Td5 Engine Surging

that resistance check might not be relevant as it is temperature sensitive so to get the same readings you should have done the measuremets at the same ambient temperature like where the "sample" readings were taken,.... as you have nanocom read the air flow live data, at idle you must get between 50-60 and at full throttle 600-650 this is dependent on the air's density/temperature there... if you get this kind of readings the MAF is ok, also on live data see how much the ambient pressure drops between idle and full throttle and report back... so, concentrate on 3 readings at idle and full throttle write them down and report back:
1. ambient pressure
2. air flow
3. manifold pressure(or turbo pressure on EVO)

Quote:

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Originally Posted by sierrafery

that resistance check might not be relevant as it is temperature sensitive so to get the same readings you should have done the measuremets at the same ambient temperature like where the "sample" readings were taken,.... as you have nanocom read the air flow live data, at idle you must get between 50-60 and at full throttle 600-650 this is dependent on the air's density/temperature there... if you get this kind of readings the MAF is ok, also on live data see how much the ambient pressure drops between idle and full throttle and report back... so, concentrate on 3 readings at idle and full throttle write them down and report back:
1. ambient pressure
2. air flow
3. manifold pressure(or turbo pressure on EVO)

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At idle the airflow is around 65 and above 600 at full throttle.


I'll check the other readings and let you know. I have a write file from my Nanocom with this data but can't get it into Excel or a csv file.

your MAF seems ok then...by the way if you know it's old replace the depression controll valve here's the info http://www.aulro.com/afvb/2198596-post9.html , part nr LLN100140L

Quote:

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Originally Posted by sierrafery

your MAF seems ok then...by the way if you know it's old replace the depression controll valve here's the info http://www.aulro.com/afvb/2198596-post9.html , part nr LLN100140L

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I just did a search for a depression control valve in RAVE and could not find anything - where is it located and what does it do?

it's at emission controll:

Quote:

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Originally Posted by Crankcase emission control; 17-1-4 DESCRIPTION AND OPERATION

.....
The breather valve is a depression limiting valve which progressively closes as engine speed increases, thereby
limiting the depression in the crankcase. The valve is of moulded plastic construction and has a port on the underside
which plugs into a port in the flexible air intake duct. A port on the side of the breather valve connects to the camshaft
cover port by means of a breather hose which is constructed from a heavy-duty braided rubber hose which is held in
place by hose clips. A corrugated plastic sleeve is used to give further protection to the breather hose. The breather
valve is orientation sensitive, and “TOP” is marked on the upper surface to ensure it is mounted correctly.
It is important that the system is airtight so hose connections to ports should be checked and the condition of the
breather hose should be periodically inspected to ensure it is in good condition.

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google out the part number and you'll see images, it's on the intake between the MAF and turbo

Franz,
Has the MAP sensor been cleaned recently?

Quote:

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Originally Posted by Graeme

Franz,
Has the MAP sensor been cleaned recently?

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Graeme,


No, I was looking at a tutorial on that today and was thinking I should get into it - that's the one on the inlet manifold - right?

I have been running with the MAF disconnected for a few days and still get the surging.


Today I tried another MAF and still have the symptoms. I guess that rules out the MAF as the culprit then.


So, tomorrow I'll clean the AAP sensor and see if that makes a difference.


I'm unable to convert the Nanocom fuelling file so that I can upload it here - the site won't let me upload the original Nanocom file - any hints?


Cheers,


Franz

see how much the AAP at idle and under load(how much it drops) and write it here, take the bottom hose off the wastegate modulator and connect it directly to the wastegate valve see if it improves things

He's already tried bypassing the modulator.
Franz, perhaps PM SPROVER on here, he had a surging issue which was linked back to his throttle position switch IIRC.