No Throttle Response after sitting on a Hill

[imck]

2008 Mazda 6 2.5 Petrol

Sat on a Hill waiting to pull out after queuing in Traffic.
No or very little response from the Throttle when attempting to pull away.
No/little response when revving in Neutral. 10-20 Seconds it will rev again and I can pull away.

This has happened 3 Times in the last few Weeks. Always after queuing on an incline.

Serviced October Last Year.(I do 8K Miles/Year) Not sure if Fuel Filter was replaced.
I have a bit of hesitation when crawling in traffic and a slight 'hiccup' around 3K RPM.
I cleaned the Throttle Body 6+ Months ago. This has only been happening in the last few Weeks.

Any Theories/ideas please?

[Pericoloso]

Does this have an OBD port to read engine fault codes ?

[imck]

Yes. Not getting an Engine Light on the Dash though.

[Munter]

imck said:

Yes. Not getting an Engine Light on the Dash though.

Say it was the throttle position not being picked up, then the engine would think all was good in the world, but you'd get no revs, even with your foot on the floor. An OBDII Bluetooth device is only a few £ and connected to your phone will help you see interesting things like that.

[imck]

I have a Bluetooth ELM327. Arrived Today and I have downloaded Torque Pro.
Bought for the Mrs Yaris which has just had the Engine Light come on !!

I see what you are saying about the TPS but odd that it only happens on Hills.
I was wondering if some sort of fuel starvation?

[Munter]

imck said:

I have a Bluetooth ELM327. Arrived Today and I have downloaded Torque Pro.
Bought for the Mrs Yaris which has just had the Engine Light come on !!

I see what you are saying about the TPS but odd that it only happens on Hills.
I was wondering if some sort of fuel starvation?

The good thing with Torque app is you can get it to log the readings to a text file. So you can review it later using excel, rather than hoping to spot it in real time on the "live" graphs. If there's a fuel pressure reading, stick that on alongside, throttle positions at pedal and throttle body.

Some error codes also don't put the light on, so there may be a useful message...found those on the MX5 when it had a misfire a few times. It'd see the misfire and record a message, but only if it got worse turn the ecu light on.

[stevieturbo]

Is there fuel in the tank ?

[E-bmw]

stevieturbo said:

Is there fuel in the tank ?

I was just about to ask if it was up or downhill, he just said incline......

[imck]

Plenty of fuel in the Tank.

Up Hill only. On all occasions after sitting stationary at idle for a minute or more.

[E-bmw]

imck said:

Yes. Not getting an Engine Light on the Dash though.

Doesn't mean you don't have anything "pending" get it read just in case.

[imck]

E-bmw said:

Doesn't mean you don't have anything "pending" get it read just in case.

My new OBD2 Reader is not showing any faults.
I think I have set it up to log as I drive. Will see if that produces anything meaningful.
I might find a quiet Hill to sit on to reproduce the symptom. Was not fun trying to get onto a busy Roundabout this Morning.

[wooden cowboy]

Have you considered giving the mass air flow sensor a clean with the appropriate spray, such as contact cleaner?

[imck]

Happened again Yesterday. Same place. Sitting in a queue going uphill after approx 30 Mins from Cold Start.

Torque Pro Logs show the Input from the Pedal Sensors increasing but no corresponding increase on the Throttle Position Sensors.

I would appreciate someone having a look at the Torque Pro Log.
I have made it more readable and highlighted the 7 Rows where the error happens.

Link to Spreadsheet on my One Drive
https://1drv.ms/x/s!AtCz6AtB1md4gY8YP9nzJXdfl3BFoA

Thanks

[GreenV8S]

imck said:

Pedal Sensors ... Throttle Position Sensors.

Does this vehicle use drive-by-wire, or a mechanical throttle linkage?

[imck]

Drive by Wire

[stevieturbo]

It would be very very unusual if the TPS is not tracking PPS and not also registering a fault/code.

Can you see all the raw voltages from the tracks both in the pedal and DBW unit ?

And any duties being applied to the DBW to see if it is actually asking to open it ?

Not sure if a generic OBD will offer you that though

[imck]

The values in the Log for both the PPS and TPS are %

At Idle
Accelerator Pedal Position D 15%
Accelerator Pedal Position E 7%
Relative Throttle Position 2%
Throttle Position Manifold 11%

Steady 50MPH 2K Revs
Accelerator Pedal Position D 24%
Accelerator Pedal Position E 12%
Relative Throttle Position 9%
Throttle Position Manifold 18%

When the Fault occured. (I kept pushing the Pedal downwards)
Accelerator Pedal Position D 34%
Accelerator Pedal Position E 16%
Relative Throttle Position 3%
Throttle Position Manifold 12%

There is a Forscan App available that is supposed to work with my OBD

[stevieturbo]

As said raw voltages would be more useful, as some of those could be calculated values and a little misleading

And a graph trace rather than a momentary snapshot

But the fact it isnt throwing any fault codes would suggest that side of things is ok.

[GreenV8S]

I don't know what's supposed to be going on under these circumstances, but the figures all seem consistent and sensible - they make me think the ECU has simply decided that it is not appropriate to open the throttle. I can think of a few faults that might prompt the ECU to decide to keep the throttle closed, but I'd expect to see fault codes for all of them. I'm intrigued to know why the hill makes any difference. You haven't accidentally engaged traction control in 'snow' mode or something daft like that, have you?

[imck]

When the fault occurs the Pedal compared to the Throttle values do not seem consistent to me.
The Pedal % Increases but the Throttle % doesn't.
I would also expect to see an error if the ECU does not see an expected Throttle response. Very odd and annoying.

It does have Traction Control (DSC). A warning light appears when it activates. No Snow Mode. Manual Gearbox.

It is very intermittent. 4 Times in the last Month or so.
Twice when giving someone a lift for a Week and sitting uphill at the same Traffic Lights.
Twice after coming up the same Motorway Slip Road and queuing on my usual Route to Work. (15 Miles/30-40 Mins)
I don't know if the Hill is a red Herring or just where I happened to be sitting at idle and not moving for some time.

The Ford/Mazda Forscan App does not work very well with my Bluetooth OBD2 Device. Connects but can't get any Data out of it.
My next step is to get something that will run Forscan.