3.0 TDI with erratic loss of boost

[Tony]

Thanks Barry, that was going to be 1st on my list, the MAF I don't think has been cleaned, unless it was cleaned when I had my intercooler cleaned out by Steves Auto about a year ago. Any idea how much the sensor costs - maybe I should replace it anyway, as I have replaced just about everything else on my motor!! I'm gonna look at your attachment now - cheers.

[gupster]

Tony a new sensor cost around R2000.00 from the agents. You have to order part number .22680AD21A. If you dont give them that they will try sell you the whole air flow unit. Lucky for me Stefan could confirm that was the same part number here in SA as in OZ.
You can compare the voltages on them when you get the new one and keep it as a reference.
Even if your old MAF is ok, having a spare one will give you added peace of mind when out in the bundu.

[Tony]

Thanks Barry, do you think that Midas would keep some kind of MAF cleaner?? I was playing around this afternoon, and decided to adjust the VNT skroeffie again, because after reading the ref. manual again, and doing a conversion from PSI to BAR, I realised that my boost levels are actually bloody high - when cruising at around 100 km/h my boost gauge shows anything between 1.1 and 1.4 BAR which is between 17 and 21 PSI - in the manual they talk about normal boost at between 8 & 10 PSI which is under 0.5 BAR I'm way over that. Another concern is my bloody Madman as i've mentioned in the past, the coolant temp jumps around like crazy if any electrics are turned on (lights can push temp up by between 5 and 15 deg. depending on who knows what!! The same goes for fan; aircon; indicators; radio etc) So even though the boost and EGT's don't seem to be affected by the same thing, I really don't have too much faith in the gadget. Tinus told me that Landyonline are the agents for Madman, so i'm going to give them a call tomorrow. On this last trip to Bots, on 3 separate occasions I had the coolant temp flashing at over the 120 deg. mark, twice I had lights on in convoy, but the third time all electrics were off - and my dashboard gauge never budged!

[gupster]

Hi Tony. I would imagine that Midas would sell a MAF cleaner, however I got mine from a shop here in Durban that sells performance mods for cars. I looked for it to give you the name but cant find it at the moment. It was about R160, but that might be cheap for a contact cleaner. I am sure Tinus will know of a good one to use. I used needles to pierce the wires going into the connector to the MAF to take the readings. You will have to remove the cover first to get to them, and afterwards you can always put on a blob of silicon to seal the small puncture marks in the wires if you want to.
It might be a good idea to first sort out the electrical problem as any reading you have at the moment might not be accurate and cause you to set up incorrectly. It might just be the earthing on the Madman. I had an old Range Rover and had the fuel gauge re-calibrated after it went out, only to find later that when I put the lights or windscreen wipers on, the gauge gave a different reading. Turned out to be a bad earth connection. Had to have the fuel gauge re-calibrated back to the way it was after fixing the earth. I did post a piece from the Reference document earlier on concerning earth probs on the 3.0 which might be of help.
My Troll runs at about .6 bar or 8.7 psi at between 90 and 100. It does however spike a lot higher when I initially put my foot down and can also be quite erratic at times too.

[Tony]

Now that sounds correct according to the ref. manual. I just spoke to Ryno from the Nissan offroad forum (ex Nissan Strijdompark's ZD30 fundi) and he says the same about the boost pressure reading at that speed - he is not too keen on cleaning MAF as he recons it is too easy to damage the sensor, however my erratic boost issue he thinks is directly related to the boost sensor at the intercooler.

[Tinus lotz]

Never touch the MAF with your finger.....according to graham while running a spray of carb cleaner into air inlet is good enough. ....for a petrol. ..just check for diesel. ..

[JoshJ]

Tony,

What is the Nissan experts advice on solving the erratic boost problem. Should one chane the sensor on the inter cooler.

On another note. I read someone say that it is the OE ECU that cannot control the boost effectively. Don't you guys think a race chip or aftermarket chip could solve this?
Is their any diesel guys running a chip that doesnt have the boost problem.

[Kagiso II]

Josh - the OE ECU was changed after 2003 -- the problem was OVER fuelling, and the Dastek or Race Chip cannot cure that .. the ECU must be 100 % -- THEN the chip works a charm.
As on AGAROB .. but not before his engine grandaed WITH the Dastek chip in [real problem was that Imperial Menlyn did nod not diagnose the problem .. their console was faulty .. at the end it cost me an engine overhaul ]
The Dastek chip could not prevent that ..

[JoshJ]

Thanx Oompi

After i adjusted the VNT screw the Troll seems happier. Even the wife is impressed with how smooth she runs.
I was racking the brain on building a catch can for the oil in the inter-cooler that ends up on the boost sensor. Then a colleague of mine showed me ready made once in one of his plat kar magazines. So as soon as i have time that's the next thing i'll tackle.

[Stefan]

Hi Josh,

On this thread there are a couple of pictures I took during my installation - maybe it can help.