Thread: turbo boost pressure

On the nanocom I believe there is the option to look at the RAW MAP sensor value on the inputs fueling page, which I have done and it shows me a MAP reading between 60 and 180kPa, I understand this is an absolute pressure reading so it matches my -0.4 bar boost pressure reading

If you are running the nanocom in instrument mode, which it appears you are, as you increase in elevation, your boost pressure reading from instrument mode will reduce. Something to do with the algorithm for that value based on ambient pressure.

Go into engine, then fuelling and look for manifold pressure. It's a true pressure value and will give the correct reading. Max is 246kpa.

Mine does this all the time whenever I am up in the mountains, and it is why you should never adjust your wastegate off that value, it should be off the manifold pressure in the aforementioned menu group.


Edited - just saw your last post. Well, if it's low then either sensor or you may have a hole somewhere?

Originally Posted by sierrafery

I know nothing about that sensor of your's, the gist is that in inputs fuelling a good MAP sensor should show similar/extremely close at idle to the AAP(ambient pressure) reading and up to 230(or even 240 with a shortened wastegate rod) under load.... if your's goes up then drops to 0 it's oveboost there which occurs if the MAP exceeds 242. The AAP should only drop a little bit under load and be very close to the real pressure there compared to a barometer. See attached how a fairly well running engine's log should be, i managed to set the forge wastegate actuator as to get 240 MAP just below the overboost at max load(pos 92) Attachment 128054

as about this
if the sensor is faulty the ECU limits the fuelling for default max 1 bar boost so not the case of overboost then

The drop to 0kPa actually occurs during a range check on the "raw" converted sensor voltage. This is the checking process that sets the Nanocom 1,x - 6,x logged high and logged low faults. Because the voltage is over the high limit for short time you don't get a logged fault.

Overboost is something different and occurs when boost exceeds the over pressure limit which is set by default at 142.00 kPa boost.
As you know boost = MAP - AAP.
So this means that overboost is influenced by pressure drop over the filter etc. which impacts the AAP reading.
If you have 4kPa pressure drop caused by your air filter, snorkel, etc so that your AAP is reading 97kPa under load, then overboost occurs at 97kPa + 142kPa = 239kPa MAP. It's only the differential between absolute pressures that matters, not the absolute pressures themselves.

Overboost causes the engine to run on a overboost protection map which cuts the amount of fuel injected in an attempt to reduce boost levels. What seems to happen in practice is that the gap between overboost limit and sensor over-voltage is only a few kPa so you rarely notice the fuel cut on the way to over-voltage.

The sensor has to be out of range, that is above the logged high or below the logged low threshold, before it is considered faulty.
Giving wayward readings is not enough.

Originally Posted by OffTrack

As you know boost = MAP - AAP.
So this means that overboost is influenced by pressure drop over the filter etc. which impacts the AAP reading.
If you have 4kPa pressure drop caused by your air filter, snorkel, etc so that your AAP is reading 97kPa under load, then overboost occurs at 97kPa + 142kPa = 239kPa MAP. It's only the differential between absolute pressures that matters, not the absolute pressures themselves.

...

Thanks for claryfing that, i was under the(it seems wrong) impression that the overboost limit is at 242 MAP period. At least i'll not be susprised if i get overboost at below 242 MAP when i'll climb on some higher hills

for the TLDR

I've resolved this issue, fitter a BOSCH MAP sensor that I got from Landy Nut and all is good, now looks like I need to replace the MAF as well but thats another story, thanks everyone for your help

however.....

Ws stated earlier when I first suspected the MAP sensor was faulty I bought one from Ebay, it was a Tridon sensor which at the time I didn't appreciate wasn't OEM....what could possibly go wrong!

http://www.ebay.com.au/itm/TRIDON-MA...:RRNTB:AU:3160

OK, so, sensor arrived and read above the results, it just was no good, I spoke to the seller, and he told me to speak with tridon, who after I explained the issue said the sensor was probably faulty and I should send it back to the seller... seller wasn't happy about this but hey.

** I posted the sensor back on 18th aug, and get a message from seller on 22nd asking if I had sent it back and did I have a tracking number, so I send him a copy of receipt with tracking number

** on 1st of September I'm still waiting for replacement sensor and ask seller if hes posted it yet, he tells me no, hes still waiting for the first one to arrive, so I check the tracking number and find they tried to delivery it to him on 21st aug and its been stuck in post office since then waiting for collection!

** on 6th September I finally get the replacement sensor and its exactly the same as first one, leaving me to conclude that there is either a fault with my ECU or these sensors are No good

** on 9th september I get a BOSCH OEM sensor from Landy Nut, he lets me try it in his drive to ensure that it works OK and that I dont need to replace my ECU, its perfect!



now the real fun starts

I send the seller a message via Ebay that I dont consider his sensor to be fit for the purpose its been sold for and request a refund

I'm afraid the new sensor you sent out is exactly the same as the previous one.


