S40: TPS - readings

[dtm]

Hi

For a wile I've had some issues with the idle of my car (2000 S40T4 1855cc engine). Tried cleaning the ICV, no change, tried 2 other ICVs, same result, changed the 2 one way valves that connect to the inlet manifold and air intake to turbo, and nothing. Cleaned the throttle body as well, and no change. The idle even out eventually, after the engine is more or less up to temperature.
The readings I get from my TPS sensor are, I guess normal, if not for the fact that with WOT the reading is 78/79%. I tried reading pressing the accelerator pedal to the floor and rotating the butterfly on the throttle body and the readings are the same. Could this be the source of my problems?

Regards,

[mitchyboy01]

Originally Posted by dtm

Hi

For a wile I've had some issues with the idle of my car (2000 S40T4 1855cc engine). Tried cleaning the ICV, no change, tried 2 other ICVs, same result, changed the 2 one way valves that connect to the inlet manifold and air intake to turbo, and nothing. Cleaned the throttle body as well, and no change. The idle even out eventually, after the engine is more or less up to temperature.
The readings I get from my TPS sensor are, I guess normal, if not for the fact that with WOT the reading is 78/79%. I tried reading pressing the accelerator pedal to the floor and rotating the butterfly on the throttle body and the readings are the same. Could this be the source of my problems?

Regards,

I thought my TPS was causing my probs as was only seeing 75% at WOT. Put a new genuine volvo sensor on and its now at 76%. It turned out to be my MAF duff and giving less voltage than it should have and my lambda was also duff. Whats the odds of that?

[dtm]

If that's the case, how can I check my MAF? The readings I get from it are steady, no sudden crashes or anything like that. I've checked the Web and have an idea on how to check the TPS sensor.
The lambda sensor or O2 sensor the seem fine, but don't really know what to expect from them in terms of readings.
Oh, the dtc (ECU) does not show any errors in mine.
Did yours present itself with the engine check light?

Regards,

Daniel

[mitchyboy01]

My MAF looked fine on the logs as the voltage was still linear but it was gradually failing. It wasn't until I tried a known good maf that I saw the new one was reading a lot more airflow. At 800rpm idle you should have around 3grams/sec airflow. Mine showed 2.2. Ran so much better after I changed it. The lambda voltage should ocsillate up and down about once per second between low and high. Didn't get a code from maf at all and lambda didn't until it had completely failed. If you have an android phone get the torque app. Its great for logging all these values.

[mitchyboy01]

I also changed the CTS but this made no difference to the problem for me.

[dtm]

Hi,

Already have torque pro. That's what I'm using. By the looks of things I guess the MAF is reading about 2.3g/s, off the top of my head, but I'm going to have to check that tomorrow.
Today I'm riding to wheels.
The MAF readings are best checked with a hot engine, right?
The coolant temperature sensor (CTS?). Did change that about 3 month ago, and yeah, not change either.

Thanks mitchyboy01,

Daniel

[mitchyboy01]

Yes check the reading with the idle as steady as possible when warm. I will hopefully be getting a trackday bike next year. Cant wait. Ive given up on road riding now as the roads here are to bad to ride like a loon these days.

[dtm]

Hello

The MAF reading is as follows: idle at ~ 800rpm MAF 2.4g/s.

According to you (mitchyboy01) this is a faulty MAF and should be replaced, right?

Thanks,

Daniel

[mitchyboy01]

Obviously I cant say 100% all I can say is mine was. Mine now reads 3.2 g/s on idle and runs much better. Ideally you need to borrow a known good maf to check before you buy.

[dtm]

Ok,

Need to find someone in Portugal to lend me one to try.
Will post the result once I have tried it.

Regards,

Daniel