locate their connectors inside engine compartment and disconnect them. Mesure the resistance between connetor therminals then engine is cold. Crankshaft sensor resistance should be between 985-1,600 ohm

And camshaft 1,630-2,740 ohm.

I have the cam sensor out and cold it's reading 1.092 ohms. Can I ask where you got the ohm values from ents? I have an avensis repair manual and according to that the cam sensor for the 1zz fe should be between 835 to 1,400 cold.

[ents]

I got the values from Avensis repair manual, under diagnostic section.

 

 

 

 

And i also found this

I really dont know what values are correct anymore.

[mikey-t]

4 hours ago, ents said:

I got the values from Avensis repair manual, under diagnostic section.

 

 

 

 

And i also found this

I really dont know what values are correct anymore.

Hmmmm, very strange indeed. Does your manual have a date range?? Mine says 2003 to 2007 but I am unable to source a 2007 to 2009 T25 manual.

[ents]

Mine is the same 2003-2007.