MAP sensor attachment

[arossco]

I have been having a recurrent problem on my 2017 TOYOTA VERSO 1.6 Diesel (1WW engine derived from BMW N47C16A). 

I'm getting these ODB2 codes :

P00BD - Mass or volume air flow 'A' circuity range/performance - air flow too high
P0471 - Exhaust pressure sensor 'A' circuit range/performance

I've had the engine carbon cleaned ( fairly quick process, injecting hydrogen Ito the inlet manifold ) and also a DPF clean, by means of a spray.
In both cases the error reappeared fairly quickly.

I've ordered a MAP pressure sensor as I really need to eliminate this as the cause.

My question is, how do I disconnect the electrical connection from the sensor ? I've attached a photo of the connector, while disconnected by my garage ( it's back on now )
It looks like I should pull back the white sliding clip, then wiggle the connector free, but it seems quite tight. I am reluctant to put too much pressure on it in case I'm doing the wrong thing.
I've also attached a photo ot the sensor while disconnected.

I will be very grateful for any help with this !

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[chippie]

Yep, you need to retract the white tab, first to unlock the connector.
If you look at the photo you can see how the tabs are further back clearing the latching part…

Once retracted the connector should pull away from the sensor body..a little wiggle and maybe a bit of WD40 spray….?

[arossco]

Great - thanks very much for the quick reply. Already glad I joined this forum :-)

I'll let you know if the new sensor does the trick - it will arrive on Thursday, and I'm hoping for the best !

[chippie]

When you fit the new sensor, make sure you clear the codes before firing up the engine…after fitting the sensor first….

[arossco]

Thanks - will do !

[valhalla]

Did you check the induction system for split intercooler and/or hoses to/from the intercooler prior to diagnosing the sensor? Your faults point in that direction.

[chippie]

The code description is a bit vague for making a decision to replace the sensor….Maybe a check on live data to see what voltage the sensor is giving first…..

[arossco]

Nov 6, 2023 23:31:36 GMT 1 valhalla said:

Did you check the induction system for split intercooler and/or hoses to/from the intercooler prior to diagnosing the sensor? Your faults point in that direction.

I offered my local mechanic the data I had gathered from my ODB2 scanner and asked him to to check for leaks in the intake system, but he insisted that he would do his own checking and ended up saying the DBF was blocked and putting a cleaner through it. I can't be certain that he did check the intake, and he is now on holiday until the 24th.

When the EML light came back on with the same codes, I ordered the new MAP sensor in case it was this all along.

I will attach the printout I made here in case it makes sense !

[arossco]

Nov 7, 2023 10:41:00 GMT 1 chippie said:

The code description is a bit vague for making a decision to replace the sensor….Maybe a check on live data to see what voltage the sensor is giving first…..

I'm not sure if this helps, but in September I took in in to a nearby Toyota dealer, and they diagnosed a *blocked* ( not cracked ) inlet manifold at a repair cost of £1080.00. 
When I expressed my dismay at this, they suggested an option was to buy a new car ! 

Here is the data which I offered to the mechanic, but he did not want. It would be great if it helped pinpoint the problem !


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[chippie]

Well the data, although a snap shot isn’t conclusive to me….I’d like to see what boost pressure is like with the engine under load and see what the map sensor reading is….but I’m leaning to a leak…but I could be wrong..,🤔

[arossco]

I'm towing our caravan on Wednesday, so that should put the engine under some sustained load.

 I can try and get some readings then.

Is it the Commanded Boost Pressure A which would be useful ? All these readings below were taken at idle.

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[chippie]

You should really check for leaks especially between the turbo and the inlet manifold...

As Valhalla pointed out earlier

[arossco]

I will do that. Thanks very much to both of you. 

[valhalla]

I can see why you would want to eliminate the MAP sensor on this engine - the freeze-frame data above is a bit unusual, to say the least, and the live data against it is also a bit suspicious. It certainly looks like either the sensor is dropping-out intermittently, or there is a partial blockage upstream of the inlet manifold that comes and goes. So replacing the MAP sensor and checking its wiring and connector/s is a good start. I would have expected a DTC for MAP circuit continuity by now, or at-least a MAP/BARO plausibility on some of the data-points you have there, but it might be that Toyota have missed a trick in their diagnostic limits for this sort DTC.

One sound reason why it would be good to have MAP_SP - the datastream that you mention above as the setpoint pressure desired - is that it would allow a side-by-side check of the actual MAP, and that would eliminate one fairly common issue, which is sticking in the turbocharger shaft - that is, a stationary compressor wheel during driving. This can manifest itself as an intermittent "blockage" upstream of the inlet manifold, which is what you seem to have. If the induction system is all clear of rags and wipes, and the air-cleaner element is fresh and dry, then compressor stall is the next thing to check.

Your towing test will properly highlight where the problem may lay, as (as Chippie says) it will give some proper loaded & boosted conditions to see if the turbo is spinning properly or not.

Let us know !!

[arossco]

Thanks for your detailed suggestions, Valhalla !

The new MAP sensor arrived today, but unfortunately it's not the correct one, so I'll have to postpone the swap for a while.

It's actually tomorrow (Thursday) that I'm towing the caravan, from Glasgow to Edinburgh, so I'll get some data then.

In the meantime, I logged the Commanded Boost Pressure A today - just driving around the city with a couple of dual carriageway spells.
It seems to peak around 240 kPa and idle at 100.5 kPa - just above atmospheric pressure at idle. Do these figures seem ok ?

This is all new to me - way back it was plugs, points and grease guns etc, but it's great to be on a learning curve ! 

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