TD5 Inlet Manifold pressure

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Originally Posted by Gold_TD5

Mark,
Mine is the same as yours, Chipped, Silicone Hoses and EGR removed.
I had the exact same problem you describe, I was thinking overboost.
Turns out it was the Ambient Air Pressure sensor, the one on the airbox.
Easy way to check, diconect and go for a drive.
Just be carful where you buy it, I got one quote of over $600.
Got mine from British Car Components in West Melbourne, 93295766.
About $250, I replaced the MAF, fuel filter and air cleaner all at the same time.
It's all good now.:D
Cheers Lionel

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Thanks Lionel,

I assume if i take it for a drive with the sensor disconnected - i should see no difference if mine is crook?,,,, or should it behave better?

Cheers, Mark

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Originally Posted by Bytemrk

Thanks Lionel,

I assume if i take it for a drive with the sensor disconnected - i should see no difference if mine is crook?,,,, or should it behave better?

Cheers, Mark

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When I dissconected mine, it was like a different car.
Lost the hesitation, put your foot to the floor and it just took off.
If it behaves the same it will be something else.
Cheers
Lionel

Ok guys, sorry but been very slack on this one.... I've been kind of busy at work and living with the problem rather than focusing on fixing it.

Bottom line is I still have weirdness....

If driven sedately the car is beautifully smooth with plenty of power to spare. (That's why I can live with it :angel:) As soon as you flatten the loud pedal suddenly .. it cuts in and out like it's starving for fuel or waste gate opening or something. If you dial the power in slowly it will happily rev past where I would normally take it.

We have bypassed the wastegate modulator, tried a different AAP sensor, swapped out the throttle position sensor, still same issue.

It does NOT log any faults when is does this at all.

Now the weird bit... if I disconnect the MAF.... runs great!... no cutting out at all. Yet.. if i put a new MAF in it's place.... still carries on again..:mad:.

The motor is chipped with silicone hoses and no EGR. But I have had this issue since before removing the egr. :(

Any more ideas from the brains trust?.......

Mark

Ok here is the problem andthe cure all in one :)

Your problem is that the air going over the MAF if producing a voltageof over 4.98volts, this tells the ecu that the air is reaching a maximium limit and the ecu shuts fuel.

There are a few reasons it could be EG , wireing issues, turbo boost to high, a very strong tuning map/chip or just one of those things that does happen to some cars when tuned.

The Cure, well the best i can do over the internet anyway.

Take a 20MM ID pipe or simlar size from the air box next to where the air flow meter goes in so you are getting clean air and route it AFTER the airflow meter, this gives some unmoniterd air into the system and all will be fine.

Pete

boom !

Has anyone checked the freedom of movement on the waste gate or that the actuator itself is working properly?

mine has don that, i have put a new ecu in it and has been jutless to all hell, and then i was doing sumthing and left the maf sence off, toke it for a drive and its like allmost as good asa chipped td5??;);)

plug the sencor back in and its slow as agen,

im thinking dead maf?

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Originally Posted by B-A-S

For reference/advise.

The ambient pressure sensor is fitted in the air box to give the ecu the atmospheric pressure .
The inlet manifold pressure sensor is to give the ecu inlet pressure.

The ecu calculates the difference between the 2 and it then knows what the actual charge pressure is for injecting the correct ammount of fuel to match :) and able to alter/change with the boost modulator if fitted on some cars easy lol.

It ECU cant just relie on a sensor in the inlet manifold if it does not know what the outside atmosperic pressure is to take away from the actual seen manifold pressure so it uses both to calculate it.
It also uses this calcualtion for adjusting fuel and others maps depending on altitude which it can work out from the seen pressures.

There is abit more to it than that but from this you get the basics and my fingers are hurting now lol, and i dont type or spell to well either :)

Boost cut for the ecu is actualy 242Kpa, if you are hitting this then you have a charge pressure problem in most cases, or it coud be a bad raading sensor.
Normaly it is when the wastegate has been tampperd with it will give boost cut if over done.
Remember you can drive normaly one day and the next under some different load and ambient pressure you an hit boost cut.
So an ideal reading to see on th inlet side is actualy 220-225kpa as a mximium on a standard car.


Also its worth making a log of the car and see if there are any other sensors hitting a limit, the problem with nanocom is that it does not im my opinion record live or log as fast as some other tools so it can take time to work out the cause of a problem.

Pete

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Concurr, Overboost fuel cut out will occur around 240Kpa (Absolute) which is about 20psi at the manifold sensor.

As previously mentioned, try winding back the wastegate actuator a few turns.

JC

just curious as to whether anyone had performed the below mod in 'The Cure' below. I have the same symptoms and have pretty much tried everything else so thought I'd give this a go!

Quote:

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Originally Posted by B-A-S

Ok here is the problem andthe cure all in one :)

Your problem is that the air going over the MAF if producing a voltageof over 4.98volts, this tells the ecu that the air is reaching a maximium limit and the ecu shuts fuel.

There are a few reasons it could be EG , wireing issues, turbo boost to high, a very strong tuning map/chip or just one of those things that does happen to some cars when tuned.

The Cure, well the best i can do over the internet anyway.

Take a 20MM ID pipe or simlar size from the air box next to where the air flow meter goes in so you are getting clean air and route it AFTER the airflow meter, this gives some unmoniterd air into the system and all will be fine.

Pete

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Quote:

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The Cure, well the best i can do over the internet anyway.

Take a 20MM ID pipe or simlar size from the air box next to where the air flow meter goes in so you are getting clean air and route it AFTER the airflow meter, this gives some unmoniterd air into the system and all will be fine.

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Any pictures :angel: please ??