Because this left me with the uncertainty that it may be the ECU that was at fault, I have had to resort to sourcing another sensor from a third party to verify if the problem is the sensor or the ECU.


The third party sensor worked perfectly, which leaves me to conclude that despite the information on your listing and the Tridon website, this sensor is absolutely not suitable for a 16P discovery 2 TD5 engine.


I will return this sensor to you ASAP and request a full refund of the sensor, and because we have concluded that the sensor is not as described in your listing I shall be requesting that you refund both this and the previous return postage as per Ebay terms of service.

his reply

Your item we sent make sure sent from Tridon
What u purchase

We are not here for try and try
This is second senors we sent u from Tridon been make sure is working

I try again

Sorry I'm unsure what you are saying here, but I bought this sensor to repair my car in good faith on the believe it was suitable for my engine, after two sensors I must conclude that it is not as described, and should not be sold for use on a 2004 16P TD5 engine.


I fully understand that you are not at fault here, the fault must lie with Tridon, as they have clearly stated that the sensor is suitable, but, after testing two failed units and a third OEM sensor I have proven that the sensor is not suitable as described.


I can understand that you are as upset by this as I am, however, you and indeed Tridon can count yourselves as fortunate that this unsuitable sensor has not done any discernible damage to my engine.

and he replies

1) we sent u brand new item at the frist . U tell us our item faulty and we been call Tridon australia been call u to resolve your item and we been test it before we sent u another brand new unit for our servies . Now u tell people as your ecu problem or our senors problem again .
I am not happy we been keep doing this for you at the end

...continued

So, anyway we exchange a few more messages like this getting nowhere, eventually he says he will need to speak with Tridon on monday, ie today the exchange proceeds as follows.... not bothering with the hesaid/Isaid bit the spelling makes it pretty clear!

what car u have i need to engine model i speak to tridon on your car and product we been make sure item is suitable for your car before we sent the second item 1) frist email u been tell us item is fauilty and we been sent second unit to replacement for u 2) second unit u tell me it not suitable for your car - what the issue your ecu have problem ???

My car is a 2004 Land Rover Discovery with a 16P TD5 engine and a NNN50030 ECU, this is a completely normal setup for this car, and matches the quoted compatibility on the Tridon Website. Both Tridon sensors sent had exactly the same fault, the ECU interprets their output as 217kPa at atmospheric pressure changing to 100kPa when the car is being driven.
I was prepared to accept that the first sensor was faulty hence why I accepted a replacement, but when the second sensor had exactly the same issue I was forced to investigate if the sensor or ECU was at fault. By using an OEM Bosch sensor I was able to establish that my ECU was functioning perfectly, and have proven that both the Tridon sensors are faulty or unsuitable for my car

we speak to tridon regard your issue for this map senors 1 st unit been sent back all fine we have report tridon say to us install problem or wiring problem or setting problem with your ecu this item all plug in this item depend on your ecu setting

Tridon are wrong, there is nothing wrong with my ECU or wiring, this was proven when my car worked perfectly with a BOSCH OEM sensor

frist item we sent to u , u been sent us pm say is not controll valve unit when reach max psi . if item not been working how can u tell me this report . tridon been say u need to setting your ecu . as this item is aftermaket need to be setting from ecu . of couse item u have from oem it will bolt striaght on without change any setting . we been test this item from tridon . and tridon professional person say . your people never know how to set this map senors on the ecu . so why this item not been working

That explanation is unacceptable
1) Your posting on Ebay included no mention that parameters would need changing.
2) Your posting on Ebay explicitly states that this sensor was specifically engineered for my vehicle.
3) The item came with no information on the settings changes required
4) The Tridon Website has no instructions for changing parameters
5) When speaking to Tridon myself they made no mention of changing parameters, they thought the sensor was faulty.
6) I would not have bought a sensor that required me to change ECU parameters.
7) Even if I did understand that there were changes needed to be done, there was no information provided on the correct parameters.

After I have wasted a month on this sensor, to turn around and say that I just needed to change some parameters is cynical, the average user cant do this anyway and even though I do have the ability to reprogram my ECU, the lack of information to make this possible just proves that the sensor is not fit for the purpose it was sold.

1st unit we sent u , u been sent us report this item what happen . we been pass the number for u been speak to tridon regard your issue we not sure how u speak to them . we been follow what u say we been sent u replacment second unit as u are customer . we been done whatever u say we do all replacment to u without check anything from the frist unit u sent back . please understand u purchase is aftermaket map senors or oem factory map senors of course is different

I really do not understand what you are saying, Im afraid I can provide you with no more information, and feel that everything I have provided you with is factual and correct. If you are refusing to pay the refund then please let Ebay know and we will proceed to arbitration immediately.

and I dare say this will continue!

Just spoke to Tridon, and even spoke to the guy who spoke to the reseller, they deny saying anything about reprogramming the ECU!

Wow... i don't even know how you understood half that stuff they emailed you.