Boost Issue

[djx11b]

code reader arrived got a memo scanner u480

Plugged in nice and easy to use no codes so good in a way but nothing easy that might be the cause

Does anyone know how to reset the service light with this as car has been serviced recently ??
I select clear all codes it goes away then when I restart the car it comes straight back

Going to take the car to someone with good knowledge and let them have a go at it

[960kg]

I really wished i hadn`t started to help as we see things differently!

What is bothering me is the fact that at a higher temp. reading this happens
Noticed when in 2nd gear will go up to about 5500 rpm before boost drops but when in 3rd or 4th gear boost drops at 4000 rpm.

The OP already has a malfunctioning rear O2 sensor due to splicing wires which will mess up the readings of the more important front sensor so the engine could be leaning out and then with the MBC forcing a boost could even make it weaker, not ideal.

When the boost drops it may be because of lack of fuel to keep it boosted.

These are only my own opinions so the OP can do what he prefers but at least he has more options.

[chomerly]

Could the temperature sender cause this problem as i notice that in the tests you have done, the issue seems to manifest itself as the car gets hotter?

Perhaps the temps are causing some kind of conflict that the ECU is having issues dealing with and is pulling back on you.
I've read that the temperature sensor isn't something that is that easy to diagnose and rarely throws up a fault code on this kind of thing.

The other option you could try is to drop in a completely standard ECU to see if there is a conflict somewhere there.
I would go with the advice of getting back to standard as much as possible and work from there.

But as a matter of course, get it to one of those garages that Scooby mentioned.
It's always good to get the eyes of a specialist cast over the motor before spending more money than is necessary.

[mitchyboy01]

Originally Posted by chomerly

Could the temperature sender cause this problem as i notice that in the tests you have done, the issue seems to manifest itself as the car gets hotter?

Perhaps the temps are causing some kind of conflict that the ECU is having issues dealing with and is pulling back on you.
I've read that the temperature sensor isn't something that is that easy to diagnose and rarely throws up a fault code on this kind of thing.

The other option you could try is to drop in a completely standard ECU to see if there is a conflict somewhere there.
I would go with the advice of getting back to standard as much as possible and work from there.

But as a matter of course, get it to one of those garages that Scooby mentioned.
It's always good to get the eyes of a specialist cast over the motor before spending more money than is necessary.

My CTS threw a code mate and when the ecu senses a temp sender fault it puts the fan on constantly as a safety measure. Still, maybe worth trying a known good sender just to 100% rule it out. He needs another good T4 to swap sensors etc to diagnose the fault witbout forking out each time. I think he has sorted some help from a fellow member now which is good so hopefully will be sorted soon.

[djx11b]

UPDATE

A member on here offered to look at the car for me free of charge so took a road trip down on saturday to see him (thanks for your help and time ). Checked over the car done a pressure test on the system no leaks, checked for codes with better system than my cheaper handheld one no codes, done some runs with his laptop plugged in checking things were running fine and they all were.

So after all that and checking it over he believes it is more towards a electrical issue as only doing it at 5000 rpm and once warmed up. Everything else is working the way it should and no cracks, leaks etc

Advised to change over the knock sensor incase that is faulty and making the ecu cut the boost and also going to change a fitting we found to be loose which was the brake servo pipe that goes on to the inlet manifold the push fitting was worn.

So once i have done them see if it fixes it or not as still losing boost at 5000 rpm

[djx11b]

Booked in to volvomax tomorrow see if they can find my fault

I replaced couple of small parts on the car but no difference

[scoobysn7x]

Good luck I'm sure volvomax will be able to sort it they know there volvos there!!

[djx11b]

Update

Dropped car off at volvomax this morning.

They checked car over and can't find what is wrong or causing my boost issue so nothing else they can do with it for me at moment.

Have recommended a tuning specialist so will try them next just waiting for a phone call back with a day there free.

Hopefully get it on the rolling road and see whats happening with fuel/air etc

[960kg]

Originally Posted by djx11b

Update

Dropped car off at volvomax this morning.

They checked car over and can't find what is wrong or causing my boost issue so nothing else they can do with it for me at moment.

Have recommended a tuning specialist so will try them next just waiting for a phone call back with a day there free.

Hopefully get it on the rolling road and see whats happening with fuel/air etc

Have you changed the rear O2 sensor yet where it is spliced in at the back of the engine?

[djx11b]

Not yet it is on my to do list but at £200 not a cheap option to do.

I know there is no codes for the lambda and anyone who has checked it over has not came back with that as the fault but on the other hand I know it is not the original one fitted so could be causing a issue without any codes showing.

It could also be the maf possibly as I know they both work together I have a good one coming from mitch so will and try swap that over first as cheaper option. (I was getting maf and the coilpacks as spares as always worth having for the car)

when it goes in to the performance specialist they will be able to do some logs on the rolling road and see if fuel is dropping off and if it is the lambda that is faulty at that point I don't mind spending out £££'s but a bit hesitant to spend £200 and then my problem is still not solved.